Sporoschisma verruculosa R.J.Xu & Q.Zhao, 2024

Xu, Rong-Ju, Zhou, De-Qun, Yang, Zhu-Liang, Li, Ying & Zhao, Qi, 2024, Two new freshwater hyphomycetous species of Sporoschisma Berk. & Broome (Chaetosphaeriales) from Tibetan Plateau, China, Cryptogamie, Mycologie 20 (3), pp. 29-37 : 34

Sporoschisma verruculosa R.J.Xu & Q.Zhao , sp. nov.

( Fig. 3 )

TYPE MATERIAL. — China • Tibet, Zayu County, Xiachayu Town ; 28°29’39.2”N, 96°59’35.25”E; alt. 1537 m; saprobic on submerged decaying wood in a freshwater stream; 14.VII.2022; R. J. Xu; MD-634; holotype: HKAS [ HKAS 129210 ]; ex-type living culture: KUNCC 10461 .

ADDITIONAL MATERIAL. — China • Zayu County, Guyu Town ; 28°53’19.64”N, 97°27’49.23”E; alt. 2805 m; saprobic on submerged decaying wood in a freshwater stream; 14.VII.2022; R. J. Xu; MD-634-2; HKAS [ HKAS 129211 ]; living culture: KUNCC 10462 .

ETYMOLOGY. — “verruculosa ” referring the verruculose conidia.

INDEX FUNGORUM. — IF900720.

FACESOFFUNGI. — FoF 14352.

DESCRIPTION

Saprobic on submerged decaying wood in a freshwater stream. Sexual morph: Undetermined. Asexual morph: Colonies superficial, effuse, dark brown, with long chains of conidia. Mycelium immersed, composed of pale to dark brown hyphae. Setae 116-204 ×5-9 µm (x̄̄ =161× 6 µm, n= 15), arising from the bulbous base, often with 1-2 at the side of conidiophores, capitate, 2-4-septate, brown, slightly constricted at some septa. Conidiophores 130-320 µm long, stipes 10-18 µm wide below venter and 16-22 µm wide above, 17-33 µm wide at the venter, macronematous, mononematous, erect, straight or slightly flexuous, solitary or 2-3 group, smooth-walled, dark brown to black, cylindrical, a cylindrical stipe and a swollen venter with a long cylindrical neck. Conidiogenous cells monophialidic, integrated, terminal, determinate, dark brown, lageniform, with a tubular collarette and swollen venter, flared margin at free end. Conidia 36-52 × 10-16 µm (x̄̄ =42 ×14 µm, n =25), catenate, emerging in a chain inside the tubular collarette, develop basipetally, guttulate, verruculose, cylindrical, slightly rounded at both ends, with conspicuously darkened septa, hyaline, 0-septate when young, brown to dark brown, 3-septate, when mature, all the cells are the same length.

CULTURE CHARACTERISTICS

Conidia germinating on PDA within 48 hours and germ tubes produced from both ends. Colonies on PDA reaching 7-10 mm diam at 30 days, with dense, grey, sparse mycelium on surface initially, white grey at the entire; in reverse with a light brown middle and white grey margin.

NOTES

Morphologically, Sporoschisma verruculosa R.J.Xu & Q.Zhao , sp.nov. shares common characteristics with S. aquaticum in having capitate setae scattered or in groups among conidiophores, cylindrical conidiophores and catenate, cylindrical, brown to dark brown septa, conidia ( Goh et al. 1997; Luo et al. 2016). However, S. verruculosa R.J.Xu & Q.Zhao , sp. nov. differs from S. aquaticum by having larger sized conidia (36-52 vs 26-32 µm) and verruculose conidia ( Luo et al. 2016). Phylogenetically, S. verruculosa R.J.Xu & Q.Zhao , sp. nov. forms a sister lineage with S. chiangraiense with 100% ML/0.99 PP support ( Fig. 1 ). However, S. verruculosa R.J.Xu & Q.Zhao , sp. nov. differs from S. chiangraiense by having 3-septate and verruculose conidia ( Hyde et al. 2019).

Figures

FIG. 3. — Sporoschisma verruculosa R.J.Xu & Q.Zhao, sp. nov. (holotype, HKAS 129210): A, B, colony on wood with long conidia chains; C, D, conidiophores with setae; E, conidiophores with conidia; F, G, conidiogenous cell with a conidium; H-M, conidia; N, culture on PDA. Scale bars: C-E, 50 μm; F-M, 20 μm.

FIG. 1. — RAxML tree based on analysis of combined ITS, LSU and TEF1-α sequences. Bootstrap support values for maximum likelihood (ML) equal to or greater than 75% were given above the nodes (left). Bayesian posterior probability (PP) equal to or greater than 0.95 were given above the nodes (right) and hyphen (-) were marked as values below 0.95. The tree was rooted to Adautomilanezia caesalpiniae LAMIC 010212. The type strains were shown in bold, and the newly generated isolates were shown in red.