Chloridium paucisetosum K.Y. Wang, T.P. Wei & Y.L. Jiang, 2022

Wei, Tian-Peng, Wang, Kun-Ying, Zhang, Hong, Luo, Ming-Yan, Jia, Wei-Yu, Zeng, Yan & Jiang, Yu-Lan, 2022, A new species and a new combination of Chloridium from southwest China, Phytotaxa 549 (1), pp. 67-76 : 71-72

Chloridium paucisetosum K.Y. Wang, T.P. Wei & Y.L. Jiang , sp. nov. ( Fig. 3 )

MycoBank: MB 841485

Etymology:—referring to the lack of setae.

Type:— CHINA, Guizhou Province: Kaili City , isolated forest soil, 26.2402°N, 107.7722°E, 1500 m above sea level, 15 March 2018, K. Y . Wang & T. P . Wei (holotype HGUP 1806 , isotype CGMCC3.19620 , ex-type living culture GUCC 1806 ) .

Description:— Mycelium consisting of smooth, subhyaline to brown, branched, thin-walled, septate, 2–4 µm diam hyphae. Conidiophores macronematous, mononematous, solitary, branched at the apex, scattered, wider at the base, erect, brown, paler and slightly tapering upward, straight or slightly flexuous, smooth, septate, cylindrical, 50–372 × 4.5–9.5 μm. Conidiogenous cells integrated, terminal, cylindrical or lageniform to ampulliform, with a conspicuous outer collarette, subhyaline to pale brown, smooth, 5.0–10 × 2.0–3.5 µm. Conidia obovoid or ellipsoidal, acrogenous, subhyaline to pale brown, solitary, aseptate, guttulate, thin-walled, 2.5–5.0 × 2–2.5 μm. Sexual stage not observed.

Culture characteristics:—Colonies on PDA effuse, thinly hairy, with sparse to moderate aerial hypha, pale to medium brown, reaching 20 mm diam at 25 ± 1 °C after 7 days.

Notes:— Chloridium paucisetosum shares a few morphological similarities with C. aquaticum , C. humicola and C. terricola in having branched conidiophores and phialidic conidiogenous cells. Nevertheless, C. paucisetosum showed high heterogeneity, forming a monophyletic clade, which was genetically distant from all species ( Fig. 1 ). Morphologically, C. paucisetosum can also be distinguished from these species. Chloridium aquaticum produces ellipsoidal to cylindrical conidia in slimy masses ( Wei et al. 2018); The conidia of the C. humicola are aggregating in hyaline slimy masses and smaller (2.7–3.6 × 1.5–2.0 µm), as well as longer conidiophores (700 × 8.0 µm; Jong & Davis 1972); C. terricola differs by its truncate at the base and smaller conidia (2–3 × 2–2.5 µm; Wang et al. 2017). Furthermore, The PHI tests revealed that no evidence of recombination (Фw = 0.2545) was detected between C. paucisetosum and its closely related taxa ( Fig. 2 ).

Figures

FIGURE 1. Phylogram of RAxML analysis based on a combined ITS and LSU sequence dataset within Chloridium. Adautomilanezia caesalpiniae was used as outgroup. Bootstrap support values for Maximum likelihood and Maximum parsimony greater than 50%, and Bayesian posterior probabilities equal to or greater than 0.8 are indicated at the nodes (ML/BI/MP). Type strains are highlighted by a “*”, and our strain is in bold.

FIGURE 2. Splitgraphs showing the results of the pairwise homoplasy index (PHI) test of newly described taxa and closely related species using both LogDet transformation and splits decomposition. PHI test results (Φw) <0.05 indicate significant recombination within the dataset. Type strains and new taxa are indicated with “*” and bold, respectively.

FIGURE 3. Chloridium paucisetosum (CGMCC3.19620). A–B: Colony on PDA for 2 weeks. C–D: Conidiophores, conidiogenous cells and conidia. E: Conidiogenous cells producing conidia. F: Conidia. Scale bars: C = 100 μm; D–E = 10 μm; F = 5 μm.