Plectosphaerella nauculaspora Zhi.Y. Zhang, Y.F. Han & Z.Q. Liang

Zhang, Zhi-Yuan, Chen, Wan-Hao, Zou, Xiao, Han, Yan-Feng, Huang, Jian-Zhong, Liang, Zong-Qi & Deshmukh, Sunil K., 2019, Phylogeny and taxonomy of two new Plectosphaerella (Plectosphaerellaceae, Glomerellales) species from China, MycoKeys 57, pp. 47-60 : 47

Plectosphaerella nauculaspora Zhi.Y. Zhang, Y.F. Han & Z.Q. Liang sp. nov. Figure 3

Etymology.

From “naucula”, referring to the navicular conidia.

Description.

Sexual morph not observed. Asexual morph on CA. Mycelium hyaline, smooth, septate, branched and thin-walled, 1-1.2 μm (x̄ =1.5 μm) wide. Conidiophores solitary, unbranched or rarely branched, hyaline, smooth, thin-walled, hyphal coils not observed. Conidiogenous cells growing from short branch or directly from mycelia, phialides, discrete, polymorphic, cylindrical, sub-cylindrical or ampulliform; terminal or lateral, hyaline, smooth, gradually tapering to the apex, straight at the apex, sometimes bent or helicoid, 3-37 × 0.5-2 μm (x̄ = 11 × 1 μm, n = 10), collarette minute, cylindrical, 0.5-1 μm deep. Conidia aggregating in slimy heads, 1- or 2-celled, mostly navicular, rarely fusiform or cylindrical, sometimes swollen at both ends, hyaline, smooth, thin-walled, 4-7 × 1-2 μm (x̄ = 5 × 1.5 μm, n = 10) (1-septate), 3-5 × 1-1.5 μm (x̄ = 4 × 1.5 μm, n = 6) (non-septate). Chlamydospores not observed.

Culture characteristics.

Colonies on PDA reaching 75-76 mm diam. in 14 d at 25 °C, milk white, flat, sub-rounded, margin regular, reverse milk white. Colonies on CA reaching 63-65 mm diam. in 14 d at 25 °C, milk white, aerial hyphae sparse, flat, margin weakly undulate to faintly fimbriate, reverse milk white.

Typification.

CHINA, Guizhou, Guiyang, Qianlingshan Park, 26°60'N, 106°69'E, 1220 m a.s.l., on soil, 10 Sep. 2016, collected and isolated by Zhi-Yuan Zhang, HMAS 248154 (holotype), ex-type CGMCC 3.19656 (= GZUIFR-QL8.12.1); ex-isotypes CGMCC 3.19657 (= GZUIFR-QL8.12.2).

Notes.

Phylogenetically, our two isolates CGMCC 3.19656 and CGMCC 3.19657 cluster together very well and form a single clade separated from the other species of Plectosphaerella ( Figure 1 ). Morphologically, Plectosphaerella nauculaspora is the only species that produces navicular conidia in this genus. Therefore, based on both morphological and phylogenetic evidence, P. nauculaspora is proposed as a novel species.

Figures

Figure 1. Phylogenetic tree of Plectosphaerella species derived from Bayesian analyses and Maximum Likelihood analyses, based on the combined sequences dataset of LSU + ITS + EF 1 α + RPB 2. Bayesian posterior probabilities (BI pp) greater than 0.7 and Maximum Likelihood bootstrap support values (MLBS) greater than 95 % are shown above branches. New isolates are in bold and blue. The tree used Brunneochlamydosporium nepalense (CBS 277.89 and CBS 971.72) as outgroup.

Figure 3. Plectosphaerella nauculaspora (HMAS 248154, holotype). A-B The front and reverse of colony on CA after 14 d at 25 ° C C-D Conidia E-P Phialides. Scale bars: 10 μm (C-P).