Dictyosporium tratense J. Yang & K.D. Hyde, MycoKeys 36: 96 (2018)

Index Fungorum number: IF 554772; Mycobank number: MB 554772; Facesoffungi number: FoF04678; Fig. 1

Saprobic on submerged decaying wood. Sexual morph: Not observed. Asexual morph: Hyphomycetes. Colonies punctiform, superficial, gregarious, black. Mycelium composed of immersed, pale brown, septate, smooth, thin-walled hyphae. Conidiophores cylindrical, micronematous, mononematous, septate, hyaline to brown, smooth-walled. Conidiogenous cells cylindrical, monoblastic, hyaline to pale brown. Conidia 40–55×20–30 μm (x̅=47.5×25 μm, n=20), cheiroid, acrogenous, brown to dark brown, complanate, consisting of 30–52 cells arranged in (2–)4–5 (mostly 5) closely compact columns, 5–10-euseptate in each column, guttulate, usually with 2–3 central columns longest and of equal length, 2–3 peripheral columns shorter and of equal length, sometimes with hyaline globose appendages at the apical cells of outer columns.

Material examined – China, Guangxi Province, Qinzhou City, on submerged wood in a river, 26 February 2023, X.Y. Shu GX5.1 (MHZU 24-0435); living culture ZHKUCC 24-0792.

GenBank numbers – ITS: PP760087, LSU: PP760086, SSU: PP760088, tef1-α: PP764532.

Notes – Phylogenetic analysis showed that our new collection D. tratense (MHZU 24-0435) clustered with the type strain of Dictyosporium tratense (MFLUCC 17-2052) with 97% ML bootstrap and 0.99 BYPP support. Our collection fits well with the morphological characteristics of D. tratense in having cheiroid, acrogenous, solitary, and euseptate conidia consisting of five rows of cells and hyaline globose appendages (Yang et al. 2018). However, the holotype (MFLUCC 17-2052) has hyaline cloud-shaped mucilaginous sheath at the apical cells of outer columns, which is lacking in our collection (Yang et al. 2018). There are two nucleotide differences across ITS and four nucleotide differences in tef1-α between our new strain (MHZU 224-0435) and the type strain (MFLUCC 17-2052). Based on the morphological and phylogenetic analysis, we therefore identified our new strain as D. tratense. Dictyosporium tratense initially was reported in Thailand (Yang et al. 2018), this study expands the known geographical distribution of this species to China.

Figure 1 – Dictyosporium tratense (MHKU 24-043, new record in China). a Colonies on the host. b, d–i Conidia. c Conidia with conidiophores. j conidia germinating on PDA. Scale bars: b–i=20 μm