Marasmius horridulus Singer

Komura, Dirce L., De Oliveira, Jadson J. S., Moncalvo, Jean-Marc, Margaritescu, Simona & Zartman, Charles E., 2016, Marasmius calvocystidiatus sp. nov. and M. horridulus (Marasmiaceae): characterization of two unusual species from central Amazonia, Phytotaxa 280 (3), pp. 222-240 : 233-237

Marasmius horridulus Singer , The Agaricales in Modern Taxonomy: 367 (1986). Figs. 5–7

Description:— Pileus 3 mm diam., plane to broadly convex, center slightly depressed with a conspicuous papilla, margin tenuously incurved, edge bulky, very hairy (more than the central disc); surface strigose all over, densely covered by thin, long ‘hairs’ as in Crinipellis , dry, dull; brown to dark brown (634017), firm consistency, context thin (<1 mm). Lamellae collariate with well-developed collar tightly adjusted on the stipe apex, close, L = 24 to c. 30, thick, a little arched, faces cream to light fawn; marginate, edge swollen or broad, rigid, velutinous, dark brown (4F3211) in both lamellae and collar. Stipe 28 × 0.5–1 mm, central, cylindrical, thin, terete to depressed, insititious; surface glabrous, smooth, glossy; horny or chitinous, flexible, hollow; dark brown (4F3211). Odour undetectable. Taste not observed.

Basidiospores 7.4–8 × 4 μm [χ m = 7.7 (± 0.4) × 4 μm; Q m = 1.9 (± 0.1); n = 3, only from DLK917], short-oblong, ellipsoid to lacrimoid or pip-shaped, smooth, thin-walled, hyaline, inamyloid. Basidioles 20–30 × 5–7 μm, clavate to subfusoid, thin-walled, hyaline, inamyloid. Pleurocystidia absent. Cheilocystidia ochraceous, abundant, in form of Chrysochaetes - type broom cells, but with short, coarse, obtuse diverticula; main body 15–40 × 6–8 μm, some not diverticulate, subfusoid, other apparently forked or presenting lateral sprouts, thick-walled (some with more tenuous wall). Lamellae trama dextrinoid, irregular, hyphae interwoven, hyaline, smooth, thin-walled. Pileus trama dextrinoid (including the trama at the edge), irregular, hyphae similar to those of the lamellae trama. Pileipellis hymeniform to irregularly hymeniform, made up of cells mostly furcate (2, 3 or 4 projections), or diverticulate like the cheilocystidia (Chrysochaetes - type broom cells) or sometimes resembling Rameales - type structures; main body 8–38 × 7–12 μm, some pyriform, cylindrical to clavate, often turbinate, or more frequently irregular in outline, thick-walled, ochraceous brown to coppery brown, sometimes golden in the lumen; diverticula 2–12 × 1–4 μm, coarse, broad, obtuse, fingerlike, solid or with lumen and projections more elongate (10–25 × 2–4 μm), finger-, tentacle-like or setiform, not sub branched, usually with lumen, obtuse to acute. Pileus hairs long filamentous hyphae, 51–570 × 5–17 μm, longer at the margin and edge of the pileus, shorter toward the central disc, rising from the hymeniform or subhymeniform pileipellis, setiform, cylindrical, clavate and cystidioid when short, sometimes tapering only in the terminal segment, apex obtuse-rounded to almost acute, not branched, septate, clamped, coppery brown, thick-walled, dextrinoid. Stipe trama parallel, cylindrical, golden brown, thick-walled. Stipitipellis with no caulocystidia, no setae and no hairs. Clamp connections present in all tissues, but not seen in the cells of the pileipellis.

Habit and habitat:—Marasmioid, solitary, saprophytic on dicotyledonous leaves at Amazonian terra firme forest.

Material examined and distribution:— BRAZIL. Amazonas State: Manaus, Embrapa , 12 July 1978, R. Singer, Souza & Aguiar, B. 11272 (Holotype, INPA82459 !) ; Amazonas State: Manaus Reserva de Desenvolvimento Sustentável do Tupé , 06 September 2012, D.L.Komura DLK917 ( INPA270735 !) .

Comments:— Marasmius horridulus Singer is a very unusual species within the genus by the fact that it presents a densely hairy, pilose or strigose pileus. This ‘crinipelloid’ habit refers to Crinipellis , one of the closest genera to Marasmius in phylogenetic analyses ( Moncalvo et al. 2000, 2002, Wilson & Desjardin 2005, Matheny et al. 2006). It is possible to morphologically differentiate M. horridulus from Crinipellis taxa by its distinctly collariate lamellae, completely glabrous stipe, and unusual diverticulate or furcate elements alongside the Crinipellis -like hairs in the hymeniform to subhymeniform pileipellis (see more in the discussion section). The few basidiospores examined from specimen DKL917 aligned with Singer’s original description: 7–8.8 × 3–4 μm, oblong, hyaline and inamyloid ( Singer 1989).

Because of its bizarre characteristics, Singer (1986) established a third, monospecific subsection in sect. Marasmius , named subsect. Horriduli. Based on M. horridulus , only formally described in Singer (1989), Horriduli differs from the other subsections “in the presence of numerous pseudoamyloid setiform hairs, especially long at the margin of the pileus” ( Singer 1986). According to Wannathes et al. (2009), there are two other species in sect. Marasmius having setiform elements in the pileipellis: M. purpureisetosus Corner and M. berambutanus Desjardin, Retn. & E. Horak. Both species are known from Thailand and also have unusual broom cells or furcate elements in the pileipellis similar to those in M. horridulus . However, they do not have densely hairy or strigose pileus, only hispid due to the presence of pileosetae instead of hairs. Thus, M. horridulus is the only taxon with true crinipelloid hairs in the pileipellis in Marasmius . Marasmius purpureisetosus and M. berambutanus also differ from M. horridulus by the: 1) rare presence of a central papilla at the pileus and complete absence of a bulky edge; 2) broad, non-arched, less-numerous, nonmarginate, lamellae, whose edges are not swollen; 3) thin-filiform stipe (up to 0.3 mm thick); 4) long basidiospores (up to 10 μm), and 5) presence of trama and cystidia/cells inamyloid in Melzer. This latter pattern diverges from the Chrysochaetes - type elements concept, and should be revised in those species.

Marasmius calvocystidiatus spec. nov. is similar to M. horridulus in: 1) the shape of the papillate pileus; 2) the presence of bulky edges; 3) the pattern of the whole hymenophore; 4) the shape of basidiospores; 5) the dextrinoid trama in all tissues; and 6) the thick-walled, dextrinoid elements (Chrysochaetes - type elements concept) along the edge of the lamellae and forming the pileipellis. In short this newly described taxon looks like a ‘bald’ version of M. horridulus , differing only in its glabrous pileus, smaller basidiospores (4.2–5.2 × 2.6–3.9 μm), one type of cheilocystidia, and pileipellis consisting mostly of smooth elements, sometimes lobed or with excrescences, never forked or diverticulate, and complete absence of pileus hairs.

Figures

FIGURE 5. Marasmius horridulus. A. Basidiomata of the holotype. A1. Detail of the lamellae. B. Basidiomata of DLK917. B1. Hairy pileus. B2. Lamellae attached to collar. Scale bars: A, B = 3 mm. A1, B1, B2 = 1.5 mm. Photos by D.L. Komura.

FIGURE 6. Marasmius horridulus. A. Basidiospores. B. Basidioles. C. Cheilocystidia. D. Short, cystidioid hairs in the pileipellis. E. Long, complete hair. F. Hairs tips in detail. Scale bars: A = 8 μm. B, C = 7 μm. D, F = 10 μm. E = 100 μm. Illustrated by D.L. Komura.

FIGURE 7. A variety of cells forming the pileipellis of Marasmius horridulus. Scale bar: 10 μm. Illustrated by D.L. Komura.