Torula strychnicola H. Z. Du, N. Wu, K. D. Hyde & Jian K. Liu sp. nov.

Fig. 6

Etymology.

The epithet ‘ strychnicola ’ refers to the host genus Strychnos from which the fungus was originally isolated.

Holotype.

HKAS 139505

Description.

Saprobic on dead branches of medicinal plant Strychnos nux-vomica L. (Loganiaceae). Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies effuse on the natural substrate, sparse, hairy, velvety, dark brown to black on the substrate. Mycelium immersed or superficial, composed of septate, branched, dark brown to black hyphae. Conidiophores 2–4 µm wide, macronematous to semi-macronematous, erect, septate, smooth, straight, or slightly flexuous, brown to dark brown, subcylindrical to subglobose, and thick-walled, with 1–2 doliiform to globose cells. Conidiogenous cells 4–6 × 3–5 μm (x ̄ = 5 × 4 μm, n = 20), monoblastic, integrated, terminal, subglobose or spherical, brown to dark brown. Conidia (16 –) 25–50 (– 65) × 5–8 μm (x ̄ = 38 × 7 μm, n = 30), catenated, acrogenous, simple, phragmosporous, arranged in branched chains, dry, brown to dark brown, cylindrical, rounded at both ends, composed of globose to ellipsoidal cells, occasionally smaller at the apex (1–2 cells black at the apex), subhyaline at the terminal cell, 2–15 - septate, constricted at septa, verrucose, with spinulose on the substrate.

Culture characteristics.

Conidia germinated on the PDA within 24 h, and germ tubes are produced from the basal cell. Colonies growing on PDA reached 40–43 mm in diam. after two weeks at 25 ° C in the dark. Colonies from above regular, white aerial mycelium slightly raised, medium dense, fluffy, filiform, velvety, pale purple; in reverse, purplish brown at the center, with greyish white at the edge, with pale brown ring between them, the color gradually lightens from the center to the margin.

Material examined.

China • Hainan Province, Wuzhishan City, Shuiman River tropical rainforest scenic area in Wuzhishan, 18°53'29"N, 109°34'36"E, elevation 1,845 m, on dead branches of Strychnos nux-vomica (Loganiaceae), 15 August 2021, Jian Ma, WZS 71.1 (HKAS 139505, holotype), ex-type living culture GZCC 24-0163; • ibid., WZS 73 (GZAAS 23-0630, isotype), living culture GZCC 24-0146.

Notes.

Multi-locus phylogeny (Fig. 1) showed that Torula strychnicola (GZCC 24-0163 and GZCC 24-0146) was sister to T. kanvae (MCC- 10010) with strong support (100 % MLBS / 1.00 BIPP) and formed a distinct lineage. Morphologically, Torula strychnicola can be distinguished from T. kanvae by the distinct spinulose conidia on the substrate. Based on the comparison of the septa and the conidial size, T. strychnicola (septa: 2–15, conidia: 25–50 × 5–8 μm) differs from T. kanvae by having 3–4 septa and conidia of 3–6 × 3–8 μm (Crous et al. 2024). The nucleotide base pair comparison between T. strychnicola (GZCC 24-0163, ex-type strain) and T. kanvae (MCC- 10010, ex-type strain) revealed 63 / 529 bp (11.9 %, 16 gaps) in ITS, 24 / 420 bp (5.7 %, 6 gaps) in tef 1 - α, and 144 / 997 bp (14.4 %, 4 gaps) in rpb 2 sequence data. In addition, Torula strychnicola and T. kanvae have a close phylogenetic relationship with T. aquatica (KUMCC 15-0435, ex-type strain), T. gaodangensis (MFLUCC 17-0234, ex-type strain), T. herbarum (CBS 140066, ex-type strain), and T. luguhuensis (KUNCC 22-12427, ex-type strain) with 99 % MLBS and 1.00 BIPP support (Fig. 1); base pair differences between the ex-type strain of T. strychnicola and these species are shown in Table 3 (Crous et al. 2015; Su et al. 2018; Hyde et al. 2017; Luan et al. 2023). Therefore, based on the morphological and phylogenetic evidence, we established T. strychnicola as a new species from Hainan Province, China.