Kirschsteiniothelia pini Y. Jin, W.H. Tian & Maharachch., Phytotaxa 664(2), 103 (2024)

Index Fungorum number: IF854777; MycoBank number: MB854777; Facesoffungi number: FoF16758

Saprobic on submerged decaying wood. Asexual morph: Colonies effuse, hairy, scattered, dark brown, shining. Mycelium mostly immersed, composed of pale brown, septate, unbranched hyphae. Conidiophores 50–230 (–330) × 3.5–5.5 (–7.6) µm (x̅ = 135.3 × 4.7 µm, n = 20), macronematous, mononematous, erect, smooth, brown to dark brown, paler towards the apex, septate, unbranched, subcylindrical to cylindrical, sometimes swollen at the base, slightly flexuous. Conidiogenous cells 12–25 (–60) × 3.6–5.9 µm (x̅ = 27.1 × 4.8 µm, n = 20), monoblastic, terminal, cylindrical, pale brown to brown, percurrent proliferating. Conidia 13–60 × 3.6–10.9 µm (x̅ = 29.2 × 7.2 µm, n = 25), acrogenous, solitary, dry, obclavate, 3–4-distoseptate when mature, smooth, straight or slightly curved, pale brown to brown, rounded apical with a rounded, gelatinous sheath, and truncate basal with a thickened scar. Sexual morph: Undetermined.

Culture characteristics – Conidia germinating on PDA within 12 h, and germ tubes produced from the apex. Colonies on PDA reaching 15 mm diameter after 3 weeks at room temperature. Mycelium dry, dense, colonies on the surface of PDA, protrusion, with regular edges, grey to brown, the lower layer is dark green, velvety. Reverse dark green, 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-3278 (HKAS 131373), living cultures CGMCC 3.25426 = KUNCC 23–13755.

Notes – Phylogenetic analysis showed that our new collection clustered with the ex-type strain of Kirschsteiniothelia pini (UESTCC 24.0131) with 100% ML/1.00 PP support (Fig. 2). The LSU, ITS, and SSU sequences of our new collection (CGMCC 3.25426) and the type strain (UESTCC 24.0131) showed 99.74% (763/765 bp), 98.88% (440/445 bp), and 100.00% (988/988 bp) similarities, respectively. Our new collection is similar to K. pini in having cylindrical, unbranched conidiophores, terminal, monoblastic conidiogenous cells with percurrent proliferating, and obclavate conidia with a truncate base. We, therefore, identify our new collection as K. pini, a species introduced by Jin et al. (2024) from a terrestrial habitat in China, and it is the first time to report this species from a freshwater habitat.

Figure 1 – Kirschsteiniothelia pini (HKAS 131373). a, b Colonies on the substratum. c, d Conidiophores e–g Conidiophores with conidia. h–j Conidia. k Germinating conidium. l, m Colony on PDA from surface and reverse. Scale bars: c–g = 20 µm, h–j = 15 µm, k = 10 µm.

Figure 2 – RAxML tree based on analysis of Kirschsteiniotheliaceae that combined LSU, ITS, and SSU dataset. The combined analyses include 68 strains with 2133 characters, including gaps (LSU: 803 bp, ITS: 491 bp, and SSU: 839 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 Pseudorobillarda eucalypti (MFLUCC 12–0417) and P. phragmitis (CBS 398.61). The new collections are indicated in red. Ex-type strains are indicated with “T” after the strain number.