Marasmius castanocephalus J.S. Oliveira, 2022

S, Jadson José, Oliveira, ouza de, Capelari, Marina, Margaritescu, Simona & Moncalvo, Jean-Marc, 2022, Disentangling cryptic species in the Marasmius haematocephalus (Mont.) Fr. and M. siccus (Schwein.) Fr. species complexes (Agaricales, Basidiomycota), Cryptogamie, Mycologie 20 (5), pp. 91-137 : 109-111

Marasmius castanocephalus J.S. Oliveira , sp. nov.

( Figs 9B ; 11 )

Differs from Marasmius davidii Antonín in having non-marginate lamellae, slightly smaller basidiospores (20-26 × 3-4 µm vs 20-27 × 4-6 µm), in having yellowish pleurocystidia, and in growing on dried leaves.

HOLOTYPE. — Brazil. São Paulo State, Iporanga City, Parque Estadual Turístico do Alto Ribeira , 29.II.2012, J.J.S. Oliveira & D.E. Desjardin JO523 (holo-, SP[SP 445573]!).

ETYMOLOGY. — From Greek Καστανός (kastanos) and ΚΕΦάλι (kephali), based on the brownish pileus.

MYCOBANK. — MB 842536.

HABIT AND SUBSTRATE. — Marasmioid ( Figs 9B ; 11A 1), close, on dried eudicotyledonous leaves in the forest litter.

DESCRIPTION

Pileus ( Figs 9B ; 11A 1)

7.5-15.7 mm diam., hemispheric to conical-campanulate, sulcate, center flat or slightly umbonate, margin decurved, edge entire to crenate; center to mid disc light chestnut to buff brown (N 50 Y 60-80 M 30-40), margin pale sepia brown (N 40 Y 40 M 30) to pale buff brown or brownish beige (N 20 Y 30 M 20 to N 10 Y 30- 40 M 10); membranous, context white, thin (<1 mm); glabrous, dry, dull, papyraceous to subvelutinous, non-hygrophanous.

Lamellae ( Fig. 11A 2 )

Free to adnexed, subclose to subdistant, L = 11-12, equal, narrow to slighty broad, simple, l = 0, opaque, smooth, pale cream (N 00 Y 10 M 00), edge even, non-marginate, interlamellar hymenium concolorous with the lamellae faces.

Stipe ( Figs 9B ; 11A 1)

61-80 × 0.5-0.8 mm, central, filiform, thin, equal, with circular caliber, chitinous, tough, hollow, apex concolorous with the lamellae, amber (N 60 Y 50 M 30) to dark brown (N 90 Y 70-99 M 50), or almost black downwards, glabrous, smooth, with a silky bright; with a scarce, cream, tomentose basal mycelium.

Odor

Not distinctive.

Basidiospores ( Fig. 11B )

20-26 × 3-4 µm (xm = 22.6 [± 1.2] × 3.7 [± 0.3] µm, Qm = 6.1 [± 0.5], n / s = 32/1), oblong, clavate to subfusoid, smooth, hyaline, thin-walled, inamyloid.

Basidia

Not observed.

Basidioles ( Fig. 11C )

(16.3-)20-25 × 5-8 µm, clavate, rarely tending to acuminate, smooth, hyaline, thin-walled, inamyloid.

Pleurocystidia ( Fig. 11D )

33-50 × 9.8-13.8 µm, abundant, broadly clavate, sometimes tapered towards the apex, some capitate, or with a small apical vesicle, or mucronate, smooth, refractive, with faint content, somewhat fuscous, yellowish, thin-walled, inamyloid.

Cheilocystidia ( Fig. 11E )

Similar to the Siccus-type broom cells in the pileipellis, pale brown when grouped, main body 8-22.5 × 5-15 µm, clavate to slightly turbinate, or pyriform to almost globose, sometimes ventricose, thin-walled; setulae apical, erect, short to generally elongate, 2.5-8.8 × 0.6-1 µm, cylindrical, filiform, thin, rarely digitiform, regular in outline, simple, pale yellow to hyaline, solid, apex somewhat obtuse or more frequently acute.

Lamellar trama

Dextrinoid, irregular, interwoven, hyphae cylindrical, 2.5- 17.5 µm diam., regular or irregular in outline, branched, hyaline, smooth, thin-walled.

Pileus trama

Dextrinoid, irregular, hyphae interwoven, cylindrical, 1.3-8 µm diam., similar to the lamellar trama, but with some inflated hyphal segments.

Pileipellis

Hymeniform, composed of Siccus - type broom cells ( Fig. 11F ), abundant, yellowish to pale chestnut when grouped; main body 8.8-18.8 × 5.6-14 µm, clavate to turbinate, rarely globose or branched, hyaline, thin-walled; setulae apical, erect, 2-7.5 × 0.5-1.3 µm, cylindrical, thin, filiform, simple, regular in outline or contorted, yellowish, solid, apex acute or slightly obtuse.

Stipe trama

Dextrinoid, cortical hyphae parallel, cylindrical, 1.8- 8.8 µm diam., regular in outline, branched, brownish, smooth, thick-walled; internal hyphae hyaline, thin-walled, 2.5-8 µm diam.

Clamp connections

Present in all tissues, except in the cortical hyphae of the stipe.

REMARKS

Marasmius castanocephalus J.S. Oliveira , sp. nov. is mainly characterized by the buff brown to brownish beige pileus, the large basidiospores (20-26 × 3-4 µm) and somewhat fuscous to yellowish pleurocystidia (33-50 × 9.8-13.8 µm). It seems a member of stirps Helvolus ( Singer 1976) in ser. Haematocephali (sensu Singer 1976) because of the brown pileus as in M. helvolus Berk.

Marasmius castanocephalus J.S. Oliveira , sp. nov. is closer to M. davidii from Sri Lanka (Indo-Malayan realm), initially described as M. helvolus var. brunneolus Berk. & Broome ( Berkeley & Broome 1873). Pegler (1986) elevated this variety to M. brunneolus (Berk. & Broome) Pegler. Marasmius helvolus has much smaller basidiospores (11-15 × 2.8-4 µm) and not projecting, inconstant, smaller (19-25 × 5-10.2 µm), opaque and thick-walled pleurocystidia ( Singer 1976). Due to the homonym with M. brunneolus (Beeli) Singer , in sect. Globulares (traditional sense) ( Singer 1964), Antonín (2003) replaced M. brunneolus (Berk. & Broome) Pegler with M. davidii . This species differs from M. castanocephalus J.S. Oliveira , sp. nov. mainly in having very distant, marginate lamellae (brown edge), slightly larger basidiospores (20-27 × 4-6 µm), only hyaline pleurocystidia and brownish cheilocystidia (setulae), and basidiomata found on dead sticks ( Pegler 1986). Marasmius brunneolus var. fuliginosus Desjardin & E.Horak was described having dark brown to fuliginous pileus ( Desjardin & Horak 1997). Marasmius castanocephalus J.S. Oliveira , sp. nov. is close to M. haematocephalus var. leucophyllus Singer , and to M. musicola Murrill , M. allocystis Singer , and M. oleiger Singer (stirps Oleiger ) because of the brownish pigmentation of the pileus within ser. Haematocephali sensu Singer ( Singer 1976). All these taxa, however, have much shorter basidiospores (up to 20.5 µm) and the last three have distinct pleurocystidia with oil-like content. No other formally published variety under M. haematocephalus seems close. Marasmius semipellucidus Berk. & Broome is discarted as conspecific with M. castanocephalus J.S. Oliveira , sp. nov. (Appendix) by the translucent stipe and geography of the original collection.

In the phylogenetic trees(Figs1;3), M.castanocephalus J.S.Oliveira , sp. nov. appears close to M. roseus J.S. Oliveira , sp. nov., but with unsupported resolution. Both species branched in haemat_cp1. Marasmius castanocephalus J.S.Oliveira , sp.nov. is close to M. haematocephalus but is 4.4%dissimilar in nrITS and2.6%in nrLSU and differs by the pale brown pileus and larger basidiospores.

Figures

FIG. 9. — Pictures of fresh basidiomata: A, Marasmius auranticapitatus J.S. Oliveira, sp. nov. (M. Capelari & L.A.S. Ramos 4554); B, M. castanocephalus J.S. Oliveira, sp. nov. (JO523); C, M. coasiaticus J.S. Oliveira, sp. nov. (JO323). Scale bars: 10 mm.

FIG. 11. — Marasmius castanocephalus J.S. Oliveira, sp. nov. (JO523): A1, A2, basidiomata; B, basidiospores; C, basidioles; D, pleurocystidia; E, cheilocystidia; F, Siccus-type broom cells of the pileipellis. Scale bar: A1, 18 mm; A2, 10 mm; B-F, 10 µm.

FIG. 2. — Best-scored Maximum Likelihood Tree (TL = 0.164547) built from multilocus (nrITS and nrLSU) analysis based on siccus_cp1 in Fig. 1 (DATASET 2a). Support values are BS (70 to 100%) and PP (0.95 to 1.0). Black, thick stems indicate high support and gray, thick stems indicate weak to moderate support. The gray shades highlight siccus_cp2a, siccus_cp2b, and M. siccus s. str. Blue arrows indicate the geographic origin of the strains. Global map is based on Olson & Dinerstein (2002) with forested areas depicted in their biogeographic realms.