Ascominuta ovalispora D.M. Hu & K.D. Hyde
Holotype: MFLU 081176
Etymology: -ovalispora, in reference to the ovoid ascospores
Sexual morph: Ascomata 90–120 µm high, 80–90 µm in diam., ostiolate, necks not visible, superficial to partly immersed in the host substrate, globose to subglobose, dark brown to black, solitary or aggregated. Ostiole periphysate. Peridium 8–13 µm wide, comprising three to five layers of hyaline compressed cells, with an outer layer of dark brown textura angularis. Pseudoparaphyses 8–20 µm long, sparse, comprising short chains of globose cells, apical cell swollen. Asci 35–38 × 25–30 µm, 4-spored, globose, non-pedicellate, bitunicate. Following the dehiscence of the ectotunica, the endotunica extends and finally the ascospores are released. Ascospores 28–30 × 9–10 µm ( = 29 × 9 µm, n = 30), multiseriate, ovoid, 1-septate, slightly constricted at the septum, with a basal papilla-like swelling, hyaline, surrounded by a sac-like persistent sheath, usually with large globule in each cell when young, germinated from both ends of the ascospores. Asexual morph: undetermined. (Description from Hu et al. 2010)
Material examined: Thailand, Chiang Mai, Mushroom Research Center stream, on submerged wood, 24 Aug 2008, leg. D. M. Hu (MFLU 08 1176).
Notes: This fungus should be placed in Ascominuta because it produces 4-spored, globose asci, 1-septate ascospores surrounded by an irregular mucilaginous sheath, sparse pseudoparaphyses comprising short chains of globose cells and relatively small ascomata. The new species differs from the type species in having larger ascomata, apically swollen pseudoparaphyses and ovoid ascospores with a sac-like persistent sheath. (Notes from Hu et al. 2010)
Freshwater distribution: Thailand (Hu et al. 2010)
Fig. 1. Ascominuta ovalispora. 1. Appearance of ascomata on submerged wood. 2. Section of ascomata. 3. Surface of peridium. 4. Pseudoparaphyses. 5–7. Asci. 8–12. Ascospores. Scale bars: 1 = 300 µm, 2 = 50 µm, 3–4 = 20 µm, 5 = 50 µm, 6–12 = 20 µm. (Hu et al. 2010)