Pseudobactrodesmium aquaticum W. Dong, H. Zhang &K.D. Hyde, sp. nov., Figure 2

MycoBank number: MB 557248; Index Fungorum number: IF 557248; Facesoffungi number: FoF07526;

Etymology: aquaticum in reference to the aquatic habitat

Holotype: MFLU 18-1171

Saprobic on submerged wood in freshwater. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies sporodochial, superficial, effuse, gregarious or scattered, brown, punctiform. Mycelium mostly immersed, composed of septate, branched, hyaline hyphae. Conidiophores 26–38    3–4.5 µm (x = 34 3.8 µm, n = 10), macronematous, mononematous, fasciculate, compact, erect, subcylindrical, the apex slightly wider than the base, septate, slightly constricted at septa, usually unbranched, brown, smooth. Conidiogenous cells enteroblastic, with inconspicuous proliferations, integrated, terminal, subcylindrical, pale brown. Conidia (80–)90–105    6–8.5 µm (x = 95      7.5 µm, n = 20), acrogenous, solitary, dry,thin-walled, smooth-walled, clavate when young, subcylindrical to narrowly fusiform, or subulate when mature, straight or slightly curved, euseptate, (15–)16–19-phragmoseptate, slightly constricted and darker at septa, pale brown to brown, obscurely guttulate, wedge-shaped at basal cell, with tapering apical cells, often enveloped by a hyaline, spherical, thin, gelatinous sheath at the apex, 13–20 µm diam. Apical cells elongated, up to 6 µm long, tapering gradually toward the apex, easily becoming senescent, subhyaline, with obscured, subglobose tuberculate ends.

Culture characteristics: On PDA, colony circular, slow growing, reaching 10 mm in 50 days at 25◦C, gray to brown from above, dark gray from below, surface rough, dry, raised, entire at edge.

Material examined: CHINA, Yunnan Province, Pingbian City, on submerged wood in a stream, 20 September 2017, W. Dong, WF-24A-1 (MFLU 18-1171, holotype), ex-type living culture MFLUCC 18-1015; ibid. WF-24A-2 (HKAS 101707, isotype),ex-isotype living culture KUMCC 18-0056.

Notes: Pseudobactrodesmium aquaticum is introduced as the type species of Pseudobactrodesmium having the typical euseptate, phragmoseptate conidia with apical sheath. The enteroblastic conidiogenous cells are particularly obvious in Figure 2e.

FIGURE 2 | Pseudobactrodesmium aquaticum (MFLU 18-1171, holotype). (a,b) Colonies on submerged wood. (c,d) Conidiophores bearing conidia. (e) Enteroblastic conidiogenous cells (arrow). (f) Conidiophore. (g–i) Conidia. (j) Conidial tips with sheaths. (k) Germinated conidium. (l) Colony on PDA (front view). (m) Colony on PDA (bottom view). Scale bars: (a) 200 µm, (b) 100 µm, (c,d,h,k) 20 µm, (e,g,i,j) 10 µm, (f) 5 µm.