Roussoella bambusarum H. M. Hu & Q. R. Li, 2022

Hu, Hong Min, Liu, Li Li, Zhang, Xu, Lin, Yan, Shen, Xiang Chun, Long, Si Han, Kang, Ji Chuan, Wijayawardene, Nalin N., Li, Qi Rui & Long, Qing De, 2022, New species and records of Neomassaria, Oxydothis and Roussoella (Pezizomycotina, Ascomycota) associated with palm and bamboo from China, MycoKeys 93, pp. 165-191 : 165

Roussoella bambusarum H. M. Hu & Q. R. Li sp. nov.

Fig. 5

Holotype.

GMB0316.

Etymology.

In reference to the host, Bambusa bambusarum (Lour.) Raeusch. ex Schult. ‘Fernleaf’ R. A. Young

Description.

Saprobic on decaying culms of B. bambusarum . Sexual morp: Ascostromata 111-146 μm high, 460-560 μm diam., (x̄ = 123 × 539 μm, n = 30), immersed under a clypeus, solitary or scattered, raised hemispherical or dome-shaped on host epidermis, black, coriaceous, glabrous, uni-loculate. Locules 335-414 μm diam., 128-212 μm high, immersed within ascostromata, black, globose to subglobose. Ostioles with minute papillate. Peridium 19-34 μm thick, composed of dark brown thin-walled cells of textura angularis. Hamathecium comprised of 1-2 μm wide, numerous, septate, branched, anastomosing, filiform, hyaline, pseudoparaphyses. Asci 120-143 × 8-12 μm (x̄ = 134 × 10 μm, n = 30), 8-spored, bitunicate, cylindrical, curved, short pedicellate with knob-like pedicel, apically rounded with an indistinct ocular chamber. Ascospores 14-20 × 6-7 μm (x̄ = 17.6 × 6.7 μm, n = 30), dark brown to brown, 1-seriate, sometimes overlapping, 2-celled, constricted at the septum, ellipsoidal to fusiform, straight, rough-walled, guttulate, conically rounded ends, with longitudinal striations. Asexual morph: Undetermined.

Culture characters.

Ascospores germinated on PDA within 24 hours at 25 °C, colonies are reaching 5 cm diam. The colony on the surface is white, grey, circular, flocculent, dense, cottony mycelium, colony reverse is white and gray, white in the middle. Not sporulating on OA nor on PDA.

Specimens examined.

China, Guizhou Province, Guiyang Huaxi National Urban Wetland Park (26°2'2.34"N, 106°34'16.22"E), on decaying culms of B. bambusarum , 12 October 2021. Altitude: 1130 m, Y.P Wu and H.M Hu, 2021 HXGY01 (GMB0316, holotype; KUN-HKAS 123431, isotype; GMBC0316, ex-type living culture) .

Other examined material.

China, Guizhou Province, Guiyang Huaxi National Urban Wetland Park (26°10'44.13"N, 106°43'13.12"E), on decaying culms of B. bambusarum , 15 October 2021. Altitude: 1201 m, Y.P Wu and H.M Hu, 2021 HXGY55 (GMB0390; GMBC0390, living culture) .

Notes.

Morphologically, Roussoella bambusarum is similar to R. thailandica D.Q. Dai et al., but differs from the latter by having larger ascospores (17.6 × 6.7 μm vs. 14.5 × 5.5 μm), larger upper cells, occasionally curve, narrowly at both ends, with irregular longitudinal striations. ( Liu et al. 2014). Phylogenetic analysis showed that R. bambusarum and R. doimaesalongensis Thambug. & K.D. Hyde were clustered together (26% ML, 0.97 BYPP; Fig. 2 ) ( Thambugala et al. 2017).

Figures

Figure 2. RAxML tree of Roussoella and related genera based on a combined ITS, LSU, rpb 2 and tef 1 sequences dataset. Bootstrap support values for ML equal to or greater than 60 % and BYPP equal to or greater than 0.95 are given above the nodes. The new collections are in red bold, type strains are in bold.

Figure 5. Roussoella bambusarum (Holotype, GMB 0316) A stromata on host substrate B ascostromata on bamboo culm C cross-section of ascostromata D-F asci G longitudinal section of ascostromata H peridium I pseudoparaphyses J apical apparatus (stained in Melzer's Reagent) K-N ascospores. Scale bars: 0.5 mm (B-C); 10 μm (D-F, H-N); 50 μm (G).