Torula chromolaenae

Torula chromolaenae Jun F. Li, Phook., Mapook & K.D. Hyde, in Li et al., Mycol. Progr. 16(4): 454 (2017)

Index Fungorum number: IF819536; Facesoffungi number: FoF 02713

Saprobic on a dead leaf vein of Musa sp. (Musaceae). Sexual morph: Undetermined. Asexual morph: hyphomycetous. Colonies effuse, black, powdery, thread–like on host. Mycelium slightly immersed, septate, unbranched, smooth, pale brown hyphae. Conidiophores 2–5 × 2–4 μm (x̄ = 3.8 × 3.3 μm, n = 10), micronematous or semi–macronematous, unbranched, straight or flexuous, subhyaline or pale brown, smooth or minutely verruculose. Conidiogenous cells 2–6 × 2–4.5 μm (x̄ = 4.5 × 3.7 μm, n =10), polyblastic or sometimes monoblastic, integrated, terminal, discrete, determinate, usually spherical, smooth, distal fertile part thin–walled, subhyaline to pale brown, proximal sterile part dark brown, thick–walled, produced conidia in multiple planes. Conidia 10–15 × 5–7 μm (x̄ = 11.4 × 6.2 μm, n = 40) dry, in simple or branched chains arising from the surface of the upper half of the characteristic conidiogenous cells, cylindrical with rounded ends, ellipsoidal or subspherical, brown or dark brown, minutely verruculose, 1–3 transverse septa, usually strongly constricted at the septa; conidial chains arranged in multiple planes.

Culture characteristics: Conidia germinating on PDA within 18 hrs and germ tubes produced from the tip cell. Colonies growing on PDA, reaching 50 mm diam. in 14 days at 25°C. Mycelium partly immersed to superficial, slightly effuse, and hairy, with dentate margin, pale pink at periphery golden brown in the middle with whitish hairy mycelial clumps. Sporulation was not observed in mature cultures.

Material examined: THAILAND, Chiang Mai Province, Mae Taeng District, on a dead leaf vein of Musa sp. (Musaceae), 15 February 2019, B.C. Samarakoon, BNS083 (MFLU 20−0698), living culture MFLUCC 20−0237.

Notes: The BLASTn search results of SSU, LSU, ITS and TEF sequence data, indicated that our strain (MFLUCC 20−0237), showed a high identity to Torula chromolaenae (KUMCC 16–0036) as follows; SSU = 100.00%, LSU = 100.00%, ITS = 100.00%, TEF = 99.5% similarities. Morphological comparison with the type specimen of T. chromolaenae showed that our new collection (MFLU 20−0698/ MFLUCC 20−0237) is typical to T. chromolaenae in having brown or dark brown, minutely verruculose, 1–3–septate conidia. However, our collection (MFLU 20−0698) has slightly smaller conidiophores (2–5 × 2–4 μm vs. 5–6.3 × 3.5–4.6 μm) and conidia (10–15 × 5– 7 μm vs. 2.1–16.5 × (3.6–) 4.1–5 μm) with respect to Li et al. (2017). A nucleotide base comparison of ITS, TEF and RPB2 regions also showed that MFLUCC 20–0237 is conspecific with T. chromolaenae (KUMCC 16–0036) (0/502 bp of ITS, 0/787 bp of TEF, and 0/817 bp of RPB2). We thus identify our new collection (MFLU 20–0698) as T. chromolaenae. Previously, T. chromolaenae was reported as a saprobe on dicotyledonous and monocotyledonous hosts from China and Thailand, indicating that the species is not specific on hosts and normally found in tropical region.

Figure 1. Maximum likelihood tree (RAxML) revealed by an analysis of a concatenated SSU, LSU, ITS, TEF and RPB2 sequence dataset of the species in Torulaceae, showing the phylogenetic position of Torula chromolaenae (MFLUCC 20–0237), T. fici (MFLUCC 20–0238) and T. masonii (MFLUCC 20–0239). ML bootstrap supports (≥ 60%) and Bayesian posterior probabilities (≥ 0.95 BYPP) are given above the branches as ML/BYPP. The tree is rooted with Roussoella nitidula (MFLUCC 11–0182), R. scabrispora (MFLUCC 11–0624) and Roussoellopsis tosaensis (KT 1659). Strains generated in this study are indicated in red bold. Ex–type strains are indicated in black bold. The scale bar 0.04 represents the expected number of nucleotide substitutions per site.