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Research Article
A key to the species of Hyphodontia sensu lato
expand article infoEugene Yurchenko, Sheng-Hua Wu§
‡ Paleski State University, Pinsk, Belarus
§ National Museum of Natural Science, Taichung, Taiwan
Open Access

Abstract

A dichotomous key to all currently accepted species of Hyphodontia in the broad sense is presented. It consists of a key to genera (Alutaceodontia, Botryodontia, Chaetoporellus, Deviodontia, Hastodontia, Hyphodontia s. str., Kneiffiella, Lagarobasidium, Lyomyces, Palifer, Rogersella, Schizopora, Xylodon) and detailed keys to species level within genera. The key also includes taxa which were published under preliminary names (such as ‘Hyphodontia species A’) and some taxa which require taxonomic clarification (like Hyphodontia macrescens). Some recently describes Hyphodontia species are placed in the keys to Palifer and Xylodon due to their morphology.

Key words

Basidiomycota, cystidia, global species diversity, Hymenochaetales, taxonomy

Introduction

Hyphodontia J. Erikss. (Hymenochaetales) in its broad sense is a genus of resupinate non-poroid Basidiomycota. Its species commonly occur on dead wood worldwide from Arctic tundra (Mukhin 2006) to evergreen equatorial forests (Hjortstam et al. 1998). In the latter case they belong in the strict sense mainly to Botryodontia and Schizopora. The latest global monograph of the genus (Langer 1994) included descriptions of 53 Hyphodontia species and 4 Schizopora species.

The aim of our work was to construct a key, which can serve as a tool for further studies of Hyphodontia s. l., especially when describing new species. The key includes 126 validly published species, four unnamed taxa (e.g. Hyphodontia sp. 1), and three taxa with affinity formulation (e.g. Kneiffiella cf. abieticola), for which brief or detailed descriptions have been published. The taxa requiring taxonomic clarification, e.g. species with poor types (Kneiffiella byssoidea, Xylodon nudisetus, X. rimosissimus; Parmasto et al. 2004), are included in the key equally with ‘good’ taxa.

For identification convenience, the species are assigned to 13 derivative genera, adopted by Hjortstam and Ryvarden (2009). However, among these genera the independence of Hastodontia, Hyphodontia s. str., Kneiffiella, and Lagarobasidium only is confirmed by molecular phylogenies (Larsson et al. 2006; Yurchenko and Wu 2014). Species of Fibrodontia were excluded because they belong to trechisporoid lineage (Larsson 2007). Palifer seychellensis Dämmrich & Rödel was excluded from consideration because of unusual cystidia with double umbrella-like incrustations and probable belonging to the genus Sceptrulum K.H. Larss. (Karasiński 2014). In addition to the concept of Hyphodontia s. l., the genus Botryodontia in the key as several species in this genus have been earlier combined in Hyphodontia s. l. as well. Botryodontia is related to Oxyporus (Sell et al. 2014), and is a presumed member of the hymenochaetoid clade.

Because of the diffuse generic borders within Hyphodontia s. l., the species are listed in the key with their main synonyms when combined in different genera. Recently described Hyphodontia species, that have never been combined in other genera, are included in the appropriate subordinate keys according to their morphology. For example, H. septocystidiata is keyed within Palifer and H. heterocystidiata within Xylodon. Morphological types of cystidia, important for the identification of genera and species, are illustrated on Fig. 1. Spore quotient (length/width ratio) is denoted in the key as Q. Distribution of each species in parts of the world is given after “distr.”

Figure 1.

Types and shapes of cystidial elements in Hyphodontia s.l.: A1 skeletocystidium A2 tubular B septocystidium C hastocystidium D gloeocystidium E astrocystidium F lagenocystidium G cylindrical apically encrusted (lamprocystidium-like) H vesicular or bladder-like (embedded) I cylindrical J subclavate K clavate L fusoid M spatuliform N moniliform (torulose) O ventricose submucronate P subcapitate Q capitate R capitate with resinous cap S capitulate T lecythiform U tapering (subulate with blunt apex) V acute W acuminate (subulate with pointed apex) X hyphoid cylindrical Y hyphoid subcapitate; Z, hyphoid capitate. See also Appendix.

Keys

Key to the segregated genera and some species within Hyphodontia s. l

1 Spores warted or minutely echinulate, globose, slightly thick-walled Rogersella [R. griseliniae (G. Cunn.) Stalpers (Hyphodontia griseliniae (G. Cunn.) E. Langer ‘griselinae’, R. asperula Liberta & A.J. Navas)]; distr.: Macaronesia, Africa, southwest Indian Ocean islands, South America, New Zealand, Oceania
The other known species in the genus, R. eburnea Hjortstam & Högholen, should according to its morphology (subceraceous basidioma, smooth hymenophore, gelatinized subhymenial hyphae, subclavate basidia, suballantoid spores) be classified as Phlebia s. l.
Spores smooth, globose to cylindrical or allantoid, thin- to thick-walled 2
2 Clamps lacking at all septa 3
Clamps present at some, at many, or at all primary septa 6
3 Basidia obovate to clavate 4
Basidia cylindrical-utriform 5
4 Hymenophore granulose to irpicoid-labyrinthoid; capitate cystidia absent Botryodontia ...(Key A)
Hymenophore poroid; small capitates cystidia numerous Xylodon poroideoefibulatus
5 Basidia with 4 sterigmata Botryodontia tetraspora
Basidia with 2 sterigmata Kneiffiella efibulata
6 Lagenocystidia or lagenocystidia-like elements (like small lamprocystidia) present in hymenium 7
Lageno- and similar encrusted cystidia lacking 8
7 With rare to numerous lagenocystidia, or with apically richly encrusted, short cylindrical cystidia Hyphodontia s. str...(Key D)
With lamprocystidia-like elements Palifer ...(Key H)
8 Hymenophore distinctly irpicoid or poroid 9
Hymenophore smooth to odontioid and hydnoid, seldom slightly irpicoid or with spathulate aculei 12
9 Hyphal system monomitic 10
Hyphal system dimitic, trimitic or pseudodimitic (subdimitic) with skeletal-like hyphae in subiculum 11
10 Spores allantoid, about 0.8 μm broad Chaetoporellus (Ch. latitans)...(Key B)
Spores subglobose to cylindrical or suballantoid, at least 2 μm broad Xylodon ...(Key J)
11 In hymenium moniliform cystidia Xylodon bresinskyi
Constricted cystidia absent Schizopora ...(Key I)
12 Spores allantoid, 0.5–1.5(–2) μm broad 13
Spores subglobose to cylindrical or suballantoid, broader, than 2 μm 16
13 Tubular thick-walled cystidia present Kneiffiella ...(Key E)
Tubular thick-walled cystidia absent, but cylindrical thin-walled cystidia sometimes present 14
14 Hymenophore with aculei reaching 1–2 mm long; spores significantly curved, 4–5 μm long Chaetoporellus (Ch. curvisporus)...(Key B)
Hymenophore with aculei less than 1 mm long; spores slightly or moderately curved, 5–8 μm long 15
15 Spores 6–8 × 1.5(–2) μm; cystidia cylindrical to torulose, mostly 50–75 × 4–7 μm; some samples with conidia 8–10 × 3–4 μm in hymenium... Alutaceodontia (Parmasto) Hjortstam & Ryvarden [A. alutacea (Fr. : Fr.) Hjortstam & Ryvarden (Hyphodontia alutacea (Fr. : Fr.) J. Erikss.]; distr.: Eurasia, North and South America
Spores 5–6 × 1–1.5 μm; only with subclavate cystidioles or basidioles, 8–10 × 3–3.5 μm, and projecting cylindrical and subcapitate hyphal ends; conidia unknown Xylodon scopinellus
16 Hyphal system dimitic with skeletal hyphae, or subdimitic because of the presence of thick-walled hypha-like bases of tubular cystidia, or pseudodimitic due to skeletoid (skeletal-like) hyphae in aculeal trama or dissepiment 17
Hyphal system monomitic, but subicular hyphae and hyphae in aculeal trama can be thick-walled 19
17 With tubular cystidia Kneiffiella ...(Key E)
Typical tubular cystidia lacking, but elements of intermediate morphology between hyphae and tubular cystidia present in aculeal trama 18
18 Aculeal trama with skeletocystidia: long, narrow, thick-walled, often yellow-pigmented in mass, naked of covered with tablet-shaped crystals; capitate or subcapitate hyphal ends or cystidia absent in aculei; basidia when mature suburniform Fibrodontia
Aculeal trama with skeletal-like hyphae or with thick-walled hyphoid cystidia, often encrusted (crystals not flattened); capitate or subcapitate cystidial elements present in aculei; basidia more or less utriform Xylodon ...(Key J)
19 Spores cyanophilous with distinctly thickened or thick wall 20
Spores acyanophilous (rarely somewhat cyanophilous) thin- or slightly thick-walled 21
20 Capitate cystidia often with a resinous cap; cylindrical cystidia embedded Xylodon crassisporus
Capitate cystidia if present, lack the resinous cap; cylindrical cystidia if present, distinctly projecting Lagarobasidium ...(Key F)
21 Hymenophore coarsely odontioid, raduloid or semiporoid, with aculei 1–5(–7) mm long; cystidia clearly capitate, with broadened base, projecting clearly over the basidia, 50–85 × 7–10 μm; basidia nearly subcylindrical Deviodontia (Parmasto) Hjortstam & Ryvarden [D. pilicystidiata (S. Lundell) Hjortstam & Ryvarden (Hyphodontia pilicystidiata (S. Lundell) J. Erikss. ‘pilaecystidiata’)]; distr.: Europe
Langer (1994) proposed to treat this taxon in Hyphoderma because of large capitate cystidia and spores with granular contents.
Hymenophore smooth to hydnoid, raduloid or poroid; aculei rarely up to 3 mm long; projecting capitate cystidia, if present, often smaller, and frequently classified as capitate hyphal ends or cystidioles; basidia usually utriform 22
22 Septocystidia present, distinct Hyphodontia s. str...(Key D)
Septocystidia absent or little differentiated 23
23 Hymenophore smooth to slightly tuberculate; generally two types of cystidia: (1) moniliform, embedded or slightly projecting, (2) projecting, capitate cystidia or hastocystidia, apically often with resinous excretion; spores subcylindrical Hastodontia ...(Key C)
If with moniliform cystidia, then hymenophore odontioid or hydnoid, or spores ellipsoid; projecting capitate cystidia naked or with resinous cap; hastocystidia if present, lacking apical excretion; spores globose to suballantoid 24
24 Hymenophore usually odontioid, sometimes almost smooth to hydnoid or poroid; usually with tufts of projecting hyphal ends or cystidia in hymenophoral aculei; hymenial surface usually cream-colored; spores thin-walled, rarely somewhat thick-walled, subglobose to suballantoid, acyanophilous, rarely somewhat cyanophilous; cystidia subulate to cylindrical, capitate or moniliform; subicular hyphae naked to richly encrusted Xylodon ...(Key J)
Hymenophore smooth to tuberculate; typically no tufts of projecting hyphal ends or cystidia; hymenial surface white or with age pale cream, in herbarium material white, cream or yellowish; spores thin- to somewhat thick-walled, globose to oblong, slightly or distinctly cyanophilous; cystidia capitate or fusoid, or of both types; subicular hyphae usually encrusted Lyomyces ...(Key G)

Key A. Botryodontia

1 Cystidia long (40‒180 μm), cylindrical, tubular, more or less thick-walled 2
Cystidia never tubular, thin-walled, sometimes indistinct, 15‒40 μm long 4
2 Spores 3‒5 × 2‒2.5 μm; hymenophore minutely warted B. tetraspora (S.S. Rattan) Hjortstam & Ryvarden [Hyphodontia efibulata f. tetraspora S.S. Rattan; H. tetraspora (S.S. Rattan) Hjortstam; Kneiffiella tetraspora (S.S. Rattan) Hjortstam & Ryvarden]; distr.: South Asia
Spores 4‒6.5 × 3‒4 μm; basidioma farinaceous-granulose or hymenophore odontioid to irpicoid 3
3 Basidioma farinaceous-granulose; spores with thin or thickened walls, 5‒6(‒6.5) × 3‒4 μm B. crassispora P. Roberts [Kneiffiella crassispora (P. Roberts) Hjortstam & Ryvarden]; distr.: Africa
Basidioma odontioid or raduloid-irpicoid; spores thin-walled, 4‒5 × 3‒3.7 μm B. subglobosa (Sheng H. Wu) Hjortstam [Hyphodontia subglobosa Sheng H. Wu; Kneiffiella subglobosa (Sheng H. Wu) Hjortstam]; distr.: East Asia
4 Hymenophore irpicoid-labyrinthoid; gloeocystidia present in hymenium, clavate or irregular-shaped (sinuous); spores broadly ellipsoid to subglobose, 4‒7 × 3.3‒5.5 μm B. millavensis (Bourdot & Galzin) Duhem & H. Michel; distr.: Europe
Hymenophore semi-odontioid to odontioid; gloeocystidia absent; spores ellipsoid, 5‒6.5 × 3.5‒4.5 μm 5
5 Hymenophoral aculei 0.1‒0.3 mm long; spores (5‒)5.5‒6(‒6.5) × 4‒5 μm B. cirrata (Hjortstam & Ryvarden) Hjortstam [B. denticulata Hjortstam; B. formosana (Sheng H. Wu & Burds.) Hjortstam; Hyphodontia formosana Sheng H. Wu & Burds.]; distr.: pantropical
Hymenophoral aculei 0.4‒0.5(‒0.75) mm long; spores 5‒5.5(‒6) × (3.5‒)3.8‒4(‒4.3) μm B. semispathulata Hjortstam & Ryvarden; distr.: South America

Key B. Chaetoporellus Bondartsev & Singer

1 Hymenophore odontioid or sometimes almost smooth; cystidia 35–70 × 4–7 μm; spores 4–5 × 1–1.5(–2) μm Ch. curvisporus (J. Erikss. & Hjortstam) J. Erikss. & Hjortstam (Hyphodontia curvispora J. Erikss. & Hjortstam); distr.: Europe, Central America
Hymenophore poroid with rounded, lacerate or labyrinthiform pores; cystidia 30–35 × 4–5 μm; spores 3–4 × 0.5–1 μm Ch. latitans (Bourdot & Galzin) Bondartsev & Singer [Hyphodontia latitans (Bourdot & Galzin) Ginns & Lefebvre]; distr.: Europe, North America, Oceania

Key C. Hastodontia (Parmasto) Hjortstam & Ryvarden

1 With capitate projecting cystidia, 30–60 × 4–5 μm, capped by resinous matter (the matter usually disappearing in microscopic slides); acute cystidia absent; spores 4.5–5.5 × 2–2.5 μm H. halonata (J. Erikss. & Hjortstam) Hjortstam & Ryvarden (Hyphodontia halonata J. Erikss. & Hjortstam); distr.: Europe
No capitate cystidia; with projecting hastocystidia, about 50 μm long, 5–7 μm wide, some of them apically with a globe of resinous matter (the matter easily dissolving in slides); spores 5–7 × 2–3 μm H. hastata (Litsch.) Hjortstam & Ryvarden [Hyphodontia hastata (Litsch.) J. Erikss.]; distr.: temperate north hemisphere

Key D. Hyphodontia J. Erikss. s. str

1 Hymenophore poroid H. borbonica Riebesehl, E. Langer & Barniske; distr.: southwest Indian Ocean islands
Hymenophore smooth to hydnoid 2
2 Capitate or subcapitate cystidial elements lacking H. wrightii Hjortstam & Ryvarden [Palifer wrightii (Hjortstam & Ryvarden) Hjortstam & Ryvarden]; distr.: South America
The species was included in Hyphodontia s. str. by Gorjon (2012).
Capitate or subcapitate cystidial elements present 3
3 With capitate or subcapitate septocystidia (usually with 2–3 septa), distinctly protruding above the hymenium; hymenophore smooth to grandinioid 4
Capitate or subcapitate cystidia usually with a basal septum only, little protruding above the hymenium, or hypha-like and arranged in tufts at aculeal apices; hymenophore smooth to hydnoid 8
4 Lagenocystidia more or less numerous 5
Lagenocystidia absent or occasional 6
5 Spores 4.5–5 × 3–3.5 μm; septocystidia up to 80 μm long H. alutaria (Burt) J. Erikss.; distr.: cosmopolitan
Spores 6–7.5 × 4–4.5 μm; septocystidia up to 110 μm long H. subdetritica S.S. Rattan (H. propinqua Hjortstam); distr.: Asia, Africa
6 Spores 3.5‒5 × 2‒3 μm; septocystidia 80–120 μm long, slightly thick-walled 7
Spores 5–8 × 4–5.5 μm; septocystidia 60–73 × 6–7 μm, thin-walled H. subpallidula H.X. Xiong, Y.C. Dai & Sheng H. Wu; distr.: East Asia
7. Hymenophore smooth or finely tuberculate; subicular hyphae thin-walled, 2‒3 μm wide, moderately densely packaged; septocystidia 4–6 μm wide; spores 3.5–5.5 × 2–3 μm H. pallidula (Bres.) J. Erikss.; distr.: Eurasia, North America
Hymenophore odontioid; subicular hyphae with thickened walls, 4‒5 μm wide, loosely arranged; septocystidia 7‒8 μm wide; spores 4.5‒5 × 3 μm H. alba Sheng H. Wu; distr.: East Asia
According to Hjortstam and Ryvarden (2009), this species has features of Hyphoderma and Lyomyces.
8 Hymenial surface smooth; no capitate cystidia; lagenocystidia few, sometimes absent H. subdetritica (see step 5)
Hymenial surface odontioid to hydnoid; capitate cystidia present; lagenocystidia scattered to numerous 9
9 Spores up to 4.5 μm long, globose to broadly ellipsoid, slightly thick-walled H. sphaerospora (N. Maek.) Hjortstam [H. arguta var. sphaerospora (N. Maek.) N. Maek.]; distr.: East and Southeast Asia, South America
Spores up to 5–6 μm long, ellipsoid to cylindrical, occasionally subglobose, thin- to slightly thick-walled 10
10 Spores ellipsoid, occasionally subglobose, (4–)4.5–6 × (3–)3.5–3.7(–4) μm H. arguta (Fr. : Fr.) J. Erikss. [H. lageniformis Sang H. Lin & Z.C. Chen, H. stipata (Fr. : Fr.) Gilb.]; distr.: cosmopolitan
H. lageniformis is synonymized with H. arguta (Langer 1994), and evidently is a variety of the latter, with smaller spores (4.5 × 3–4 μm) and shorter basidia (10–11 μm, according to the original description).
Spores narrowly ellipsoid to cylindrical, 4.3–5.3 × 2–3 μm 11
11 Hymenophoral aculei up to 3 mm long; spores 4.5–5 × 2–2.5(–3) μm; mucronate (apically papillate) cystidia present; lagenocystidia scattered; capitate cystidia in aculeal apices; basidia 10–15 μm long H. ochroflava (Pat.) Nakasone; distr.: Southeast Asia
Hymenophoral aculei up to 6 mm long; spores 4.3‒5.3 × 2.5‒3 μm; no mucronate cystidia; capitate cystidia also on lateral surfaces of aculei; lagenocystidia numerous; basidia 22‒28 μm long H. dhingrae Samita & Sanyal; distr.: South Asia

Key E. Kneiffiella P. Karst

1 Clamps absent at all septa 2
Clamps present at all or most primary septa 3
2 Spores subglobose to ellipsoid, 4‒4.5(‒5) × (2.5–)3(‒3.5) μm K. byssoidea (H. Furuk.) Hjortstam & Ryvarden ‘byssoideus’ [Hyphodontia byssoidea (H. Furuk.) N. Maek. ‘byssoideum’]; distr.: East Asia
Spores oblong to cylindrical, adaxially flat or concave, 5–5.5 × 2–2.5 μm K. efibulata (J. Erikss. & Hjortstam) Jülich & Stalpers (Hyphodontia efibulata J. Erikss. & Hjortstam); distr.: Europe
3 Spores broadly ellipsoid to short cylindrical, Q = 1.4–2.2 4
Spores cylindrical to allantoid, Q = (1.9–)2.3–4 11
4 Spores broadly ellipsoid to ellipsoid, Q = 1.4–1.7; hymenophore odontioid to hydnoid 5
Spores narrowly ellipsoid to short cylindrical, Q = (1.6–)1.8–2.2; hymenophore smooth to odontioid 7
5 Subicular hyphae with clamps at all primary septa; spores 4.5–6 × 3–4.5 μm 6
Subicular hyphae partly simple septate; sometimes clamps only scattered on sibicular hyphae and on projecting hyphae in the aculei; spores 3.5–5 × 2.5–3.5 μm Hyphodontia orasinusensis Gilb. & M. Blackw. [Kneiffiella crassa (Rick) Hjortstam & Ryvarden, non Hyphodontia crassa Z.C. Chen & Sang H. Lin; K. stereicola (Bres.) Nakasone]; distr.: North America
6 Hymenophore hydnoid with aculei 1–3 mm long; tubular cystidia 6–8 μm broad; spores often broadly ellipsoid, 4.5–5.5(–6) × 3.5–4.5 μm K. barba-jovis (Bull. : Fr.) P. Karst. [Hyphodontia barba-jovis (Bull. : Fr.) J. Erikss., H. irpicoides (P. Karst.) Burds. & M.J. Larsen]; distr.: Eurasia, North America
Hymenophore odontioid or minutely hydnoid, with aculei less 1 mm long; tubular cystidia 4–6 μm broad; spores ellipsoid, 5–6 × 3–3.5 μm K. cf. abieticola (Hjortstam and Ryvarden 2007b); distr.: South America
7 Some tubular cystidia with excreted resinous matter near or on apex; excretion stable or slowly disappearing in 5% KOH solution 8
Tubular cystidia without resinous excretion in apical part 9
8 Hymenial surface smooth to odontioid, cream to beige; spores 2.5–4.5 × 1.5–2.5 μm, ellipsoid to cylindrical; tubular cystidia reaching about 100 × 8 μm in size, with the wall up to 2 μm thick; cystidial apical or subapical excretion crust-like, preserving in KOH; subicular hyphae 2–3 μm broad, with wall up to 1 μm thick K. microspora (J. Erikss. & Hjortstam) Jülich & Stalpers (Hyphodontia microspora J. Erikss. & Hjortstam); distr.: cosmopolitan
Hymenial surface odontioid, ochraceous; spores 4–5.5 × 2.5–3 μm, cylindrical to somewhat depressed adaxially; tubular cystidia reaching about 1000 × 14 μm in size, with wall up to 1.5 μm thick; cystidial apical or subapical excretion granular, dissolving in KOH; subicular hyphae 3–4 μm diam, with wall up to 0.5 μm thick K. palmae (Rick) Hjortstam & Ryvarden [Hyphodontia palmae (Rick) E. Langer]; distr.: South America, East Asia
This taxon is conspecific with K. microspora according to Hjortstam and Larsson (1995).
9 Hymenial surface smooth; tubular cystidia usually 80–100 μm long, normally encrusted in the middle part by coarse crystals K. alienata (S. Lundell) Jülich & Stalpers [Hyphodontia alienata (S. Lundell) J. Erikss.]; distr.: Europe, Africa, North and South America
Hymenial surface warted to odontioid; tubular cystidia mostly 100–150 μm long, naked, sometimes scarcely encrusted 10
10 Tubular cystidia cylindrical, with walls up to 2.5 μm thick K. abieticola (Bourdot & Galzin) Jülich & Stalpers [Hyphodontia abieticola (Bourdot & Galzin) J. Erikss.]; distr.: Eurasia, North America
Tubular cystidia thin-walled and tapering in upper half, in lower half with walls up to 1.5 μm thick Hyphodontia sp. A (Eriksson and Ryvarden 1976; Ginns and Lefebvre 1993); distr.: North America
11 Hymenophore smooth (under the lens often porose-reticulate or finely furfuraceous) 12
Hymenophore warted, odontioid or distinctly floccose 15
12 Spores 1.5–2 μm broad 13
Spores 2–3 μm broad 14
13 Spores 4.5–6 μm long; tubular cystidia up to 10 μm broad, reaching about 300 μm in length K. altaica (Parmasto) Hjortstam & Ryvarden (Hyphodontia altaica Parmasto); distr.: Asia
Spores 6–8 μm long; tubular cystidia up to 7(–8) μm broad, reaching about 150(–200) μm in length K. subalutacea (P. Karst.) Jülich & Stalpers [Hyphodontia subalutacea (P. Karst.) J. Erikss.]; distr.: cosmopolitan
14 Tubular cystidia very long (up to 250–280 μm) and very thick-walled (up to 6 μm); spores 7–10 μm long K. decorticans (Gresl. & Rajchenb.) Hjortstam & Ryvarden (Hyphodontia decorticans Gresl. & Rajchenb.); distr.: South America
Tubular cystidia usually not exceeding 120 μm in length, moderately thick-walled; spores 5.5–7 μm long K. cineracea (Bourdot & Galzin) Jülich & Stalpers [Hyphodontia cineracea (Bourdot & Galzin) J. Erikss. & Ryvarden]; distr.: Europe, West Asia, South America
15 Tubular cystidia very thick-walled (up to 6 μm); spores 2.5–3 μm broad K. decorticans (see step 14)
Tubular cystidia moderately thick-walled (0.5–2.5 μm); spores 1.5–2.2 μm broad 16
16 Spores cylindrical, slightly concave adaxially, 4.7–5.5 μm long; basidia 7–13 μm long; walls in subicular hyphae thickened to thick (up to 1.2 μm) K. tubuliformis Sheng H. Wu [Hyphodontia tubuliformis (Sheng H. Wu) Hjortstam & Ryvarden]; distr.: East Asia
Spores allantoid, 5.5–8 μm long; basidia 12–20 μm long; walls in subicular hyphae usually thin or somewhat thickened (less 1 μm) 17
17 Hymenophore distinctly floccose to odontioid; tubular cystidia often in clusters at apices of the aculei K. floccosa (Bourdot & Galzin) Jülich & Stalpers [Hyphodontia floccosa (Bourdot & Galzin) J. Erikss.]; distr.: Eurasia, North America
Hyphodontia intermedia (Bourdot & Galzin) Parmasto is considered as a synonym of K. floccosa (Hjortstam and Ryvarden 1988). According to the descriptions in Bourdot and Galzin (1928), there are some differences in spore morphology between the two taxa: spores in Odontia alutacea subsp. intermedia Bourdot & Galzin are 6–7.5(–9) × 1.5–2 μm, and in O. alutacea subsp. floccosa Bourdot & Galzin – 4.5–7.5 × 1.5–2.5 μm.
Hymenophore minutely furfuraceous to slightly warted; tubular cystidia not aggregated K. subalutacea (see step 13)

Key F. Lagarobasidium Jülich

1 Cylindrical, thick- or very thick-walled cystidia present, 140–360 μm long 2
Cylindrical cystidia, if present, then thin-walled and 70–110 μm long 3
2 Basidioma odontioid, with large, 140–360 × 10–12 μm, usually aseptate tubular cystidia in aculeal trama; projecting capitate cystidia apically 12–19 μm broad; spores 5–6 × 4–5 μm, with thickened wall L. magnificum (Gresl. & Rajchenb.) Hjortstam & Ryvarden (Hyphodontia magnifica Gresl. & Rajchenb.); distr.: South America
Basidioma smooth to grandinioid, with skeletocystidia 140–160 × 5–9 μm, often with adventitiuos septa; projecting capitate (spatuliform) cystidia apically 6–7 μm broad; spores 7–8 × 5–6 μm, thick-walled L. calongei M. Dueñas, Tellería, Melo & M.P. Martín; distr.: Macaronesia
3 Cystidia of one type: projecting, clavate to spathuliform in outline; hymenophore first smooth, then papillose to odontioid; hyphae with numerous crystals; spores ellipsoid, 4–5.5(–6) × 4–4.5(–5) μm L. detriticum (Bourdot) Jülich [Hyphodontia detritica (Bourdot) J. Erikss., Hyphodontia magnacystidiata Lindsey & Gilb., H. nikolajevae Parmasto, Hypochnicium detriticum (Bourdot) J. Erikss. & Ryvarden, Lagarobasidium nikolajevae (Parmasto) Jülich, L. pruinosum (Bres.) Jülich]; distr.: Eurasia, South America, southwest Indian Ocean islands
L. pruinosum is evidently a form of L. detriticum with narrowly clavate cystidia that are not spathuliform in outline.
Cystidia of two types: (1) projecting, capitate with small capitulum, (2) immersed, cylindrical or somewhat moniliform; hymenophore smooth; hyphae naked; spores subglobose to broadly ellipsoid and broadly ovoid, (4–)5–6(–6.5) × 4–5(–5.5) μm L. pumilium (Gresl. & Rajchenb.) Hjortstam & Ryvarden (Hyphodontia pumilia Gresl. & Rajchenb.); distr.: South America

Key G. Lyomyces P. Karst

1 Spores globose to broadly ellipsoid, (5.5–)6–7 × 5–6.3 μm; cystidia, basidia, and especially basidioles moderately to richly encrusted by fine crystals; cylindrical or subcylindrical cystidia present, up to 53 × 7 μm; basidioma often very thin, hypochnoid; subicular hyphae naked L. incrustatus (Kotir. & Saaren.) Hjortstam & Ryvarden (Hyphodontia incrustata Kotir. & Saaren.); distr.: Europe
Spores broadly ellipsoid to oblong, 2.5–4.5 μm broad; cystidia and basidioles smooth to moderately encrusted, basidia usually smooth; cylindrical cystidia absent or intermediate in shape to subulate and fusiform; basidioma usually moderately thick; subicular hyphae naked to moderately encrusted 2
2 Capitate cystidia/cystidioles present, usually numerous 3
Capitate cystidia/cystidioles absent 4
3 Spores narrowly ellipsoid to subcylindrical, (4.5–)5–5.7 × (2.5–)3–3.5 μm, thin-walled; subicular hyphae thin-walled; subhymenial hyphae usually non-encrusted L. erastii (Saaren. & Kotir.) Hjortstam & Ryvarden (Hyphodontia erastii Saaren. & Kotir.); distr.: temperate Eurasia
Spores broadly ellipsoid to ellipsoid, sometimes narrowly ellipsoid, 4.5–6(–7) × (3–)3.5–4(–4.5) μm, when mature somewhat thick-walled; subicular hyphae thick-walled; subhymenium rich of crystalline material L. sambuci (Pers.: Fr.) P. Karst. [Hyphodontia sambuci (Pers. : Fr.) J. Erikss., H. hariotii (Bres.) Parmasto, Hyphoderma sambuci (Pers.: Fr.) Jülich, Rogersella sambuci (Pers.: Fr.) Liberta & A.J. Navas]; distr.: cosmopolitan
4 Basidia with 2(3) sterigmata; spores broadly ellipsoid, 5–6 × 3.5–4.5 μm; no typical cystidia, only fusiform cystidioles 18–24 × 4(–6) μm; hyphae often encrusted, up to 3 μm wide L. bisterigmatus (Boidin & Gilles) Hjortstam & Ryvarden (Hyphodontia bisterigmata Boidin & Gilles); distr.: southwest Indian Ocean islands
Basidia with 4 sterigmata; spores oblong, 4.5–7.5 × 3–4.5 μm; with fusiform cystidia 25–35 × 5–7 μm; hyphae naked, up to 4 μm wide L. boninensis (S. Ito & S. Imai) Hjortstam & Ryvarden [Hyphodontia boninensis (S. Ito & S. Imai) N. Maek. ‘boninense’]; distr.: East Asia, Oceania

Key H. Palifer Stalpers & P.K. Buchanan

1 Spores thick-walled 2
Spores thin-walled 3
2 Projecting, naked, thin-walled septocystidia present in aculei and hymenium between them, 40–80 × 4–5 μm; spores 3.2–4.3 μm broad Hyphodontia septocystidiata H.X. Xiong, Y.C. Dai & Sheng H. Wu; distr.: East and Southeast Asia, Central America
This species is considered to be in the genus Palifer due to the presence of numerous short, thick-walled, apically encrusted cystidia.
True septocystidia absent, but some encrusted cystidia with adventitious septa; spores 3–3.5 μm broad Hyphodontia rickii (Hjortstam & Ryvarden) Gresl. & Rajchenb. [Lagarobasidium rickii (Hjortstam & Ryvarden) Hjortstam & Ryvarden, Hypochnicium rickii Hjortstam & Ryvarden]; distr.: South America
According to Gorjón (2012), this species should be excluded from Lagarobasidium because of encrusted cystidia, similar to those in P. gamundiae and H. erikssonii.
3 Hymenophore smooth or slightly grandinioid; cylindrical cystidia naked, apically obtuse or capitulate, 40–150 × 4.5–7 μm P. verecundus (G. Cunn.) Stalpers & P.K. Buchanan [Hyphodontia verecunda (G. Cunn.) Hjortstam & Ryvarden]; distr.: South America, New Zealand
According to Gorjón (2012), H. verecunda possesses true lagenocystidia, but in other features fits Xylodon.
Hymenophore grandinioid to odontioid; large cylindrical cystidia absent 4
4 Spores oblong to cylindrical, (5–)6–6.5 μm long P. gamundiae (Gresl. & Rajchenb.) Hjortstam & Ryvarden (Hyphodontia gamundiae Gresl. & Rajchenb.); distr.: South America
Spores broadly ellipsoid to ellipsoid, 4–6 μm long 5
5 Spores 4–5 × 3–3.5 μm; capitate cystidia apically 8–12 μm broad, usually naked Hyphodontia erikssonii (R. Galan & J.E. Wright) Hjortstam & Ryvarden; distr.: South America
This taxon was included in Hyphodontia s. str. by Hjortstam et al. (2005) and Hjortstam and Ryvarden (2009). However, instead of true lagenocystidia, it possesses cylindrical, naked or apically encrusted elements, called in the protologue as “hyphis paraphysoideis”.
Spores 5–6 × 4–4.5 μm; capitate cystidia apically 7–10 μm broad, usually with resinous cap P. hjortstamii (Gresl. & Rajchenb.) Hjortstam & Ryvarden (Hyphodontia hjortstamii Gresl. & Rajchenb.); distr.: South America
According to Gorjón (2012), this species has encrusted cystidia and spores almost identical to H. erikssonii, and can be treated as a probable synonym of the latter.

Key I. Schizopora Velen

1 Basidioma pileate, broadly dimidiate or with tapering base, sometimes with effused part; hyphal system trimitic with skeletal and binding hyphae; binding hyphae almost lacking a lumen, tortuous, up to 3.5 μm in diam, both in subiculum and trama Sch. trametoides Núñez; distr.: Southeast Asia
Basidioma effused or effused-reflexed; hyphal system dimitic or seemingly dimitic, with skeletals or skeletal-like hyphae 2
2 In hymenium numerous bottle-shaped cystidia, apically with stellate group of big, rhomboid crystals Sch. cystidiata David & Rajchenb. [Hyphodontia cystidiata (David & Rajchenb.) Hjortstam & K.H. Larss.]; distr.: Africa, southwest Indian Ocean islands
According to Hjortstam and Ryvarden (2009), this species does not belong to Schizopora, but is possibly related to Poriodontia.
Cystidia apically without stellate incrustations 3
3 Spores 2.8–4(–4.3) μm long 4
Spores 4–6.5 μm long 5
4 Hyphal system dimitic, skeletals abundant in subiculum, 3.5–6 μm diam.; capitate cystidial elements present in hymenium and dissepiment edges, lacking a cap of resinous matter; fusoid cystidia present, about 20 × 4 μm; basidia 2-sterigmate; spores 3–4 × 2.3–3 μm, many spores with a conspicuous papilla at one or both ends, reminiscent of conidia formation Sch. crassihypha Douanla-Meli; distr.: Africa
Hyphal system seemingly dimitic, skeletal-like hyphae 2.5–5 μm diam, abundant in central trama; capitate cystidial elements present in subiculum, trama and hymenium, often provided with a cap of resinous matter; fusoid cystidia absent; basidia 4-sterigmate; spores 3.7–4.3 × 2.8–3.3 μm, without papillae Sch. ovispora (Corner) Hjortstam & Ryvarden [Hyphodontia ovispora (Corner) T. Hatt., H. tropica Sheng H. Wu nom. inval.]; distr.: East Asia
5 Hyphal system dimitic with skeletals 6
Hyphal system subdimitic: some hyphae in trama very thick-walled 8
6 Pores 1–2(–4)/mm; spores (5–)5.5–6(–6.5) × (3.3–)3.5–4(–4.5) μm; hymenophore irpicoid, denticulate, labyrinthiform, rarely poroid or irregularly-hydnoid; capitate cystidia usually few Sch. paradoxa (Schrad. : Fr.) Donk [Hyphodontia paradoxa (Schrad. : Fr.) E. Langer & Vesterh., Sch. versipora (Pers.) Teixeira]; distr.: cosmopolitan
Pores (3)4–6(‒8)/mm; spores (3‒)4‒5 × 3‒3.5(‒4) μm; hymenophore poroid; capitate cystidia common, especially as ‘tramal vesicles’ 7
7 Subulate or fusoid cystidia in hymenium common, apically with crystalline incrustation; capitate cystidia in hymenium inabundant; spores 4–5 × 3–3.5 μm Sch. flavipora (Berk. & M.A. Curtis) Ryvarden [Hyphodontia flavipora (Berk. & M.A. Curtis) Sheng H. Wu, H. nongravis (Lloyd) Sheng H. Wu, H. subiculoides (Lloyd) Sheng H. Wu, Sch. hypolateritia (Berk. ex Cooke) Parmasto, Sch. phellinoides (Pilát) Domański, Sch. subiculoides (Lloyd) Ryvarden, Sch. trichiliae (Van der Byl) Ryvarden]; distr.: cosmopolitan
Subulate or fusoid cystidia in hymenium scattered, mostly naked; capitate cystidia in hymenium abundant; spores (3‒)3.5‒4.8(‒5) × (2.8‒)3‒3.5(‒4) μm Sch. carneolutea (Rodway & Cleland) Kotl. & Pouzar; distr.: Australia
This name is synonymized with Sch. flavipora by Hjortstam and Ryvarden (2007a).
8 Hymenophore poroid with angular or elongate pores, sometimes irpicoid; capitate cystidia usually numerous; spores (4–)4.5–5(–5.5) × (2.8–)3–3.5 (–3.8) μm Sch. radula (Pers.: Fr.) Hallenb. [Hyphodontia radula (Pers.: Fr.) E. Langer & Vesterh.]; distr.: cosmopolitan
Pores soon torn into narrow teeth, in old specimens teeth aggregated into groups; cystidia absent or not pronounced; spores 5‒6 × 2.5‒3 μm Sch. archeri (Berk.) Nakasone [Xylodon archeri (Berk.) Kuntze]; distr.: Australia, New Zealand

Key J. Xylodon (Pers.) Gray

1 Hymenophore poroid, predominantly poroid or irpicoid/raduloid 2
Hymenophore smooth to odontioid or hydnoid 12
2 All hyphae simple-septate X. poroideoefibulatus (Sheng H. Wu) Hjortstam & Ryvarden (Hyphodontia poroideoefibulata Sheng H. Wu); distr.: East Asia
Hyphae clamped at all primary septa 3
3 Tapering or acuminate cystidia present in hymenium 4
Hymenial cystidia apically rounded to capitate; tapering cystidial elements absent 8
4 Spores cylindrical to suballantoid X. nothofagi (G. Cunn.) Hjortstam & Ryvarden [Hyphodontia nothofagi (G. Cunn.) E. Langer, Schizopora nothofagi (G. Cunn.) P.K. Buchanan & Ryvarden]; distr.: New Zealand
Spores broadly ellipsoid to ellipsoid 5
5 Hyphal system pseudodimitic due to thick-walled (up to 1.5 μm) hyphae in subiculum and dissepiment; cystidia moniliform, often with a small acuminate apical segment X. bresinskyi (E. Langer) Hjortstam & Ryvarden (Schizopora bresinskyi E. Langer); distr.: Europe
Hyphal system monomitic, hyphal walls up to 0.5 μm thick; cystidia not moniliform or only faintly constricted 6
6 Spores 4–5.5 μm broad; pores up to 2 mm deep; subiculum up to 0.5 mm thick; capitate hyphal ends usually absent in subiculum, but present in dissepiment; tapering hymenial cystidia reaching 50 × 8 μm in size; basidia 5–7 μm broad, usually not repetitive; X. apacheriensis (Gilb. & Canf.) Hjortstam & Ryvarden [Hyphodontia apacheriensis (Gilb. & Canf.) Hjortstam & Ryvarden]; distr.: North America
Spores up to 4(–4.5) μm broad; pores to 0.3 mm deep; subiculum to 0.15 mm thick; capitate hyphal ends in subiculum numerous; tapering hymenial cystidia reaching about 30 × 6 μm in size; basidia 4.5–5 μm broad, often repetitive 7
7 Pores rounded; spores (3–)3.3–4 μm broad X. niemelaei (Sheng H. Wu) Hjortstam & Ryvarden (Hyphodontia niemelaei Sheng H. Wu subsp. niemelaei Sheng H. Wu); distr.: East Asia, Africa, South America
Pores somewhat elongated; spores 3.7–4(–4.5) μm broad X. gracilis (Hjortstam & Ryvarden) Hjortstam & Ryvarden (Hyphodontia niemelaei subsp. gracilis Hjortstam & Ryvarden); distr.: South America
8 Spores suballantoid X. syringae (E. Langer) Hjortstam & Ryvarden (Hyphodontia syringae E. Langer); distr.: East Asia
Spores subglobose to oblong 9
9 Pores 1‒3/mm; spores subglobose to broadly ellipsoid 10
Pores 4‒7/mm; spores narrowly ellipsoid to oblong, 4‒5.5 × 2.5‒3.2 μm 11
10 Pores about 3/mm; margin filamentous-arachnoid, without rhizomorphs; spores subglobose, 4.2‒5 × 4‒4.3 μm; capitate cystidia 15‒23 × 4.5‒3 μm X. hallenbergii (Sheng H. Wu) Hjortstam & Ryvarden (Hyphodontia hallenbergii Sheng H. Wu); distr.: East Asia
Pores 1‒2/mm; margin with white rhizomorphs; spores broadly ellipsoid/ellipsoid, (4‒)4.3‒5.5(‒6) × 3.5‒4(‒4.3) μm; capitate cystidia 20–27 × 6–7 μm Hyphodontia rhizomorpha C.L. Zhao, B.K. Cui & Y.C. Dai; distr.: East Asia
11 Pores 4–6/mm, up to 0.35 mm deep; capitate cystidia 10‒45 × 3.5‒5 μm, apically capped with resinous matter; basidia 14‒20 μm long; spores 4.5–5.5 μm long X. taiwanianus (Sheng H. Wu) Hjortstam & Ryvarden (Hyphodontia taiwaniana Sheng H. Wu); distr.: East Asia
Pores 6‒7/mm, to about 1 mm deep; capitate cystidia 11‒13.5 × 4‒6 μm, without resinous cap; basidia 9‒12.5 μm long; spores (4‒)4.3‒5 μm long Hyphodontia pseudotropica C.L. Zhao, B.K. Cui & Y.C. Dai; distr.: East Asia
12 Spores allantoid, 1–1.5 μm broad X. scopinellus (Berk.) Hjortstam & Ryvarden [Odontia scopinella (Berk.) Berk.]; distr.: Australia, New Zealand
Spores subglobose to cylindrical or suballantoid, at least 2 μm broad 13
13 Apically acute cystidia or acuminate hyphal ends regularly present in hymenium and/or at sterile apices of aculei 14
All cystidia apically blunt (but can be tapering), or acuminate elements rare and only at aculeal apices or occasionally in hymenium 35
14 Acuminate hyphal ends or acuminate cystidia confined to sterile aculeal apices 15
Acuminate cystidia or cystidioles also in hymenium 20
15 With hypha-like, thick-walled tramal cystidia, somewhat constricted and flexuous, often richly encrusted and with adventitious septa, apically blunt, subcapitate or acute X. lanatus (Burds. & Nakasone) Hjortstam & Ryvarden (Hyphodontia lanata Burds. & Nakasone); distr.: North and South America, East Asia
Thick-walled tramal cystidia absent 16
16 With hastocystidia, 40–60 × 6–8 μm, at aculeal apices X. hastifer (Hjortstam & Ryvarden) Hjortstam & Ryvarden (Hyphodontia hastifera Hjortstam & Ryvarden); distr.: South America
No hastocystidia; acuminate hyphal ends in aculei 2–4 μm broad 17
17 With enclosed, more or less constricted (torulose) cystidia; capitate and subcapitate cystidia often provided with resinous cap 18
Torulose cystidia absent; capitate and subcapitate cystidia naked, seldom with resinous cap 19
18 Cylindrical sterile elements in hymenium (if present) up to 4 μm broad; torulose cystidia with oily contents (like gloeocystidia), sometimes very rare; spores ellipsoid, 4–5 × 3–3.5 μm X. brevisetus (P. Karst.) Hjortstam & Ryvarden [Hyphodontia breviseta (P. Karst.) J. Erikss.]; distr.: temperate north hemisphere
Subclavate/short cylindrical cystidia common or scattered in hymenium, 4.5‒8.5 μm broad; torulose cystidia with non-oily contents; most basidiospores broadly ellipsoid, some subglobose, 4‒5.5(‒6) × (3‒)3.5‒4(‒4.5) μm Hyphodontia subclavata Yurchenko, H.X. Xiong & Sheng H. Wu; distr.: East Asia
19 Spores ellipsoid to oblong, convex or flat adaxially, 5.5–6.5(–7) × 3.5–4.5 μm; capitate cystidia present in hymenium X. pruni (Lasch) Hjortstam & Ryvarden [Hyphodontia pruni (Lasch) Svrček]; distr.: Eurasia, North Africa, North America
Spores ellipsoid, flat or depressed adaxially, (5‒)6–7 × 2.5–3.5 μm; capitate cystidia absent, subcapitate elements very few Hyphodontia novozelandica Gorjón & Gresl.; distr.: New Zealand
20 All hyphae covered with dark yellow or brown granular material, dissolving and turning violet in KOH X. australis (Berk.) Hjortstam & Ryvarden [Hyphodontia australis (Berk.) Hjortstam]; distr.: Australia, South America
The hyphal incrustations colorless or pale colored, not turning violet in KOH 21
21 Hymenophore smooth to minutely odontioid, with the longest aculei reaching 0.05–0.3 mm in length 22
Hymenophore odontioid to hydnoid and almost irpicoid, with aculei reaching 0.5–3 mm long 31
22 Spores cylindrical to suballantoid, (2‒)2.5–3(–3.5) μm broad 23
Spores subglobose to oblong, 3–4 μm broad 25
23 Basidioma very thin (mostly about 25 μm thick); hymenial surface smooth Hyphodontia tenuissima Yurchenko & Sheng H. Wu; distr.: East Asia
Basidioma usually 50 μm or more thick; hymenial surface scarcely aculeate (in younger parts smooth) to densely odontioid 24
24 Hymenial surface whitish or greyish, with sterile peg-like projections (11‒15 projections/mm) Hyphodontia vietnamensis Yurchenko & Sheng H. Wu; distr.: Southeast Asia
Hymenial surface yellowish or cream-colored, with at least partly fertile aculei (about 5 aculei/mm) X. crustosus (Pers.: Fr.) Chevall [Hyphodontia crustosa (Pers.: Fr.) J. Erikss., H. burtii (Peck) Gilb.]; distr.: cosmopolitan
The species is very variable, especially in macromorphology and spore morphology. Hjortstam and Ryvarden (1997) noted a specimen from Colombia under the name Hyphodontia cf. crustosa, with ellipsoid spores. A morphological variant called Hyphodontia crustosajacutica” (Eriksson et al. 1981), or H. jacutica (Eriksson and Ryvarden 1976), differs from H. crustosa by narrowly ellipsoid spores, and this may represent a taxon of its own.
25 Spores subglobose; hymenophore smooth or scanty odontioid 26
Spores broadly ellipsoid to oblong; hymenophore smooth to densely odontioid 27
26 Basidia bisterigmate; spores 5.5–7 × 4.5–6 μm, thin-walled; subulate cystidia 18–25 × 4.5–6 μm; hymenophore smooth X. bisporus (Boidin & Gilles) Hjortstam & Ryvarden (Hyphodontia bispora Boidin & Gilles); distr.: Europe
Basidia with (2)4 sterigmata; spores about 5 × 3.8–4 μm, slightly thick-walled; subulate cystidia 30–40 × 3.5–5 μm; hymenophore at first smooth, later with minute, separated aculei X. crustosoglobosus (Hallenb. & Hjortstam) Hjortstam & Ryvarden (Hyphodontia crustosoglobosa Hallenb. & Hjortstam); distr.: South America
27 Capitate (including lecythiform) elements present in hymenium 28
Capitate cystidial elements absent, or present only in aculei or in subhymenium 29
28 Hymenial surface salmon-colored when dry; hymenial cystidia of three types: tapering, 2–3.5 μm wide, capitate, and lecythiform; spores ellipsoid Hyphodontia macrescens (Banker) Ginns & Lefebvre; distr.: North America
According to Hjortstam and Ryvarden (2009), this is a name of unknown application.
Hymenial surface ochraceous- or cinnamon-yellow; cystidia of two types: tapering, 3–5 μm wide, and lecythiform; spores ellipsoid to narrowly ellipsoid X. rimosissimus (Peck) Hjortstam & Ryvarden [Hyphodontia rimosissima (Peck) Gilb. sensu Gilbertson (1962)]; distr.: North America
29 Hymenophoral aculei consisting of strongly flexuous hyphae with blunt, subcapitate or capitulate apices X. candidissimus (Berk. & M.A. Curtis) Hjortstam & Ryvarden [Hyphodontia candidissima (Berk. & M.A. Curtis) E. Langer]; distr.: North and South America
Hymenophoral aculei, if present, consisting apically of acute cystidial elements 30
30 Hymenophore smooth to minutely tuberculate, white to yellowish; basidioma not stratified, except at the differentiation zone of subhymenium and subiculum; hymenial surface more or less matt X. juniperi (Bourdot & Galzin) Hjortstam & Ryvarden [Hyphodontia juniperi (Bourdot & Galzin) J. Erikss. & Hjortstam]; distr.: Eurasia, Macaronesia, North and South America
Hymenophore distinctly warted to odontioid (basidioma can be partly smooth), yellowish to ochraceous; basidioma when well developed, somewhat stratified; hymenial surface more or less glossy X. stratosus (Hjortstam & Ryvarden) Hjortstam & Ryvarden (Hyphodontia stratosa Hjortstam & Ryvarden); distr.: Africa, South America
31 Spores cylindrical to suballantoid, 2.5–3.5 μm broad X. quercinus (Pers.: Fr.) Gray [Hyphodontia quercina (Pers.: Fr.) J. Erikss.]; distr.: temperate north hemisphere
Spores subglobose to narrowly ellipsoid, (3.2–)3.5‒4.5 μm broad 32
32 Basidioma up to 0.8 mm thick between aculei; torulose, apically rounded cystidia with 2‒9 constrictions present Hyphodontia anmashanensis Yurchenko, H.X. Xiong & Sheng H. Wu; distr.: East Asia
Basidioma about 0.05 mm thick between aculei; constricted cystidia if present, with 1‒5 constrictions and apically acute 33
33 Spores narrowly ellipsoid or oblong, 5–6.3 × 3–4 μm; capitate hyphal ends, if present, without resinous cap; cystidia ventricose-submucronate, thin- or slightly thick-walled towards the base X. submucronatus (Hjortstam & Renvall) Hjortstam & Ryvarden (Hyphodontia submucronata Hjortstam & Renvall); distr.: Africa
Spores subglobose to ellipsoid, 4.5–5(–5.5) × (3.5–)4–4.5 μm; capitate hyphal ends in hymenium often with resinous caps; cystidia fusoid with 1–5 constrictions, acuminate, thin-walled 34
34 Hymenophoral aculei flattened, incised, rarely conical or subcylindrical X. spathulatus (Schrad. : Fr.) Kuntze [Hyphodontia spathulata (Schrad. : Fr.) Parmasto]; distr.: cosmopolitan
Hymenophoral aculei triangular at base, subulate above, arranged in more or less parallel rows Hyphodontia fimbriiformis (Berk. & M.A. Curtis) Ginns & Lefebvre ‘fimbriaeformis’; distr.: North America
Hjortstam and Ryvarden (2009) synonymized this name with X. spathulatus.
35 Astrocystidia present on subicular hyphae Hyphodontia astrocystidiata Yurchenko & Sheng H. Wu; distr.: East Asia
Astrocystidia lacking in subiculum 36
36 Thick-walled, hypha-like, more or less encrusted, constricted and septate cystidia present, projecting in bundles at aculeal apices 37
All cystidia thin-walled or slightly thick-walled in lower part, aseptate 40
37 Spores cylindrical 2–2.5(–3) μm wide; hymenial cystidia subcapitate X. nespori (Bres.) Hjortstam & Ryvarden [Hyphodontia nespori (Bres.) J. Erikss. & Hjortstam, Odontia papillosa (Fr.) Bres. sensu Nikolajeva, 1961]; distr.: cosmopolitan
Spores in O. papillosa, according to Nikolajeva (1961), are larger than X. nespori measuring 5–8 × 2–3.5 μm.
Spores broadly ellipsoid to oblong 3–4(‒5) μm wide 38
38 Capitate hyphal ends (vesicles) present in subiculum X. lanatus (see step 15)
No capitate hyphal ends in subiculum 39
39 Cystidia at aculeal apices flexuous and subcapitate; aculei fertile at base; basidia 15‒17 μm long X. serpentiformis (E. Langer) Hjortstam & Ryvarden (Hyphodontia serpentiformis E. Langer); distr.: East Asia, Macaronesia
Hyphodontia crassa Sang H. Lin & Z.C. Chen was considered as synonym of H. serpentiformis by Dai et al. (2004).
Cystidia straight or slightly wavy, apically hypha-like, forming sterile peg-like fascicles; basidia 15‒35 μm long Hyphodontia echinata Yurchenko & Sheng H. Wu; distr.: East Asia
40 Lepto- or gloeocystidia present, of tramal or subhymenial origin, longer, than 30 μm, or if shorter, then reaching 8–15 μm in width 41
Lepto- or gloeocystidia absent, or if hymenial leptocystidia present, then up to 30 × 8 μm, or somewhat thick-walled in lower 1/2–2/3 48
41 Hymenophore smooth to tuberculate 42
Hymenophore odontioid to hydnoid 43
42 Cystidia of three types: enclosed cylindrical gloeocystidia, capitate and hyphoid cystidia; cylindrical hyphoid cystidia 40‒70(‒80) × (3‒)4‒5(‒5.5) μm X. tuberculatus (Kotir. & Saaren.) Hjortstam & Ryvarden (Hyphodontia tuberculata Kotir. & Saaren.); distr.: Europe
Cystidia of one type, cylindrical or subcylindrical, 90‒100 × 4‒6 μm; gloeocystidia absent X. tenuicystidius (Hjortstam & Ryvarden) Hjortstam & Ryvarden (Hyphodontia tenuicystidia Hjortstam & Ryvarden nom. inval.); distr.: South America
43 Capitate cystidial elements present in hymenium or subiculum, sometimes projecting from aculeal apices 44
Capitate cystidial elements lacking 47
44 Hyphae in aculeal trama thin- to slightly thick-walled; spores thin-walled, the biggest ones 5–5.5 × 3.5 μm 45
Aculeal trama with thick-walled or pseudoskeletal hyphae; spores often slightly thick-walled or distinctly thick-walled, the biggest ones 6–7 × 4–4.5 μm 46
45 Lepto- or gloeocystidia mostly of tramal origin, submoniliform, sometimes cylindrical, 40–60(–125) × 4–5(–7) μm, enclosed, sometimes difficult to find; capitate cystidia in hymenium and in aculeal apices, sometimes in subiculum, naked and apically 3.5–5.5 μm broad, or provided with a cap of resinous matter; spores ellipsoid X. brevisetus (see step 18)
Hyphodontia cf. breviseta, briefly described and illustrated in Kotiranta and Saarenoksa (2000) also keys here. It has long (about 100 μm and more), acute sterile aculeal apices, consisting of strictly parallel, tightly agglutinated, amyloid hyphae; gloeocystidia more 90 μm long; spores (4.5–)5–5.5 × 3–3.5(–4) μm. In H. breviseta, following to the same authors, sterile aculeal apices are shorter (near 70 μm), and consisting of subparallel, loosely arranged, inamyloid hyphae; gloeocystidia usually (45–)50–70 μm long; spores 4–4.5(–6) × (2.7–)3–3.5(–5) μm. Distr.: Europe
Leptocystidia of subhymenial origin, cylindrical, fusoid or clavate, often apically projecting, 35–50 × (5.5–)6–8(–9) μm; capitate cystidia only embedded in subiculum and aculeal trama, naked, apically 5–8 μm broad; spores narrowly ellipsoid to oblong Hyphodontia heterocystidiata H.X. Xiong, Y.C. Dai & Sheng H. Wu; distr.: East Asia
The species is referred by Gorjón (2012) to the H. breviseta complex.
46 Capitate cystidia enclosed or projecting, mostly capped with resinous matter; leptocystidia enclosed; spores thick-walled, (5–)5.5–6(–7) × 4–4.5 μm X. crassisporus (Gresl. & Rajchenb.) Hjortstam & Ryvarden (Hyphodontia crassispora Gresl. & Rajchenb.); distr.: South America
Capitate cystidia in subiculum only, without resinous cap; leptocystidia enclosed or projecting up to 30 μm; spores thin- to slightly thick-walled, 4–6 × 3–4 μm Hyphodontia sinensis H.X. Xiong, Y.C. Dai & Sheng H. Wu; distr.: East Asia
47 Hymenophore odontioid-hydnoid, with aculei 0.2–0.8 mm long; leptocystidia of tramal and subhymenial origin, cylindrical to torulose, 15–70 × 5–8 μm; spores 4–5 × 3–3.5 μm X. lenis Hjortstam & Ryvarden (Hyphodontia mollis Sheng H. Wu); distr.: East Asia
Hymenophore odontioid, with aculei up to 0.4 mm long; leptocystidia only hymenial, subcylindrical, clavate, almost pyriform, 20–35 × 4.5–15 μm; spores 5–6 × 3.5–4.5 μm Hyphodontia pelliculae (H. Furuk.) N. Maek.; distr.: East Asia
48 Capitate, subcapitate or capitulate cystidial elements abundant to scattered, but regularly present in hymenium or at aculeal apices 49
Capitate and similar cystidial elements absent or occasional 68
49 Resinous caps present on some or many capitate cystidia 50
Capitate cystidia lacking resinous cap 53
50 Hymenial surface with fairly sparse aculei (1–3/mm), separated or connected by crests 51
Hymenial surface densely tuberculate to densely odontioid (6–10 aculei/mm), without crests 52
51 Aculei separated; capitate cystidia 4.5–5.5(–6) μm broad, often lacking resinous cap; spores subglobose to broadly ellipsoid, 3.5–4.5(–5) μm broad X. asperus (Fr.) Hjortstam & Ryvarden [Hyphodontia aspera (Fr.) J. Erikss., H. granulosa (Pers.: Fr.) Ginns & Lefebvre nom. superfl.]; distr.: temperate Eurasia
Aculei often connected by crests; capitate cystidia 3–4.5 μm broad, usually with a cap of resinous matter; spores ellipsoid, 3.5–4 μm broad Hyphodontia subspathulata (H. Furuk.) N. Maek.; distr.: East Asia
Hjortstam and Ryvarden (2009) consider this name as a synonym of X. spathulatus. However, in Maekawa’s description (1993) no acuminate, constricted gloeocystidia were mentioned.
52 Basidioma white or cream-colored, with age pale ochraceous; aculei narrowly conical or subcylindrical; hyphal texture in subiculum and trama loose; spores (5–)5.5–6.5(–7) × 3.5–4.5(–5) μm X. pruni (see step 19)
Basidioma creamish or often pale ochraceous and reddish ochraceous; aculei conical to almost semiglobose; hyphal texture in subiculum and trama fairly dense; spores 5–6 × 3.5–4 μm X. verruculosus (J. Erikss. & Hjortstam) Hjortstam & Ryvarden [Hyphodontia verruculosa J. Erikss. & Hjortstam; H. papillosa (Fr.) J. Erikss. p.p., sensu Eriksson and Ryvarden (1976); Lyomyces papillosus (Fr.) P. Karst.]; distr.: Europe
In many taxonomical works Hyphodontia verrucolosa is considered to be a synonym of H. rimosissima. However, Hjortstam and Ryvarden (2009) treated X. verruculosus separately from X. rimosissimus (see step 28).
53 Spores 7.5–10 μm long, ovoid to suballantoid; aculeal apices with subulate or hypha-like, apically capitulate cystidia X. adhaerisporus (E. Langer) Hjortstam & Ryvarden (Hyphodontia adhaerispora E. Langer); distr.: southwest Indian Ocean islands
Spores up to 7 μm long, subglobose to oblong, never concave adaxially; aculeal apices with hypha-like, tapering, capitate or capitulate cystidia 54
54 Capitate cystidia apically 8–12 μm broad, projecting about 20 μm X. capitatus (G. Cunn.) Hjortstam & Ryvarden [Hyphodontia cunninghamii Gresl. & Rajchenb., non Hyphodontia capitata (Boidin & Gilles) Hjortstam]; distr.: Australia, New Zealand
Capitate or subcapitate cystidia apically up to 6(–7) μm broad, projecting or enclosed 55
55 Capitate cystidia predominating at aculeal apices, naked or slightly encrusted Hyphodontia capitatocystidiata H.X. Xiong, Y.C. Dai & Sheng H. Wu; distr.: East Asia
Aculeal apices consisting predominantly of tapering or cylindrical cystidia or hyphal ends, otherwise capitate cystidia richly encrusted (incrustation dissolving in KOH) 56
56 With fairly straight, hyphoid, projecting cystidia, somewhat broadened apically and thick-walled there, and somewhat broadened basally X. borealis (Kotir. & Saaren.) Hjortstam & Ryvarden (Hyphodontia borealis Kotir. & Saaren.); distr.: temperate Eurasia
This taxon was depicted under the name Hyphodontia aff. nudiseta in Langer (1994).
Hyphoid cystidia if present, then not broadened and thick-walled apically 57
57 Spores (5–)5.5–6.5(–7) μm long 58
Spores 3.8–5(–6) μm long 61
58 Hymenophoral aculei 10–15/mm; capitate, subcapitate and capitulate cystidia 20–60 × 4–6 μm, typically present in aculei X. fimbriatus (Sheng H. Wu) Hjortstam & Ryvarden (Hyphodontia fimbriata Sheng H. Wu); distr.: East Asia, South America
Hymenophoral aculei 6–12/mm; capitate and similar cystidia 15–40 × 3–5 μm, often absent in aculei 59
59 Spores thin-walled, 3.5–4.5(–5) μm broad; projecting hyphal ends in aculei subulate, obtuse, capitulate X. pruni (see step 19)
Spores slightly thick-walled when mature, 3.5‒4 μm broad; projecting hyphal ends in aculei nearly cylindrical or tapering 60
60 Hymenial cystidia tibiiform to lecythiform X. bugellensis (Ces.) Hjortstam & Ryvarden sensu Hjortstam and Ryvarden (2007a) [Hyphodontia bugellensis (Ces.) J. Erikss.]; distr.: Macaronesia, Africa
In earlier works (Eriksson and Ryvarden 1976; Langer 1994) this name was synonymized with Hyphodontia pruni.
Hymenial cystidia cylindrical or subcapitate X. subscopinellus (G. Cunn.) Hjortstam & Ryvarden [Hyphodontia subscopinella (G. Cunn.) Greslebin & Rajchenb.]; distr.: Australia, New Zealand
61 Subulate cystidial elements regularly present at aculeal tips and/or in hymenium 62
Subulate cystidia absent, rare, or little distinguishing from cylindrical hyphal ends 64
62 Many capitate cystidia with olive brownish contents; all hyphae thin-walled; spores narrowly ellipsoid, 3–3.5(–4) μm broad Hyphodontia sp. 2 (Kotiranta and Saarenoksa 2000); distr.: Europe
Capitate cystidia colorless; subicular hyphae with thickened to moderately thick walls; spores broadly ellipsoid to ellipsoid, 3.5–4 μm broad 63
63 Cystidia subulate, rarely capitate; tramal hyphae with thickened walls; spores thin- or slightly thick-walled Hyphodontia sp. 1 (Kotiranta and Saarenoksa 2000); distr.: Europe.
European samples, treated under the name X. nudisetus, and having, besides subulate cystidia, also slightly capitate ones (Langer 1994), possibly belong here (Kotiranta and Saarenoksa 2000).
Cystidia subcapitate and almost subulate; tramal hyphae thin-walled; spores thin-walled X. pruniaceus (Hjortstam & Ryvarden) Hjortstam & Ryvarden (Hyphodontia pruniacea Hjortstam & Ryvarden); distr.: Africa
64 With skeletal-like, strongly light-refractive hyphae in aculeal trama and partly in subiculum X. rudis (Hjortstam & Ryvarden) Hjortstam & Ryvarden (Hyphodontia rudis Hjortstam & Ryvarden); distr.: South America
Skeletal-like hyphae absent, hyphae in aculeal trama thin- to slightly thick-walled 65
65 Hyphae in aculeal apices richly encrusted; spores 4‒5 μm long 66
Hyphae in aculeal apices scarcely to moderately encrusted; spores up to 5.5‒6 μm long 67
66 Capitate cystidia in hymenium between aculei, 15‒18 μm long; hyphae in aculei (peg-like fascicles) flexuous, 2.5‒3.5 μm wide; spores 4–5 × 3–3.5 μm Hyphodontia microfasciculata Yurchenko & Sheng H. Wu; distr.: East Asia
Capitate cystidia mainly in aculei, 30–60 μm long; hyphae in aculeal apices straight, 3‒4 μm wide; spores 4.3–4.5 × 4–4.3 μm X. tenellus Hjortstam & Ryvarden; distr.: South Americ
67 Hymenophoral aculei more or less scattered, usually 1–3/mm; spores subglobose to broadly ellipsoid, 5–6 × (3.5–)4–5(–5.8) μm X. asperus (see step 51)
Hymenophoral aculei more crowded; spores broadly ellipsoid, (4.2–)4.5–5(–5.5) × 3.5–4 μm Hyphodontia sp. 3 (Kotiranta and Saarenoksa 2000); distr.: Europe
68 Spores 2.2–3 μm broad 69
Spores ≥ 3 μm broad 70
69 Spores (6–)6.5–7 × 2.2–2.5 μm; cystidia or hyphal ends in aculei tapering, thin- to moderately thick-walled; hymenophore densely odontioid; subicular hyphae (2.5–)3–4 μm diam; basidia 25–30 × 4.5–5 μm X. nesporina (Hallenb. & Hjortstam) Hjortstam & Ryvarden (Hyphodontia nesporina Hallenb. & Hjortstam); distr.: South America
Spores 4.5–6 × 2.5–3 μm; cystidia or hyphal ends in aculei cylindrical, thin-walled; hymenophore smooth to grandinioid; subicular hyphae 2–3 μm in diam; basidia about 15 × 3.5–4 μm Hyphodontia papillosa (Fr. : Fr.) J. Erikss. sensu Gilbertson (1974); distr.: North America
The concept of this species in Gilbertson differs from the concept of H. verruculosa (Ginns and Lefebvre 1993; see step 52), and resembles X. nespori with naked cystidia (see step 37).
70 Cystidia or hyphal ends in aculei with crystalline incrustations 71
Cystidia or hyphal ends in aculei naked or almost naked 72
71 Cystidia torulose; spores thick-walled when mature X. bugellensis sensu Bernicchia and Gorjón (2010) [Hyphodontia bugellensis sensu Melo and Tellería (1997); see also step 60]; distr.: Europe, Southwest Asia
Cystidia subulate, often with somewhat broadened base; spores thin-walled X. knysnanus (Van der Byl) Hjortstam & Ryvarden [Hyphodontia knysnana (Van der Byl) D.A. Reid]; distr.: Africa, South America
72 Hymenophoral aculei 2–4/mm; cystidia 3–4 μm broad, usually flexuous; spores ellipsoid, (6–)6.5–7(–7.5) × (3–)3.5–4 μm X. lutescens (Hjortstam & Ryvarden) Hjortstam & Ryvarden (Hyphodontia lutescens Hjortstam & Ryvarden); distr.: South America
Langer (1994) noted that this taxon should be treated in the genus Hyphoderma because of Hyphodontia-like hyphae are absent and spores are with granular contents. However, Hjortstam and Ryvarden (2009) referred X. lutescens to the same morphological group as X. asperus and X. brevisetus.
Hymenophoral aculei crowded, more than 4/mm; cystidia basally up to 7 μm broad, straight or weakly flexuous; spores subglobose to ellipsoid, 4.5–6 × 3–4.5 μm X. nudisetus (Warcup & P.H.B. Talbot) Hjortstam & Ryvarden (Hyphodontia nudiseta Warcup & P.H.B. Talbot; see also step 63); distr.: East Asia, Australia

Acknowledgements

The authors are grateful to Heikki Kotiranta (Finnish Environment Institute, Helsinki) for critical review of the MS and to David Mitchel (Northern Ireland Fungus Group, Belfast) for linguistic improvement of the text.

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Appendix

Species and specimens from which various cystidial elements were depicted (Fig. 1; collection acronyms follow Index Herbariorumhttp://sweetgum.nybg.org/science/ih): A1, Lagarobasidium calongei (MA-Fungi 73256, from Dueñas et al. 2009); A2, Kneiffiella floccosa (MSK-F 4755); B, Hyphodontia pallidula (MSK-F 6937); C, Hastodontia hastata (GB 94809, from Eriksson and Ryvarden 1976); D, X. brevisetus (MSK-F 5105); E, Hyphodontia astrocystidiata (TNM F24764); F, H. arguta (TNM F24822); G, H. rickii (CIEFAP Rick 208 47, from Gorjón 2012); H, Xylodon lanatus, (TNM F1225); I, X. lenis (TNM F21833); J, Hyphodontia subclavata (TNM F24744); K, H. heterocystidiata (TNM F, Wu 9209-33); L, H. heterocystidiata (TNM F, Wu 911107-38); M, Lagarobasidium detriticum (MSK-F 4146); N, Hyphodontia anmashanensis (TNM F15201); O, Xylodon spathulatus (MSK-F 5663); P, X. fimbriatus (TNM F111); Q, X. asperus (TNM F17159); R, Hyphodontia subclavata (TNM F24742); S, Lyomyces sambuci (MSK-F 4155); T, Xylodon fimbriatus (TNM F7890); U, Hyphodontia anmashanensis (TNM F15201); V, Xylodon candidissimus (TNM F9278); W, X. juniper (TNM F15343); X, X. tuberculatus (MSK-F 7352); Y, Z, X. brevisetus (MSK-F 5105).