Public Description of Marasmius Fr.

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Name: Marasmius Fr.
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Description status: Unreviewed

General Description:

Discussion: Diagnostic features of Marasmius xestocephalus include: a greyish yellow to yellowish orange pileus with yellowish brown disc; subdistant (15-18), narrow, pale yellow lamellae; a pubescent to subvelutinous stipe; fusoid basidiospores with mean 12.5 × 3.7 μm; and apically forked caulocystidia. The Thai material is indistinguishable from the protologue (Singer, 1964) and redescription of M. xestocephalus by Pegler, (1977), and differs only slightly from the recent description provided by Antonín (2007) who reported broader basidiospores (4.5-5.5 μm diam.). Until further material of this species is collected, sequenced and compared with Thai specimens, we tentatively recognize our species as M. xestocephalus.

Diagnostic Description:

Pileus 5-23 mm diam., convex to plano- convex, umbonate, striate to pellucid-striate, pruinose, dull, disc yellowish brown (6D8), margin greyish yellow (4B4-5) to yellowish orange (4B7). Context pale yellow, thin. Lamellae adnexed to adnate, subdistant (15-18) with 3-4 series of lamellulae, narrow, pale yellow with or without light orangish brown edges, non-intervenose. Stipe 18-35 × 0.5-1 mm, central, cylindrical, hollow, pubescent to subvelutinous, non-insititious, apex light yellow (3A4), base light brown (6D6) to reddish brown (8E7). Odor and taste not distinctive.

Basidiospores (10-)11-14(-15) × 3-4 μm [xmr = 11.8-13 × 3.5-3.8 μm, xmm = 12.5 ± 0.6 × 3.7 ± 0.2 μm, Qmr = 3.4, Qmm = 3.4 ± 0.0, n = 25 spores, s = 3 specimens], ellipsoid to fusoid, smooth, hyaline, inamyloid, thin-walled. Basidia not observed. Basidioles fusoid to clavate. Cheilocystidia abundant, of Siccus- type broom cells; main body 10-18 × 6-9 μm, cylindrical to clavate, broadly clavate or irregular in outline, often lobed, hyaline, inamyloid, thin-walled; apical setulae 3-10 × 1- 1.5 μm, cylindrical, obtuse to subacute, pale yellow to yellow, thick-walled. Pleurocystidia absent. Pileipellis hymeniform, weakly mottled to non-mottled, composed of Siccus-type broom cells; main body (9-)12-24 × 5-11μm, clavate to broadly clavate, often branched, hyaline, inamyloid, thin-walled; apical setulae 2-5 × 1-1.5 μm, crowded, cylindrical, obtuse to subacute, yellowish brown, thick-walled. Pileus trama interwoven, dextrinoid. Lamellar trama hyphae 3-10 μm diam., interwoven, cylindrical, smooth, hyaline, dextrinoid, thin- walled, non-gelatinous. Stipitipellis hyphae (2-)4-8 μm diam., subparallel, cylindrical, brown to yellowish brown, smooth, weakly dextrinoid, thick-walled (up to 1 μm), non- gelatinous. Stipe trama hyphae 3-8(-10) μm diam., subparallel, cylindrical, hyaline, smooth, dextrinoid, thin-walled, non-gelatinous. Caulo- cystidia numerous, usually apically forked; main body 25-54 × 6-10 μm, cylindrical to irregular in outline, hyaline to pale yellow, weakly dextrinoid, thin- to thick-walled (up to 1 μm); apical fork 10-20 × 4-7 μm, cylindrical, obtuse, hyaline to pale yellow, thin- to thick- walled; Siccus-type broom cells absent on stipe surface. Clamp connections present in all tissues.

Habit, habitat and known distribution: Scattered to gregarious on dicotyledonous leaves, Africa and Northern Thailand.

Description author: Image Sharer (Request Authorship Credit)
Description editor: Joseph D. Cohen

Created: 2018-11-20 04:50:17 PST (-0800) by Image Sharer (image sharer)
Last modified: 2019-09-27 18:20:27 PDT (-0700) by Image Sharer (image sharer)
Viewed: once, last viewed: 2018-11-20 04:50:18 PST (-0800)