Myrmecridium pulvericola Koppel, Visagie, Hirooka & Seifert, in Crous et al., Persoonia 37: 227 (2016)

Index Fungorum number: IF 815486; MycoBank number: MB 815486; Facesoffungi number: FoF 16385; Figs. 1, 2

Saprobic on submerged decaying wood. Asexual morph: Colonies on natural substrate superficial, scattered, solitary or gathered, brown, hairy. Mycelium partly immersed, partly superficial, composed of septate, smooth-walled, pale brown to hyaline hyphae. Conidiophores 74–135 × 2.1–3.2 µm (x̄ = 104.1 × 2.7 µm, n = 20), macronematous, mononematous, erect, unbranched, mostly straight, cylindrical, sometimes inflated at the basal cells, sparse septate, brown, slightly paler towards the apex, subhyaline to pale brown at the apex, with multiple denticulate conidiogenous loci. Conidiogenous cells integrated, polyblastic, terminal, becoming intercalary, sympodial, short, pimple-like denticles. Conidia 3.6–6.9 × 2.3–3.6 µm (x̄ = 5.2 × 2.8 µm, n = 30), solitary, ellipsoidal to obovoid, pale brown, thin-walled, finely verrucose, aseptate, rounded apical and tapering to the base, with a small hilum. Sexual morph: Undetermined.

Culture characteristics – Conidia germinating on PDA within 12 h, and germ tubes produced from the apex. Colonies growing on PDA, and after 3 weeks of incubation at room temperature, the diameter reaches about 15 mm. Mycelia damp, dense, colonies on the surface of PDA, slightly raised but concave in the center, surface pucker, with regular edges, pale pink. Reverse white to pale pink, smooth.

Material examined – CHINA, Guangxi Zhuang Autonomous Region, Nanning City (22°59’48.12″N 108°13’32.30″E), on unknown species submerged decaying wood, 17 November 2023, Qiu-Xia Yang, S-5965 (HKAS 136941), living culture KUNCC 23–17,553.

GenBank – PQ143312 (ITS), PQ143314 (LSU).

Notes – Phylogenetic analysis showed that the new collection (KUNCC 23–17,553) clustered with the ex-type strain of Myrmecridium pulvericola (DAOMC 21694) with 98% ML support (Fig. 2). The new collection is similar to M. pulvericola in having unbranched, septate, cylindrical conidiophores sometimes inflated at the basal cells, pimple-like denticles conidiogenous cells, and ellipsoidal to obovoid, aseptate conidia with finely verrucose walled. Comparisons the ITS and LSU sequence data of the new collection and the ex-type strain of M. pulvericola showed 99.76% (420/421 bp) and 100.00% (813/813 bp, three gaps) sequence similarity, respectively. Thus, we identify the new collection as M. pulvericola, a species was introduced by Crous et al. (2016a) from house dust in Uruguay, therefore, it is the first introduced this species from freshwater habitat in China.

Figure 1 – Myrmecridium pulvericola (HKAS 136941). a Colonies on the substratum. b–e Conidiophores. f, g Denticulate conidiogenous loci. h–m Conidia. n Germinating conidium. o, p Colonies on PDA from surface and reverse. Scale bars: b–e = 20 µm, f, n = 10 µm, g = 5 µm, h–m = 2 µm.

Figure 2 – Maximum Likelihood tree based on ITS and LSU sequences date. Bootstrap support values for ML greater than 70% and Bayesian posterior probabilities (PP) greater than 0.95 are given as ML/P above the nodes. Newly obtained sequences are indicated in red and ex-type strains are in bold.