Velutinus sichuanensis N. Wu & Jian K. Liu

MycoBank number: MB 901519, Facesoffungi number: FoF 15234, Fig. 1

Etymology — The epithet refers to the location where the fungus was collected, Sichuan Province, China.

Holotype — HKAS 131317
Saprobic on dead branches of Loropetalum chinense (Hamamelidaceae) in terrestrial habitats. Sexual morph: Not observed. Asexual morph: Conidiomata 180–250 μm high, 250–360 μm diam. (x̄ = 210 × 300 μm, n = 10), sporodochial, solitary, scattered, convex, spherical, dark brown to black, glistening, velvety. Mycelium mostly immersed, hyaline to pale brown hyphae. Conidiophores 60–120 × 7–9 μm (x̄ = 96 × 8 μm, n = 20), hyaline, cylindrical, straight or slightly curved, 3–4-septate, smooth-walled, unbranched, constricted at septa, guttulate, covered with a 2–4 μm (x̄ = 3.5 μm, n = 10) thick, mucilaginous sheath, sometimes reduced to conidiogenous cells. Conidiogenous cells monoblastic, holoblastic, integrated, terminal, determinate, hyaline to pale brown. Conidia 25–38 × 23–30 μm (x̄ = 33 × 25 μm, n = 50), acrogenous, hyaline when young, pale brown when mature, proliferating with several short, lateral, acropetal, branched chains, with 1–2 hyaline, globose to subglobose basal appendages that are thin, easy to rupture and shrink, guttulate, eccentric. Primary branches give rise to secondary branches which eventually form ellipsoidal to spherical, whole conidia that are made from an infinite number of tiny, closely compact cells.

Material examined — China, Sichuan Province, Chengdu City, Dujiangyan City, Qingcheng Mountain scenic spot, 103°28′36′′E, 30°55′9′′N, on dead branches of medicinal plant Loropetalum chinense, 27 March 2021, Na Wu, YW322 (HKAS 131317, holotype; HUEST 23.0222, isotype); ibid., 10 July 2022, YW385 (HUEST 23.0584).

Notes — Our two collections share similar morphology and can be identified as one species, and the molecular data (ITS and LSU gene regions) also confirm this identification. Thus, the new species Velutinus sichuanensis is introduced to accommodate these taxa. In addition, V. sichuanensis resembles the asexual morph of Patellariopsis atrovinosa in having holoblastic conidiogenous cells and dark brown, septate, smooth conidia. However, V. sichuanensis differs from P. atrovinosa by having guttulate conidiophores covered with a thick mucilaginous sheath and hyaline to pale brown, ellipsoidal to spherical conidia with globose to subglobose appendages, while P. atrovinosa has branched conidiophores without sheath and dark brown, and irregularly spherical conidia without appendages (Karunarathna et al. 2020). A comparison of ITS and LSU nucleotides shows that V. sichuanensis is significantly different from its sister clade, P. atrovinosa, by having 39/459 bp differences (8.5%) in ITS and 10/843 bp differences (1.2%) in LSU.

Figure 1. Velutinus sichuanensis (HKAS 131317 holotype). a–c. Colonies on woody substrate. d. Squash mount of a sporodochium. e–h. Conidia attached to the conidiophores. i–o. Conidia. p. Partial conidiophores. Scale bars: d = 100 μm, e–h = 20 μm, i–p = 10 μm.

Figure 2. Phylogenetic tree generated from the maximum likelihood analysis based on the combined ITS and LSU sequence data of Helotiales. The ML (≥ 75%) and BI (≥ 95%) bootstrap supports are given near the nodes, respectively. The new isolates obtained in this study are indicated in red and ex-type strains are in bold. The tree is rooted with Lambertella seditiosa (WU 32446) and Rutstroemia longipes (TNS F-40097).