New reports, phylogenetic analysis, and a key to Lactarius Pers. in the Greater Yellowstone Ecosystem informed by molecular data

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.


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 andAnderson 1991, Knight 1994).
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(Buyck et al. , 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 Mc-Knight (1982), Moser and McKnight (1987), Cripps and Miller (1993), Cripps (2001Cripps ( , 2003Cripps ( , 2011, Mohatt et al. (2008), Cripps and Horak (2008), Cripps and Antibus (2011), 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).

Study sites
This study was performed in the GYE (Figure 1 (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.

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 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.
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.
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).
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 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. 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.

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 typi- 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. cally 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.  Figure 3 Description. Pileus 8-20 mm in diameter (to 80 mm in Hesler and Smith 1979), planoconvex to infundibuliform, ± papillate, dry, finely rimulose to minutely squamulose, redbrown 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. 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 4 The following morphological description includes data from Colorado specimens listed in Barge et al. (2016).

Lactarius nanus J. Favre
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 graybrown 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. Cheilo- Discussion. L. nanus is morphologically and phylogenetically close to L. hysginoides Korhonen & T. Ulvinen (Figure 2A), however, the latter has a more cinnamontoned 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 5 The following morphological description includes data from Colorado specimens listed in Barge et al. (2016).
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. 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).
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. 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 7 The following morphological description is based on Barge et al. (2016).
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. 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 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 in- curved 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.

Lactarius pallidomarginatus Barge & C.L. Cripps
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.
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 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.
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.  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.
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. 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 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 graybrown 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.
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. 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 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 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 (Hesler and Smith 1979). 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 pinktan, 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.
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. 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 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.
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.  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).
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.

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)
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. 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 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.
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. 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).
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 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.
Ecology and distribution. In montane, rich, moist habitats with Picea engelmannii, mid to late summer. 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 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 yellowbrown 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.
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.  Figure 2B), previously shown by . 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 ).  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.
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. 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 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.
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 andAntibus 2011), and one collection is reported here with Arctostaphylos uva-ursi, wellseparated from any conifers. Discussion. While section Deliciosi (Fr.:Fr.) Redeuilh, Verbeken & Walleyn has been resolved as monophyletic   (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,  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 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.
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. Discussion. This is the first report of this species from the GYE under the name L. badiosanguineus. In North American treatments (e.g. 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

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 orangetan 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.
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. 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 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  Barge. 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.
Ecology and distribution. In western North America with conifers. In the GYE it occurs in the montane spruce-fir zone, summer. 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.
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 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 redbrown pileus which is often darker toward the center and lighter toward the margin. 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.

Lactarius lanceolatus O.K. Mill. & Laursen
L. scrobiculatus v. montanus, and L. aff. tuomikoskii) requires clarification with respect to introduction The "Flora Mycologica Iberica Project dataset" is one of the main results produced by the "Flora Mycologica Iberica", a research project that stood from 1988 to 2008 and involved over 30 researchers from Spain and Portugal. This dataset contains information on 2,445 species of fungi recorded from The Iberian Peninsula and Balearic Islands. As an online resource, it is a valuable source of information on fungi growing in that area, with a high reuse potential, given its coverage, taxonomic scrutiny --carried out by taxonomic experts in the different groups--and validation processes of the associate information (location, habitat). The other major outcome of the project were the monographs of the studied groups: Aphyllophorales [p.p.] (Telleria and Melo 1995), Myxomycetes [p.p.] , Gasteromycetes [p.p.] (Calonge 1998), Laboulbeniales  and Dictyosporic Dothideales (Checa 2004). These publications provide descriptions, illustrations, identification keys and additional information on many of the species and taxa included in this dataset.

General description
Purpose: This dataset was conceived within the Flora Mycologica Iberica Project (FMI).
The ultimate objective of the FMI project was to make a critical flora which enables the identification of fungi naturally growing in the Iberian Peninsula and Balearic Islands (excluding parasites of humans and other mammals).
The purpose of the dataset was: that information at hand, we could target the specific publications and occurrences needed for the check-lists and monographs to be prepared within the FMI project. Data entry management and publication were carried out using the Bibmaster software v. 3.7 .
Manuals and guidelines were prepared to establish a clear standard basis regarding data entry and quality control procedures (Pando 1991, Pando et al. 1999.

Taxonomic coverage
General taxonomic coverage description: Dataset comprising distribution records of fungal species belonging to selected groups (Agaricomycetes, Dothideomycetes, Mycetozoa, Laboulbeniomycetes, Ustilaginomycetes and aquatic Hyphomycetes) found in the Iberian Peninsula and Balearic Islands (Western Europe). Sources included literature, herbaria and field surveys.

Taxonomic ranks
The consensus classification provided by Index Fungorum in Catalogue of Life (Kirk 2016) has been followed for taxonomic categories above genus.
It is worth mentioning that recent and profound changes in fungal classification have rendered some categories used in the project such as "Gasteromycetes" or "Aphyllophorales" obsolete. These groups, now referred informally as Gasteroid and Corticioid fungi, are especially well-covered, but scattered across a number of orders (cf. Pegler et al. 1995, Kirk et al. 2008, Larsson 2007.

Spatial coverage
General spatial coverage: Iberian Peninsula, Balearic Islands, South-Western Europe Coordinates: 35°45'36"N and 44°2'60"N Latitude; 9°56'60"W and 4°54'36"E Longitude This comprises: Continental Portugal and Spain, Andorra and Balearic Islands. No records from Gibraltar (UK) have been included. A map showing georeference records and its density is provided (Fig. 3). Two additional maps showing records aggregated by province are presented here to show how records with coordinates provide only a partial view of the actual knowledge on Iberian fungi (Figs 4, 5). This highlights the importance of retrospective georeferencing when carrying on species distribution models and other geospatial analyses.

Study extent description:
Scientific literature was the main source for fungal occurrence records. Herbarium revisions, which included published and unpublished records, supplemented literature information. Additionally, targeted field campaigns were carried out within the framework of the project to fill gaps on sites poorly known and of ecological or conservation relevance such as national parks, and other protected areas. Unpublished relevant data were published as the "Bases Corológicas series in "Cuadernos de Trabajo" and reflected in the AssociatedReference field. Sampling description: These two data avenues were subjected to different methodologies, as explained below.
Data collation from literature references. Three procedures are defined in this area: 1) Identifying and obtaining relevant publications. A set of explicit criteria to determine whether a publication was eligible to be included into the database was defined. These were published by Pando (1996: 215-217). The Library of the Real Jardín Botánico-CSIC was the main source for literature. When an eligible publication was identified and not found in this library, a copy was obtained by the usual procedures (library exchange, colleagues, etc.) and deposited in that Library.
2) Treated genus data entry. Genus names were extracted in a systematic way from the publications and entered into the database. Publications and genus names compiled up to, and including, 1995 were published in three volumes of the "Cuadernos de Trabajo" series , Cardoso and Melo 1992, Pando 1996. At this point, the database contained data from c. 5,000 publications, at the end of the project this gathered data pertaining to c. 10,000 publications. Although teleomorph nomenclature is used in the dataset, literature collation was made for anamorphic as well as teleomorphic genera.
3) Occurrence data entry. A protocol in which occurrence records were entered targeting specific taxonomic groups --on the basis of the project's priorities and the schedule for the publication of the monographs--was implemented at the early stages of the project. An effort was made to record all information associated to each occurrence, following an established schema, as described by Pando (1991). Besides scientific name, date and locality details, habitat -including host -is provided for the 78% of the records.
These works were mostly carried out by a small team of data entry technicians and supervisors, with the support of the Project's scientific team.
Primary data produced and compiled as part of the research conducted within the project, by researchers involved in the project, were also incorporated into the database. These come from studied specimens held in herbaria or fields surveys carried out within the framework of the project. These data, when relevant, were published as the "Bases Corológicas series in "Cuadernos de Trabajo" (14 volumes published between 1991 and 2008. See References). No species have been retrieved from molecular data.
Quality control description: Quality control and assurance comprises a number of procedures, references and tools along the data life cycle. These can be summarized as follows: • A data-entry manual on what to capture and what not and how to capture the information was developed and published (Pando 1991). • International standards approved or endorsed by the "Biodiversity Information Standards/TDWG). Specifically, the following were used: Brummitt and Powell (1992), Lawrence et al. (1968), and TL-2 (Stafleu and Cowan 1976, Stafleu and Mennega 1992-2000, Dorr and Nicolson 2008). • When herbarium information was available, this was recorded under column "oth-erCatalogNumbers" following "Index Herbariorum" (Thiers 2016) standard abbreviations. • Additionally, the following works were used as a reference for taxonomic names: Farr et al. (1979aFarr et al. ( , b, c, 1986, and the Dictionary of the Fungi (Hawksworth et al. 1983, Kirk et al. 2001, 2008, Saccardo (1882Saccardo ( -1931. • The database management system used ) had many of these standards build-in as dictionaries and controlled vocabularies. • All newly entered records were checked against the actual publications by the supervisors as part of the database work flow. • A final check was done by the "Bases Corológicas" authors and editors as part of the publication process. • Dataset publication in the GBIF network include data transformation to comply with the Darwin Core specification (Wieczorek et al. 2012) and further validation procedures (geographic coordinate format, coordinates within country/provincial boundaries, absence of ASCII anomalous characters in the dataset) using DAR-WIN_TEST (v3.3) software (Ortega-Maqueda and Pando 2008).
Host information as well as geographic coordinates have been taken from the sources. Obvious errors and typos have been corrected, but no in-depth interpretation of these details nor retrospective georeferencing was carried out. This approach guarantees fidelity to the sources, but also results in some unavoidable heterogeneity in the information made available.