Neokalmusia karka H. M. Hu & Q. R. Li, 2023

Hu, Hongmin, He, Minghui, Wu, Youpeng, Long, Sihan, Zhang, Xu, Liu, Lili, Shen, Xiangchun, Wijayawardene, Nalin N., Meng, Zebin, Long, Qingde, Kang, Jichuan & Li, Qirui, 2023, Taxonomic and phylogenetic characterisations of six species of Pleosporales (in Didymosphaeriaceae, Roussoellaceae and Nigrogranaceae) from China, MycoKeys 100, pp. 123-151 : 123

Neokalmusia karka H. M. Hu & Q. R. Li sp. nov.

Fig. 4

Type material.

Holotype: GMB0494.

Etymology.

In reference to the host, Phragmites karka (Retz.) Trin. ex Steud.

Description.

Saprobic on dead culms of P. karka .

Sexual morph: Clypeus visible as black dots on the host surface, breaking through slightly raised cracks at the centre. Ascomata 241-386 × 161-231 μm (average = 375 × 197 μm, n = 5), smooth, semi-immersed, scattered, solitary or in small groups, black, oval, with ostiole. Peridium 12-20 μm wide, composed of a few layers of thin-walled, brown to dark brown, cells of textura angularis. Hamathecium comprising 1.5-2.8 μm wide, numerous, cellular, pseudoparaphyses, embedded in a mucilaginous matrix. Asci 80-109 × 10-14 μm (average = 95 × 11.4 μm, n = 15), 8-spored, bitunicate, fissitunicate, cylindrical-clavate, with bulbous pedicel, apically rounded with an indistinct ocular chamber, with a J-subapical ring. Ascospores 14-17 × 4-6 μm (average = 15.8 × 5.3 μm, n = 30), overlapping 1-2-seriate, fusiform, pale brown to brown, 1-septate, constricted at the septum, often enlarged near septum in the upper cell, distinctly verrucose on the surface, without a mucilaginous sheath. Asexual morph: undetermined.

Culture characters.

After 4 weeks of cultivation at 25 °C, the colonies on PDA measure around 2-2.5 cm in diameter. The surface appears smooth to velvety with an entire or slightly irregular margin, ranging from white to grey olivaceous. The colour is white near the margin with dense circular to filamentous growth. The reverse side of the colonies black to greenish-olivaceous.

Specimens examined.

China, Guizhou Province, Zunyi City, Suiyang County, Kuanqwashui Nature Reserve (28°31'51.04"N, 107°9'33.65"E), 1544 m elev., on decaying culms, 12 October 2022, Y.P Wu and H.M Hu, 2022KKS49 (GMB0494, holotype; GMBC0494, ex-type; KUN-HKAS 129179, isotype) .

Other examined material.

China, Guizhou Province, Huaxi District, Shilihetan Wetland Park (26°41'34.3"N, 106°67'68.8"E), 1500 m elev., on decaying culms, 8 October 2022, Y.P Wu and H.M Hu, 2022SLZH11 (GMB0500; GMBC0500, living culture) .

Notes.

This fungus shares morphological characters similar to Neokalmusia in having immersed ascomata, a clypeus-like structure composed of thin-walled cells and verrucose ascospores ( Tanaka et al. 2009; Ariyawansa et al. 2014b). Other than Neokalmusia karka , only two species, N. arundinis Thambug. & K.D. Hyde and N. didymospora D.Q. Dai & K.D. Hyde have been reported with 1-septate ascospores. However, N. karka can be distinguished, based on differences in asci size ( N. karka , 80-109 × 10-14 μm; N. arundinis 60-85 × (7.5-) 8.5-10.5 μm; N. didymospora 125-160 × 9.5-14 μm) and the obvious oval shape of its ascomata ( Wanasinghe et al. 2018; Flakus et al. 2019). In our phylogram, Neokalmusia karka formed a well-supported separate clade (100% ML, 1 BYPP; Fig. 1 ) in a sister relationship with N. arundinis and N. didymospora . The macro and micro-morphological differences and phylogenetic analyses support the recognition of N. karka as a new species (Fig. 1 ).

Figures

Figure 1. RAxML phylogram of Didymosphaeriaceae, based on a combined dataset of partial ITS, LSU, SSU and tef 1 DNA sequences. The tree is rooted by Bimuria novae-zelandiae (CBS 107.79) and Bimuria omanensis (SQUCC 15280). Bootstrap supports ML (MLB ≥ 75 %) and Bayesian posterior probabilities (BYPP ≥ 0.95) are given as MLB / BYPP above the branches. Sequences from newly-generated isolates are in red, bold letters, while those of ex-type isolates are shown in black, bold letters.

Figure 4. Neokalmusia karka (GMB 0494, holotype) A type specimen B, C appearance of ascomata on substrate D, E longitudinal section of an ascoma F peridium G pseudoparaphyses H-K asci L-N ascospores O, J ascus subapical ring in Melzer's Reagent. Scale bars: 0.5 mm (B-D); 10 μm (E-O).