Longipedicellata megafusiformis Chandrasiri, Boonmee & K.D. Hyde, sp. nov.

Index Fungorum number: IF 558538; MycoBank number: MB 558538; Facesoffungi number: FoF 09947; Fig. 1

Etymology – The specific epithet “megafusiformis”, in reference to the large and broad fusiform ascospores compared to other described species of Longipedicellata.

Holotype – MFLU 21-0062

Saprobic on decaying submerged wood in the river. Sexual morph Ascomata 153–204 μm high, 130–236 μm diam., solitary, scattered, semi-immersed to superficial, globose or subglobose, uni-loculate, black, with a bright ostiole. Peridium 20–30 μm thick, composed of several layers of brown to dark brown cells of textura angularis. Hamathecium comprising numerous, 1–1.5 μm wide, cylindrical filiform, sparsely branched, cellular pseudoparaphyses, embedded in gelatinous matrix. Asci 60–99×12–26 μm (x̅=72×17 μm, n=20), 8-spored, bitunicate, narrowly to broadly clavate. Ascospores 22–30 × 7–16 μm (x̅= 26 × 11 μm, n = 20), 2–3-seriate, ellipsoidal to fusiform, asymmetrical, upper cell wider, rounded at both ends, 1-septate, constricted at the septum, with a prominent guttule in both cells when immature, hyaline, surrounded by a large mucilaginous sheath, smooth-walled. Asexual morph Undetermined.

Culture characteristics – Ascospores germinating on water agar within 12 h at room temperature. Colonies growing on PDA, circular, dense, umbonate, edge entire in surface view and fimbriate in lateral view, opaque, with distinct colour zones, from periphery to middle dark grey, light grey, white and getting darker in the middle.

Material examined – THAILAND, Chiang Rai Province, Muang, Mae Yao, Kok River on decaying submerged wood in the river shore, 4 December 2019, S. Boonmee and S.K.U. Chandrasiri, SJ-KR4 (MFLU 21-0062, holotype), ex-type living culture, MFLUCC 21-0085.

GenBank numbers – ITS=MZ538512, LSU=MZ538546, TEF1-α=MZ567090.

Notes – The phylogenetic analysis of a combined LSU, ITS, TEF1-α and SSU sequence dataset indicates that Longipedicellata megafusiformis forms a distinct lineage basal to L. aquatica with 94% MLBS, 1.00 BYPP support (Fig. 2). Longipedicellata megafusiformis is different from L. aptrootii and L. aquatica in terms of the ascomata features in having single loculate with a bright ostiole on the top view and the size of ascospores (Fig. 1). However, its mucilaginous sheath and septate are not significantly different from other Longipedicellata species. Longipedicellata megafusiformis has larger ascospores (22-30×7–16 μm) than other species such as L. aptrootii (17.5–22 × 8–8.5 μm) and L. aquatica (19–22×8.5–10.5 μm) (Dong et al. 2020b). Therefore, we introduce L. megafusiformis as a new species in Longipedicellata based on morphological and phylogenetic analyses in Longipedicellata.

Figure 1 – Longipedicellata megafusiformis (MFLU 21-0062, holotype). a, b Appearance of ascomata on decaying submerged wood substrate. c Section through ascoma. d Section of peridium. e Pseudoparaphyses. f, g Asci. h–k Ascospores. l Ascospores stained in Indian Ink showing a mucilaginous sheath. m, n Culture on PDA (m=from above, n=from below). Scale bars: c=100 μm, b–g=20 μm, h–l=10 μm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, ITS, TEF1-α and SSU sequence data of genera in Longipedicellataceae. The tree is rooted with Bambusicola bambusae (MFLUCC 11-0614). Bootstrap support values for maximum likelihood (MLBS, left) equal to or greater than 70% is given above the nodes. Bayesian posterior probabilities (BYPP, right) equal to or greater than 0.95 are given above the nodes. Ex-type strains are in bold and newly generated sequences are in blue