Plectosphaerella sichuanensis Z.F. Yu & X.Q. Yang, 2021

Yang, Xiao Qian, Ma, Shi Yun, Peng, Ze Xiang, Wang, Zhong Qiao, Qiao, Min & Yu, Zefen, 2021, Diversity of Plectosphaerella within aquatic plants from southwest China, with P. endophytica and P. sichuanensis spp. nov., MycoKeys 80, pp. 57-75 : 57

Plectosphaerella sichuanensis Z.F. Yu & X.Q. Yang sp. nov. Figure 4

Etymology.

Latin, Plectosphaerella sichuanensis , referred to Sichuan Province, the locality where the fungus was found.

Description.

Colony on CMA after 3 d, vegetative hyphae hyaline, septate, commonly branched, smooth, thin-walled, mostly 2.5-3.5 μm (x̄ = 2.9 μm, n = 10) wide. Conidiophores macronematous, mononematous, erect, straight or flexuous to sinuate, hyaline, smooth, unbranched or rarely branched, aseptate. Conidiogenous cells phialides, integrated, terminal, determinate, subulate, hyaline, smooth. Conidia acrogenous, ellipsoidal, unicellular, smooth-walled, hyaline, 1-3 guttulate, 4.2-6.8 × 2.5-3.7 μm (x̄ = 5.2 × 3.3 µm, n = 30), forming hyaline to white mucilaginous masses. Sexual morph and chlamydospores absent.

Culture characteristics.

Colonies on OA reaching 50 mm diameter, on PDA reaching 47 mm diameter and on CMA reaching 42 mm diameter in 14 d at 25 °C. On PDA, colonies pale brown to white, flat, repressed, plicated, partly immersed, a few white aerial hyphae grew in the middle of the medium, margin regular, frontier distinct, reverse pale brown to white.

Typification.

China, Sichuan Province, Daofu, 30°98'N, 101°13'E, 2960 m alt., isolated from Potamogeton pectinatus as an endophyte, 20 Jul. 2015, Z.F. Yu, YMF 1.05081 (Holotype), ex-type CCTCC AF 2021054, another strain checked: YMF 1.05082.

Notes.

In the phylogenetic tree, the closest species to Plectosphaerella sichuanensis is P. populi , but P. populi can be distinguished from P. sichuanensis by its smaller aseptate conidia ( Crous et al. 2015). The size and shape of conidia of P. sichuanensis is more similar to P. cucumerina , expect that P. cucumerina presents longer phialides (up to 69 μm) ( Carlucci et al. 2012). In addition, P. sichuanensis resembles P. citrullae Carlucci et al., P. pauciseptata and P. oratosquillae in lacking septate conidia. However, it can be distinguished from P. citrullae by polyphialides conidiogenous cells; from P. pauciseptata and P. oratosquillae by bi-guttulate conidia ( Duc et al. 2009; Carlucci et al. 2012).

Figures

Figure 4. Plectosphaerella sichuanensis (YMF 1.05081, holotype) A-C colony on OA, PDA and CMA after 14 d D-H conidiophores and Phialides I conidia. Scale bars: 1.35 cm (A-C), 10 µm (D-I).