Myrmecridium thailandicum Crous & Cheew., Persoonia 31, 251 (2013)

Index Fungorum number: IF805854; MycoBank number: MB805854; Facesoffungi number: FoF16110

Saprobic on submerged decaying wood. Asexual morph: Colonies superficial, effuse, scattered or aggregated, hairy, dark brown. Mycelium partly immersed, partly superficial, composed of aseptate, smooth-walled, hyaline to pale brown hyphae. Conidiophores (70–) 83–160 × 2.7–3.8 µm (x̅ = 116.8 × 3.1 µm, n = 25), macronematous, mononematous, erect, solitary, straight or slightly flexuous, cylindrical, septate, pale brown to reddish brown, paler towards the apex, unbranched. Conidiogenous cells polyblastic, integrated, terminal and intercalary, sympodial, obscure denticulate, subhyaline to brown. Conidia 4.1–6.9 × 2.3–3.6 µm (x̅ = 5.7 × 3 µm, n = 40), acropleurogenous, solitary, obovoidal, pale brown, aseptate, smooth or finely verrucose, thin-walled, rounded apical and slightly truncate at the base. Sexual morph: Undetermined.

Culture characteristics – Colonies on PDA reaching 40 mm diameter after 4 weeks at room temperature. Mycelium dry, dense, colonies on the surface of PDA, with irregular edges, circular, wrinkled, has a protrusion in the center, yellow to brick red. Reverse circular, crack, yellow to reddish brown, smooth.

Material examined – China, Yunnan Province, Wenshan Zhuang and Miao Autonomous Prefecture, Bamei Town, on submerged decaying wood, 28 February 2023, W.P. Wang, S-4354 (HKAS 131399), living culture KUNCC 23–13739.

Notes – Our new collection is indistinguishable from the holotype of Myrmecridium thailandicum. Phylogenetic analysis showed that our new collection clustered with the ex-type strain of M. thailandicum (CPC 21694) with 100 ML/1.00 PP support (Fig. 2). We therefore identified our new collection as M. thailandicum. Myrmecridium thailandicum was introduced by Crous et al. (2013) on reed litter next to pond in Thailand. While our collection, found on submerged wood in freshwater habitat in China, represents a new record for the country.

Figure 1 – Myrmecridium thailandicum (HKAS 131399). a Colonies on the substratum. b, e, f Conidiophores. c, d, g, h Conidiophores with conidia. i–k Apex of conidiophores with conidia. l–p Conidia. q, r Colonies on PDA from surface and reverse. Scale bars: b–h = 20 µm, i–k = 10 µm, l, m = 5 µm, n–p = 2 µm.

Figure 2 – RAxML tree based on analysis of Myrmecridium that combined LSU and ITS dataset. The combined analyses include 28 strains with 1338 characters including gaps (LSU: 799 bp and ITS: 539 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 Neomyrmecridium naviculare (GZCC 20–0484 and MFLUCC 19–0303). The new collection is indicated in red. Ex-type strains are indicated with “T” after the strain number.