Nigrosynnema guangdongense C. F. Liao, K. D. Hyde & Doilom, 2025

Nigrosynnema guangdongense C. F. Liao, K. D. Hyde & Doilom sp. nov.

Figs 3 View Figure 3 , 4 View Figure 4

Etymology.

The epithet “guangdongense” refers to the locality, Guangdong Province, China, where the holotype was collected.

Holotype.

MHZU 23-0255 .

Description.

Saprobic on dead stem of Wurfbainia villosa . Sexual morph: undetermined. Asexual morph: Synnemata on the natural substrate, 370–570 × 20–50 µm (av. 470 × 33 μm, n = 20), erect, unbranched, subcylindrical, with a robust base, narrowed towards fertile apex, olivaceous brown to black, straight or curved in the upper portion, consisting of parallelly arranged, tightly compacted conidiophores. Conidiophores 2–4 µm wide, subcylindrical, branched, olivaceous brown, slightly tapering towards the apex, verrucose. Conidiogenous cells 10.5–32.5 × 1.5–3 µm (av. 22 × 2.5 μm, n = 30), enteroblastic, monophialidic, discrete, terminal, subcylindrical, mostly hyaline, sometimes pale olivaceous brown in the lower portion, mostly smooth-walled in above half, often verruculose at below half, with a conspicuous collarette. Conidia 10–12.5 × 3–4.5 µm (av. 11.5 × 4 μm, n = 30), solitary, slimy, fusiform to ellipsoidal, aseptate, longitudinally striated, olivaceous brown to dark brown, guttulate, obtuse at both ends, with a distinct dark basal hilum.

Culture characteristics.

Colonies on PDA reaching 4.5–6.5 cm in two weeks at 28 ± 2 ° C, medium dense, flat or effuse, diffuse, rough, circular, filiform with curled, large circle in the middle becoming a wave and extends outward, cream from above; cream from the reverse. The spores produced on PDA after three weeks. Conidiomata 220–300 × 15–20 µm, sporodochial, superficial, scattered, irregular, with white mycelia surrounding an olivaceous green mass of conidia, with or without covering the slimy mass of conidia, without setae. Conidiophores arising from the basal stroma, consisting of a stipe and a penicillately branched conidiogenous apparatus; stipes unbranched or rarely branched, hyaline, septate, smooth, 10–30 × 2.5–3.5 µm (av. 18 × 3.0 μm, n = 20), conidiogenous apparatus consisting of a whorl of 2–5 primary branches, each terminating in 2–5 conidiogenous cells; primary branches, 1, 2 - septate, smooth, unbranched, 8–20 × 2–6 µm, secondary branches, aseptate, smooth, unbranched, 6–20 × 2–5 µm. Conidiogenous cells 10–20 × 2–4 µm (av. 14 × 2.5 μm, n = 30), phialidic, terminal, with a conspicuous collarette, clavate to cylindrical, hyaline, smooth. Conidia 7–10 × 3–5 µm (av. 8.5 × 3.5 μm, n = 30), acrogenous, longitudinally striated, fusiform to ellipsoidal, aseptate, initially hyaline, becoming olivaceous green when mature.

Material examined.

China • Guangdong Province, Yangchun City, Yongning Town (22.256185 ° N, 111.609037 ° E, 270 m), on dead stems of Wurfbainia villosa (Lour.) Škorničk. & A. D. Poulsen. ( Zingiberaceae ), 10 April 2022, C. F. Liao & Y. H. Yang, YAM 19 ( MHZU 23-0255 , holotype) • ex-type, ZHKUCC 23-1014 GoogleMaps • ibid., living culture ZHKUCC 23-1015 GoogleMaps .

Notes.

Nigrosynnema guangdongense is established here as the type species. It is similar to Virgatospora natarajanensis described by D’Souza et al. (2002) in having synnematous conidiomata, with fusiform, aseptate, and striated conidia. However, N. guangdongense has verrucose, olivaceous, brown conidiophores, conidia with obtuse apices, and a distinct dark basal hilum, whereas V. natarajanensis has distinctly echinulate, subhyaline conidiophores that are narrower and smooth towards the apex, and conidia are rounded at both ends. Additionally, the conidiogenous cells of V. natarajanensis are occasionally found in the subterminal position, while they have not been observed in N. guangdongense . Nigrosynnema guangdongense has longer conidiogenous cells (10.5–32.5 × 1.5–3 µm) compared to V. natarajanensis (18–25 × 1.5–3.5 μm).

Nigrosynnema guangdongense and Virgatospora echinofibrosa (the type species of Virgatospora ) ( Finley 1967) are similar in having synnematous conidiomata and striate, phialidic conidia. However, N. guangdongense has shorter synnemata (370–570 × 20–50 µm) than V. echinofibrosa (up to 1500 µm). Synnemata of N. guangdongense are robust at the base, narrower towards the apex of the stipe, and olivaceous brown to black, whereas they are simple or branched, sometimes proliferated, cylindrical throughout the greater part, somewhat broader at the apex and base, white or yellow at the base, yellow-black or blackish black at the apex in V. echinofibrosa .

Additionally, N. guangdongense has smaller (10–12.5 × 3–4.5), fusiform, aseptate conidia compared to ellipsoidal to limoniform, 3 - (sometimes 2 - or 4) - septate conidia (39–50 × 9–15 µm) of V. echinofibrosa .