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Type study of Mycena phaeophylla reveals its conspecificity with M. clavata

     Institute of Botany, Polish Academy of Sciences, Lubicz 46, 31-512 Kraków, Poland

Arne Aronsen

     Torødveien 54, N-3135 Torød, Norway

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION KEY TO THE SPECIES... CONCLUSIONS LITERATURE CITED

 

An extensive taxonomic study based on the type collection of Mycena phaeophylla revealed its conspecificity with M. clavata. Redescription of Kühner’s original collections of M. phaeophylla is provided as well as a detailed description of M. clavata based on European material. A lectotype for M. phaeophylla is designated. Additional study on collections of M. speirea confirmed that this closely related species can be separated easily from M. clavata. New key to subsection Omphaliariae of section Hiemales is proposed.

Key words: Basidiomycota, Europe, North America, subsection Omphaliariae, taxonomy, Tricholomatales

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION KEY TO THE SPECIES... CONCLUSIONS LITERATURE CITED

 
Section Hiemales Konrad & Maubl., subsection Omphaliariae Kühner ex Maas Geest. comprises species of Mycena characterized by small to medium size basidiomes, white to gray-brown, absence of odor, arcuate lamellae and nonamyloid spores (Maas Geesteranus 1991a). Apart from the widely distributed and common species M. speirea (Fr.) Gillet the few others belonging to this subsection are rare or insufficiently known. This is why there are many difficulties in species delimitation in this group. Two problematic species where identity and affinities to one another have not been demonstrated clearly are Mycena phaeophylla Kühner and M. clavata (Peck) Redhead. The recent proposal to treat M. phaeophylla synonymous with M. speirea (Horak 2005) brought additional complications to the taxonomy of the subsection.

M. clavata was described from North America in the genus Omphalia by Peck (1898). Redhead (1986), based on the type study of Omphalia clavata Peck, proposed the new combination Mycena clavata (Peck) Redhead. He also synonymized another American species, Mycena thujina A.H. Sm., with M. clavata. Smith (1947) synonimized M. phaeophylla with M. pallida (Murrill) A.H. Sm., but this was rejected by Redhead (1986) and Maas Geesteranus (1991a) who, after re-examination of the type of this taxon, Omphalopsis pallida Murrill, concluded that it does not belong to genus Mycena. Mycena phaeophylla was described by Kühner (1938), and since then it has been reported from several countries although it seems to be rare in Europe.

Difficulties in the precise identification of specimens belonging to M. phaeophylla and M. clavata collected or examined recently by us encouraged us to study the type collection of M. phaeophylla as well as to re-examine other collections of M. phaeophylla and M. clavata deposited in some European herbaria to find the answer to the question about their conspecificity. Comparative analysis of M. speirea also was included.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION KEY TO THE SPECIES... CONCLUSIONS LITERATURE CITED

 
The revision is based on the study of 35 European collections labeled ‘Mycena phaeophylla’ or ‘M. clavata’: seven from C, five from S, 13 from G (including the type), six from KRAM, one from O and three other Norwegian collections (herbarium Aronsen). Some collections were misidentified therefore they were excluded from the present study. All descriptions of both species available in the literature (Peck 1898; Kühner 1938; Smith 1947; Favre 1948; Redhead 1986; Maas Geesteranus 1991a, b) also were taken into consideration. The type collection of M. clavata was not examined because it is scanty; Maas Geesteranus (1991a) was allowed to study only the pileipellis and stipe cortex. We recognize Peck’s type description and especially the notes from Redhead’s (1986) and Maas Geesteranus’ (1991a) re-examinations as sufficient for our analysis. In addition five collections of the most closely related species, M. speirea from O and KRAM, were examined to check its affinity to M. clavata.

The material was examined following the standard methods used in the taxonomy of Basidiomycetes. The spores were measured in 5% KOH. Whenever possible 30 spores of each collection were measured (apart from a few collections where not enough mature spores could be found). For each collection spore length and width ratio (q) were calculated and the average quotient value (q_av) is given in the description. Melzer’s reagent was used to check amyloidity of spore walls. Spores to be measured were taken when possible from natural spore deposit present at stipe apex or pileus surface. Drawings of microcharacters were made with a drawing tube (Nikon Y-IDT). All measurements were taken directly through the microscope (under oil immersion objective), not from drawings. The description of morphological characters is based on our own observations as well as notes of collectors included in herbarium material and descriptions available from literature. SEM pictures were taken at the Laboratory of Field Emission Scanning Electron Microscopy and Microanalysis, Institute of Geological Sciences, Jagiellonian University, Kraków, with a Hitachi S-4700 microscope at 20 kV and a working distance of about 12 mm. Air dried spores were coated with gold. Chart presenting spore size was prepared with Statistica 6 software.

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION KEY TO THE SPECIES... CONCLUSIONS LITERATURE CITED

 
When describing the new species M. phaeophylla Kühner (1938) gave descriptions of two collections representing two forms: "tétrasporique" and "bisporique". We studied both collections and provide their detailed descriptions based on our own observations.

Mycena phaeophylla Kühner, Le Genre Mycena: 590, 687, FIG. 270. 1938.

Diagnosis (Kühner 1938). «Omphalia, Mycenarii, Campanellae.» Sporis hypisque non amyloideis. Pileo (5–10 mm) semiglobato, magis minusve striato, fusco vel e fusco griseo. Lamellis distantibus, fuscidulis vel e fusco murinis, latissime adnatis atque uncinato-decurrentibus. Stipite (2–4 cm x 0.7–1 mm) deorsum hirto, e fusco pallide murino, sub lente pruinoso. Sporis 6.2–9.5 x 4.5–7.2 µm. Cystidiis solum in marginibus lamellarum praesentibus, filiformibus vel fusiformibus. Pigmento fusco pilei in tunica hypharum concreto. Ad stipes vel cortices muscis oblitas et humi jacentes.

"La forme tétrasporique".— – Collection: FRANCE. ISÈRE: Grande Chartreuse, sur souche pourrie moussue des bois mêlés, leg. R. Kühner, 10 août 1934. "GC 64", No. G53734. [GenBank] The collection is preserved in a paper envelope containing: one-half of a carpophore (a cap with a short fragment of stipe) 0.4 cm diam, brown, with half a stipe (whole length), orange brown, pruinose at upper part, with pale rhizomorphs at base, lamellae decurrent (at least seven reaching the stipe); one-half of a cap (probably the half of the previous one), the same color, at least eight lamellae reaching the stipe, edge of lamellae slightly ciliate; two lower halves of stipe, less than 0.5 mm diam; two small pieces of a cap.

Spores 7–9 x 6–7 µm, av. 7.65 x 6.08 µm (q = 1.08–1.45; q_av = 1.26), broadly elliptic, broadly amygdaliform to subglobose with rounded or more often slightly conical apex (FIG. 1A). Basidia 28–37 x 6.5–8.5 µm, narrowly clavate, with four sterigmata and a basal clamp (FIG. 1B). Cheilocystidia abundant, 44–88 x 6.5–13 µm, narrowly lageniform to fusiform, usually with long, often flexuous neck, 2–5 µm wide at apex, with a basal clamp (FIG. 1C) and sometimes capped with a large drop of gelatinous matter. Near the margin of a cap another type of cheilocystidia was observed; they were scarce, narrowly clavate with irregular outgrowths (FIG. 1D). Pleurocystidia not seen, but some cystidia lying on the lamella surface close to the lamellar edge were observed (FIG. 1E). Lamellar trama not staining with Melzer’s reagent. Caulocystidia 42–62 x 6–7 µm, cylindrical and flexuous, numerous especially at stipe apex (FIG. 1F), in tufts or more sparsely distributed down the stipe, at the stipe apex more similar to the cheilocystidia, slightly broadened at lower part. Hyphae of the cortical layer of the stipe smooth. Pileipellis composed of clamped hyphae 2–3 µm wide, covered with branched, densely packed excrescences (FIG. 1G), some diverticulae are elongated and protruding above the pileipellis surface forming pileocystidia-like hairs. Lower layers (hypoderm and context) composed of wider hyphae 2.5–7 µm diam, distinctly encrusted with brownish pigment. Clamp connections present.

View larger version (17K): [in this window] [in a new window]   FIG. 1. A–G. Mycena phaeophylla (coll. G 53734 –LECTOTYPE). A. Spores. B. Basidia. C. Cheilocystidia. D. Second type of cheilocystidia. E. Cross section of lamella edge with cheilocystidia laying at edge and lamella surface close to the edge. F. Caulocystidia. G. Elements of pileipellis. Bar = 10 µm.

Spores 7–9 x 5.5–7.5 µm, av.: 8.11 x 6.6 µm (q = 0.93–1.42; q_av = 1.24), broadly elliptic, broadly amygdaliform to subglobose with rounded, or more often slightly conical apex (FIG. 2A). Basidia 22–27 x 7–9 µm, clavate, with two sterigmata (FIG. 2B). Cheilocystidia abundant, 35–50 x 8–11 µm, narrowly lageniform to fusiform, usually with long, often flexuous neck 2–3.5 µm wide at apex, sometimes capped with a large drop of gelatinous matter (FIG. 2C). Pleurocystidia not seen. Lamellar trama not staining with Melzer’s reagent. Caulocystidia 35–78 x 5–7 µm, cylindrical and flexuous, often with irregular outgrowths (FIG. 2D), numerous especially at stipe apex, in tufts or more sparsely distributed down the stipe. Hyphae of the cortical layer of the stipe smooth or occasionally with sparse small excrescences. Pileipellis composed of hyphae 2–3.5 µm wide, covered with branched, densely packed excrescences (FIG. 2E); some diverticulae are elongated and protruding above the pileipellis surface forming pileocystidia-like hairs. Lower layers (hypoderm and context) composed of wider hyphae 3–10 µm diam, distinctly encrusted with brownish pigment. Clamp connections absent.

View larger version (17K): [in this window] [in a new window]   FIG. 2. A–E. Mycena phaeophylla (coll. G 53735). A. Spores. B. Basidia. C. Cheilocystidia. D. Caulocystidia. E. Elements of pileipellis. Bar = 10 µm.

LECTOTYPUS. Sur souche pourrie et moussue, dans les bois mêlés, non loin du monastère de la Grande Chartreuse (Isère), 10 août 1934, "GC 64", (G53734 [GenBank] ), here designated.

The study of the collections of M. phaeophylla described above as well as the other collections deposited in some European herbaria together with careful analysis of the descriptions of the type collection of M. clavata (Peck 1898, Redhead 1986, Maas Geesteranus 1991a) let us conclude that the two species are conspecific. The description provided below is based on all the material we studied.

Mycena clavata (Peck) Redhead, Mycologia 78(4):523, FIGS. 1–4. 1986. Omphalia clavata Peck, Rep. NY St Mus Nat Hist 51:285. 1898. TYPE: USA, North Elba, on trunks of arbour-vitae, Chas H. Peck, Aug 1997 (holotype: NYS).

View larger version (95K): [in this window] [in a new window]   FIG. 3. A, B. Mycena clavata. A. Carpophores (coll. KRAM F-54292). B. encrusting pigment in hypoderm (coll. G53738). C. Mycena speirea, intracellular pigment in hypoderm (KRAM F-11290). Bars: A = 1 cm; B, C = 10 µm.

View larger version (19K): [in this window] [in a new window]   FIG. 4. A–K. Mycena clavata basidia. A. coll. G53729. B. coll. G53730(401d). C. coll. G53730(401b). D. coll. G53730(401a). E. coll. KRAM F-54292. F. coll. G53728. G. coll. G53731. H. coll. C 32056. I. coll. C43330. J. coll. C32403. K. coll. C without number, leg. Th. Læssøe & S.A. Elborne. Bar = 10 µm.

Omphalopsis clavata (Peck) Murrill, North Am Flora 9(5):313. 1916.

= Mycena thujina A.H. Sm., North American Species of Mycena: 361, pl. 86D, FIG. 45(9, 10). 1947. TYPE: CANADA, Ontario, near Lake Timagami, on log of Thuja occidentalis, 2 Sep 1936, A.H. Smith, 4444 (holotype: MICH).

= Mycena phaeophylla Kühner, Le Genre Mycena: 590, 687, FIG. 207. 1938, TYPE: FRANCE, non loin du monastère de la Grande Chartreuse (Isère), sur souche pourrie et mousse, dans les bois mêlés, 10 août 1934, R. Kühner, "GC 64", G53734 [GenBank] (lectotype: G).

= Marasmiellus phaeophyllus (Kühner) Singer, Lilloa 22:302. 1951. FIGS. 3–9

View larger version (19K): [in this window] [in a new window]   FIG. 5. A–N. Mycena clavata spores. A. coll. G53729. B. coll. G53738. C. coll. G53730(401d). D. coll. G53730(401b). E. coll. KRAM F-54292. F. coll. G53730(401a). G. coll. G53733. H. coll. G53728. I. coll. G53731. J. coll. C32403. K. coll. C 32056. L. coll. C43330. M. coll. C21363. N. coll. C without number, leg. Th. Læssøe & S.A. Elborne. A–G. 4-spored collections. H–M. 2-spored collections. N. collection with 2- and 4-spored basidia. Bar = 10 µm.

View larger version (21K): [in this window] [in a new window]   FIG. 6. A–L. Mycena clavata cheilocystidia. A. coll. G53729. B. coll. G53738. C. coll. G53730(401d). D. coll. G53730(401b). E. coll. G53730(401a). F. coll. G53733. G. coll. G53731. H. coll. C without number, TL 0502. I. coll. G53728. J. coll. C32402. K. coll. C 32056. L. coll. C43330. A–F. 4-spored collections. G–L. 2-spored collections. Bar = 10 µm.

View larger version (17K): [in this window] [in a new window]   FIG. 7. A–E. Mycena clavata cheilocystidia (the second type). A. coll. G53730(401d). B. coll. KRAM F-54292. C. coll. G53731. D. coll. C 32056. E. coll. C without number, leg. Th. Læssøe & S.A. Elborne. A–B. 4-spored collections. C–D. 2-spored collections. E. collection with 2- and 4-spored basidia. Bar = 10 µm.

View larger version (26K): [in this window] [in a new window]   FIG. 8. A–L. Mycena clavata hyphae of pileipellis. A. coll. G53729. B. coll. G53738. C. coll. G53730(401d). D. coll. G53733. E. coll. G53730(401a). F. coll. KRAM F-54292. G. coll. G53731. H. coll. G53728. I. coll. C32403. J. coll. C 32056. K. coll. C32402. L. coll. C43330. A–F. 4-spored collections. G–L. 2-spored collections. Bar = 10 µm.

View larger version (23K): [in this window] [in a new window]   FIG. 9. A–K. Mycena clavata caulocystidia. A. coll. G53729. B. coll. G53738. C. coll. G53730(401a). D. coll. G53730(401d). E. coll. G53730(401b). F. coll. G53733. G. coll. KRAM F-54292. H. coll. C32403. I. coll. G53731. J. coll. C43330. K. coll. G53728. A–G. 4-spored collections. H–K. 2-spored collections. Bar = 10 µm.

Basidia 21–39 x 5–9 µm, slender-clavate or clavate, 2-spored, clampless, with sterigmata 6–7 µm long or 4-spored, clamped (FIG. 4). Spores 7–11 x 5.5–8.5 (–9.5) µm, q_av ~ 1.25 (2-spored basidia), or 6.5–10.5 x 5–7.5 µm, q_av ~ 1.28 (4-spored basidia), broadly ellipsoid, broadly amygdaliform to subglobose, with rounded to slightly conical apex, smooth, nonamyloid (FIG. 5). Cheilocystidia 20–88 x 4–16 µm, forming a sterile band, subcylindrical, fusiform to lageniform, clamped or clampless, apically passing into a slender, straight to curved or somewhat flexuous, simple, forked or somewhat branched neck 2–5 µm wide, often capped with a large drop of gelatinous matter (FIG. 6). More rarely and mostly situated near the pileus margin another type of cheilocystidia appears that is shorter, 17–35 x 6–15 µm, narrowly clavate to clavate and with several simple to branched, cylindrical excrescences (FIG. 7). Pleurocystidia apparently absent, but cystidia may be present near the pileus margin (FIG. 1E). Lamellar trama not staining with Melzer’s reagent. Hyphae of the pileipellis 2.5–6.5 µm wide, clamped or clampless, covered with simple to much branched excrescences up to 22.5 x 1–2 µm, which may develop into dense masses, sometimes becoming somewhat gelatinized, with some of the diverticulae elongated into projecting, pileocystidia-like hairs up to 32 µm long (FIG. 8). Lower layers (hypoderm and context) composed of wider hyphae, 3–10 µm, distinctly encrusted with brownish pigment (FIG. 3B). Hyphae of the cortical layer of the stipe 1.5–3.5 µm wide, clamped or clampless, smooth for the greater part but covered with side branches and caulocystidia 35–78 x 3–11 µm; the caulocystidia abundant, especially at the stipe apex, in tufts or more sparsely distributed down the stipe, cylindrical and curved or flexuous, often with irregular outgrowths, simple to forked, sometimes capped with a large drop of gelatinous matter (FIG. 9).

Collections examined:. DENMARK. NORDJYLLAND: Rubjerg Knude Plantage, on Pinus, 12 Apr 1992, leg. J. Vesterholt (C21363); the same place, on Pinus and on Picea, 28 May 2003, leg. J. Vesterholt (C43330); Rubjerg Knude, Hjørring Kommunes Klitplantage, in litter, 17 Oct 1988, leg. Th. Læssøe (C32402); the same place, on Pinus, 17 Oct 1988, leg. Th. Læssøe & J.H. Petersen (C32403); Livø, on Abies twigs, ass. M. speirea, 29 Sep 1995, leg. Th. Læssøe (C32056); Tole Bakker, ‘Påkvasdynge i grøft’, 2 Oct 1981, leg. Th. Læssøe & S.A. Elborne (C without number); SJÆLLAND: Sorø Sønderskov, on twigs in dense heap in fern/Urtica stand (Pinus?), ass. Mycena speirea, hiemalis, acicula, 18 Oct 1982, leg. T. Læssøe & S.A. Elborne (C without number, TL0502); FRANCE. ISÈRE: Grande Chartreuse, mixed forest, on decayed, mossy trunk, 10 Aug 1934, leg. R. Kühner (G53734 [GenBank] , LECTOTYPE); the same place, mixed forest, on fallen, mossy pieces of bark, 15 Aug 1934, leg. R. Kühner (G53735 [GenBank] ); Grande Chartreuse, near St Laurent du Pont, edge of a forest, among mosses, at the base of Abies pectinata trunk, 1 Nov 1933, leg. Josserand (G53737 [GenBank] ); AIN: vicinity of Lyon, Hauteville, 26 Oct 1956, leg. R. Kühner (G53733 [GenBank] ); Hauteville, 26 Oct 1953, leg. ? (G53738 [GenBank] ). NORWAY. VESTFOLD: Nøtterøy, Torød, one specimen among needles under Juniperus, 10 Aug 1993, leg. A. Aronsen (Aronsen 34/93); Tjøme: Hvasser, Sønstegård, on branches of Juniperus communis, 3 Dec 2006, leg. A. Aronsen (A21/06); AKERSHUS: Frogn, Bonn, NM 967 213, in moss, on a fallen trunk of Picea abies, 2 Oct 1983, leg. R. Kristiansen (O163104); NORD-TRØNDELAG: Namdalseid, Flåbekkåsen skogreservat, alt. 180–240 m., on Picea bark in old Picea forest, 3 Oct 2001, leg. H. Holien & S. Sivertsen; POLAND. THE CARPATHIANS: the Western Tatra Mountains, summit area of the Sarnia Skala massif, northern slope, N 49°15'53″, E 19°56'38″, alt. 1370 m., Pinetum mugi carpaticum, on litter, 22 Jun 2001, leg. A. Ronikier (KRAM F-54295); the same place, among mosses (probably on wood), 4 Jul 2001, leg. A. Ronikier (KRAM F-54292); the same place, among mosses, on litter, 11 Jun 2003, leg. A. Ronikier (KRAM F-54294); the same place, on wood (branch of ?Pinus mugo), 11 Jun 2003, leg. A. Ronikier (KRAM F-54293); the same place, among mosses, 10 Jun 2002, leg. A. Ronikier (KRAM F-54296); the same place, on litter, 20 Jun 2000, leg. A. Ronikier (KRAM F-54357). SWITZERLAND. VAUD: Tourbière des Piguet-Dessus, close to Sentier Vallée de Joux, 19 Sep 1941, leg. ? (G53731 [GenBank] ); JURA: Tourbière des Rousses, 7 Oct 1938, leg. J. Favre (G53728 [GenBank] ); GRAUBÜNDEN: Val Sesvenna, near S-carl, alder forest, alt. 1900 m., 2 Sep 1952, leg. J. Favre (G53729 [GenBank] ); Haute Engadine, God Trid, Val Trupschun, alder forest, alt. 1900 m., 1 Sep 1957, leg. J. Favre (G53730 [GenBank] ); near S-carl, left side of Val Sesvenna, alt. 2000 m., 14 Aug 1948, leg. J. Favre (G53730 [GenBank] ); near S-carl, Val Sesvenna, alt. 1900 m., 9 Sep 1944, leg. J. Favre (G53730 [GenBank] ).

Habitat: Growing solitary or in clusters on bark of coniferous wood or on coniferous litter, once found on deciduous wood (Elborne and Læssøe 1982).

Known distribution: Canada, Denmark, France, Norway, Poland, Switzerland, USA.

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION KEY TO THE SPECIES... CONCLUSIONS LITERATURE CITED

 
Evidence for synonymy of M. clavata and M. phaeophylla.— – The affinity of M. clavata and M. phaeophylla has been mentioned a few times in the literature. Redhead (1986) was the first to say that Mycena phaeophylla might be conspecific with M. clavata and put this name among synonyms of the latter but with a question mark. He was not sure because he did not study the type material of Mycena phaeophylla but only one of J. Favre’s collections (coll. G25729 [GenBank] ). Moreover Redhead (1986) noted a few differences between the two species: slightly larger spores and darker colors of carpophores in European material. Maas Geesteranus (1991a), who studied only parts of the type, the hyphae of the pileipellis and the stipe cortex of Omphalia clavata because of scanty material of the type collection, took up the discussion and brought forward two other differences: "Mycena clavata is known to possess pleurocystidia, whereas they are absent in M. phaeophylla, and the caulocystidia of M. clavata are strikingly shaped, tortuous, simple to somewhat branched, while they are cylindrical and rather banal in M. phaeophylla, at least going by Kühner’s illustration." In another paper based on examination of a Norwegian collection Maas Geesteranus (1991b) said that Mycena clavata may be just as dark as indicated in M. phaeophylla and that it also may possess 2-spored basidia. Still he was reluctant to synonymize the two species because "Kühner (1938) stated that both the 4- and 2-spored forms of M. phaeophylla lacked pleurocystidia; indicated the spores of the 4-spored form as definitely more pip-shaped than globose; apparently did not observe any branched excrescences of the hyphae of the pileipellis; and failed to give information on the nature of the substratum (wood of coniferous or deciduous tree)."

Our re-examination of Kühner’s original collections (both 4- and 2-spored forms) of M. phaeophylla showed broadly elliptic, broadly amygdaliform to subglobose spores. Indeed they are on average slightly larger than measured by Redhead (1986) in the type of Omphalia clavata, but those measurements are within the range of M. phaeophylla. The type of M. phaeophylla does not possess pleurocystidia, but some cystidia were seen on the lamella face close to the edge (FIG. 1E) and hence did not appear as true pleurocystidia. This feature also was observed by Redhead (1986) in the type collection of Omphalia clavata. He mentioned that "‘pleurocystidia’ occur on the lamellae but they are confined to the area near the lamellar edge." Maas Geesteranus (1991b) observed scarce pleurocystidia in one European collection. Unfortunately we did not examine this collection. We saw the specimens found by the same collector on the same day but in another location (coll. O163104) and we could not find true pleurocystidia in this collection either. The presence of true pleurocystidia is the only feature that we could not confirm, either in the type collection of M. phaeophylla or in any other collections examined by us. Following Redhead’s (1986) remarks on pleurocystidia of the type of O. clavata (lacking or present only close to the lamellar edge) and taking into account the scarcity of pleurocystidia in the only one European collection (Maas Geesteranus 1991b) we assume that either this feature is not stable or difficult to observe in dried specimens, and therefore it should not be considered as taxonomically important.

Kühner (1938) described the excrescences of the hyphae of the pileipellis in M. phaeophylla as simple and cylindrical, different from the much branched excrescences of M. clavata. Our observations however showed branched, densely packed excrescences both in the 4-spored and the 2-spored forms of Kühner’s collections of M. phaeophylla (FIGS. 1G, 2E) similar to the observations of Maas Geesteranus (1991a) on the type of Omphalia clavata. Our observations also show that the caulocystidia in M. phaeophylla are shaped much more strikingly than in Kühner’s (1938) illustration and they are similar to the caulocystidia of M. clavata (FIG. 9).

Further features indicate the conspecificity of M. clavata and M. phaeophylla. Between the much branched excrescences of the hyphae of the pileipellis some diverticulae are elongated into projecting hairs (FIG. 8). This was mentioned by Kühner (1938) for the type of M. phaeophylla and by Redhead (1986) for the type of O. clavata and was present in all collections examined by us. These projections are more or less cystidia-like and up to 32 µm long. They sometimes are difficult to observe and they usually are scarce toward the margin of the cap while they are more abundant at the center of the cap. They vary also in shape and size among collections. The most clearly visible and the largest pileocystidia were observed in collection G53733 [GenBank] (FIG. 8D).

Redhead (1986) said that the cheilocystidia of O. clavata vary from "narrowly ventricose with somewhat uneven necks to occasionally branched, or with clavate bases" (and with several more or less branched excrescences, according to his illustration). The second type of cheilocystidia with branched excrescences was observed in the 4-spored form of Kühner’s Mycena phaeophylla collection as well and also in some of the other collections that we examined (FIG. 7).

In the collections examined by us the necks of the cheilocystidia and the caulocystidia were capped by a large drop of gelatinous material (FIGS. 2C; 6E, F, G, K, L; 9A, F). This feature is present in M. clavata mentioned by Redhead (1986) as well as in M. phaeophylla both in its 4- and 2-spored forms.

Kühner (1938) said that the hyphae of hypoderm of M. phaeophylla have brownish encrusting pigmentation "à membrane brunâtre, souvent ruguleusezébrée." This feature also was observed in the type of O. clavata (Redhead 1986). This pigmentation is distinct and present in all our collections (FIG. 3B). Encrusting pigment is rare in the genus Mycena. It is present only in two species, M. phaeophylla and M. corticola (=M. meliigena [Berk. & Cooke] Sacc.), according to Kühner (1938)

Relationship with Mycena speirea.— – The species most closely related to M. clavata is M. speirea (FIG. 10). This common and widely distributed fungus is similar in habit; it also has nonamyloid spores and belongs to the same group (sect. Hiemales, subsect. Omphaliariae). It is also brown, has arcuate lamellae and occurs on similar substrate. Horak (2005) synonymized these species, but we do not concur in his opinion, following Kühner (1938), Moser (1983) and Maas Geesteranus (1991a). Although the two species are undoubtedly close, M. speirea can be separated easily from M. clavata on account of (i) the shape of the spores (M. speirea ellipsoid to amygdaliform, 8–11 x 4.5–5.8 µm, q_av ~ 1.9; M. clavata broadly ellipsoid to subglobose, q_av ~ 1.3); (ii) the shape of the cheilocystidia (M. speirea mostly subcylindrical; M. clavata mostly fusiform or lageniform, apically passing into a slender neck); (iii) the hyphae of the pileipellis (more branched in M. clavata and with some of the diverticulae elongated into projecting pileocystidia-like hairs); (iv) the character of pigmentation in lower layers of the pileipellis and pileitrama-hypoderm (M. clavata encrusting (FIG. 3B); M. speirea intracellular (FIG. 3C).

View larger version (18K): [in this window] [in a new window]   FIG. 10. A–D. Mycena speirea. A. hypha of pileipellis. B. spores. C. cheilocystidia. D. caulocystidia. A–C. (coll. O 163000). D. (coll. O 163003). Bar = 10 µm.

Differences between 2- and 4-spored forms of M. clavata.— – According to Smith (1934), "it has long been known that within the genus Mycena there exists an unusually large number of forms bearing basidia which produce two instead of the usual four spores." Such forms are variously treated in different species. For instance Maas Geesteranus (1977) discovered that in the Dutch populations of Mycena galericulata (Scop.) Gray the 2-spored form is more common than the 4-spored form and that the latter can be found in specimens collected later in the season (Oct–Dec), while the 2-spored form can be found throughout the year. He did not recognize the two forms as taxonomically separate, although he said they might represent genetically different taxa (Maas Geesteranus 1977, 1985). Similarly Aronsen and Maas Geesteranus (1989) describing a new species, M. ustalis Aronsen & Maas Geest., report 2- and 4-spored forms from the same locality, the latter collected several days later than the previous one. They also did not find any morphological differences between the two forms that might justify their separation. On the other hand another species Mycena radicifera J. Favre recently was re-examined by Moreau and Courtecuisse (2003) who recognized two varieties, 4-spored, clamped, typical variety radicifera and 2-spored, clampless, apogamic M. radicifera var. apogama P.A. Moreau & Courtec., which in addition differs from the var. radicifera with a structure of suprapellis.

A few characters are slightly different between the two 2- and 4-spored forms of Mycena clavata. They are presence of clamp connections, number of sterigmata, spore size as well as shape and size of basidia.

In general the 2-spored form is characterized by slightly larger spores (7–11 x 5.5–8.5 µm) than the 4-spored form (6.5–10.5 x 5–7.5 µm). According to our measurements (7–9 x 6–7 µm) spores of the type collection (4-spored form) are slightly larger than stated in the original description; according to Kühner (1938) they were 6.2–8 x 4.5–5.7. Individual measurements of spores of 2- and 4-spored collections largely overlap (FIG. 11), however mean spore values show tendency for 4-spored form to be smaller. The differences in spore size between the 2-spored and 4-spored forms of the same species are widely known. According to Smith (1934) the spores of 2-spored forms are usually one-quarter to one-sixth bigger than spores of 4-spored collections, but according to Kühner (1938) the difference in size might be smaller in some species. The differences in size of basidia and presence or absence of clamp connections usually go together with the differences in number of sterigmata. Kühner (1938) demonstrates that basidia of 2-spored forms are constantly slightly smaller than those of 4-spored forms. Because no other clear characteristics (e.g. in pileipellis structure, size of carpophores, size and shape of cystidia) differentiated the two forms of M. clavata we consider these small differences not taxonomically significant and not sufficient for recognition of separate taxa, either on a level of variety or a form. It is possible that the 2-spored M. clavata represents an apogamic form, but in our opinion different reproductive strategy alone should not be considered a basis for creation of a new variety unless it is supported by stable morphological characters suggesting an evolutionary differentiation toward a parthenogenetic lineage (cf. Moreau and Courtecuisse 2003). Moreover two collections (C without number and C32403) are characterized by co-occurrence of 2- and 4-spored basidia. We did not find a correlation in number of sterigmata and time of collection, as noticed for M. galericulata (Maas Geesteranus 1977) and M. ustalis (Aronsen and Maas Geesteranus 1989), but we noticed that the 4-spored form was found more frequently in central and southern Europe while it was almost absent in Scandinavian countries.

View larger version (10K): [in this window] [in a new window]   FIG. 11. Spore size of all examined collections of Mycena clavata; square 4-spored collections, cross 2-spored collections.

View larger version (109K): [in this window] [in a new window]   FIG. 12. A–B. Spores of Mycena phaeophylla (coll. G 53734 – LECTOTYPE). Bar = 1 µm.

	KEY TO THE SPECIES OF SUBSECTION OMPHALIARIAE

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION KEY TO THE SPECIES... CONCLUSIONS LITERATURE CITED

1. Spores ellipsoid, amygdaliform (q > 1.6, qav ~ 1.9), pigment in hypoderm intracellular, brown M. speirea 1. Spores globose to broadly ellipsoid (q 1.6, qav ~ 1.3), pigment in hypoderm encrusting or intracellular 2 2. Cheilocystidia clavate to subcylindrical, pileipellis with inflated excrescences, pigment in hypoderm intracellular, poorly visible M. alba 2. Cheilocystidia lageniform to fusiform with simple or branched neck, pileipellis with cylindrical excrescences, pigment in hypoderm encrusting M. clavata

	CONCLUSIONS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION KEY TO THE SPECIES... CONCLUSIONS LITERATURE CITED

 
A taxonomic study based on the type collection of Mycena phaeophylla revealed its conspecificity with M. clavata. The characters considered so far differentiating the two species (shape of spores, structure of the pileipellis, shape of caulocystidia) turned out to be identical. Kühner (1938) described two forms of M. phaeophylla (2-spored and 4-spored), but in our opinion the differences between them are not sufficient for their recognition either on a level of variety or a form. The 2-spored form differs slightly in spore and basidia size, which usually is observed also in other 2-spored forms of Agaricales. No correlation with other characters was observed.

Mycena clavata can be distinguished easily from M. speirea on account of several features, of which the most eminent is encrusting pigment.

M. clavata is a rare but widely distributed species known from North America and Europe. In Europe it is connected mostly to coniferous wood and litter (Pinus, Picea, Abies, Juniperus) and it occurs in mountainous habitats as well as in northern part of the continent; therefore it probably can be considered a mountain-boreal species.

	ACKNOWLEDGMENTS

 
We thank David Hawksworth (University of Madrid, Spain) for the nomenclatural advice, Pierre-Arthur Moreau (University of Lille, France) for valuable discussions on the present study, Isobel Simonsen for linguistic corrections, Richard W. Kerrigan and two anonymous reviewers for the valuable comments on the manuscript. We also thank keepers of herbaria C, S, G, O for kind loan of the material. This work is partly a result of studies carried out under grant No. 6 P04G 083 20, financed by the Polish State Committee of Scientific Research (KBN).

	FOOTNOTES

 
Accepted for publication August 13, 2007.

¹ Corresponding author. E-mail: a.ronikier{at}ib-pan.krakow.pl

	LITERATURE CITED

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION KEY TO THE SPECIES... CONCLUSIONS LITERATURE CITED

 
Aronsen A, Maas Geesteranus RA. 1989. Mycena ustalis, a new species from Southern Norway. Persoonia 14(1):61–64.

Elborne SA, Læssøe T. 1982. Huesvampe (Mycena)—Nye eller lidet kendte danske arter. Svampe 6:96–102.

Favre J. 1948. Les associations fongiques des hauts-marais jurassiens et de quelques regions voisines. Matériaux Flore Crypto Suisse 10(3):1–228.

Horak E. 2005. Röhrlinge und Blätterpilze in Europa. Kryptogamenflora, Band IIb/2, 6. Aufläge. Heidelberg: Spektrum Akad Verlag. 575 p.

Kühner R. 1938. Le Genre Mycena (Fries). In: Paul Lechevalier, ed. Encyclopedie Mycologique 10. Paris: Paul Lechevalier. 710 p.

Maas Geesteranus RA. 1977. Mycena galericulata—usually 2-spored? Persoonia 9(2):267–280.

———. 1985. Conspectus of the Mycenas of the northern hemisphere 4. Section Mycena. Proc Kon Ned Akad Wetensch C 88(3):339–369.

———. 1991a. Conspectus of the Mycenas of the northern hemisphere 15. Sections Hiemales and Exornatae. Proc Kon Ned Akad Wetensch C 94(1):81–102.

———. 1991b. Studies in Mycena. Additions and corrections 1. Proc Kon Ned Akad Wetensch C 94(3):377–403.

Moreau P.-A, Courecuisse R. 2003. Une réévaluation de Mycena radicifera J. Favre. Czech Mycol 54(3–4):161–175.

Moser M. 1983. Die Röhrlinge und Blätterpilze. Kleine Kryptogamenflora Band II b/2. Basidiomyceten, 2 Teil. Ed. 5. Jena: VEB Gustav Fischer Verlag. 533 p.

Peck CH. 1898. Report of the state botanist. Ann Rep NY Mus 51:267–321.

Redhead SA. 1986. Mycological observations 15–16: on Omphalia and Pleurotus. Mycologia 78(4):522–528.[CrossRef]

Smith AH. 1934. Investigations of two-spored forms in the genus Mycena. Mycologia 26:305–331.[CrossRef]

———. 1947 reprint 1971. North American species of Mycena. Biblioth Mycol 31. Lehre: Verlag von J. Cramer.

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