Neohelicascus elaterascus 2020

Neohelicascus elaterascus (Shearer) W. Dong, K.D. Hyde & H. Zhang, comb. nov.2020

Index Fungorum number: IF557925; Facesoffungi number: FoF09267

Holotype: Brunei (Ho et al. 2001), Chile (Shearer 1993b), China (Tsui et al. 2000; Luo et al. 2004), Japan (Tanaka et al. 2015), Peru (Shearer et al. 2015), South Africa (Hyde et al. 1998), Thailand (Hyde et al. 2020a; this study), USA (Shearer 1993b; Raja et al. 2009b)

Morphological description 

Saprobic on decaying wood submerged in freshwater. Sexual morph: Pseudostromata 205–250 μm high, 170–200 μm diam., clustered, immersed, unilocular, mammiform, coriaceous, with ostiolate papilla, visible on the host surface as blackened ostiolar dots. Peridium 20–30 μm thick, comprising several layers of brown, thin-walled, pseudoparenchymatous cells, outer layer partially occluded with the host cells, deeply pigmented, inwardly hyaline, forming a textura angularis in the upper regions and a Habitat: submerged wood textura prismatica at sides and angles of base. Pseudoparaphyses 1–3 μm diam., abundant, cellular, cylindrical, hyaline, sparsely septate. Asci 95–130 × 17–24 μm ( ^x̄ = 112 × 21 μm, n = 15), 8-spored, bitunicate, fissitunicate, clavate, endoascus separating from ectoascus at time of ectoascus dehiscence, base of endoascus long, narrow and coiled within ectoascus, up to 210 μm long. Ascospores 23–28 × 8–11 μm ( ^x̄ = 25 × 9 μm, n = 25), overlapping uni- or bi-seriate, sometimes overlapping tri-seriate, ellipsoidal, brown, 1-septate, constricted at septum, asymmetrical, apical cell slightly longer than basal cell, curved, thin-walled, smooth in optical microscope, surrounded by a gelatinous sheath. Asexual morph: Undetermined.Culture characteristics: On PDA, colony circular, reaching 40 mm in 45 days at 25 °C, dark brown to black from above, black from below, surface rough, dry, raised, edge undulate.

Habitat

Distribution: 

GenBank Accession:

Notes: Our new collections MFLUCC 18-0985 and MFLUCC 18-0993 are identified as Neohelicascus elaterascus based on morphological and molecular evidence (Fig. 84). Shearer (1993b) described verrucose ascospores from the holotype (C-76-1), while our collections have smooth ascospores which are also described by Hyde et al. (2020a). Helicascus elaterascus is commonly reported on submerged wood from many countries as listed above.

Reference: Freshwater Dothideomycetes are a highly diverse group of fungi, which are mostly saprobic in freshwater habitats worldwide. They are important decomposers of submerged woody debris and leaves in water. In this paper, we outline the genera of freshwater Dothideomycetes with notes and keys to species. Based on multigene analyses and morphology, we introduce nine new genera, viz. Aquimassariosphaeria, Aquatospora, Aquihelicascus, Fusiformiseptata, Neohelicascus, Neojahnula, Pseudojahnula, Purpureofaciens, Submersispora; 33 new species, viz. Acrocalymma bipolare, Aquimassariosphaeria kunmingensis, Aquatospora cylindrica, Aquihelicascus songkhlaensis, A. yunnanensis, Ascagilis submersa, A. thailandensis, Bambusicola aquatica, Caryospora submersa, Dictyocheirospora thailandica, Fusiformiseptata crocea, Helicosporium thailandense, Hongkongmyces aquaticus, Lentistoma aquaticum, Lentithecium kunmingense, Lindgomyces aquaticus, Longipedicellata aquatica, Neohelicascus submersus, Neohelicomyces dehongensis, N. thailandicus, Neohelicosporium submersum, Nigrograna aquatica, Occultibambusa kunmingensis, Parabambusicola aquatica, Pseudoasteromassaria aquatica, Pseudoastrosphaeriella aquatica, Pseudoxylomyces aquaticus, Purpureofaciens aquatica, Roussoella aquatica, Shrungabeeja aquatica, Submersispora variabilis, Tetraploa puzheheiensis, T. yunnanensis; 16 new combinations, viz. Aquimassariosphaeria typhicola, Aquihelicascus thalassioideus, Ascagilis guttulaspora, A. queenslandica, A. seychellensis, A. sunyatsenii, Ernakulamia xishuangbannaensis, Neohelicascus aquaticus, N. chiangraiensis, N. egyptiacus, N. elaterascus, N. gallicus, N. unilocularis, N. uniseptatus, Neojahnula australiensis, Pseudojahnula potamophila; 17 new geographical and habitat records, viz. Aliquandostipite khaoyaiensis, Aquastroma magniostiolata, Caryospora aquatica, C. quercus, Dendryphiella vinosa, Ernakulamia cochinensis, Fissuroma neoaggregatum, Helicotruncatum palmigenum, Jahnula rostrata, Neoroussoella bambusae, N. leucaenae, Occultibambusa pustula, Paramonodictys solitarius, Pleopunctum pseudoellipsoideum, Pseudocapulatispora longiappendiculata, Seriascoma didymosporum, Shrungabeeja vadirajensis and ten new collections from China and Thailand, viz. Amniculicola guttulata, Aquaphila albicans, Berkleasmium latisporum, Clohesyomyces aquaticus, Dictyocheirospora rotunda, Flabellascoma fusiforme, Pseudoastrosphaeriella bambusae, Pseudoxylomyces elegans, Tubeufa aquatica and T. cylindrothecia. Dendryphiella phitsanulokensis and Tubeufa roseohelicospora are synonymized with D. vinosa and T. tectonae, respectively. Six orders, 43 families and 145 genera which belong to freshwater Dothideomycetes are reviewed. Of these, 46 genera occur exclusively in freshwater habitats. A world map illustrates the distribution of freshwater Dothideomycetes

Fig. 82  Neohelicascus elaterascus (c, d, h, j–m from MFLU 18-1007, e–g, i, n–p from MFLU 18-0997). a, b Immersed pseudostromata with blackened ostiolar dots. c Vertical section of pseudostroma. d Structure of peridium. e–h Bitunicate asci. i–m Ascospores. (l, m in Indian Ink). n Germinated ascospore. o, p Colony on PDA (left-front, right-reverse). Scale bars: c = 50 μm, d–n = 20 μm