Tetraploa dashaoensis C.F. Liao & Doilom, sp. nov.
Index Fungorum number: IF 559273; MycoBank number: MB 559273; Facesoffungi number: FoF 10585; Fig. 1
Etymology – In reference to the location where the fungus was collected.
Holotype – KUN–HKAS 107636
Saprobic on dead stem of Saccharum arundinaceum. Sexual morph: Not observed. Asexual morph: hyphomycetous. Colonies superficial, effuse, gregarious, brown to dull green. Mycelium partly immersed in natural substratum, brunched, septate, hyaline. Conidiophores absent. Conidiogenous cells micronematous, integrated, monoblastic, intercalary, short cylindrical. Conidia 25–43 × 13–36 µm (x̄ =31 × 23 µm, n = 30), solitary, straight, septate, unbranched, mostly smooth-walled at the base of immature conidia, becoming verrucose at mature conidia, composed of 1–4 columns at the base, 1–3-septate in each column, with 1–4 apical appendages. Appendage 148–258 µm long ( x̄ =186 µm, n=30), 6–15 µm wide at the base with dull green, 3–8 µm wide at the apex with hyaline, usually composed of three to four appendages, rarely one or two, euseptate, 6–23-septate, smooth, straight or divergent to intertwined; immature appendages 21–81 µm long (x̄ =43 µm, n=30), with 1–5-septate.
Culture characteristics – Conidia germinating on PDA, germination tube growing from both ends. Colonies on PDA reaching 10 to 14 mm diam. in 17 days at room temperature (25±2 °C), mycelium dense, floccose, surface smooth, velutinous spot centre with flat substrate, circle or irregular margin, light brown to yellow–brown, dark brown towards to white margin in above; white at centre, dark brown towards margin in reverse. No pigment production.
Material examined – China, Yunnan Province, Kunming City, from dead stem of Saccharum arundinaceum (Retz.) (Poaceae), 4 July 2020, C.F. Liao, (KUN–HKAS 107636, holotype), ex-type living culture KUMCC 21-0010.
GenBank number – OL473549 (ITS), OL473555 (LSU), OL473556 (SSU), OL505601 (tub2), OL505599 (tef1).
Notes – Phylogenetic analyses of the combined LSU, ITS, SSU, tub2 and tef1 sequence data showed that our new collection Tetraploa dashaoensis KUMCC 21-0010 is related to Tetraploa aquatica (MFLU 19-0995, MFLU 19-0996), but forms a distinct linage with 98% ML, 83% MP and 0.99 BYPP values (Fig. 2). Tetraploa dashaoensis shares some morphological characteristics with the phylogenetically closest species T. aquatica in having cylindrical conidiogenous cells, a verrucose conidial base and 1–4 apical appendages with euseptate. However, T. dashaoensis differs from T. aquatica in having a different conidial colour (dull green vs. brown to pale brown), longer conidia (25–43 µm vs. 22.5–27 µm), longer appendages (148–258 µm vs. 98–134 μm), and more septate appendages (6–23-septate vs. 6–10-septate). In addition, T. dashaoensis has intertwined appendages, which were absent in T. aquatic (Li et al. 2021a, b). Phylogenetic analyses and morphological characters support our collection to be different species. Thus, we introduce T. dashaoensis as a new species based on morphology and phylogeny.
Figure 1 – Tetraploa dashaoensis (KUN–HKAS 107,636, holotype). a–b. Conidia on host substrate; c–g. Conidia; k. Verrucose conidia; l. Germinating conidium; m. Colony on PDA (left-front, right-reverse); Scale bars: c–f, k=50 μm, g–j, l=100 μm
Figure 2 – Phylogram generated from maximum likelihood analysis of Tetraploa including related genera based on a combined LSU, ITS, SSU, tub2 and tef1 sequence data. Relevant sequences were referred from Dong et al. (2020), Hyde et al. (2020a), and Li et al. (2021a, b). The data set consisted of 3720 characters with gaps. Tree topology of the ML analysis was similar to the MP and BYPP tree topologies. Bootstrap support values of ML and MP≥75% with BYPP≥0.95 are given at the nodes. The ex-type cultures are indicated using ″T″; the new isolate is in blue