Neohelicosporium wuzhishanense X. Y. Ma, J. Ma & Y. Z. Lu, 2025

Neohelicosporium wuzhishanense X. Y. Ma, J. Ma & Y. Z. Lu sp. nov.

Fig. 3 View Figure 3

Etymology.

The epithet “ wuzhishanense ” refers to Wuzhishan City, Hainan Province, where the fungus was collected.

Holotype.

HKAS 128903 View Materials

Description.

Saprobic on submerged decaying wood in freshwater habitats. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on natural substrate superficial, effuse, solitary, scattered, or gregarious, white to pale brown. Mycelium mostly superficial, partly immersed, composed of pale brown to brown, branched, septate, guttulate, smooth, with mass glistening conidia. Conidiophores 75.5–203 μm long, 5.5–6.5 μm wide (x ̄ = 134.5 × 6 μm, n = 25), macronematous, mononematous, erect, solitary, cylindrical, straight or slightly flexuous, occasionally branched, septate, smooth-walled, thick-walled, wider at the base and narrower towards the apex, and brown at the base, becoming hyaline to pale brown towards the apex. Conidiogenous cells 13–29 μm long, 3.5–5 μm wide (x ̄ = 19 × 4.5 μm, n = 25), holoblastic, mono- to poly-blastic, integrated, intercalary or terminal, determinate, hyaline to brown, smooth-walled, cylindrical, truncate at the apex after conidial secession, with tiny tooth-like and / or bladder-like protrusions (7–16 μm long, 3–6 μm wide (x ̄ = 10.5 × 4.5 μm, n = 15 )). Conidia solitary, acropleurogenous, helicoid, tapering toward the ends, developing on tooth-like or bladder-like protrusions, 20.5–28.5 μm diam. and conidial filament 4.5–6 μm wide (x ̄ = 25 × 5 μm, n = 30), 92.5–138 μm long (x ̄ = 118 μm, n = 30), indistinctly multi-septate, slightly constricted at septa, tightly coiled 2 ½ – 3 ½ times, not becoming loose in water, guttulate, hyaline, smooth-walled.

Culture characteristics.

Conidia germinating on PDA within 18 h and germ tubes arising from the middle of the conidium. Colonies reached 37 mm diam. after 41 days of incubation at 25 ° C, irregular, with raised, white to brown mycelia on the surface, in reverse brown to black-brown, with undulate margin.

Material examined.

China • Hainan Province, Wuzhishan City, Wuzhishan National Nature Reserve , on decaying wood in a freshwater stream, 28 December 2021, Jian Ma, WS 68 ( HKAS 128903 View Materials , holotype), ex-type living culture GZCC 23-0326 ; • Ibid., WS 19 ( GZAAS 23-0282 , paratype), living culture GZCC 23-0278 ; • Ibid., WS 20 ( GZAAS 23-0283 ), living culture GZCC 23-0279 .

Notes.

Morphologically, Neohelicosporium wuzhishanense ( HKAS 128903 ) closely resembles N. latisporum ( HKAS 128955 ) in having macronematous, mononematous, erect, cylindrical, septate conidiophores; holoblastic, monoblastic, or polyblastic, integrated, cylindrical conidiogenous cells; and solitary, acrogenous, helicoid conidia ( Ma et al. 2024 b). However, based on multi-gene phylogenetic analyses, Neohelicosporium wuzhishanense formed a sister clade with N. guizhouense , which is phylogenetically distant from N. latisporum (Fig. 1 View Figure 1 ). Morphologically, Neohelicosporium wuzhishanense ( HKAS 128903 ) differs from N. latisporum ( HKAS 128955 ) by its unique conidiogenous cells (tooth-like and / or bladder-like vs. tooth-like) and longer conidia (92.5–138 μm vs. 48.5–67.5) ( Ma et al. 2024 b). Based on morphological characteristics and DNA sequence data, we identified GZCC 23-0278 , GZCC 23-0279 , and GZCC 23-0326 as a new species, Neohelicosporium wuzhishanense .