Neohelicomyces aquisubtropicus X. Y. Ma, Y. Z. Lu & J. Ma, 2025

Neohelicomyces aquisubtropicus X. Y. Ma, Y. Z. Lu & J. Ma sp. nov.

Fig. 2 View Figure 2

Etymology.

“ aqui- ’’ refers to the aquatic habitat of this fungus, and ‘‘ - subtropicus ’’ means the climate type where the fungus was collected.

Holotype.

HKAS 128947 View Materials

Description.

Saprobic on decaying wood in a terrestrial habitat. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on natural substrate superficial, white, effuse, gregarious, with massive glistening conidia. Mycelium partly superficial, composed of hyaline to pale brown, branched, septate, guttulate, smooth hyphae. Conidiophores 144–193.5 × 3.5–6.5 μm (x – ̄ = 167.5 × 5 μm, n = 25), macronematous, mononematous, erect, cylindrical, straight or slightly flexuous, typically curved at the apex, unbranched, septate, subhyaline to pale brown, thick-walled. Conidiogenous cells 11.5–15 × 3.5–5 μm (x – ̄ = 13.5 × 4 μm, n = 30), holoblastic, monoblastic, or polyblastic, integrated, intercalary, cylindrical, with denticles, subhyaline to pale brown, smooth-walled. Conidia solitary, pleurogenous, helicoid, tapering towards the rounded ends, developing on tooth-like protrusions, 14.5–17 μm diam., and conidial filament 2–4 μm wide (x – ̄ = 15.5 × 3 μm, n = 25), 82.5–126.5 μm long (x – ̄ = 105.5 μm, n = 30), tightly coiled up to 3 1 / 2 times, becoming loosely coiled in water, aseptate, guttulate, hyaline, smooth-walled.

Culture characteristics.

Conidia germinate on PDA within 10 hours, producing germ tubes from the conidial body. Colonies on PDA are circular with a raised surface and entire margin, reaching 5 cm in diameter after 45 days at room temperature (approximately 25 ° C), and are pale brown to dark brown on both the surface and reverse sides.

Material examined.

China • Guizhou Province, Qiannan Buyi and Miao Autonomous Prefecture, Libo County , on decaying wood in a terrestrial habitat, 10 April 2022, Jian Ma, MN 6 ( HKAS 128947 View Materials , holotype), ex-type living cultures GZCC 23-0080 ; • Ibid., MN 6.1 ( GZAAS 24-0077 , paratype), living culture GZCC 24-0163 .

Notes.

Based on phylogenetic analyses, our isolates ( GZCC 23-0080 and GZCC 24-0163 ) clustered with Neohelicomyces denticulatus ( GZCC 19-0444 ), N. edgeworthiae ( CGMCC 3.25565 ), and N. pandanicola ( KUMCC 16-0143 ) (Fig. 1 View Figure 1 ). Neohelicomyces aquisubtropicus ( HKAS 128947 ) differs from N. edgeworthiae ( HKAS 128877 ) in having smaller conidia (14.5–17 μm diam. and 82.5–126.5 μm long vs. 21.5–34 μm diam. and 121–177 μm long) ( Ma et al. 2024 b). Additionally, N. denticulatus ( GZAAS 20-0339 ) and N. pandanicola ( HKAS 96202 ) can be distinguished from N. aquisubtropicus ( HKAS 128947 ) by their wider conidial diameters (16–22 μm and 28–44 μm vs. 14.5–17 μm) ( Tibpromma et al. 2018; Yang et al. 2023). Moreover, base pair comparisons between N. aquisubtropicus ( GZCC 23-0080 ) and related species reveal the following differences. Compared to N. denticulatus ( GZCC 19-0444 ), there are 23 / 487 bp differences in ITS (4.7 %, with 13 gaps). Compared to N. edgeworthiae ( CGMCC 3.25565 ), there are 26 / 521 bp differences in ITS (5.0 %, with 14 gaps), 21 / 929 bp differences in tef 1 - α (2.3 %, with 7 gaps), and 27 / 811 bp differences in rpb 2 (3.3 %, with 10 gaps). In comparison with N. pandanicola ( KUMCC 16-0143 ), there are 27 / 509 bp differences in ITS (5.3 %, with 13 gaps) and 15 / 827 bp differences in tef 1 - α (1.8 %, with 7 gaps). Therefore, we introduce N. aquisubtropicus as a new species based on morphology and multigene phylogenetic analysis.