Marasmiellomycena De la Peña-Lastra, Mateos, Kolařík, Ševčíková & Antonín, gen. nov.

Index Fungorum number: IF839731; MycoBank number: MB839731; Facesoffungi number: FoF 14222

Etymology – Epithet reflects its similarity to Marasmiellus and (Hemi) mycenoid genera. Diagnosis: Basidiomata omphaloid or marasmioid, nonfragile. Pileus thin-fleshed, minutely tomentose, pubescent, granulose to subsquamulose. Lamellae well-developed, frequently forked, anastomose, adnate, sub-decurrent or decurrent, triangular or arcuate. Stipe central, filiform, entirely pruinose or pruinose-floccose, flesh thin. Basal tomentum present. Spores smooth, inamyloid. Basidia mostly tetrasporic. Cheilocystidia less distinct. Pleurocystidia absent. Pileipellis a cutis or with transitions to a trichoderm, terminal elements cylindrical, fusiform, lageniform or mucronate with or without excrescences or long rostrum (pileocystidioid structures). Clamp connections present. Chemical reactions metachromatic in cresyl blue or not, no other part of basidiomata dextrinoid or amyloid. Ecology saprotrophic, on dead wood and decayin leaves.

Type species – Marasmiellomycena pseudoomphaliiformis Antonín & Ševčíková.

Notes – Our three new collections (BRNM 552658, BRNM 552721, BRNM 552654) are morphologically identical and they shares many similar characters with Porotheleum omphaliiforme. Therefore, this well-supported clade herein introduce as Marasmiellomycena gen. nov. Vu et al. (2018) predicted that optimal thresholds for fungi (at least for filamentous) at the genus level of 98.2% based on LSU barcodes and 94.3% based on ITS barcodes. The genetic similarity of the genus Marasmiellomycena to neighboring genera, expressed by the similarity of M. pseudoomphaliiformis (type collection) to P. parvulum and (sequences identified as) P. fimbriatum, is 97.8% for LSU, and 88.9% for ITS. Marasmiellomycena has morphological affinities with Marasmiellus, Hemimycena, Pulverulina, and several mycenoid genera in Mycenaceae (Redhead and Singer 1981; Moncalvo et al. 2002; Matheny et al. 2006, 2020; Redhead 2012; See discussion under M. pseudoomphaliiformis for detailed comparison with the most similar species).

Species