Sporoschisma lignicola 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 : 32-34

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

( Fig. 2 )

TYPE MATERIAL. — China • Yunnan Province, Shangri-La City, Napa Lake ; 27°50’58.9”N, 99°38’17.9”E; alt. 3273 m; saprobic on submerged decaying wood in a freshwater lake; 26.XII.2020; R. J. Xu; MD-207; holotype: HKAS [ HKAS 129208 ]; ex-type living culture: KUNCC 10403 .

ADDITIONAL MATERIAL. — China • Shangri-La City , Giligu River; 27°47’53.7”N, 99°54’49.9”E; alt. 3423 m; saprobic on submerged decaying wood in a freshwater river; 25.XII.2020; R. J. Xu; SW-807; HKAS [ HKAS 129209 ]; living culture: KUNCC 10460 .

ETYMOLOGY. — Referring to this taxon dwelling on wood.

INDEX FUNGORUM. — IF 900719.

FACESOFFUNGI. — FoF 14351.

DESCRIPTION

Saprobic on submerged decaying wood in a freshwater habitat. Sexual morph: Undetermined. Asexual morph: Colonies superficial, effuse, dark brown. Mycelium immersed, composed of pale to dark brown hyphae. Setae 81-135 × 4-5 µm (x̄ =103 × 4 µm, n= 15), arising from the bulbous base, often with 1-2 at the side of conidiophores, capitate, 2-3-septate, brown, slightly constricted at some septa. Conidiophores 131-278 µm long, stipes 9-11 µm wide below venter and 9-15 µm wide above, 13-20 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 28-34 × 7-10 µm (x̄ = 30 × 9 µm, n = 20), catenate, emerging in a chain inside the tubular collarette, develop basipetally, cylindrical, truncate at both ends, 5-septate, with conspicuously darkened septa, hyaline when young, brown to dark brown when mature, with pale brown to subhyaline end cells.

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, greyish, sparse mycelium on surface initially, white grey at the undulant edge; in reverse with a brown middle and sparse, light brown margin.

NOTES

Morphologically, Sporoschisma lignicola R.J.Xu & Q.Zhao , sp. nov. is highly similar to S. atroviride J.Yang, J.K.Liu & K.D.Hyde , S. longicatenatum , and S. nigroseptatum in having capitate setae scattered or in groups among conidiophores, cylindrical conidiophores and catenate, cylindrical, septa, with hyaline end cells conidia ( Goh et al. 1997; Yang et al. 2016, 2023). However, S. lignicola R.J.Xu & Q.Zhao , sp. nov. differs from S. atroviride in having shorter conidiophores (131- 278 vs 275-390 µm) and smaller conidia (28-34× 7-10 vs 36-49(-53) × (13-)14-15.5(-16) µm) ( Yang et al. 2023). Sporoschisma lignicola R.J.Xu & Q.Zhao , sp. nov. differs from S. longicatenatum in having smaller sized conidia (28- 34×7-10 vs 35-45.5×9-11 µm) and cylindrical, brown conidia ( Yang et al. 2016). Sporoschisma nigroseptatum differs from S. lignicola R.J.Xu & Q.Zhao , sp. nov. in having longer conidiophores (300-410 vs 131-278 µm) and doliiform conidia ( Goh et al. 1997).

Phylogenetic analysis showed that Sporoschisma lignicola R.J.Xu & Q.Zhao , sp. nov. is located in a distinct clade within Sporoschisma , and formed a sister lineage with S. taitense with 89% ML/1.00 PP support ( Fig. 1 ). However, comparison of the ITS gene region between the ex-holotype of Sporoschisma lignicola R.J.Xu & Q.Zhao , sp. nov. ( KUNCC 10403) and S. taitense (KUMCC 15-0241) revealed a 2.1% (11/536 bp, excluding gap) difference ( Jeewon & Hyde 2016; Luo et al. 2016). In addition, S. lignicola R.J.Xu & Q.Zhao , sp. nov. is distinguished from S. taitense by having shorter setae (81- 135 vs 192-204 µm), shorter conidiophores (131-278 vs 299-322 µm), and cylindrical to doliiform conidia ( Luo et al. 2016).

Figures

FIG. 2. — Sporoschisma lignicola R.J.Xu & Q.Zhao,sp.nov.(holotype,HKAS 129208):A, colonies on substrate;B, D, conidiophores with conidia;C, conidiophores with setae; E-G, conidia; H, conidiogenous cell; I, culture on PDA. Scale bars: B-D, 50 μm; E-H, 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.