Pseudorobillarda multiguttulata W.P. Wang, H.W. Shen, K.D. Hyde & Z.L. Luo, in Wang, Hyde, Bao, Wanasinghe, Lin, Shen, Lu, Zhang, Su, Li, Al-Otibi, Yang & Luo, Mycosphere 15(1): 6579 (2024)

Index Fungorum number: IF902427; MycoBank number: MB902427; Facesoffungi number: FoF16101

Etymology – Referring to the conidia with multiple guttules in spores of this taxon.

Holotype – HKAS 130437

Saprobic on submerged decaying wood. Asexual morph: Conidiomata 170–180 µm diam, 120– 140 µm high., scattered, semi-immersed, unilocular, coriaceous, subcylindrical, black, without ostiole. Conidiomatal wall 9.9–30 µm thick, consisting of 3–5-layered cells of textura angularis, outer layers with brown to black, oblong, thin-walled cells, inner layers with subhyaline to brown, ovoid, thin-walled cells. Conidiophores arising all around the cavity of the conidiomata, subcylindrical, aseptate, hyaline, smooth, or reduced to conidiogenous cells, embedded in a mucilaginous matrix. Paraphyses 18.8–49.2 × 1.2–2.9 µm (x̅ = 28 × 2.1 µm, n = 10), hyaline, unbranched, narrowly cylindrical, aseptate, smooth-walled, rounded at the apex. Conidiogenous cells 9.5–15 × 1.8–3.6 µm (x̅ = 12 × 2.8 µm, n = 10), enteroblastic, monophialidic, integrated, cylindrical, hyaline, straight, smooth-walled. Conidia 25–31 × 4.2–5.6 µm (x̅ = 28.8 × 4.9 µm, n = 30), subcylindrical, hyaline, rounded or sharp at the apex, straight or slightly curved, aseptate, multi-guttulate, smooth-walled, with 2–4 unbranched, filiform, flexuous, attenuated, supple apical appendages (25–31 µm long). Sexual morph: Undetermined.

Culture characteristics – Conidia germinating on PDA within 12 h, and germ tubes produced from the base. Colonies on PDA reaching 20 mm diameter after 2 weeks at room temperature. Mycelium dry, dense, colonies on the surface of PDA, with regular edges, flat surface, has a punctate protrusion in the center, white to pale brown, velvety. Reverse pale yellow, smooth.

Material examined – China, Yunnan Province, Wenshan Zhuang and Miao Autonomous Prefecture, Bamei Town, on submerged decaying wood, 7 February 2022, W.P. Wang, S-3261 (HKAS 130437, holotype).

Notes – The multi-loci phylogenetic analysis showed that Pseudorobillarda multiguttulata is sister to P. texana with 81% ML/0.96 PP support (Fig. 2). Pseudorobillarda multiguttulata resembles P. texana in having narrowly cylindrical paraphyses, hyaline, guttulate, smooth conidia with flexuous appendages at the end. However, it differs from P. texana in having subcylindrical conidiomata without ostiole, aseptate paraphyses, larger conidia (25–31 × 4.2–5.6 vs. 12.5–18.5 × 2.5–3.5 µm), and longer conidial appendages (25–31 vs. 12.5–20.5) (Plaingam et al. 2005). The LSU and SSU sequences of P. multiguttulata revealed 2.64% (22/834 bp, four gaps) and 0.91% (9/988 bp) different from P. texana, respectively. Therefore, P. multiguttulata (HKAS 130437) is identified as a new species based on both phylogenetic analysis and characteristics.

Figure 1 – Pseudorobillarda multiguttulata (HKAS 130437, holotype). a Conidiomata on the substratum. b Vertical section of conidioma. c, d Structure of conidiomatal wall. e Paraphyses. f, g Conidiogenous cells with developing conidia. h–m Conidia with appendages. n Germinating conidium. o, p Colonies on PDA from surface and reverse. Scale bars: b = 50 µm, c, e = 10 µm, d, f, g, n = 5 µm, h–m = 15 µm.

Figure 2 – RAxML tree based on analysis of Pseudorobillarda that combined LSU, ITS, SSU, and rpb2 dataset. The combined analyses include 20 strains with 3094 characters including gaps (LSU: 813 bp, ITS: 516 bp, SSU: 987 bp, and rpb2: 778 bp). Bootstrap support values for maximum likelihood (ML) greater than 75% and Bayesian posterior probabilities greater than 0.95 are indicated above branches as ML/PP. The tree is rooted with Speiropsis pedatospora (CBS 397.59). The new collections are indicated in red. Ex-type strains are indicated with “T” after the strain number.