Microascales » Microascaceae » Microascus

Microascus trigonus

Microascus trigonus Z.F. Zhang & L. Cai, sp. nov.

Index Fungorum number: 557748, Facesofungi number: FoF 08457; Fig. 42

Etymology: Referring the shape of the ascospores.

Holotype: HMAS 248001.

Hyphae hyaline, septate, branched, smooth, thin-walled, 1.5–3.0 µm diam. Sexual morph Ascomata abundant, black, superfcial, glabrous, subglobose to globose, 182–294 µm diam, with a short cylindrical ostiolar neck; peridium with a textura angularis. Asci short clavate, subglobose to globose, hyaline, 8-spored, 9.0–17 × 8.0–12 µm. Ascospores triangular, smooth, thick-walled, pale brown, 4.5–6.0 × 3.5–5.5 µm (x̄ ± SD = 5.7 ± 0.43 × 4.3 ± 0.53 µm, n = 50). Asexual morph conidiophores simple, straight, septate, occasionally branched, hyaline. Conidiogenous cells solitary on aerial hyphae, or in whorls of 2–3 on apex of conidiophores, lageniform to ampulliform, straight or slightly curved, pale brown, 4.5–10.0 (−14.5) × 2.5–4.5 µm. Conidia in long chains, ellipsoidal to globose, smooth, thick-walled, hyaline to pale brown, 3.5–5.5 × 3.0–4.5 µm (x̄ ± SD = 4.5 ± 0.47 × 3.8 ± 0.29 µm, n = 70). Culture characteristics—Colonies on PDA attaining 26–30 mm diam after 3 weeks, felty, compact, plicated, convex, margin undulate, beige (30A2) to whitesmoke (4A2) with lightgrey (1C4) ring. Reverse plicated, crack, beige (30A2) to oldlace (5A2) with lightgray ring (1C4). Colonies on OA attaining 34–36 mm diam after 3 weeks, fat, margin entire, white to dark brown (5F8). Reverse white to pale brown (5B3). Colonies on SNA attaining 28–36 mm diam after 3 weeks, fat, margin fmbriate, foralwhite (1A2) to yellow-green (2A2). Reverse foralwhite (1A2) to pale yellow-green (2A2). Sporulation within 15 days.

Material examined: CHINA, Guangxi, Guilin, Luotian Cave, N 24.948°, E 110.524°, on soil, May 2016, Z.F. Zhang, HMAS 248001 (holotype designated here), ex-type living culture CGMCC3.19636 = LC12520; ibid., LC12513; Guangxi, Guilin, E’gu Cave, N 24.942°, E 110.511°, animal faeces, May 2016, Z.F. Zhang, LC12559; ibid., LC12586; ibid., LC12631.

Notes: Microascus trigonus is phylogenetically closely allied to M. chartarus (G. Sm.) Sand.-Den. (Fig. 37), but can be distinguished by the absence of sexual morph with ovate, green-brown, and frequently pointed conidia. Morphologically, M. alveolaris resembles M. trigonus. However, the conidia in M. alveolaris are ellipsoidal, navicular or bullet-shaped rather than ellipsoidal to globose in M. trigonus.

 

Fig. X Microascus trigonus (from ex-holotype CGMCC3.19636). a– c Upper and reverse views of cultures on PDA, OA and SNA 3 weeks after inoculation; d, e ascoma; f peridium; g–i asci; j ascospore; k–n conidiogenous cells and conidia; o conidia. Scale bars: e 100 µm; h 20 µm; f, g, i–o 10 µm.

 

Retrieved from:

Zhang ZF, Zhou SY, Eurwilaichitr L, Ingsriswang S  et al.  2021 – Culturable mycobiota from Karst caves in China II, with descriptions of 33 new species. Fungal Diversity 106(1), 29-136. https://doi.org/10.1007/s13225-020-00453-7

 

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