Hysterobrevium baoshanense M. Raza & M. Hussain, sp. nov.

Index Fungorum number: IF 900236; MycoBank number: MB 900236; Facesoffungi number: FoF 14165; Fig. 1

Etymology – Referring to the the region (Baoshan) where sample has been collected.

Saprobic on decaying wood of Pinus armandii Franch. Sexual morph: Ascomata 310–400 μm high, 200–280 μm wide (x=383×255 µm, n=10), hysterothecial, superficial, scattered, solitary to rarely clustered, uni-loculate, black, flexuous, glabrous, rough-walled, with a thick slit-like opening. Peridium 35–60 μm wide, thick-walled of unequal thickness, thinner at the base (50–85 μm), thicker at the sides towards its apex, with several layers of dark brown to black cells and brittle, carbonaceous tissues. The inner layer contains simple flattened cells and the outer layers contains several layers of dark and black, thick-walled, polygonal pseudoparenchymatous cells, arranged in a textura angularis. Hamathecium composed of 1–2 μm wide, dense, filamentous, septate, unbranched, cellular pseudoparaphyses, not constricted at the septa, anastomosing at the apex, embedded in a gelatinous matrix. Asci 70–110×15–25 μm (x = 87.5 × 18.5 μm, n = 25), 8-spored, bitunicate, fissitunicate, cylindric-clavate, short pedicellate, apically rounded, with well-developed ocular chamber. Ascospores 20–28×8–10 μm (x=24.9×9.1 μm, n=35), overlapping bi-seriate, hyaline, becoming pale brown at maturity, fusiform to ellipsoidal, obvoid or muriform, 3–6-transverse septate, 1–2-longitudinally septate, with several segments, constricted at the septum, smooth-walled, with guttules, surrounded by mucilagenous sheath. Asexual morph: Undetermined.

Material examined – China, Yunnan Province, Baoshan City (25° 16′ 21.0″ N, 99° 18′ 00.1″ E), on decaying wood of Pinus armandii (Pinaceae), 7 October 2015, M. Raza (MFLU 16-2162, holotype).

GenBank numbers – ITS: MZ467049, LSU: KX772765, SSU: KX772767, tef1-α: KX772769.

Notes – This collection is morphologically similar to “Hysterobrevium constrictum” (KUN-HKAS 102101) which was collected from China (Hyde et al. 2020a). However, except for other morphological characters, the ascospore length of KUN-HKAS 102101 is larger than the type specimen of H. constrictum (SMH5211) (27–35 × 10–12 µm vs 13–23×5–12 μm) (Boehm et al. 2009b). The base-pair difference between ITS locus of our collection and KUNHKAS 102101 is 2% while these differences for LSU, SSU and tef1-α are 9%, 0% and 16% respectively. Therefore, the taxonomy of KUN-HKAS 102101 needs a revision as it is mistakenly identified as H. constrictum.

Figure 1 – Hysterobrevium baoshanense (MFLU 16-2162, holotype). a Blackish ascomata on substrate. b Vertical section of hysterothecia. c Peridium. d Pseudoparaphyses. e–h Asci. i–m Ascospores. n Ascospore mounted in Indian ink to show mucilaginous sheath. Scale bars: b=50 μm, c–h=20 μm, i–n=5 μm