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Research Article
New reports, phylogenetic analysis, and a key to Lactarius Pers. in the Greater Yellowstone Ecosystem informed by molecular data
expand article infoEdward G. Barge, Cathy L. Cripps
‡ Montana State University, Bozeman, United States of America
Open Access

Abstract

The Greater Yellowstone Ecosystem (GYE), located in the Central Rocky Mountains of western North America, is one of the largest nearly intact temperate-zone ecosystems on Earth. Here, Lactarius is an important component of ectomycorrhizal communities in many habitat types, from low elevation riparian areas to high elevation conifer forests and alpine tundra. Molecular phylogenetic analyses of ITS and RPB2 gene sequences along with detailed morphological examination confirm at least 20 Lactarius species, as well as three varieties, and one unresolved species group in the GYE. Eight taxa are reported from the GYE for the first time, and nearly every major ectomycorrhizal host plant in the GYE appears to have at least one Lactarius species associated with it. Broad intercontinental distributions are suggested for alpine Salix and Betula associates, and for certain subalpine Picea and aspen (Populus spp.) associates. Some species appear to be restricted to western North America with Pinus, Pseudotsuga or Abies. The distribution and/or host affinities of others is not clear due in part to ambiguous host assignment, taxonomic problems or the relative rarity with which they have been reported.

Key words

ITS, RPB2, Russulaceae, Rocky Mountains, fungal biodiversity, ectomycorrhizal, systematics

Introduction

The Greater Yellowstone Ecosystem (GYE), located in the Central Rocky Mountains of North America, is one of the largest nearly intact temperate-zone ecosystems on Earth. While a definitive boundary does not exist, the GYE roughly includes Yellowstone National Park at its center, Grand Teton National Park, and portions of surrounding national forests and other lands in Montana, Wyoming, and Idaho (Keiter and Boyce 1991) (Figure 1). The Rocky Mountains, which stretch from Northern Alaska to Northern New Mexico make up the defining landform upon which the ecosystem rests. The mosaic of geology and microclimates created by the Rocky Mountains form a variety of distinct habitats for plants and fungi in the GYE from low elevation grasslands and sagebrush steppe to high elevation alpine tundra (Marston and Anderson 1991, Knight 1994).

Figure 1. 

Map showing the location of the Greater Yellowstone Ecosystem (GYE). The GYE is located in the Central Rocky Mountains of North America and includes over 20 mountain ranges, with Yellowstone National Park at its center, Grand Teton National Park, and portions of surrounding national forests and other lands in Montana, Wyoming, and Idaho. The GYE is outlined by the black box, and the Rocky Mountains by the dotted line.

The genus Lactarius Pers. (Russulales, Russulaceae) is an important component of ectomycorrhizal fungal communities throughout the Rocky Mountains, where it associates with most major ectomycorrhizal plant families. Lactarius as originally defined, includes species with sporocarps that exude a milky latex when damaged, in addition to the amyloid ornamented basidiospores characteristic of the family. The original genus is now recognized as nonmonophyletic and has been split into three genera within Russulaceae: Lactarius, Lactifluus (Pers.) Roussel, and Multifurca Buyck & Hoffstetter (Buyck et al. 2008, 2010); although approximately 80% of the traditional species are still retained in Lactarius sensu stricto (Verbeken and Nuytinck 2013).

Lactarius is well-documented from the Rocky Mountains and western North America (Hesler and Smith 1979, Laursen and Ammirati 1982, Methven 1997, Bessette et al. 2009, Geml et al. 2009). For alpine areas of the Rocky Mountains, including material from the GYE, Cripps and Barge (2013) and Barge et al. (2016) delineated six to seven species, most with broad, intercontinental distributions using molecular and morphological techniques. Other previous reports of Lactarius from the GYE specifically include McKnight (1982), Moser and McKnight (1987), Cripps and Miller (1993), Cripps (2001, 2003, 2011), Mohatt et al. (2008), Cripps and Horak (2008), Cripps and Antibus (2011), Cripps and Eddington (2005, 2012), and Cripps et al. (2016). While the above-cited works provide crucial information on Lactarius occurring in western North America and the Rockies, we felt it would be beneficial to provide an updated summary of the genus in the Greater Yellowstone Ecosystem as a whole, report new records, add phylogenetic information, and bring to light groups which may require further taxonomic clarification.

For this study, collections of Lactarius from the GYE are evaluated through detailed morphological study and phylogenetic analyses of sequences from two genetic loci: nuclear rDNA ITS1–5.8S–ITS2 (ITS region) and the region between conserved domains six and seven of the second largest subunit of the RNA polymerase II (RPB2) gene. Data were compared to type specimens and specimens from type localities where available, and to related taxa represented by sequences in databases (GenBank, UNITE). Information previously generated in Barge et al. (2016) was also included and forms the backbone of this study. A key to species, morphological descriptions, insight into ecology and distribution, as well as species photographs are provided. The key should also be relevant elsewhere in the Rocky Mountains, however, less so where host plants not present in the GYE occur, such as Northwestern Montana, and Northern Idaho. Genus-specific guides covering western North American species include Hesler and Smith (1979), Methven (1997), Bessette et al. (2009), and the Pacific Northwest Key Council’s Key to Lactarius species in the Pacific Northwest (http://www.svims.ca/council/Lactar.htm).

Methods

Study sites

This study was performed in the GYE (Figure 1), with a focus on northern portions of the ecosystem. Major ectomycorrhizal host plants targeted include Populus spp. (cottonwoods) and Alnus incana (L.) Moench (gray alder) in riparian areas; Pinus flexilis James (limber pine), Pseudotsuga menziesii (Mirb.) Franco (Douglas fir), Cercocarpus ledifolius Nutt. (curl-leaf mountain mahogany) and Populus tremuloides Michx. (quaking aspen) in low to mid-elevation montane areas; Pinus contorta Dougl. ex Loud. (lodgepole pine), Pinus albicaulis Engelm. (whitebark pine), Picea engelmannii Parry ex Engelm. (Engelmann spruce), Abies lasiocarpa (Hook.) Nutt. (subalpine fir), Betula glandulosa Michx. (dwarf birch), and Arctostaphylos uva-ursi (L.) Spreng. (kinnikinnick) in mid to high-elevation montane areas; and dwarf willows (Salix arctica Pall., S. reticulata L.), shrubby willows (S. glauca L., S. planifolia Pursh), Dryas octopetala L. (mountain avens), Betula glandulosa, and Arctostaphylos uva-ursi at or above treeline. Pinus ponderosa Dougl. ex Laws., which occurs sporadically along the northeastern edge of the ecosystem, was not surveyed. The locations of specimens are included in the Taxonomy section under Specimens examined and locations of specimens used in the phylogenetic analysis are shown in Table 1.

Voucher, locality information and GenBank or UNITE (UDB) accession numbers for DNA sequences used in the phylogenetic analysis. Herbarium acronyms follow Thiers http://sweetgum.nybg.org/ih/ (continuously updated). Specimens from the Greater Yellowstone Ecosystem (GYE) are in bold type. Newly generated accessions are in bold type.

Taxon Voucher Location ITS RPB2
L. akahatsu JN2004-141 (GENT) Thailand KF133269 KF133333
L. albocarneus AV98-080 (GENT) France KF241545 NA
L. alnicola EB0064-14 (MONT) Gallatin Range, MT, U.S.A. KX394276 NA
L. alpinus v. alpinus FNL GNP-125 (DAOM) Newfoundland, Canada KX094937 NA
L. alpinus v. mitis EB161-15 (MONT) Red Lodge, MT, U.S.A. KX394277 NA
L. alpinus v. mitis DBG-F-021979 (DBG) Pike National Forest, CO, U.S.A. KX394278 KX394303
L. aspideoides RL Shaffer 6957 (MICH) Emmet Co., MI, U.S.A. KR090893 NA
L. aspideus JV24534 (TURA) Varsinais-Suomi, Finland KR090894 KR090972
L. atroviridis AV05-306 (GENT) U.S.A. KF133270 KF133334
L. aurantiacus JV94-422 (C) Uppland, Sweden KR090896 KR090974
L. cf. aurantiacus JV15112F (TURA) Nordland, Norway KR090895 KR090973
L. auriolla RW1601 (GENT) Sweden KF133257 KF133321
L. barrowsii EB015-15 (MONT) Story Hill, Bozeman, MT, U.S.A. KX394279 NA
L. barrowsii N Gray 91878 (RMS) Washington, U.S.A. EF685047 NA
L. barrowsii States J AEF 1271 (MICH) Arizona, U.S.A. EF685046 NA
L. badiosanguineus EB200-13 (MONT) Gallatin Range, MT, U.S.A. KX394280 NA
L. badiosanguineus EB0069-14 (MONT) Tobacco Root Mtns., MT, U.S.A. KX394281 NA
L. badiosanguineus DBG-F-017093 (DBG) Front Range, CO, U.S.A. KX394282 KX394304
L. badiosanguineus AV04-235 (GENT) France KF432983 NA
L. badiosanguineus AV10-044 (GENT) Norway KR025578 KR025655
L. brunneohepaticus PAM08090315 (LIP) Corse-du-Sud, France HQ714726 HQ714858
L. brunneoviolaceus Verbeken 04-220 (GENT) France KJ742392 NA
L. aff. brunneoviolaceus CLC3098 (MONT) Beartooth Plateau, MT, U.S.A. KX394283 NA
L. aff. brunneoviolaceus CLC2133 (MONT) Finse, Norway KR090899 KR090977
L. caespitosus EB102-13 (MONT) Gallatin Range, MT, U.S.A. KX394284 KX394305
L. caespitosus EB121-13 (MONT) Madison Range, MT, U.S.A. KX394285 KX394306
L. camphoratus UE04.09.2004-5 (UPS) Sweden DQ422009 DQ421933
L. chrysorrheus UE04.10.2002-8 (UPS) Italy KF133261 KF133325
L. citriolens UE20.09.2004-03 (UPS) Sweden DQ422003 DQ421931
L. controversus EB110-15 (MONT) Beartooth Mtns, MT, U.S.A. KX394286 NA
L. controversus UP508 Sweden DQ658881 NA
L. controversus AV00-117 (GENT) Italy KF241544 NA
L. cuspidoaurantiacus LM4823 (XAL) Mexico KF891367 KF891374
L. cuspidoaurantiacus LM4908 (XAL) Mexico KF891366 KF891373
L. cyathuliformis PAM08100409 (LIP) Orne, France HQ714738 HQ714869
L. dryadophilus EL57-10 (GB) Latnjavagge, Sweden KR090902 KR090980
L. deliciosus JN2001-046 (GENT) Slovakia KF133272 KF133337
L. deliciosus v. deterrimus JR Herr 650 (RMS) Wyoming, U.S.A. EF685056 NA
L. deliciosus v. olivaceosordidus J Ammirati 10762 (RMS) Washington, U.S.A. EF685059 NA
L. deliciosus” group EB0063-14 (MONT) Gallatin Range, MT, U.S.A. KX394287 NA
L. deliciosus” group EB089-15 (MONT) Madison Range, MT, U.S.A. KX394288 NA
L. deliciosus” group EB107-15 (MONT) Hellroaring Plateau, MT, U.S.A. KX394289 NA
L. deliciosus” group EB0047 (MONT) Sawatch Range, CO, U.S.A. KX394290 NA
L. deterrimus UE05.09.2004-04 (UPS) Sweden UDB000866 NA
L. evosmus UP536 Sweden DQ58882 NA
L. evosmus UE27.09.2002-1 (UPS) France UDB000860 NA
L. flavopalustris JV23334 (TURA) Koillismaa, Finland KR090904 KR090982
L. flexuosus UE06.09.2002-1 (UPS) Sweden DQ421992 DQ421925
L. fulvissimus JN2012-025 (GENT) Germany KR025576 KR025660
L. glyciosmus TWO269 (MONT) Beartooth Plateau, MT, U.S.A. KR090905 KR090983
L. glyciosmus EB133 (MONT) San Juan Range, CO, U.S.A. KR090909 KR090986
L. glyciosmus M Moser 19810148 (IB) Femsjö, Sweden KR090910 NA
L. helvus UE08.09.2004-1 (UPS) Sweden KF133263 KF133327
L. hepaticus JN02-049 (GENT) Belgium KF432980 KR025674
L. hysginoides JV28432 (TURA) Koillismaa, Finland KR090914 KR090988
L. intermedius f324 (AQUI) Italy UDB000368 NA
L. kauffmanii F28471 (UBC) British Columbia, Canada KP406573 NA
L. lacunarum JKLAC11092901 (GENT) Germany KF432982 KR025638
L. lanceolatus CLC2358 (MONT) Beartooth Plateau, MT, U.S.A. KR090918 KR090992
L. lanceolatus EB105-13 (MONT) Beartooth Plateau, WY, U.S.A. KR090919 KR090993
L. lanceolatus (Holotype) F4239 (VPI) Beaufort Lagoon, AK, U.S.A. KR090915 KR090989
L. lapponicus JV28335 (TURA) Koillismaa, Finland KX394291 NA
L. leonis TU106315 (TU) Estonia UDB011465 NA
L. lepidotus PAM08090304 (LIP) Corse-du-Sud, France HQ714722 HQ714854
L. lignyotus UE06.09.2003-5 (UPS) Sweden DQ421993 DQ421926
L. lilacinus EDB08101401 (LIP) France HQ714748 HQ714879
L. lilacinus RW3774 (GENT) Belgium KF133275 KF133340
L. luculentus v. luculentus AH Smith 79943 (MICH) OR, U.S.A. KR090920 NA
L. luculentus v. laetus EB097-15 (MONT) Crazy Mtns., MT, U.S.A. KX394292 NA
L. luculentus v. laetus DBG-F-024643 (DBG) CO, U.S.A. KR090922 KR090994
L. luridus OB11-011 (GENT) Belgium KF241547 NA
L. mammosus UE09.09.2004-5 (UPS) Sweden KF133265 NA
L. montanus EB120-13 (MONT) Madison Range, MT, U.S.A. KR090925 KR090996
L. montanus CLC3001 (MONT) Tobacco Root Mtns., MT, U.S.A. KR090926 KR090997
L. montanus (Paratype) AH Smith 81954 (MICH) Bonner County, ID, U.S.A. KR090924 NA
L. nanus EB106-13 (MONT) Beartooth Plateau, MT, U.S.A. KR090928 KR091000
L. nanus CLC1716 (MONT) San Juan Range, CO, U.S.A. KR090929 KR091001
L. nanus Bon 89093 (LIP) Savoie, France KR090935 NA
L. necator AV04-231 (GENT) France KF133276 KF133341
L. olivinus TU101411 (TU) Estonia UDB019698 NA
L. olivinus TU106674 (TU) Estonia UDB015721 NA
L. aff. olivinus EB0051-14 (MONT) Silver Gate, MT, U.S.A. KX394293 NA
L. olympianus EB0070-14 (MONT) Tobacco Root Mtns., MT, U.S.A. KX394294 NA
L. olympianus J Nuytinck 2003-032 (GENT) U.S.A. EF685079 NA
L. pallescens (Holotype) AH Smith 81936 (MICH) Boundary County, ID, U.S.A. KR090938 NA
L. pallidomarginatus (Holotype) EB0041 (MONT) San Juan Range, CO, U.S.A. KR090940 KR091010
L. pseudodelicatus CLC512 (MONT) Teton Range, ID, U.S.A. KX394295 NA
L. pseudomucidus F16301 (UBC) British Columbia, Canada EU486439 NA
L. aff. pseudouvidus U Peintner 20040156 (IB) Trentino, Italy KR090942 KR091014
L. pubescens EB300-15 (MONT) Silver Bow Co., MT, U.S.A. KX394296 NA
L. pubescens CLC539 (MONT) Cinnabar Basin, MT, U.S.A. KX394297 NA
L. pubescens CLC1611 (MONT) Front Range, CO, U.S.A. KX394298 NA
L. pubescens UE15.09.2002-2 (UPS) Sweden DQ421996 DQ421929
L. pubescens UP516 Sweden DQ658884 NA
L. quieticolor UE10.09.2004-1 (UPS) Sweden DQ422002 DQ421930
L. quietus UE16.09.2004 (UPS) Sweden KF133264 KF133328
L. repraesentaneus EB107-13 (MONT) Beartooth Plateau, MT, U.S.A. KR090949 KR091021
L. repraesentaneus CLC1747 (MONT) Sawatch Range, CO, U.S.A. KR090951 KR091023
L. repraesentaneus EL92-07 (GB) Latnjavagge, Sweden KR090953 KR091025
L. romagnesii UE29.09.2006-6 (UPS) France DQ421989 DQ421923
L. rubrilacteus EB13-040 (MONT) Bridger Range, MT, U.S.A. KX394299 NA
L. rubrilacteus SL Miller 19-04 (RMS) California, U.S.A. EF685085 NA
L. rufus EB125-13 (MONT) Gallatin Range, MT, U.S.A. KX394300 KX394307
L. rufus JN2002-008 (GENT) Norway KF241543 NA
L. rufus DG15 (AMG) United Kingdom UDB001601 NA
L. salicis-herbaceae CLC1536 (MONT) Sismiut, Greenland KR090955 KR091027
L. salicis-reticulatae EB0057-14 (MONT) Beartooth Plateau WY, U.S.A. KR090958 KR091029
L. salicis-reticulatae JV15133 (TURA) Sweden KR090961 KR091032
L. aff. salicis-reticulatae CLC1710 (MONT) San Juan Range, CO, U.S.A. KR090962 KR091033
L. sanguifluus Hue470 (UPS) Germany UDB000876 NA
L. scrobiculatus JN01-058 (GENT) Slovakia KF432968 NA
L. scrobiculatus TU117089 (TU) Latvia UDB022822 NA
L. sphagneti PL2805 (herb. P. Leonard) United Kingdom KF133268 KF133332
L. spinosulus AT2003068 (UPS) Sweden KF133262 KF133326
L. subdulcis JV2006-024 (GENT) Belgium KF133279 KF133344
L. subflammeus (Holotype) AH Smith 83602 (MICH) Tillamook County, OR, U.S.A. KR090967 NA
L. substriatus AH Smith 83693 (MICH) Tillamook Co., OR, U.S.A. KR090968 NA
L. subviscidus (Paratype) AH Smith 83066 (MICH) Lewis Co., WA, U.S.A. KR090970 NA
L. tabidus ED2008-026 (GENT) Belgium KT165309 KR025667
L. thyinos A Voitk23-08-2004 (GENT) Canada KF133271 KF133336
L. torminosus RW3183 (GENT) Czech Republic KF133281 KF133346
L. trivialis UE27.08.2002-17a (UPS) Sweden DQ421991 DQ421924
L. tuomikoskii TU101882 (TU) Finland UDB016033 NA
L. aff. tuomikoskii EB052-14 (MONT) Silvergate, MT, U.S.A. KX394301 NA
L. uvidus mh0963 (TUB) Germany AY606957 NA
L. vietus UE11.19.2004-1 (UPS) Sweden KF133267 KF133331
L. aff. wenquanensis LTH143 (GENT) Thailand EF141537 NA
L. zonarioides E Bizio 2516 (MCVE) Italy JF908300 NA
L. zonarius UE27.09.2002-4 (UPS) France EU278678 EU278679
L. zonarius v. riparius CLC2933 (MONT) Bozeman, MT, U.S.A. KX394302 NA

Taxon sampling and processing

Sporocarps were collected from late May to late September 1992–2015. All collections were described in detail when fresh, and select collections were photographed. Ectomycorrhizal host plants near sporocarps were noted for each collection. Sporocarps were dried on an electric, warm-air dryer and deposited in the Montana State University herbarium (MONT). For comparison, additional specimens were obtained from numerous herbaria. For Rocky Mountain material, most herbarium specimens studied originated from the Montana State University Herbarium (MONT), the Denver Botanic Gardens’ Sam Mitchel Herbarium of Fungi, Denver, Colorado (DBG), and the University of Michigan fungal herbarium, Ann Arbor, Michigan (MICH). See Barge et al. (2016), for a complete list of herbaria.

Morphological descriptions

Macromorphological measurements and descriptions were made from fresh material. Micromorphological descriptions and measurements were made from dry material reconstituted in ethanol and 2.5% KOH. In Melzer’s reagent, length and width were measured at 1000× magnification for a random sample of 25 basidiospores per collection, excluding ornamentation and the hilar appendix. The length to width ratio (Q) was calculated for each basidiospore. Length and width were measured at 400× magnification for a random sample of 10 pleuromacrocystidia and 10 cheilomacrocystidia per collection. Morphological descriptions for alpine specimens were previously reported in Barge et al. (2016).

Phylogenetic analysis

DNA extraction, PCR amplification, and sequencing of the ITS region and partial RPB2 gene were performed as in Barge et al. (2016) or at ALVALAB, Santander, Spain (http://www.alvalab.es/index.html). Raw sequences were edited and contigs constructed with SeqTrace 0.8.1 (Stucky 2012).

In addition to the sequences generated in this study, select close BLAST matches to the ITS region of GYE specimens and select additional ITS and RPB2 sequences mainly from Buyck et al. (2008), Verbeken et al. (2014), and Wisitrassameewong et al. (2016) were downloaded from GenBank (http://www.ncbi.nlm.nih.gov/) and UNITE (https://unite.ut.ee/). Many sequences generated in Barge et al. (2016) were also included.

Alignments were performed with MUSCLE (http://www.ebi.ac.uk/Tools/msa/muscle/) under default parameters and manually edited using PhyDE v.0.9971 (http://www.phyde.de/index.html). Ambiguously aligned regions of the ITS alignment were highlighted and removed with the online version of GBlocks 0.91b (Castresana 2000) under the least stringent settings. Also removed was a 268–269 base pair insertion present in the ITS1 region of several taxa (Barge et al. 2016, Rosenblad et al. 2016).

Maximum likelihood (ML) analyses were carried out using RAxML v.8 (Stamatakis 2014) on the CIPRES Science Gateway (Miller et al. 2010). Previous phylogenetic analyses by Barge et al. (2016) suggested that Lactarius romagnesii Bon and L. lignyotus Fr. of subg. Plinthogalus (Burl.) Hesler & A.H. Sm. form a monophyletic group distinct from subg. Piperites (Fr.) Kauffman and Russularia (Fr.) Kauffman which contain all of the ingroup species of interest in this study. Thus, L. lignyotus and L. romagnesii were selected as outgroup taxa. An ML search combined with rapid bootstrapping was run until bootstrap convergence was reached using the autoMRE option. The GTRGAMMA model was estimated separately for ITS1, 5.8S, ITS2, RPB2 exon first, second and third codon positions, and RPB2 intron. Single-gene and combined ML analyses were performed. Slight conflicts were detected between ITS and RPB2 phylogenies, however, the conflicts received low support (bootstrap support <70%), thus the combined phylogeny was used. The program TreeGraph2 (Stöver and Müller 2010) was used to draw and edit the final tree.

Results

A total of 27 ITS and 5 RPB2 sequences were generated in this study (Table 1). Based on morphological and molecular examination we report 20 Lactarius species, three varieties, and one putatively unresolved species group from the GYE. Lactarius alpinus v. mitis Hesler & A.H. Sm., L. badiosanguineus Kühner & Romagn., L. barrowsii Hesler & A.H. Sm., L. aff. brunneoviolaceus M.P. Christ., L. luculentus v. laetus Hesler & A.H. Sm., L. aff. olivinus Kytöv., L. pseudodelicatus A.H. Sm., and L. aff. tuomikoskii Kytöv. are reported from the GYE for the first time. In addition, the first publicly available vouchered sequences are provided for L. alpinus v. mitis, L. lapponicus (syn.: L. duplicatus), L. pseudodelicatus, and L. zonarius v. riparius; the first publicly available vouchered sequences from North America are provided for L. badiosanguineus, L. aff. brunneoviolaceus, L. aff. olivinus, and L. aff. tuomikoskii.

Subgenera Piperites and Russularia are well-represented in the GYE, however, species of subg. Plinthogalus appear to be absent, as are species of the recently segregated genus Lactifluus. Most major ectomycorrhizal host plants in the Greater Yellowstone Ecosystem appear to have at least one Lactarius species associated with them (Table 2).

Major ectomycorrhizal host plants in the Greater Yellowstone Ecosystem (GYE) with putatively associated Lactarius species. (?) denotes host plant uncertainty.

Host Plant Lactarius species
Abies lasiocarpa L. caespitosus, L. luculentus v. laetus (?)
Alnus incana L. alpinus v. mitis
Arctostaphylos uva-ursi L. deliciosus” group
Betula glandulosa/Betula spp. L. glyciosmus, L. pubescens
Cercocarpus ledifolius None detected
Dryas octopetala None detected
Picea engelmannii L. alnicola, L. badiosanguineus, “L. deliciosus” group, L. luculentus v. laetus (?), L. montanus, L. olympianus, L. rufus (?), L. repraesentaneus, L. aff. olivinus and L. aff. tuomikoskii
Pinus albicaulis L. deliciosus” group, L. rufus (?)
Pinus contorta L. deliciosus” group (?), L. rufus
Pinus flexilis L. barrowsii, “L. deliciosus” group
Pinus ponderosa None detected
Pseudotsuga menziesii L. rubrilacteus
Populus tremuloides L. controversus, L. pseudodelicatus, L. pubescens
Populus spp. (cottonwoods) L. zonarius v. riparius
Salix spp. (alpine) L. aff. brunneoviolaceus, L. nanus, L. lanceolatus, L. pallidomarginatus, L. repraesentaneus (?), L. salicis-reticulatae
Salix spp. (subalpine) None detected

The phylogenetic position of species for which molecular data was obtained is shown (Figure 2). The backbone of the phylogeny is poorly resolved, thus we refrain from making any novel inferences regarding broad-scale infrageneric relationships. Species are organized in the Taxonomy section based on the phylogenetic results. See comments under individual species in the Taxonomy section for discussion of relationships.

Figure 2A. 

Upper part of maximum likelihood phylogeny of ITS and RPB2 molecular data. Bootstrap support values ≥ 50% are shown above or below branches leading to clades. Thickened branches lead to clades receiving ≥ 70% bootstrap support. Boldface type labels represent specimens from the Greater Yellowstone Ecosystem (GYE). Boldface numbers refer to the taxa treated in the Key and Taxonomy sections.

Figure 2B. 

Middle part of maximum likelihood phylogeny of ITS and RPB2 molecular data. Bootstrap support values ≥ 50% are shown above or below branches leading to clades. Thickened branches lead to clades receiving ≥ 70% bootstrap support. Boldface type labels represent specimens from the Greater Yellowstone Ecosystem (GYE). Boldface numbers refer to the taxa treated in the Key and Taxonomy sections.

Figure 2C. 

Lower part of maximum likelihood phylogeny of ITS and RPB2 molecular data. Bootstrap support values ≥ 50% are shown above or below branches leading to clades. Thickened branches lead to clades receiving ≥ 70% bootstrap support. Boldface type labels represent specimens from the Greater Yellowstone Ecosystem (GYE). Boldface numbers refer to the taxa treated in the Key and Taxonomy sections.

Key to Lactarius species of the Greater Yellowstone Ecosystem

Due to dry conditions common throughout the Rocky Mountains, Lactarius sporocarps collected here often do not exude any noticeable latex. However, for species which have changing latex, the cut flesh often displays characteristic color changes similar to the latex or reacts with the latex to display a characteristic color, and it typically does so under dry conditions even when no latex is detected. Thus, if no latex is detected, examining cut surfaces of sporocarps for color change can be very useful for identifying Lactarius species.

1 Latex orange to red; cut flesh staining orange to red and eventually green 2
Latex watery or whitish, unchanging or becoming violet or yellow; cut flesh unchanging or staining lilac, yellow or brownish 4
2 Latex orange, often undetectable; cut flesh staining orange to ± red and eventually green; with conifers 20. “L. deliciosus” group
Latex red, often undetectable; cut flesh quickly staining red and eventually green 3
3 Pileus cream to pale straw yellow, lamellae dingy pinkish orange to creamy yellow-orange; with Pinus flexilis and possibly other Pinus spp. 18. L. barrowsii
Pileus light brown to yellow-orange to dingy orange; lamellae pinkish cinnamon to dull pink; with Pseudotsuga menziesii, and possibly Pinus spp. 19. L. rubrilacteus
4 Latex unchanging or turning violet; cut flesh staining violet 5
Latex unchanging or turning yellow; cut flesh unchanging or staining yellow or brownish 9
5 Pileus cream to yellowish 6
Pileus violaceous to brownish or greyish 7
6 Pileus margin bearded; stipe scrobiculate; with Picea engelmannii and possibly Salix glauca in subalpine to low alpine krummholz habitats 4. L. repraesentaneus
Pileus margin glabrous; stipe non-scrobiculate; with Salix spp. in alpine areas 5. L. salicis-reticulatae
7 Subalpine with conifers in the spruce-fir zone; pileus cuticle staining green in KOH 7. L. montanus
Alpine with Salix; pileus cuticle staining green in KOH or not 8
8 Pileus light tan to light brown; pileus cuticle unchanging in KOH 6. L. pallidomarginatus
Pileus brownish with lavender hues; pileus cuticle staining green in KOH 8. L. aff. brunneoviolaceus
9 Pileus margin conspicuously bearded or tomentose at least when young 10
Pileus margin glabrous or only very finely pubescent 14
10 Latex unchanging or turning yellow; cut flesh staining yellow; with conifers 11
Latex unchanging; cut flesh unchanging or staining brownish; with hardwoods 12
11 Pileus with matted fibrils especially near the margin, pale yellow-cream to yellow-tan; margin densely bearded; under Picea engelmannii 16. L. aff. tuomikoskii
Pileus with appressed scales of confluent hairs especially near the margin, cream to olive-buff to orange-tan; margin merely tomentose to cottony; under Picea engelmannii. 17. L. aff. olivinus
12 Pileus azonate to faintly zonate and predominately cream to pinkish; with aspen or Betula 13. L. pubescens
Pileus zonate and predominately yellow-buff to orange-brown; with aspen or cottonwood 13
13 Pileus yellow-buff to pale orange-brown, lighter toward the margin; odor orange-citrusy; with aspen 12. L. pseudodelicatus
Pileus yellow-brown to orange brown, ± lighter toward the margin; odor sweet, fruity; with cottonwood 14. L. zonarius v. riparius
14 Pileus reddish, red-brown or orange 15
Pileus whitish, yellowish or brownish 20
15 Taste acrid 16
Taste mild to slightly bitter 17
16 Pileus red-brown to orange-brown, azonate; with conifers 22. L. rufus
Pileus rich to dull orange, zonate; with conifers 11. L. olympianus
17 Pileus finely rimulose to minutely squamulose; with Alnus 1. L. alpinus v. mitis
Pileus smooth; with conifers or Salix 18
18 Alpine with Salix 24. L. lanceolatus
Subalpine with conifers 19
19 Pileus red-brown to orange-brown, often lighter toward the margin 21. L. badiosanguineus
Pileus bright orange to yellow-orange to orange-brown, evenly colored 23. L. luculentus v. laetus
20 Pileus brownish or pinkish buff; taste mild to only slightly acrid 21
Pileus whitish, yellowish, brownish or gray-brown; taste acrid 22
21 Odor mild; taste mild to slightly acrid; arctic-alpine with Salix 2. L. nanus
Odor of coconut; taste mild to slightly acrid; alpine to subalpine with Betula 3. L. glyciosmus
22 Pileus yellowish; flesh staining yellow; with Picea engelmannii 15. L. alnicola
Pileus whitish, brownish or vinaceous 23
23 Pileus whitish overall; lamellae pinkish; with aspen 10. L. controversus
Pileus more brown to gray-brown overall; lamellae white to cream; with Abies 9. L. caespitosus

Taxonomy

Lactarius alpinus v. mitis Hesler & A.H. Sm.

Figure 3

Description

Pileus 8–20 mm in diameter (to 80 mm in Hesler and Smith 1979), plano-convex to infundibuliform, ± papillate, dry, finely rimulose to minutely squamulose, red-brown to orange-brown to pinkish cinnamon; margin finely crenulate, incurved when young, becoming straight to wavy in age. Lamellae adnate to subdecurrent, subdistant to crowded, cream to creamy tan, discoloring slightly darker where damaged. Stipe 8–23 × 5–8 mm (30–50 × 10–15 mm in Hesler and Smith 1979), equal to slightly clavate, smooth, dry, pale creamy yellow to creamy tan, solid, becoming hollow. Context concolorous with pileus. Latex scarce, watery, white, unchanging. Odor mild. Taste mild.

Basidiospores 7–9.5 × 5–7.5 µm, Q = 1.3–1.5, ellipsoid; ornamentation forming a broken to partial reticulum. Pleuromacrocystidia 60–100 × 6–10 µm, numerous, strongly projecting, mucronate to fusoid; apex acute to moniliform. Cheilomacrocystidia 50–80 × 6–10 µm, numerous, strongly projecting, mucronate to fusoid; apex acute to moniliform.

Ecology and distribution

In western and into eastern North America with Alnus. In the GYE only one collection has been made thus far and it was from a riparian area near Alnus incana and Populus trichocarpa, late summer. Further sampling under Alnus in the Rocky Mountains is necessary.

Specimens examined

U.S.A. MONTANA: Carbon County, Red Lodge, along Rock Creek, under Alnus incana and Populus trichocarpa, 6 Sept 2015, EB161-15 (MONT).

Discussion

This is the first report of L. alpinus v. mitis from the GYE. According to Hesler and Smith (1979), L. alpinus v. mitis has duller pileus and lamellae colors than L. alpinus v. alpinus Peck, which typically develops bright yellow to apricot colors; variety mitis also has longer and more conspicuous macrocystidia and a mild rather than slowly acrid taste. The collection described here likely did not reach full maturity, and the basidiomes are smaller than reported in Hesler and Smith (1979). Phylogenetic analyses including material of L. alpinus v. alpinus from near the type locality suggest that L. alpinus v. mitis and L. alpinus v. alpinus are distinct species (Figure 2A, 2C), however a more in depth analysis incorporating type material of at least L. alpinus v. mitis should be carried out before making this determination final. For an interesting discussion on L. alpinus see Nuytinck and Voitk (2016) and Rochet et al. (2011).

While L. alpinus v. mitis appears to be quite distantly related to L. alpinus v. alpinus, it is very closely related to the European L. lilacinus (Lasch) Fr., the recently described Mexican L. cuspidoaurantiacus Montoya, Bandala & Garay-Serr., and to a lesser extent L. lepidotus Hesler & A.H. Sm., all of which are also associated with Alnus (Figure 2A). Lactarius lilacinus is typically more pink to violet in color and has a fruity smell. Lactarius cuspidoaurantiacus appears to have more yellow-orange basidiomes, more orange colored, distant lamellae, and a Pelargonium-like odor (Montoya et al. 2014). Lactarius lepidotus has a more gray-brown to beige pileus. Neither L. lilacinus, L. cuspidoaurantiacus or L. lepidotus have been reported from the Rocky Mountains.

Figure 3. 

Lactarius alpinus v. mitis. Top collection EB161-15 under Alnus incana and Populus trichocarpa, Red Lodge, Montana, USA. Bottom collection EB516-15 under Alnus rubra, western Oregon, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius nanus J. Favre

Figure 4

The following morphological description includes data from Colorado specimens listed in Barge et al. (2016).

Description

Pileus 10–50 mm in diameter, shallowly convex to plano-convex becoming plane to infundibuliform, ± papillate, smooth, slightly viscid to dry, with whitish glaucous coating when immature, easily rubbing away or fading in age, deep brown to gray-brown to liver brown with lighter and darker areas present, often lighter toward margin, becoming lighter overall upon desiccation; margin straight when young becoming upturned and wavy to convoluted in age. Lamellae adnate to subdecurrent, subdistant, cream when immature becoming dingy cream to light tan in age, sometimes with a faint pinkish tinge, discoloring to dingy tan where damaged. Stipe 5–30 × 3–15 mm, equal to clavate, central, smooth, dry, at first covered with whitish glaucous coating as in pileus, pale apricot to dingy cream-tan, hollow. Context dingy cream to brownish. Latex scarce to undetectable, watery, white, unchanging. Odor mild. Taste mild to slightly acrid.

Basidiospores 7–10.5(–12) × 5–8 µm, Q = 1.1–1.6, subglobose to ellipsoid; ornamentation forming an incomplete reticulum. Pleuromacrocystidia 53–96.5(–114) × 6.5–11.5 µm, scattered to abundant, lanceolate; apex acute to moniliform. Cheilomacrocystidia 26–91.5 × 7.5–10 µm, scattered to abundant, subulate to linear; apex acute to rounded.

Ecology and distribution

Widespread in arctic-alpine areas in the Northern Hemisphere with Salix. In the GYE and elsewhere in the Rocky Mountains it occurs above tree line in alpine areas with Salix arctica, S. reticulata, and S. planifolia, late summer.

Specimens examined

U.S.A. MONTANA: Carbon County, Beartooth Plateau, Highline Trail, among shrubby and dwarf Salix, 7 Aug 1998, CLC1221 (MONT); among Salix reticulata and other Salix spp., 8 Aug 1998, ZT6422 (MONT); among Salix arctica, S. planifolia and S. reticulata, 18 Aug 2013, EB106-13 (MONT). WYOMING: Park County, Beartooth Plateau, Frozen Lakes, among Salix arctica, 21 Aug 1999, CLC1403 (MONT); Park County, Beartooth Plateau, Solifluction Terraces, among Salix arctica, S. planifolia and S. reticulata, 11 Aug 2012, EB125 (MONT).

Discussion

L. nanus is morphologically and phylogenetically close to L. hysginoides Korhonen & T. Ulvinen (Figure 2A), however, the latter has a more cinnamon-toned pileus, smaller basidiospores (6.5–8.5 × 4.9–7.1 µm), and occurs in boreal areas with Betula, Picea and Salix; it has not been reported from the Rocky Mountains. Lactarius pallidomarginatus Barge and C.L. Cripps is also similar, however, it is a violet staining species. Differences between L. nanus and L. glyciosmus (Fr.) Fr. are discussed in the comments section under the latter.

Figure 4. 

Lactarius nanus. Collection EB106-13 near Salix arctica (pictured), S. reticulata, and S. planifolia, Beartooth Plateau, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius glyciosmus (Fr.) Fr.

Figure 5

The following morphological description includes data from Colorado specimens listed in Barge et al. (2016).

Description

Pileus 15–50 mm in diameter, broadly convex, later becoming plane with or without a depressed center and small papilla, smooth, dry, azonate to lightly zoned especially near the margin, pale gray-brown to violet-brown with a whitish glaucous coating when immature, fading in age; margin incurved when young and remaining so or becoming straight in age. Lamellae adnate to subdecurrent, subdistant to crowded, cream to pale pinkish to pale yellow-orange. Stipe 10–40 × 3–12 mm, equal to slightly clavate, central to eccentric, smooth, dry, buff or pale salmon with a faint glaucous coating at first as in pileus, stuffed, becoming hollow, often white-mycelioid toward the base. Context pale cream. Latex scarce to undetectable, watery, white, unchanging. Odor of coconut. Taste mild to slightly acrid.

Basidiospores 7–9 × 5–7 µm, Q = 1.2–1.4, broadly ellipsoid to ellipsoid, ornamentation forming an incomplete to nearly complete reticulum. Pleuromacrocystidia 45.5–63.5 × 6.5–7.5 µm, scarce to scattered, subclavate to lanceolate; apex rounded to mucronate. Cheilomacrocystidia 33–66 × 5–9 µm, scattered to abundant, cylindrical to subclavate; apex rounded.

Ecology and distribution

Widespread in the Northern Hemisphere in temperate, boreal, and arctic-alpine areas with Betula. In the GYE and elsewhere in the Rocky Mountains, it occurs in subalpine and alpine areas with Betula glandulosa and possibly other Betula spp., late summer.

Specimens examined

U.S.A. MONTANA: Carbon County, Beartooth Plateau, Birch Site, near Betula glandulosa, 29 July 1997, CLC1134 = ZT6096 (MONT); 8 Aug 1998, CLC1217 (MONT); 10 Aug 1999, TWO269 (MONT); 19 Aug 1999, CLC1380 (MONT); 13 Aug 2007, ZT12723 (MONT); Carbon County, Hellroaring Plateau, Hellroaring Creek, near Betula glandulosa, 9 Aug 2015, EB111-15 (MONT). WYOMING: Park County, Beartooth Plateau, Island Lake, near Betula glandulosa, 6 Sept 2015, EB160-15 (MONT).

Discussion

Lactarius glyciosmus is very closely related to L. mammosus Fr. (Figure 2A), however, the latter has a browner pileus, stouter stature, and ecology with Pinaceae (although it has been reported with Betula) (Heilmann-Clausen et al. 1998). Lactarius vietus (Fr.) Fr. has a distinct pale zone near the stipe apex, latex that dries greenish gray, longer pleuromacrocystidia (50–90 × 7–12 µm), a mild to slightly fruity odor, and a strongly acrid taste (Heilmann-Clausen et al. 1998). The presence of L. mammosus and L. vietus in the Rocky Mountains is unclear. Lactarius trivialis (Fr.) Fr., which has been reported from the GYE (McKnight 1982), but could not be confirmed, is typically larger with slightly larger basidiospores (7.3–10 × 5.9–7.8 µm), more numerous pleuromacrocystidia, and a mild to acidic-fruity odor (Heilmann-Clausen et al. 1998). Lactarius nanus has larger basidiospores (7–10.5(–12) × 5–8 µm), larger and differently shaped pleuromacrocystidia (53–96.5(–114) × 6.5–11.5 µm), a mild odor, and associates with Salix.

Figure 5. 

Lactarius glyciosmus. Collection EB111-15 under Betula glandulosa, Hellroaring Plateau, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius repraesentaneus Britzelm.

Figure 6

The following morphological description includes data from Colorado specimens listed in Barge et al. (2016).

Description

Pileus 60–100 mm in diameter, convex to plano-convex usually with a depressed center and sometimes with a papilla, smooth at center, becoming increasingly hairy to bearded toward margin, viscid to dry, azonate, surface orange-brown at center, becoming pale yellow-brown to cream toward margin; hairs pale yellow-brown to red-brown; margin strongly incurved, remaining so or becoming nearly straight in age. Lamellae adnate to decurrent, crowded, cream to pale-yellow, staining violet where damaged. Stipe 30–70 × 15–35 mm, stout, equal to clavate, viscid to dry, cream to pale-yellow, often with numerous dingy yellow, golden yellow, yellow-brown, or light orange-brown scrobicules, hollow. Context white, staining violet where damaged. Latex scarce to abundant, white, becoming violet. Odor spicy-floral, resinous. Taste resinous to slightly acrid.

Basidiospores 8–10.5 × 6–8.5 µm, Q = 1.1–1.4, broadly ellipsoid to ellipsoid; ornamentation forming an incomplete to dense reticulum. Pleuromacrocystidia 78.5–145 × 9–13 µm, scattered to abundant, strongly projecting, subfusiform to lanceolate; apex acute to moniliform. Cheilomacrocystidia 56–140 × 7.5–13 µm, scattered to abundant, strongly projecting, subfusiform to lanceolate; apex acute moniliform.

Ecology and distribution

Widespread in the Northern Hemisphere in temperate, boreal, and arctic-alpine areas with Picea, Betula, and possibly Salix. In the GYE, it occurs in the spruce-fir and krummholz zone, typically near Salix glauca and Picea engelmannii, sometimes also intermixed with Arctostaphylos uva-ursi and Betula glandulosa, late summer.

Specimens examined

U.S.A. MONTANA: Carbon County, Beartooth Plateau, Birch Site, among Salix glauca and krummholz Picea engelmannii, 12 Aug 2002, CLC1971 (MONT); 13 Aug 2007, CLC2318 (MONT); 18 Aug 2013, EB107-13 (MONT); Carbon County, Hellroaring Plateau, Hellroaring Creek, among Arctostaphylos uva-ursi, Salix glauca and krummholz Picea engelmannii, 9 Aug 2015, EB116-15 (MONT). WYOMING: Park County, Beartooth Plateau, Frozen Lakes, among Salix glauca and krummholz Picea engelmannii, 21 Aug 1999, CLC1394 (MONT).

Discussion

Due to its conspicuously bearded margin, and violet staining tissue, L. repraesentaneus is difficult to confuse with anything else in the Rocky Mountains. It is very closely related to the arctic-alpine Dryas and Salix associate L. dryadophilus Kühner (Figure 2A), however, the latter features a cream to yellow, smoother pileus with hairs restricted to near the margin, and a basidiospore ornamentation consisting of sparse, thinner ridges (Heilmann-Clausen et al. 1998). Lactarius dryadophilus has not been reported from the Rocky Mountains. Lactarius repraesentaneus and other violet-staining species such as L. uvidus (Fr.) Fr., L. aspideus (Fr.) Fr., L. salicis-reticulatae Kühner, L. montanus (Hesler & A.H. Sm.) Montoya & Bandala, L. pallidomarginatus, and L. brunneoviolaceus M.P. Christ., etc. occur together in a weakly supported clade, that corresponds with section Uvidi (Konr.) Bon (Figure 2A).

Figure 6. 

Lactarius repraesentaneus. Collection EB107-13 near krummholz Picea engelmannii and Salix glauca, Beartooth Plateau, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius salicis-reticulatae Kühner

Figure 7

The following morphological description is based on Barge et al. (2016).

Description

Pileus 20–40 mm in diameter, convex to broadly convex, usually with a depressed center, smooth, viscid to dry, azonate, cream, pale yellow, or pale ocher, sometimes darker toward the center, staining violet where damaged; margin incurved, remaining so or becoming merely downturned in age. Lamellae adnate to subdecurrent, subdistant to distant, cream, pale yellow, or pale orange-ocher often with a pinkish-buff tint, staining violet where damaged. Stipe 15–20 × 10–15 mm, equal to clavate, viscid to dry, cream to pale-yellow, staining violet where damaged, hollow. Context white, staining violet where damaged. Latex scarce to undetectable, watery, white, becoming violet. Odor mild to slightly sweet. Taste mild.

Basidiospores (7–)8.5–11.5 × (7–)8–10 µm, Q = (1–)1.1–1.4, subglobose to ellipsoid; ornamentation forming an incomplete reticulum. Pleuromacrocystidia 76–101.5 × 7.5–11.5 µm, scarce, strongly projecting, subfusiform to fusiform; apex rounded to acute to moniliform. Cheilomacrocystidia 68.5–91.5 × 7.5–10.5 µm, scattered to abundant, strongly projecting, subfusiform to fusiform; apex acute to rounded to moniliform.

Ecology and distribution

Widespread in arctic-alpine areas in the Northern Hemisphere with Salix. In the GYE, it occurs in alpine areas with S. arctica, S. reticulata, as well as shrubby Salix spp., sometimes also intermixed with Dryas octopetala, late summer.

Specimens examined

U.S.A. MONTANA: Carbon County, Beartooth Plateau, Birch Site, among Salix reticulata, 17 Aug 2011, CLC2776 (MONT); Carbon County, Beartooth Plateau, Highline Trail, among dwarf Salix spp., 8 Aug 1998, CLC1211 (MONT); Carbon County, Hellroaring Plateau, Hellroaring Creek, under shrubby Salix sp., 8 Aug 2015, EB112-15 (MONT); among shrubby Salix sp. and S. reticulata, 8 Aug 2015, EB113-15 (MONT); among Dryas octopetala, shrubby Salix sp. and S. reticulata, 8 Aug 2015, EB117-15 (MONT), EB118-15 (MONT), EB119-15 (MONT); Sweet Grass County, Crazy Mountains, above Blue and Granite Lakes, among Salix arctica, 1 Aug 2015, EB101-15 (MONT). WYOMING: Park County, Beartooth Plateau, Gardner Lake, under shrubby Salix sp., 16 Aug 2014, EB0057-14 (MONT).

Discussion

Lactarius aspideoides Burl., described from eastern North America is closely related (Figure 2A), however, it is generally larger, with a somewhat zonate pileus. It also has more crowded lamellae that lack salmon-colored hues, slightly smaller basidiospores (7–10 × 7–8–µm) with broader ridges, a bitter to slightly acrid taste, and a subalpine ecology (Hesler and Smith 1979). The status of L. aspideoides in western North America is unclear. Lactarius aspideus, another similar species which was described from northern Europe with Salix, has smaller basidiospores (6.7–9.5 × 5.6–7.8 µm) with denser reticulation, more crowded, creamier colored lamellae, and a habitat mainly in subalpine areas (Heilmann-Clausen et al. 1998). The presence of L. aspideus in North America is unclear. Lactarius salicis-herbaceae Kühner, a closely related (Figure 2A) arctic-alpine Salix associate, which has not been reported from the Rocky Mountains, has darker yellow to yellow-brown sporocarps, pale cream to grayish buff lamellae, and more densely reticulate basidiospores (Heilmann-Clausen et al. 1998).

Figure 7. 

Lactarius salicis-reticulatae. Collection EB0057-14 under shrubby Salix sp., Beartooth Plateau, Wyoming, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius pallidomarginatus Barge & C.L. Cripps

Figure 8

The following morphological description is from Colorado material which includes the holotype and all are listed in Barge et al. (2016)

Description

Pileus 20–50 mm in diameter, convex to broadly convex to plane with or without a depressed center, smooth, subviscid to dry, azonate, blotchy light tan to light brown, developing violet stains, lighter (to cream) toward margin; margin incurved when young, remaining so or becoming nearly straight in age. Lamellae adnate to subdecurrent, subdistant to slightly crowded, white to pale yellow-cream, staining violet where damaged. Stipe 10–40 × 5–10 mm, equal to slightly clavate, smooth, dry, white to cream, staining violet where damaged, hollow. Context white to cream, staining violet where damaged. Latex scarce to undetectable, watery, white, staining tissue violet. Odor mild. Taste mild.

Basidiospores 8–10 × 6.5–8 µm, Q = 1.1–1.4, broadly ellipsoid to ellipsoid; ornamentation forming an incomplete to dense reticulum. Pleuromacrocystidia 81.5–112 × 9–10 µm, scarce to scattered, cylindrical to lanceolate; apex acute to moniliform. Cheilomacrocystidia 48–101.5 × 7.5–13 µm, scattered, cylindrical to lanceolate; apex acute to moniliform.

Ecology and distribution

Known from only a few alpine localities in the central and southern Rocky Mountains with Salix planifolia and possibly also S. glauca, late summer.

Specimens examined

U.S.A. WYOMING: Sublette County, Wind River Range, Union Peak, near Salix glauca, 22 Aug 1994, ZT5229 (MONT).

Discussion

This species was recently described (Barge et al. 2016) from the alpine zone in Southern Colorado with Salix. It is tentatively included here because a collection morphologically matching the type was made by Dr Egon Horak from the Wind River Range of Wyoming (technically in the southern GYE) with Salix glauca. Interestingly, out of all of the species examined thus far, L. pallidomarginatus appears most closely related to the bright yellow, violet-staining Salix associate L. aspideus (Figure 2A), to which it bares little resemblance.

In the Rocky Mountains, L. pallidomarginatus is most easily confused with L. nanus, L. glyciosmus, L. montanus, and L. aff. brunneoviolaceus. The basidiomes of L. nanus do not stain violet where damaged and it produces basidiospores with thicker, more jagged ridges, and macrocystidia with more rounded apices (see Barge et al. 2016). Lactarius glyciosmus also does not stain violet where damaged, it has an odor of coconut, slightly smaller basidiospores (7–9 × 5–7 µm), and smaller cheilomacrocystidia (33–66 × 5–9 µm). The closely related violet-staining L. montanus produces basidiomes which are typically much more robust and stain green on the stipe and pileus surface with KOH. Lactarius montanus also has a strongly resinous odor and taste, and is mainly subalpine with conifers. See comments under L. aff. brunneoviolaceus for features differentiating L. pallidomarginatus from that taxon. See Barge et al. (2016) for features differentiating L. pallidomarginatus from the European taxon L. pseudouvidus Kühner.

Figure 8. 

Lactarius pallidomarginatus. Collection EB0041 under Salix planifolia, San Juan Mountains, Colorado, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius montanus (Hesler & A.H. Sm.) Montoya & Bandala

Figure 9

Description

Pileus 30–100 mm in diameter, convex to ± depressed–convex to infundibuliform, viscid, smooth, azonate to zonate, zones consisting of darker spots arranged concentrically, gray–brown to vinaceous–gray to violet–brown; margin straight to slightly incurved when young, becoming straight and ± wavy. KOH on pileus cuticle and stipe green. Lamellae adnate to subdecurrent, crowded to subdistant, cream, discoloring violet where damaged with rust brown stains also often present on older material. Stipe 30–70 × 10–30 mm, equal to clavate, smooth with light tomentum often present especially toward base, dry, white to light brown, discoloring violet and eventually rust brown where damaged, solid, becoming hollow. Context white, discoloring violet and eventually rust brown where damaged. Latex scarce to copious, white, staining tissue violet. Odor strongly resinous. Taste strongly resinous.

Basidiospores 7–10.5 × 6–8 µm, Q = 1.2–1.5, broadly ellipsoid to ellipsoid; ornamentation forming a broken to partial reticulum. Pleuromacrocystidia 50–90 × 5–10 µm scarce to scattered, fusoid–acuminate; apex acute to moniliform. Cheilomacrocystidia 30–55 × 4–9 µm, scarce, fusoid–acuminate; apex acute to moniliform.

Ecology and distribution

Under conifers in western North America. In the GYE, it occurs in wet areas, often along streams in the montane spruce-fir and krummholz zones, possibly always in the presence of Picea engelmannii, summer and fall.

Specimens examined

U.S.A. MONTANA: Madison County, Madison Range, Mirror Lake, swampy area under Abies lasiocarpa and Picea engelmannii. 3 Sept 2013, EB120-13 (MONT); Madison County, Tobacco Root Mountains, Branham Lakes, under Picea engelmannii and Salix planifolia, 31 Aug 2013, CLC3001 (MONT), under Picea engelmannii, 1 Sept 2014, EB0071-14 (MONT), EB0072-14 (MONT), EB0073-14 (MONT).

Discussion

In western North America, similar species with violet-staining flesh include L. pallescens Hesler & A.H. Sm., L. californiensis Hesler & A.H. Sm., and L. cordovaensis Hesler & A.H. Sm. Lactarius pallescens and L. californiensis are generally more white overall in color, have a slightly acrid to acrid taste (not strongly resinous), and do not stain green in KOH. Lactarius cordovaensis has orange–tan lamellae when young, and possibly slightly smaller basidiospores (7.5–9.5 × 6.5–8 µm). Lactarius uvidus, a European species whose presence has not been confirmed molecularly for North America, typically has a lighter pileus, a bitter taste (not strongly resinous), and does not stain green in KOH. Previous reports of L. uvidus from the GYE (McKnight 1982) and the Central and Southern Rocky Mountains in general likely refer to L. montanus. See comments under L. aff. brunneoviolaceus and L. pallidomarginatus for features differentiating L. montanus from those taxa.

Figure 9. 

Lactarius montanus. Top collection EB0072-14 and bottom collection EB0073-14 under Picea engelmannii, Tobacco Root Mountains, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius aff. brunneoviolaceus M.P. Christ.

Figure 10

Description

Pileus 30–60 mm in diameter, convex to slightly depressed–convex, smooth, viscid, faintly zonate, brownish with lavender hues, marbled, whitish near margin; margin incurved and faintly tomentose when young. KOH on pileus cuticle green. Lamellae adnate, crowded, cream, staining violet where damaged. Stipe 25–30 × 20–25 mm, clavate, smooth, white with hoary coating, staining violet where damaged, hollow. Context not observed. Latex white, unchanging, staining tissue violet. Odor sweet. Taste mild, becoming slightly bitter.

Basidiospores 8–12 × 6.5–8 µm, Q = 1.2–1.5, broadly ellipsoid to ellipsoid; ornamentation forming an incomplete reticulum. Pleuromacrocystidia 40–90 × 8–12 µm, scattered to numerous, subfusiform to fusiform; apex mucronate. Cheilomacrocystidia 40–88 × 7–12 µm, numerous, fusiform; apex mucronate.

Ecology and distribution

Lactarius brunneoviolaceus occurs in arctic-alpine areas with Salix. The species described here was found growing near tree line (krummholz spruce present) on the Beartooth Plateau amongst Salix reticulata and S. planifolia, late summer.

Specimens examined

U.S.A. MONTANA: Custer County, Beartooth Plateau, Birch Site, among krummholz Picea engelmannii, Salix reticulata and Salix planifolia, 15 Aug 2014, CLC3098 (MONT).

Discussion

More collections and molecular data from this species are needed, however, this is the first report of a species from the GYE, and to the best of our knowledge, North America, bearing affinities to the arctic-alpine Salix associate L. brunneoviolaceus. Unfortunately, high quality sequence data was not obtained for this collection, and only a small portion of ITS1 could be used for phylogenetic analyses, which placed it with L. brunneoviolaceus. Morphologically, it is also a close match, except that the pileus of the species described here stains green with KOH, which is not historically mentioned for L. brunneoviolaceus. It is possible that the pileus of L. brunneoviolaceus stains green in KOH as well but that it has not been thoroughly tested. In CLC2133 from Norway, another specimen closely matching L. brunneoviolaceus which was examined, the pileus (of dried material) also stained green in KOH.

This species is very closely related to L. montanus (Figure 2A), however, the latter features slightly smaller basidiospores (7–10.5 × 6–8 µm, although sometimes to 12 µm long), and is typically below tree line with conifers. Lactarius pallidomarginatus, which is also closely related, has lighter colored, less violaceous pilei that do not stain green in KOH, and smaller basidiospores (8–10 × 6.5–8 µm).

Figure 10. 

Lactarius aff. brunneoviolaceus. Collection CLC3098 near Salix reticulata (pictured), S. planifolia, and krummholz Picea engelmannii, Beartooth Plateau, Montana, USA. Scale bar: 2 cm. Photo by C. Cripps.

Lactarius caespitosus Hesler & A.H. Sm.

Figure 11

Description

Pileus 35–100 µm in diameter, convex to broadly convex to nearly plane, ± centrally depressed, viscid to dry, smooth, more or less azonate, cream to pale gray–brown to pale vinaceous–brown, ± discoloring ochraceous in places; margin incurved when young, becoming straight in age. Lamellae adnate to subdecurrent, crowded to subdistant, white at first, becoming pale creamy buff, ± discoloring ochraceous to brown where damaged. Stipe 30–80 × 10–35 mm, equal to clavate, viscid to dry, smooth, white, developing ochraceous to faintly violet areas where damaged, solid, becoming hollow. Context white. Latex scarce to undetectable, white, unchanging. Odor mild. Taste acrid.

Basidiospores 8–12 × 7–9 µm, Q = 1.2–1.4, broadly ellipsoid to ellipsoid; ornamentation forming a broken to partial reticulum. Pleuromacrocystidia 50–110 × 8–12 µm, scattered to numerous, subcylindric to fusoid; apex rounded to acute. Cheilomacrocystidia 40–60 × 8–12 µm, scattered to abundant, clavate to mucronate; apex rounded to acute.

Ecology and distribution

In mountainous areas in western North America with conifers. Hesler and Smith (1979) report it as the common montane Lactarius of wet places in the spruce-fir zone of the Rocky Mountains during the summer and early fall. In the GYE, it occurs in wet depressions and near seeps as well as in drier upland sites in the montane spruce-fir zone, possibly always in the presence of Abies lasiocarpa, summer to fall.

Specimens examined

U.S.A. MONTANA: Gallatin County, Gallatin Range, East Fork Hyalite Creek, under Abies lasiocarpa and Picea engelmannii, 25 Aug 2015, EB158-15 (MONT); Gallatin County, Gallatin Range, Windy Pass Trail, under Abies lasiocarpa and Pinus contorta, 10 Aug 2013, EB102-13 (MONT); Madison County, Madison Range, Big Sky, under Abies lasiocarpa, Picea engelmannii and Pinus albicaulis, 4 Sept 2004, CLC2052 (MONT); Madison County, Madison Range, Mirror Lake, under Abies lasiocarpa, 3 Sept 2013, EB121-13 (MONT); Madison County, Tobacco Root Mountains, Branham Lakes, under Abies lasiocarpa, 1 Sept 2014, EB0074-14 (MONT); Sweet Grass County, Crazy Mountains, Big Timber Creek, under Abies lasiocarpa and Picea engelmannii, 1 Aug 2015, EB095-15 (MONT). WYOMING: Park County, Beartooth Plateau, Beartooth Lake Campground, under Abies lasiocarpa and Picea engelmannii, 5 Sept 2015, EB159-15 (MONT).

Discussion

The European Abies associate L. albocarneus Britzelm. appears to be closely related (Figure 2B), however, it has a lighter cream to dingy whitish pileus, and slowly yellowing latex and flesh (Heilmann-Clausen et al. 1998). The western North American L. kauffmanii Hesler & A.H. Sm. and L. pseudomucidus Hesler & A.H. Sm. also appear to be related (Figure 2B). Lactarius kauffmanii has a dark to blackish brown pileus (although it can be lighter), smaller basidiospores (7–10 × 6.5–8 µm), and a vinaceous to tan stipe. Lactarius pseudomucidus typically has a darker and more slimy pileus, a gray to gray–brown stipe, and smaller basidiospores (7–9 × 6–7 µm). Both L. kauffmanii and L. pseudomucidus may be confined to Douglas fir/western hemlock forests of the Pacific Northwest (Hesler and Smith 1979). The western North American L. circellatus v. borealis Hesler & A.H. Sm. is also similar, however, its pileus is pruinose at first and generally darker and faintly zonate to zonate, it has a dry stipe (never viscid as in L. caespitosus), and its lamellae are unstaining when cut (Hesler and Smith 1979, Methven 1997). Lactarius trivialis is also similar, however it appears to be fairly distantly related (Figure 2A); it has purplish gray to vinaceous colors of the pileus at least when young and smaller basidiospores (7.3–10 × 5.9–7.8 µm) (Heilmann-Clausen et al. 1998). Lactarius argillaceifolius Hesler & A.H. Sm. and its varieties are also similar, however, all feature a more purplish gray pileus at least when young (similar to L. trivialis) and smaller basidiospores. Variety argillaceifolius appears to be confined to oak forests in central and eastern North America, v. megacarpus Hesler & A.H. Sm. to oak forests in coastal western North America, and v. dissimilis Hesler & A.H. Sm. is represented by only one collection from South Carolina (Hesler and Smith 1979).

Figure 11. 

Lactarius caespitosus. Top collection EB0074-14 under Abies lasiocarpa, Tobacco Root Mountains, Montana, USA. Bottom collection EB095-15 under Abies lasiocarpa and Picea engelmannii, Crazy Mountains, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius controversus Pers.

Figure 12

Description

Pileus 50–120 mm in diameter, depressed–convex to infundibuliform, smooth, viscid to dry, faintly zonate, zones narrow and often more conspicuous near the margin, cream to pale tan–cream, often with tan to rust brown blotches; margin incurved and faintly short–tomentose when young, becoming glabrous and straight to undulating in age. Lamellae adnate to subdecurrent, crowded, creamy pink to pink–tan, discoloring tawny light brown where damaged. Stipe 25–50 × 17–28 mm, short, equal to tapering toward the base, subviscid to dry, smooth, ± scrobiculate, white, discoloring pale yellow to tawny light brown where damaged, solid, becoming hollow. Context white, discoloring tawny light brown. Latex scarce, white, unchanging. Odor faint to slightly spermatic. Taste slowly acrid.

Basidiospores 5.5–8 × 4.5–5.5 µm, Q = 1.2–1.5, broadly ellipsoid to ellipsoid; ornamentation forming a nearly complete reticulum. Pleuromacrocystidia 25–50 × 3–7 µm, scarce, cylindric to fusiform; apex acute to moniliform. Cheilomacrocystidia 25–40 × 3–6 µm, scarce, cylindric to fusiform; apex rounded to acute.

Ecology and distribution

Widely distributed in the northern hemisphere with Populus (aspen), Salix, and possibly Betula. In the GYE it occurs in montane areas near Populus tremuloides, summer and fall.

Specimens examined

U.S.A. IDAHO: Teton County, Teton Mountains, under Populus tremuloides, CLC290 (MONT). MONTANA: Carbon County, near Red Lodge, along Rock Creek, under Populus tremuloides, 8 Aug 2015, EB110-15 (MONT); Park County, Cinnabar Basin, under Populus tremuloides, 18 July 1990, CLC106 (MONT), 2 Aug 1990, CLC116 (MONT), 11 Sept 1991, CLC262 (MONT), 13 July 1992, CLC462 (MONT); Silverbow County, Butte, East Ridge, under Populus tremuloides, 15 Aug 1993, CLC699 (MONT). WYOMING: Park County, along Beartooth Highway, under Populus tremuloides, 16 Aug 2014, EB0061-14 (MONT).

Discussion

L. controversus is fairly easily recognized by its small basidiospores, whitish pileus, pinkish lamellae, acrid taste, and association with aspen. No other species is similar in the Rocky Mountains. While morphological differences between European and GYE material were not detected, there is some molecular divergence, which could indicate separate species, although more material needs to be examined (Figure 2B).

Figure 12. 

Lactarius controversus. Collection EB110-15 under Populus tremuloides, Beartooth Mountains, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius olympianus Hesler & A.H. Sm.

Figure 13

Description

Pileus 20–100 mm in diameter, depressed–convex to infundibuliform, smooth, viscid, zonate, color alternating between rich and dull orange; margin incurved when young becoming straight to wavy in age. Lamellae adnate, crowded to subdistant, cream to dingy yellow, staining orange–brown in age or where damaged. Stipe 20–50 × 10–25 mm, equal to tapering toward the base, smooth, white, at first with a white bloom, staining dingy orange–brown where damaged, solid, becoming hollow. Context white. Latex white, unchanging, staining lamellae orange–brown. Odor mild. Taste acrid.

Basidiospores 8–11.5 × 7.5–9.5 µm, Q = 1.1–1.3, broadly ellipsoid; ornamentation forming a broken to nearly complete reticulum. Pleuromacrocystidia 20–50 × 3–6 µm, scattered to numerous, fusiform; apex acute to moniliform. Cheilomacrocystidia 20–35 × 3–6 µm, scattered, fusiform; apex acute to moniliform.

Ecology and distribution

In montane conifer forests in western North America. In the GYE, it occurs in seeps and along streams in the spruce-fir zone possibly always in the presence of Picea engelmannii.

Specimens examined

U.S.A. MONTANA: Gallatin County, Gallatin Range, Windy Pass Trail, under Picea engelmannii, 4 Aug 2012, EB0114 (MONT); Madison County, Tobacco Root Mountains, Branham Lakes, under Picea engelmannii, 1 Sept 2014, EB0070-14 (MONT).

Discussion

This species is very close to and likely conspecific with L. zonarioides Kühner & Romagn. (Figure 2B), which occurs in similar habitats and was described from Europe (Hesler and Smith 1979).

Figure 13. 

Lactarius olympianus. Collection EB0070-14 under Picea engelmannii, Tobacco Root Mountains, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius pseudodelicatus A.H. Sm.

Figure 14

Description

Pileus 70–140 mm in diameter, broadly depressed–convex to broadly infundibuliform, viscid to dry, smooth to matted–tomentose especially near the margin, zonate to faintly zonate, yellow–buff to buff to pale orange–brown, lighter toward the margin; margin incurved and matted–tomentose to cottony–tomentose when young, remaining so or becoming straight and ± glabrous in age. Lamellae subdecurrent to decurrent, many of them branching, crowded, white to pale cream when young, becoming orange–buff to brown to gray–brown in age. Stipe 20–90 × 15–20 mm, tapering toward the base, smooth, white to pale buff, discoloring brown, often with scattered small scrobicules, hollow. Context firm. Latex copious, white, unchanging. Odor pleasant, fruity, of orange–citrus. Taste acrid.

Basidiospores 6–8 × 5–6.5 µm, Q = 1.2–1.5, broadly ellipsoid to ellipsoid; ornamentation forming a broken to partial reticulum. Pleuromacrocystidia 60–100 × 7–12 µm, numerous, strongly projecting, fusiform; apex acute. Cheilomacrocystidia 40–61 × 7–10 µm, numerous, strongly projecting, fusiform; apex acute.

Ecology and distribution

Originally described from Michigan under aspen. There are very few subsequent reports. In the GYE, it is here reported with Populus tremuloides from the Teton Range of Idaho, summer.

Specimens examined

U.S.A. IDAHO: Teton County, Teton, under Populus tremuloides, 27 July 1991, CLC233 (MONT), 24 Aug 1991, CLC296 (MONT), 26 July 1992, CLC512 (MONT).

Discussion

This represents the first report of this species from the GYE under the name L. pseudodelicatus. It was previously reported from the GYE as L. cf. zonarius Fr. in Cripps and Miller (1993) and Cripps (2001). The European L. zonarius has slightly larger basidiospores (6.3–9.2 × 5.1–7.4 µm), shorter pleuromacrocystidia (40–50 × 4–6 µm), and an ecology with Quercus (Heilmann-Clausen et al. 1998).

Molecularly, L. pseudodelicatus is very close to a specimen identified as L. aff. wenquanensis Y. Wang & Z.X. Xie, from a humid montane rainforest with Quercus, Castanopsis, and Lithocarpus echinops Hjelmq. in Thailand (Figure 2B) (Le et al. 2007). Lactarius aff. wenquanensis appears to be less robust with shorter pleuromacrocystidia (54–76 × 9.5–12 µm); it also appears to have a different ecology. Lactarius wenquanensis Y. Wang & Z.X. Xie, originally described from China has larger basidiospores (7.5–9.5 × (6–)6.5–7.5 µm) and the type was collected under Picea and Abies, as opposed to aspen (Wang 2007). Lactarius torminosus (Schaeff.) Gray is closely related to L. pseudodelicatus (Fig. 2B), however, L. torminosus typically has smaller basidiomes, a more pink to brick pileus, slightly larger basidiospores (7.5–9.6 × 5.6–6.9 µm), and associates with Betula (Heilmann-Clausen et al. 1998). Lactarius pubescens Fr. is also closely related to L. pseudodelicatus (Figure 2B), and both associate with aspen in similar habitats. Lactarius pubescens is typically less robust and features a more pale pileus, a non-scrobiculate stipe, and smaller pleuromacrocystidia (30–60 × 6.5–10 µm) (Heilmann-Clausen et al. 1998). Lactarius delicatus Burl., described from a deciduous forest in Eastern North America produces white latex that turns yellow (Hesler and Smith 1979).

Figure 14. 

Lactarius pseudodelicatus. Collection CLC512 under Populus tremuloides, Teton Range, Idaho, USA. Scale bar: 2 cm. Photo by C. Cripps.

Lactarius pubescens Fr.

Figure 15

Description

Pileus 20–100 mm in diameter, depressed–convex to infundibuliform, dry, smooth, hairy toward margin, pale cream to cream or pale pinkish buff; margin bearded, incurved when young becoming straight to wavy in age. Lamellae adnate to decurrent, crowded, pale cream to pale pinkish buff. Stipe 25–50 × 10–15 mm, equal, smooth, dry, pale pinkish buff to pale orange, becoming hollow. Context whitish to pale pinkish buff. Latex not abundant, white, unchanging. Odor fragrant. Taste acrid.

Basidiospores 6–8.5 × 4–6 µm, Q = 1.2–1.5, broadly ellipsoid to ellipsoid; ornamentation forming an incomplete reticulum. Pleuromacrocystidia 25–55 × 7–10 µm, scattered, clavate to fusiform; apex acute to moniliform. Cheilomacrocystidia 25–48 × 5–9 µm, numerous, clavate to fusiform; apex acute to moniliform.

Ecology and distribution

Originally described from Europe and apparently widespread with Betula and aspen. It also appears to associate with certain herbaceous plants in alpine areas (China) based on publicly available sequences on GenBank isolated from ectomycorrhizal root tips. In the GYE, it occurs with Populus tremuloides and Betula.

Specimens examined

U.S.A. MONTANA: Deerlodge County, Anaconda Superfund site, under Betula sp., 24 Sept 1996, CLC1045 (MONT); Park County, Gallatin Range, Cinnabar Basin, under Populus tremuloides, 1992, CLC539 (MONT); Silver Bow County, 23 Sept 2015, EB300-15 (MONT).

Discussion

Morphologically and molecularly (at least at the ITS region), material from the GYE is identical to European material (Figure 2B). In North America, Hesler and Smith (1979) distinguish an L. pubescens v. betulae (A.H. Sm.) Hesler & A.H. Sm. based on yellowing latex among other subtle features, however yellowing latex was not noted in our collections. Further investigation of L. pubescens in North America is warranted. The Betula associate L. torminosus is similar, and closely related (Figure 2B) but its basidiomes are typically more pink colored and it has larger basidiospores (7.5–9.6 × 5.6–6.9 µm) (Heilmann-Clausen et al. 1998). Lactarius resimus (Fr.) Fr. is also similar, however it has strongly yellowing latex and flesh and larger basidiospores (7.0–9.7 × 5.3–7.2 µm) (Heilmann-Clausen et al. 1998). See comments under L. pseudodelicatus for distinguishing features for that taxon.

Figure 15. 

Lactarius pubescens. Collection EB303-15 under Betula sp., Boise, Idaho, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius zonarius v. riparius Hesler & A.H. Sm.

Figure 16

Description

Pileus 50–80 mm in diameter, depressed–convex to broadly infundibuliform, viscid to dry, smooth to ± matted–tomentose toward the margin, zonate to faintly zonate, yellow–brown to orange–brown, ± lighter toward the margin; margin incurved and matted–tomentose to cottony–tomentose when young, becoming straight and glabrous in age. Lamellae subdecurrent to decurrent, crowded, cream, staining brownish where damaged. Stipe 20–40 × 15–25 mm, equal to tapering toward the base, smooth, dry, cream, ± with small pale brown scrobicules. Context very firm, cream. Latex white, unchanging, staining lamellae brownish. Odor sweet, fruity. Taste slowly acrid.

Basidiospores 7–9 × 5.5–7.5 µm, Q = 1.2–1.4, broadly ellipsoid to ellipsoid; ornamentation forming a highly broken reticulum. Pleuromacrocystidia 40–66 × 4.5–7.4 µm, scarce to scattered, narrowly subfusiform to fusiform; apex acute to moniliform. Cheilomacrocystidia 25–49 × 4.5–5.5 µm, numerous, narrowly subfusiform to fusiform; apex acute to moniliform.

Ecology and distribution

Originally described and reported from rich wet humus along small streams in hardwood forests in Michigan. There are very few subsequent reports. In the GYE, it occurs in rich, moist riparian areas with Populus trichocarpa, summer to fall.

Specimens examined

U.S.A. MONTANA: Gallatin County, Bozeman, along Sourdough Creek, under Populus trichocarpa, 2013, CLC2933 (MONT).

Discussion

Molecularly, this taxon is very close to the European L. evosmus Kühner & Romagn. (Figure 2B), which also associates with Populus, as well as Quercus, and occasionally Salix (Heilmann-Clausen et al. 1998). It is also close to but distinct from the European L. zonarius (Figure 2B). Neither L. evosmus or L. zonarius feature a bearded pileus margin at any point in sporocarp development. Lactarius zonarius v. riparius will likely need to be given species level status and a new name, although this hinges on examination of type material.

Similar taxa in western North America include L. sanmiguelensis Hesler & A.H. Sm., described from under cottonwood in southwestern Colorado that has a pileus with cinnamon–buff zones on a pinkish buff ground color, the role of felt along the margin is pinkish buff, it does not have a distinctive odor, it is instantly and very strongly acrid, the lamellae are strongly anastomosed, pinkish buff, and do not discolor where injured, and the stipe is longer and pale pinkish buff (Hesler and Smith 1979). Bessette et al. (2009) synonymize L. sanmiguelensis and L. subvillosus Hesler & A.H. Sm., the latter being undoubtedly different from the species described here. Lactarius pseudodelicatus is somewhat similar but it has a longer stipe, smaller basidiospores (6–8 × 5–6.5 µm), and much larger pleuromacrocystidia (60–100 × 7–12 µm). Lactarius psammicola A.H. Sm. and L. yazooensis Hesler & A.H. Sm. are similar species with a more Eastern North American distribution in Quercus forests (Hesler and Smith 1979).

Figure 16. 

Lactarius zonarius v. riparius. Collection CLC2933 under Populus trichocarpa, Bozeman, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius alnicola A.H. Sm.

Figure 17

Description

Pileus 60–170 mm in diameter, depressed–convex to infundibuliform, glutinous when wet, with matted fibrils beneath the gluten especially near the margin, ± faintly zonate, pale creamy yellow to pale yellow–brown to golden yellow–brown, discoloring orange–brown to brown where damaged; margin ± faintly tomentose, incurved when young, becoming straight to wavy. Lamellae subdecurrent to decurrent, some forked toward the stipe, crowded, pale cream to pale buff, ± slowly discoloring yellow and eventually orange–brown where damaged. Stipe 20–60 × 30–50 mm, equal to clavate to tapering toward the base, smooth, dry, conspicuously scrobiculate, white, discoloring orange–brown where damaged or in age, solid, becoming hollow. Context firm, white, ± slowly discoloring yellow to orange–brown where damaged. Latex scarce to undetectable, white, ± becoming very pale yellow, and slowly staining damaged tissue yellow. Odor mild to sweet. Taste quickly very acrid.

Basidiospores 7.5–10 × 6–8.5 µm, Q = 1.2–1.5, broadly ellipsoid to ellipsoid; ornamentation forming a partial reticulum. Pleuromacrocystidia 60–90 × 3–8 µm, rare, mostly near the pileus and between the lamellae, cylindric to fusiform; apex acute to moniliform. Cheilomacrocystidia absent.

Ecology and distribution

In western North America and Mexico under conifers. Also reported from California with Quercus. In the GYE, L. alnicola occurs in wet areas, often along streams in the spruce-fir zone, possibly always in the presence of Picea engelmannii, summer and early fall.

Specimens examined

U.S.A. MONTANA: Gallatin County, Gallatin Range, Langhor Road, under Picea engelmannii, 27 Aug, EB0064-14 (MONT); Madison County, Tobacco Root Mountains, Branham Lakes, under Picea engelmannii, 1 Sept 2014, EB0067-14 (MONT).

Discussion

Lactarius alnicola is phylogenetically very closely related to the European L. scrobiculatus (Scop.) Fr., and may be conspecific, however more specimens need to be sequenced before making this determination final (Figure 2B). For morphological differences, L. scrobiculatus features a heavily bearded pileus margin, and produces white latex which rapidly turns yellow (Kytövuori 1984). Lactarius alnicola, and other members of subsection Scrobiculati Hesler & A.H. Sm. sensu Kytövuori (1984) form a strongly supported clade in the phylogeny (Figure 2B).

Two varieties of L. alnicola have been described: L. alnicola v. pitkinensis Hesler & A.H. Sm., described from Colorado under aspen and conifers, has cream colored to white basidiomes, an acrid taste, unchanging latex, and unchanging (non-yellowing) flesh; L. alnicola v. pungens Hesler & A.H. Sm., described from Michigan in mixed forest, has a dull ochraceous to ochraceous–tan, subviscid, glabrous pileus, an acrid taste, and white, unchanging latex, which stains white paper yellow (Hesler and Smith 1979). Neither appear to fit the taxon described here.

Figure 17. 

Lactarius alnicola. Top and bottom collection EB0064-14 under Picea engelmannii, Gallatin Range, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius aff. tuomikoskii Kytöv.

Figure 18

Description

Pileus to 80 mm in diameter, broadly convex with a depressed center, glutinous when wet, with matted fibrils beneath the gluten especially near the margin, azonate, pale yellow–cream to yellow–tan, discoloring brown in places; margin densely bearded, incurved at least when young. Lamellae subdecurrent, crowded, cream to pale yellow–cream, ± discoloring yellow and eventually rusty brown where damaged. Stipe 30 × 20 mm, tapering toward the base, smooth, dry, white to pale yellow–tan, with small, faint, dull yellow–tan scrobicules, hollow. Context white, ± slowly discoloring pale yellow to faintly tan where damaged. Latex scarce, white, becoming very pale yellow, and slowly staining damaged tissue pale yellow. Odor sweet. Taste acrid.

Basidiospores 7–10 × 5.5–7.5 µm, Q = 1.2–1.5, broadly ellipsoid to ellipsoid; ornamentation forming a broken to nearly complete reticulum. Pleuromacrocystidia 50–100 × 7–12 µm, abundant, strongly projecting, fusiform to lanceolate; apex acute to moniliform. Cheilomacrocystidia absent.

Ecology and distribution

In montane, rich, moist habitats with Picea engelmannii, late summer.

Specimens examined

U.S.A. MONTANA: Park County, Silver Gate, under Picea engelmannii, 13 Aug 2014, EB0052-14 (MONT).

Discussion

This species, along with L. alnicola, and L. aff. olivinus Kytöv. described below, fall in subsection Scrobiculati as recognized by Kytövuori (1984). Morphologically, it is quite close to the European L. tuomikoskii Kytöv. It is also very close to some interpretations of L. scrobiculatus v. canadensis A.H. Sm., and L. gossypinus Hesler & A.H. Sm., except it has larger basidiospores and pleuromacrocystidia. Lactarius payettensis A.H. Sm. is also similar, but differs by having a more robust, heavily scrobiculate stipe and apparently unchanging latex (Hesler and Smith 1979). Both L. gossypinus and L. payettensis have been previously reported from the GYE (McKnight 1982), however neither were examined for this treatment. Overall, the complex of species surrounding L. scrobiculatus in North America, which includes L. alnicola, L. gossypinus, L. payettensis, L. scrobiculatus v. canadensis, L. scrobiculatus v. montanus Methven, and the two taxa described here (L. aff. tuomikoskii, and L. aff. olivinus) appears to be in need of revision, especially in relation to European taxa such as L. auriolla Kytöv., L. leonis Kytöv., L. olivinus, L. scrobiculatus, and L. tuomikoskii (Kytövuori 1984).

Figure 18. 

Lactarius aff. tuomikoskii. Top and bottom collection EB0052-14 under Picea engelmannii, Silver Gate, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius aff. olivinus Kytöv.

Figure 19

Description

Pileus 30–110 mm in diameter, depressed–convex to infundibuliform, viscid when wet, with appressed, agglutinated scales of confluent hairs, especially near the margin, more or less azonate, cream to olive–buff to yellow–tan to orange–tan, ± darker toward the center; margin incurved and wooly–tomentose when young, often forming a cottony rim, becoming straight and more or less glabrous. Lamellae subdecurrent, crowded, cream, staining yellow where damaged and then fading or eventually becoming pale ochraceous. Stipe 30–45 × 10–25 mm, equal to clavate to tapering toward the base, smooth, dry, cream to pale yellow–tan to orange–tan, ± with pale yellow–tan scrobicules, often with a white ring near the apex, solid, becoming hollow. Context white, staining pale yellow at first and then fading. Latex scarce to undetectable, white, becoming yellow, staining tissue yellow and then fading. Odor faintly sweet to faintly spermatic. Taste mild.

Basidiospores 7.5–10 × 5.5–7 µm, Q = 1.3–1.5, ellipsoid; ornamentation forming a partial reticulum. Pleuromacrocystidia 51–100 × 9–14 µm, abundant, strongly projecting, fusiform to lanceolate; apex acute to moniliform. Cheilomacrocystidia absent.

Ecology and distribution

In montane, rich, moist habitats with Picea engelmannii, mid to late summer.

Specimens examined

U.S.A. MONTANA: Park County, Silver Gate, under Picea engelmannii, 13 Aug 2014, EB0050-14 (MONT), EB0051-14 (MONT).

Discussion

This species is morphologically close to the European L. olivinus except for the mild rather than acrid taste. Molecularly (Figure 2B), and ecologically, it is also close, however we refrain from calling it that species until more collections are examined and compared with European material. It is also very close to some interpretations of the North American taxa L. scrobiculatus v. canadensis, and L. gossypinus, except it has larger basidiospores and pleuromacrocystidia. Lactarius payettensis is also similar, but it has unchanging latex, and a strongly acrid taste. See comments under L. aff. tuomikoskii for additional information.

Figure 19. 

Lactarius aff. olivinus. Top collection EB0051-14 and bottom collection EB0050-14 under Picea engelmannii, Silver Gate, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius barrowsii Hesler & A.H. Sm.

Figure 20

Description

Pileus 30–140 mm in diameter, depressed–convex to broadly infundibuliform, viscid to dry, smooth, azonate, cream to dingy pinkish orange to pale yellow–brown to straw yellow, discoloring red and eventally green in age or where damaged; margin incurved with a white bloom when young, becoming straight to upturned and wavy in age. Lamellae adnate to subdecurrent, crowded to subdistant, dingy pinkish orange to creamy yellow–orange, discoloring red and eventually green where damaged. Stipe 15–50 × 10–30 mm, equal to tapering toward the base, dry, smooth, at first with a white bloom, becoming dingy pinkish orange to yellow–brown in places, staining red and eventually green where damaged, solid, becoming hollow. Context whitish, staining red. Latex scarce to undetectable, watery, red, staining flesh red and eventually green. Odor faintly sweet to spermatic in age. Taste mild.

Basidiospores 8.5–10 × 6–7.5 µm, Q = 1.3–1.5, ellipsoid; ornamentation forming a broken reticulum. Pleuromacrocystidia none observed (absent in Hesler and Smith 1979). Cheilomacrocystidia 30–50 × 2–6 µm, scattered, fusoid; apex acute.

Ecology and distribution

In Western North America, previously reported with ponderosa and pinyon pine. In the GYE, it occurs in foothills to low montane dry scrubland, so far reported only from under Pinus flexilis, spring and early summer. This is the first report of this species with Pinus flexilis.

Specimens examined

U.S.A. MONTANA: Gallatin County, Story Hill, under Pinus flexilis, 30 May 2015, EB008-15, EB015-15, EB028-15 (all at MONT); Madison County, Revenue Flats, under Pinus flexilis, 1 June 2015, EB037-15 (MONT).

Discussion

This is the first report of L. barrowsii from the GYE. Lactarius barrowsii, and other members of section Deliciosi (Fr.:Fr.) Redeuilh, Verbeken & Walleyn, such as L. deliciosus (L.) Gray, L. deterrimus Gröger, and L. rubrilacteus Hesler & A.H. Sm. form a monophyletic group (Figure 2B), previously shown by Nuytinck et al. (2007). Lactarius barrowsii is morphologically close to the western North American L. rubrilacteus. However, in L. barrowsii, the lamellae are more orange, the pileus is lighter and more yellow, the margin has a white bloom when young, and the stipe is often whiter. Phylogenetically, L. barrowsii is very close to the hypogeous, spring fruiting, pine associated L. rubriviridis Desjardin, H.M. Saylor & Thiers, which occurs in similar dry habitats in western North America (Nuytinck et al. 2007).

Figure 20. 

Lactarius barrowsii. Top collection EB008-15 (left and right) and bottom collection EB015-15 under Pinus flexilis, Story Hill, Bozeman, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius rubrilacteus Hesler & A.H. Sm.

Figure 21

Description

Pileus 45–90 mm in diameter, shallowly depressed–convex to broadly infundibuliform, smooth, viscid, zonate, light brown to orange–cream to yellow–orange to orange–brown to carrot to dingy orange, often with green stains; margin incurved when young becoming straight. Lamellae adnate to subdecurrent, crowded to subdistant, cream to pinkish cinnamon to dull pink, discoloring wine red and eventually green where damaged. Stipe 20–40 × 10–25 mm, equal to tapering toward the base, dry, smooth, at first with a light glaucous coating, ± scrobiculate, cream to dull pink to orange–cream, discoloring wine red and eventually green where damaged, solid, becoming hollow. Context white, immediately staining deep wine–red to burgundy. Latex scarce, wine red, staining tissue wine–red to burgundy and eventually green. Odor mild. Taste mild.

Basidiospores 7.5–9.5 × 5–7.5 µm, Q = 1.3–1.5, ellipsoid; ornamentation forming a partial reticulum. Pleuromacrocystidia 40–80 × 4–6 µm, sparse, fusoid; apex acute. Cheilomacrocystidia 30–65 × 6–9 µm, scattered, fusoid; apex acute.

Ecology and distribution

In western North America with Pseudotsuga menziesii and Pinus. In the GYE this species occurs in foothills to low montane areas, near Pseudotsuga menziesii, spring and early summer.

Specimens examined

U.S.A. MONTANA: Gallatin County, Bridger Range, Fairy Lake Road, under Pseudotsuga menziesii, 25 June 2013, EB13-040 (MONT); Park County, Absaroka Mountains, George Lake Trailhead, under Pseudotsuga menziesii, 27 June 2014, EB900-14 (MONT).

Discussion

The European L. sanguifluus (Paulet) Fr. is morphologically similar, however, its lamellae are typically more violet tinged and its stipe is often scrobiculate. Western North American members of the “L. deliciosus” group can appear similar, however, their latex does not start out red as in L. rubrilacteus. The western North American Lactarius barrowsii also has reddish latex, however, it features a whitish to straw colored pileus and ochraceous to pinkish orange lamellae.

Figure 21. 

Lactarius rubrilacteus. Collection EB13-040 under Pseudotsuga menziesii, Bridger Range, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactariusdeliciosus (L.) Gray (group)

Figure 22

Description

Pileus 30–100 mm in diameter, convex to broadly infundibuliform, smooth to faintly areolate, viscid to dry, ± faintly zonate, pale cream to pale yellow to carrot orange, often with green stains especially in age; margin striate when wet, incurved when young and becoming straight. Lamellae adnate to subdecurrent, crowded to subdistant, creamy orange to carrot orange, discoloring orange to reddish and eventally green where damaged. Stipe 30–70 × 5–25 mm, equal to clavate to tapering toward the base, viscid to dry, smooth, creamy orange to carrot orange with a white band toward the apex; discoloring carrot orange to dull reddish and eventually green where damaged, hollow. Context yellowish, immediately staining carrot orange to dull reddish and eventally green. Latex scarce, carrot orange, staining tissue carrot orange to dull reddish and eventually green. Odor mild. Taste mild.

Basidiospores 7.5–10.5 × 5.5–7.5 µm, Q = 1.3–1.5, ellipsoid; ornamentation forming a partial reticulum. Pleuromacrocystidia 40–55 × 3–6 µm, very sparse, subfusiform; apex moniliform. Cheilomacrocystidia 45–60 × 4–9 µm, scarce to numerous, subfusiform; apex moniliform.

Ecology and distribution

In North America with conifers. In the GYE, members of this group occur in montane mixed lodgepole/spruce-fir forests, the spruce-fir zone, and the krummholz zone, summer to fall; there are also reports specifically with Pinus flexilis (Cripps and Antibus 2011) and Pinus albicaulis (Mohatt et al. 2008, Cripps and Antibus 2011), and one collection is reported here with Arctostaphylos uva-ursi, well-separated from any conifers.

Specimens examined

U.S.A. MONTANA: Carbon County, Hellroaring Plateau, Hellroaring Creek, among Arctostaphylos uva-ursi, 9 Aug 2015, EB107-15 (MONT); Gallatin County, Gallatin Range, East Fork Hyalite Creek, under Picea engelmannii, 24 Aug 2014, EB0063-14 (MONT); Madison County, Madison Range, Taylor Creek, under Abies lasiocarpa, Picea engelmannii and Pinus contorta, 25 July 2015, EB089-15 (MONT).

Discussion

While section Deliciosi (Fr.:Fr.) Redeuilh, Verbeken & Walleyn has been resolved as monophyletic (Nuytinck et al. 2007) (Figure 2B), the complex of species surrounding L. deliciosus (L.) Gray in North America is poorly resolved. Using molecular techniques, Nuytinck et al. (2007) showed that L. deliciosus and L. deterrimus Gröger likely do not occur in North America. The collections of the North American varieties of L. deliciosus described by Hesler and Smith (1979) that they analyzed formed a clade separate from the European L. deliciosus and L. deterrimus, but were poorly resolved, with the exception of L. deliciosus v. areolatus A.H. Smith, which formed a monophyletic group. For descriptions of North American members of this group see Hesler and Smith (1979) and Methven (1997).

Lactarius deliciosus and all of its North American varieties, as well as L. deterrimus have been previously reported from the GYE (McKnight 1982, Mohatt et al. 2008, Cripps 2011, Cripps and Antibus 2011). Specimens from the GYE included in the phylogenetic analysis in the present study fall in the poorly resolved North American “L. deliciosus” group including “L. deliciosus v. deterrimus” (Gröger) Hesler & A.H. Sm. and L. deliciosus v. olivaceosordidus Hesler & A.H. Sm. (Figure 2B). Previous reports of L. thyinos from the GYE (McKnight 1982), a northeastern North American member of sect. Deliciosi that occurs in Thuja bogs may refer to the “L. deliciosus” group described here. Overall, this group is in need of revision.

Figure 22. 

Lactarius deliciosus” group. Top collection EB107-15 among Arctostaphylos uva-ursi, Hellroaring Plateau, Montana, USA. Bottom collection EB089-15 under Picea engelmannii, Pinus contorta, and Abies lasiocarpa, Madison Range, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius badiosanguineus Kühner & Romagn.

Figure 23

Description

Pileus 15–70 mm in diameter, broadly convex to depressed–convex to broadly infundibuliform, ± umbonate, subviscid to dry, smooth to wrinkled–veined, typically darker when young, liver colored to deep scarlet red to red–brown to orange–brown to dingy orange, conspicuously lighter (to yellow–orange) toward the margin in age; margin ± striate when wet, slightly incurved to straight when young, remaining straight or becoming slightly wavy in age. Lamellae subdecurrent, crowded to subdistant, cream to creamy yellow to pale tan to pale orange–tan. Stipe 20–70 × 8–13 mm, equal to slightly clavate, smooth, dry, faintly white–pruinose when young, dingy orange to red–orange, solid, becoming hollow. Context pale tan to red–orange. Latex scarce to abundant, white, unchanging. Odor mild. Taste mild to slightly bitter.

Basidiospores 7–9.5 × 6–8 µm, Q = 1.1–1.4, subglobose to ellipsoid; ornamentation forming a broken to nearly complete reticulum. Pleuromacrocystidia 40–90 × 5–10 µm, scattered to numerous, subfusiform; apex obtuse to broadly acute. Cheilomacrocystidia 20–50 × 5–9 µm, scattered to numerous, subfusiform; apex obtuse to broadly acute.

Ecology and distribution

In Eurasia and North America with Picea. In the GYE, this species occurs in moist areas and along streams (although it can also occur on drier upland sites) in the montane spruce-fir zone, possibly always in the presence of Picea engelmannii, summer to fall.

Specimens examined

U.S.A. MONTANA: Gallatin County, Gallatin Range, East Fork Hyalite Creek, under Abies lasiocarpa and Picea engelmannii, 25 Sept 2013, EB200-13 (MONT); under Abies lasiocarpa, Picea engelmannii and Pinus contorta, 24 Aug 2014, EB0062-14 (MONT); Madison County, Tobacco Root Mountains, Branham Lakes, under Picea engelmannii; 1 Sept 2014, EB0069-14 (MONT); Sweet Grass County, Crazy Mountains, Big Timber Creek, under Abies lasiocarpa and Picea engelmannii, 1 Aug 2015, EB094-15 (MONT).

Discussion

This is the first report of this species from the GYE under the name L. badiosanguineus. In North American treatments (e.g. Hesler and Smith 1979, Bessette et al. 2009), this species may have gone under the name L. hepaticus Plowr. Previous reports of L. subdulcis (Pers.) Gray from the GYE (McKnight 1982) likely refer to L. badiosanguineus. The European L. hepaticus has a duller, browner pileus (although it can be deep red), yellowing latex and flesh, an acrid taste, and it associates with Pinus in nutrient-poor, acidic soils (Kränzlin 2005). The European L. subdulcis has a more orange–brown to brown pileus (although it can be reddish), a mild to unpleasant smell, a bitter–acrid taste, and an association with Fagus (Heilmann-Clausen et al. 1998, Kränzlin 2005). Phylogenetically, L. badiosanguineus appears to be fairly closely related to but distinct from both L. subdulcis and L. hepaticus (Figure 2C).

Lactarius badiosanguineus is closely related to L. subviscidus Hesler & A.H. Sm., L. sphagneti (Fr.) Neuhoff, and L. fulvissimus Romagn. Lactarius subviscidus features typically smaller, more fragile basidiomes with a more uniformly orange pileus, and latex that stains white paper yellow (Hesler and Smith 1979); L. subviscidus appears to be confined to the coastal forests of the Pacific Northwest of North America. According to Heilmann-Clausen et al. (1998), the European L. sphagneti features a more distinctly two-toned pileus with a paler margin and darker center (although L. badiosanguineus also often displays this character at least in the GYE) as well as more densely reticulate spores with a stronger amyloid reaction. The European L. fulvissimus typically features basidiomes which are more orange overall, white latex which often turns yellow, basidiospores with an ornamentation of small pointed warts, and an ecology with deciduous trees such as Fagus, Quercus, Tilia, Populus, and Corylus, more rarely with conifers (Heilmann-Clausen et al. 1998, Kränzlin 2005).

Lactarius badiosanguineus is also very similar to L. atrobadius Hesler & A.H. Sm., reported from the Pacific coastal Picea sitchensis belt in North America. Lactarius atrobadius appears to have darker basidiomes, however, a more in depth molecular and morphological comparison between the two taxa is warranted. Lactarius lanceolatus O.K. Mill. & Laursen is also similar, however it typically produces basidiomes which are overall more orange with larger pleuromacrocystidia (73.5–127 × 6.5–10 µm), and it occurs above tree line with Salix. See comments under L. luculentus v. laetus Hesler & A.H. Sm. for features distinguishing it from L. badiosanguineus.

Figure 23. 

Lactarius badiosanguineus. Top collection EB0069-14 under Picea engelmannii, Tobacco Root Mountains, Montana, USA. Bottom collection EB200-13 under Picea engelmannii and Abies lasiocarpa, Gallatin Range, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.

Lactarius rufus (Scop.) Fr.

Figure 24

Description

Pileus 45–110 mm in diameter, convex to ± depressed–convex to broadly infundibuliform, smooth, at first covered with a fine bloom becoming ± faintly areolate in age, subviscid when wet, becoming dry, azonate, deep red–brown to orange–brown, sometimes with gray–brown bands or blotches; margin incurved when young, becoming straight. Lamellae adnate to subdecurrent, subdistant to crowded, cream to dingy orange–tan in age, discoloring dingy brown where damaged. Stipe 40–90 × 10–15 mm, equal to subclavate, smooth, at first with a fine bloom, dry, cream to tan–pink to red–brown, typically remaining cream toward the base, solid, becoming hollow. Context white to vinaceous–buff. Latex scarce to abundant, white, unchanging. Odor mild. Taste acrid.

Basidiospores 6.8–9.2 × 5.1–7.1 µm, Q = 1.3–1.5, ellipsoid; ornamentation forming a complete reticulum. Pleuromacrocystidia 26–70 × 6–12 µm, scattered to abundant, subfusiform to fusiform; apex obtuse to mucronate. Cheilomacrocystidia 20–50 × 5–9 µm, scattered, subfusiform to fusiform; apex obtuse to broadly acute.

Ecology and distribution

Widely distributed in the northern hemisphere with conifers and Betula. In the GYE, it occurs in montane mid-elevation mixed lodgepole/spruce-fir forests up through to high elevation mixed lodgepole/spruce-fir/whitebark pine forests, typically on drier, upland sites, summer to fall.

Specimens examined

U.S.A. MONTANA: Gallatin County, Gallatin Range, Fox Meadow, under Abies lasiocarpa, Picea engelmannii and Pinus albicaulis, 7 Sept 2013, EB125-13 (MONT); Gallatin County, Gallatin Range, Blackmore Trailhead, under Abies lasiocarpa and Pinus contorta, 15 Sept 2015, EB301-15 (MONT); Gallatin County, Gallatin Range, Lick Creek, under Picea engelmannii and Pinus contorta, 27 Aug 2014, EB0076-14 (MONT). WYOMING: Park County, Washburn Range, Dunraven Pass, under Pinus albicaulis and Pinus contorta, 10 Sept 2005, CLC2205 (MONT).

Discussion

Lactarius rufus appears to be an extremely morphologically and ecologically variable species, although more research is needed to see if this is backed up molecularly. At the ITS region, specimens from the GYE are molecularly identical to European specimens (RPB2 data missing for European collections) (Figure 2C). Similar species in the Rocky Mountains include L. badiosanguineus and L. luculentus v. laetus, both of which are less robust and not acrid.

Figure 24. 

Lactarius rufus. Collection EB0076-14 under Pinus contorta and Picea engelmannii, Gallatin Range, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius luculentus v. laetus Hesler & A.H. Sm.

Figure 25

Description

Pileus 30–50 mm in diameter, broadly convex to broadly infundibuliform, ± umbonate, smooth, viscid when wet but soon dry, yellow–orange to dull orange to brilliant orange to orange–brown; margin straight when young to wavy in age. Lamellae adnate to decurrent, crowded to subdistant, cream to pale yellow–orange. Stipe 20–60 × 5–10 mm, equal to slightly clavate to tapering toward the base, smooth, subviscid to dry, lighter than to concolorous with the pileus, typically getting lighter toward the apex, sometimes with scattered small scrobicules present, solid, becoming hollow. Context cream to pale yellow. Latex scarce, white, unchanging. Odor mild. Taste mild to slightly bitter.

Basidiospores 7–10 × 5.5–8 µm, Q = 1.2–1.5, broadly ellipsoid to ellipsoid; ornamentation forming a very broken reticulum. Pleuromacrocystidia 60–98 × 8–12 µm, scattered to numerous, strongly projecting, subfusiform to fusiform; apex acute. Cheilomacrocystidia none observed, possibly absent.

Ecology and distribution

In western North America with conifers. In the GYE it occurs in the montane spruce-fir zone, summer.

Specimens examined

U.S.A. MONTANA: Sweet Grass County, Crazy Mountains, Big Timber Creek, under Abies lasiocarpa and Picea engelmannii, 1 Aug 2015, EB097-15 (MONT).

Discussion

This is the first report of this taxon from the GYE under the name L. luculentus v. laetus. Previous reports of L. aurantiacus (Pers.) Gray from subalpine areas in the GYE (McKnight 1982) may refer to L. luculentus v. laetus.

Variety laetus is distinguished from var. luculentus by a brighter orange pileus as opposed to orange–brown and a mild to slightly bitter taste as opposed to slightly acrid (Hesler and Smith 1979). At the molecular level, there is some divergence within L. luculentus (Figure 2C, see also Barge et al. 2016) and there may be more than one species hiding under the name, although more specimens need to be examined and sequenced before making any nomenclatural changes.

Lactarius luculentus v. laetus is very closely related to L. aurantiacus and L. lanceolatus (Figure 2C) and morphological differences between them are subtle. Lactarius lanceolatus appears to have longer and more numerous cheilomacrocystidia (35.5–89 × 5–10 µm), longer pleuromacrocystidia (73.5–127 × 6.5–10 µm), as well as an alpine ecology with Salix. Lactarius aurantiacus also appears to have slightly longer pleuromacrocystidia (68.6–119.4 × 7.6–12.7 µm), and, while it occupies similar habitats to L. luculentus v. laetus, it may be absent from western North America outside of Alaska (Barge 2015).

The closely related Betula associate L. lapponicus Harmaja (syn.: L. duplicatus A.H. Sm.) (Figure 2C) has yellowing latex as opposed to white, unchanging latex, and appears to have a more boreal to arctic distribution (Heilmann-Clausen et al. 1998); it has not been reported from the Rocky Mountains. The closely related L. substriatus A.H. Sm. and L. subflammeus Hesler & A.H. Sm. (Figure 2C) have slightly smaller basidiospores (6.5–9 × 6–8 µm, 7.5–9 × 6.5–7.5 µm respectively), a slightly acrid taste, and are scarlet when young (Hesler and Smith 1979). The latex of L. substriatus also slowly stains pale yellow. Phylogenetic analyses suggest L. substriatus and L. subflammeus are conspecific, and that yellowing latex is a variable feature within the combined species, although more specimens should be sequenced before making this determination final. Neither of these taxa have been reported from the GYE and their distribution seems to be centered along the Pacific Northwest coast. The morphologically similar L. subviscidus, also centered along the Pacific Northwest coast, typically has smaller and more fragile basidiomes, a slightly acrid taste and unchanging latex which stains white paper yellow (Hesler and Smith 1979). In the Rocky Mountains, L. luculentus v. laetus and L. badiosanguineus occur in the same habitat and can easily be confused. However, the latter has slightly smaller basidiospores (7–9.5 × 6–8 µm) and typically has a more red–brown pileus which is often darker toward the center and lighter toward the margin.

Figure 25. 

Lactarius luculentus v. laetus. Collection EB097-15 under Abies lasiocarpa and Picea engelmannii, Crazy Mountains, Montana, USA. Scale bar: 2 cm. Photo by E. Barge.

Lactarius lanceolatus O.K. Mill. & Laursen

Figure 26

The following description is based on Barge et al. (2016)

Description

Pileus 10–45 mm in diameter, convex to depressed–convex at first, becoming plane to infundibuliform, with or without a small papilla, smooth, sometimes faintly scaly toward the center, viscid to dry, azonate, deep orange–brown to deep orange when immature becoming light to deep orange, often blotchy; margin incurved to straight when immature, becoming straight to upturned and often slightly wavy when mature, ± slightly crenulate. Lamellae adnate to subdecurrent, slightly crowded, pale cream to pale yellow to pale orange, discoloring brownish orange in age or where damaged. Stipe 10–20 × 2.5–7.5 mm, equal to clavate, smooth, dry, at first covered by faint whitish pubescence, pale orange, discoloring dingy orange to dingy light brown where damaged, hollow. Context pale orange. Latex scarce to undetectable, watery, white, unchanging. Odor mild. Taste mild.

Basidiospores 8–10 × 6–8 µm, Q = 1.1–1.4, broadly ellipsoid; ornamentation forming a broken reticulum. Pleuromacrocystidia 73.5–127 × 6.5–10 µm, scattered to abundant, strongly projecting, fusiform to lanceolate; apex acute to moniliform. Cheilomacrocystidia 35.5–89 × 5–10 µm, sparse to abundant, strongly projecting, conical to fusiform; apex acute to moniliform.

Ecology and distribution

Widespread in arctic-alpine areas in the northern hemisphere with Salix. In the GYE, it occurs above tree line in alpine areas with Salix reticulata, S. arctica, and S. planifolia, late summer.

Specimens examined

U.S.A. MONTANA: Carbon County, Beartooth Plateau, Highline Trail, among dwarf and shrubby Salix spp., 1 Aug 1997, ZT6214 (MONT); among Salix spp. 7 Aug 1998, ZT6412 (MONT); among Salix reticulata, 20 Aug 1999, CLC1389 (MONT); 5 Aug 2008, CLC2358 (MONT); 27 July 1997, CLC1139 (MONT); Carbon County, Hellroaring Plateau, Hellroaring Creek, among Dryas octopetala and shrubby Salix spp., 8 Aug 2015, EB104-15 (MONT); among Dryas octopetala, shrubby Salix spp. and S. reticulata, 8 Aug 2015, EB105-15 (MONT); among Betula glandulosa and shrubby Salix spp., 9 Aug 2015, EB103-15 (MONT). WYOMING: Park County, Beartooth Plateau, Solifluction Terraces, among Salix reticulata, 20 July 2001, CLC1578 (MONT); 13 Aug 2007, CLC2319 (MONT); among Salix arctica, S. planifolia and S. reticulata, 17 Aug 2013, EB 105-13 (MONT).

Discussion

Lactarius lanceolatus is closely related to L. aurantiacus, and L. luculentus/L. luculentus v. laetus (Figure 2C). It can be distinguished from L. luculentus/L. luculentus v. laetus in having longer cheilomacrocystidia and an alpine ecology with Salix, whereas the latter occur with conifers. Currently, we are unaware of any solid morphological differences between L. lanceolatus and L. aurantiacus. Lactarius lapponicus (syn.: L. duplicatus), which occurs in boreal and arctic-alpine areas in the Northern Hemisphere with Betula, and possibly other hosts, is also closely related, yet it features strongly yellowing latex (Heilmann-Clausen et al. 1998). Other similar orange taxa in western North America such as L. substriatus, L. subflammeus, and L. subviscidus all occur below tree line with conifers, and their distributions seem to be centered along the Pacific Northwest coast (Hesler and Smith 1979). See comments under L. badiosanguineus for features differentiating L. lanceolatus from that species.

Figure 26. 

Lactarius lanceolatus. Top collection EB103-15 under shrubby Salix spp. and Betula glandulosa, Hellroaring Plateau, Montana, USA. Bottom collection EB105-13 among Salix arctica, S. reticulata, and S. planifolia, Beartooth Plateau, Wyoming, USA. Scale bars: 2 cm. Photos by E. Barge.

Discussion

This study reports 20 Lactarius species, three varieties, and one unresolved species group from the GYE. Lactarius alpinus v. mitis with Alnus incana, L. barrowsii with Pinus flexilis, L. aff. brunneoviolaceus with Salix reticulata, L. luculentus v. laetus under mixed conifers, L. aff. olivinus with Picea engelmannii, L. pseudodelicatus with Populus tremuloides, and L. aff. tuomikoskii with Picea engelmannii are reported from the GYE for the first time. Lactarius badiosanguineus is also reported from the GYE for the first time, and it appears to fairly common throughout the Rockies with Picea, however, it has likely been misidentified in past treatments as L. hepaticus (Hesler and Smith 1979, Bessette et al. 2009) and L. subdulcis (McKnight 1982).

Several taxonomic problems in need of clarification were encountered. In the Rocky Mountains and North America in general, the group of species surrounding L. scrobiculatus (L. alnicola, L. gossypinus, L. aff. olivinus, L. payettensis, L. scrobiculatus v. canadensis, L. scrobiculatus v. montanus, and L. aff. tuomikoskii) requires clarification with respect to European taxa such as L. auriolla, L. leonis, L. olivinus, and L. tuomikoskii as was already highlighted by Kytövuori (1984). The “L. deliciosus” group, whose members are commonly encountered under conifers during the summer and fall in the GYE and elsewhere in western North America is also in need of clarification (Nuytinck et al. 2007). Species delimitation in the L. aurantiacusL. lanceolatusL. luculentus complex bares further scrutiny (Barge et al. 2016). The varieties L. alpinus v. mitis, and L. zonarius v. riparius may need to be raised to the species level. Potential conspecificity between the North American L. olympianus and the European L. zonarioides should be investigated. Further, the presence of L. helvus, L. resimus, L. torminosus, and L. trivialis in the GYE (McKnight 1982) and North America in general needs clarification (Hesler and Smith 1979).

Barge et al. (2016) reinforced the traditional concept of broad intercontinental distributions for alpine species associated with Salix (L. lanceolatus, L. nanus, L. salicis-reticulatae) and Betula (L. glyciosmus, L. pubescens). Based on the results of the present study, broad intercontinental distributions are also suggested for some Picea associates (e.g. L. badiosanguineus, L. repraesentaneus), some aspen associates (L. controversus, L. pubescens), and L. rufus, whose range of host affinities within the GYE remain difficult to untangle. However, it has been shown that at least some regions of the Lactarius genome, particularly the ITS region, are relatively slowly evolving (Verbeken and Nuytinck 2013, Barge et al. 2016), thus inclusion of more loci and individuals in phylogenetic analyses would likely reveal finer biogeographic patterns for these taxa. Broad intercontinental distributions have also been confirmed for some western North American arctic-alpine and subalpine members of the ectomycorrhizal genus Inocybe (Cripps et al. 2010, Larsson et al. 2014) as well as for some members of the ectomycorrhizal genus Cortinarius subg. Phlegmacium associated with P. tremuloides in western North America (Cripps et al. 2015).

Lactarius species reported from the GYE such as L. barrowsii with Pinus flexilis, L. rubrilacteus with Pseudotsuga menziesii, and L. caespitosus with Abies lasiocarpa, appear to be restricted to western North America. The distribution and host affinities of some species is not clear due in part to taxonomic problems (e.g. “L. deliciosus” group) or the relative rarity with which they have been collected and reported (e.g. L. pallidomarginatus, L. pseudodelicatus, L. zonarius v. riparius). Interestingly, nearly every major ectomycorrhizal host plant in the GYE has at least one Lactarius species associated with it, with some species appearing to be highly host specific (Table 2), highlighting the importance of this genus in the GYE.

Acknowledgments

We thank Vera Evenson, Dr Egon Horak, Jukka Vauras, Dr Ellen Larsson, Dr Pierre-Arthur Moreau, Dr Ursula Peintner, and herbaria G, IB, TU, O, GB, TURA, C, LIP, MICH, DBG, VPI, ZT and NY for loan of specimens. Support from the Montana Institute on Ecosystems graduate enhancement fund is also gratefully acknowledged.

References

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