Gymnopus nidus-avis Cesar , Bandala & Montoya

Cesar, Enrique, Bandala, Victor M., Montoya, Leticia & Ramos, Antero, 2018, A new Gymnopus species with rhizomorphs and its record as nesting material by birds (Tyrannidae) in the subtropical cloud forest from eastern Mexico, MycoKeys 42, pp. 21-34 : 21

Gymnopus nidus-avis Cesar, Bandala & Montoya sp. nov. Figs 2, 3, 4

Holotype.

MEXICO. Veracruz: Municipality of Xalapa, Santuario del Bosque de Niebla, Instituto de Ecología A.C., 1343 m a.s.l., gregarious, on fallen twigs of Quercus , 20 April 2016, Cesar 36 (XAL).

Diagnosis.

Pileus pale brown to brown. Lamellae adnexed, distant, very pale brown. Basidiospores ellipsoid to subcylindrical. Basidia 2-4-spored, narrowly clavate. Cheilocystidia 20-39 × 3-8 µm, irregularly cylindrical, with constrictions and small lateral appendages. Pileipellis hyphae with colourless incrustations; terminal elements appendiculate. Pileus and lamellar tissues clampless.

Gene sequences ex-holotype.

MH560576 (ITS).

Etymology.

Referring to the use of rhizomorphs as nesting material by birds.

Basidiomata marcescent. Pileus 1-7 mm diam., convex to plano-convex, usually somewhat depressed over the disc and occasionally slightly infundibuliform with age, some developing a weak umbo, smooth or weakly rugulose, subtly striate when young becoming somewhat sulcate and then wavy towards the margin, this latter slightly decurved, surface dry, minutely granulose under lens, matt, pale brown (7.5 YR 7/4-6; 10YR 7/4) to brown (7.5 YR 5/6; 10 YR 4/4); context thin (up 1 mm thick), soft, whitish. Lamellae adnexed, distant (7-17), very pale brown (2.5 Y 8/2), narrow to moderately broad (up to 1 mm broad), sometimes forked, lamellulae of two different lengths, rarely weakly intervenose with age, margin entire. Stipe 1-12 × 0.2-0.3 mm, central, sometimes only slightly eccentric, cylindrical or tapered towards the base, straight, often curved, solid, glabrous, very finely striate (under lens), reddish-brown at the apex (2.5 YR 4/6), dark brown to black below (10YR 2/1, 7.5YR 2.5/2), insititious, at times erumpent, arising either from the substratum or from rhizomorphs; context light brown (2.5Y 6/4). Rhizomorphs up to 500 × 1 mm, simple, black, wiry, abundant. Odour and taste not distinctive.

Basidiospores 7-10 × 3-5.5 µm, x̄m = 8.3-9.1 × 3.7-4; q̄m = 2-2.4 (n = 4), ellipsoid to subcylindrical, somewhat lacrymoid with a weak suprahilar depression, hyaline, inamyloid, thin-walled. Basidia 20-41 × 5-10 µm, 2-4-spored, clavate to narrowly clavate, hyaline, inamyloid, thin-walled, clampless. Cheilocystidia 20-39 × 3-8 µm, irregularly cylindrical to narrowly-claviform, simple or usually bifurcate, with small lateral appendages and constrictions, moderately abundant, shortly projected beyond the hymenium level, hyaline, inamyloid, thin-walled, clampless. Pilleipellis composed of compactly interwoven, cylindrical, non-gelatinised, thin-walled, clampless, hyaline hyphae, 4-8 µm diam., irregularly covered by colourless, refractive incrustations of fine or moderately broad, discontinuous lines, arranged in a more or less irregularly transversal pattern, bearing repent or slightly erect, hyaline, slightly dextrinoid terminal elements which are irregularly cylindrical, with numerous appendages or with short to moderately large lateral outgrowths, thin-walled or the apices often thick-walled, with a morphology similar to a Rameales-structure. Pileus trama hyphae interwoven, 4-6 μm diam., cylindrical, often bifurcate, thin-walled, hyaline, weakly dextrinoid, smooth, often intermixed, some covered with colourless refractive encrusting material. Hymenophoral trama regular to subregular, with cylindrical, thin-walled, hyaline, inamyloid to weakly dextrinoid, clampless hyphae 3-5 μm diam. Stipitipellis composed of repent, cylindrical, thick-walled, heavily dark brown pigment-encrusted, clampless hyphae 5-6 μm diam., dextrinoid; with scattered, hyaline or brown-pigmented, diverticulate terminal elements 4-19 (-21) × 3-4 (-5) µm, thin-walled. Stipe trama hyphae more or less parallel, composed by cylindrical or more or less ventricose hyphae, 4-15 (-20) μm diam., thick-walled (1-5 μm thick), smooth or with colourless encrusting material, towards the central medulla they appear intermixed with hyaline, smooth, cylindrical hyphae, 3-6 µm diam., thin or slightly thick-walled (<1 µm thick), occasionally clamped. Clamp connections absent in pileus and lamellar tissues, present in the slender, medullary hyphae of stipe.

Habitat.

In subtropical cloud forest, scattered or gregarious on fallen twigs of Quercus , often the basidiomes arising directly from the wiry, black rhizomorphs and these latter at times are entangled, hanging from aerial branches.

Additional specimens examined.

MEXICO. Veracruz, Municipality of Xalapa, Santuario del Bosque de Niebla, Instituto de Ecología A.C., 1343 m a.s.l., 18 May 2006, Bandala 4052; 7 July 2016, César 41; 10 Aug 2016, Ramos 682 (all at XAL).