Neopalmiascoma macadamiae X. Zhang, K.D. Hyde, Tibpromma & Karunarathna, 2024

Zhang, Xian, Karunarathna, Samantha C., Tibpromma, Saowaluck, Du, Tian-Ye, Elgorban, Abdallah M., Lumyong, Saisamorn, Dai, Dong-Qin & Hyde, Kevin D., 2024, Morphology and phylogenetic analyses reveal Neopalmiascoma gen. nov. (Bambusicolaceae, Pleosporales) on Macadamia integrifolia in Yunnan Province, China, Phytotaxa 633 (3), pp. 230-240 : 235-236

Neopalmiascoma macadamiae X. Zhang, K.D. Hyde, Tibpromma & Karunarathna , sp. nov.

Index Fungorum IF901496, Facesoffungi FoF 15279; FIGURE 2 .

Etymology: Named after the host genus, Macadamia.

Holotype: ZHKU 23-0096

Saprobic on a dead branch of Macadamia integrifolia. Sexual morph: Ascomata 70–190 μm × 100–160 μm (x̄ = 102 × 128 μm, n = 10), solitary, semi-immersed, dark brown to black, unilocular, subglobose to ampulliform, ostiolate, papillate. Ostioles centric or eccentric, periphysate, carbonaceous. Peridium 10–25 μm wide (x̄ = 19.5 μm, n = 20), thick-walled, outer cells merging with the host epidermal cells, tending to be smaller, brown to dark brown cells of textura angularis, thin-walled towards the outside, and inner cells composed thick-walled, light-brown of textura angularis cells. Hamathecium comprising 1–5 μm wide (x̄ = 2.3 μm, n = 30), branched, dense, cellular pseudoparaphyses, longer than asci. Asci 40–90 × 7–15 μm (x̄ = 54 × 11 μm, n = 30), 6–8-spored, cylindric-clavate, fissitunicate, bitunicate, pedicellate, slightly curved, rounded at the apex. Ascospores 8–13 × 3–6 μm (x̄ = 11.1 × 5 μm, n = 40), overlapping, didymosporous, fusiform with obtuse ends, broadly fusiform to ellipsoid, constricted at the septum, 1-septate, hyaline to yellowish-brown when immature, brown to dark-brown when mature, slightly wider upper cell, tapering towards the slightly rounded ends, straight or slightly curved, with 2–3 guttules, with mucilaginous sheath, echinulate, rough-walled. Asexual morph: Undetermined.

Culture characteristics: Ascospores germinated on PDA within 24 h. Above: pure colonies on PDA after one month is flossy, irregular, umbonate, undulate edge, white to pale brown in above, forming tufts on surface, wrinkled. Reverse: white to grey from the edge to the center, accompanied by cracks in the middle, white to grey at the margin, a brown ring in the middle to separate it.

Material examined: China, Yunnan Province, Baoshan City , 24°55′17″ N, 98°50′37″ E, 958 m elevation, on a dead branch of Macadamia integrifolia, 29 July 2022, X. Zhang, MBL72 (holotype, ZHKU 23-0096) ; ex-type culture, ZHKUCC 23-0746, ZHKUCC 23-0747.

Notes: The NCBI BLASTn search of our new collection matched with Palmiascoma gregariascomum (MFLUCC 11-0175) by giving 96.78% percent identity in ITS sequences; the LSU sequences matched with Bambusicola loculata (MFLUCC 13-0856) with 98.75% similarity; the TEF1-α matched with Palmiascoma qujingense (KUMCC 19-0201) with 91.75% similarity; the RPB2 matched with Bambusicola pustulata (MFLUCC 15-0190) with 78.54% similarity; and the SSU sequences of our new collection matched with Palmiascoma qujingense (KUMCC 19-0201) with 99.30% similarity.

Neopalmiascoma macadamiae (ZHKU 23-0096) can be distinguished from Palmiascoma gregariascomum (MFLUCC 11-0175) and P. qujingense (KUMCC 19-0201) by having solitary, semi-immersed ascomata, 6–8-spored asci, constricted at the septum ascospores with echinulate, rough-walled, the culture on PDA is flossy, irregular, umbonate, undulate edge, white to pale brown in above, wrinkled, reverse accompanied by cracks in the middle, white to grey at the margin; P. gregariascomum has gregarious, scattered to clustered, semi-immersed to erumpent ascomata, 8-spored and well-developed ocular chamber asci, ascospores not constricted at the septa, the culture on PDA is greenish-grey to grey, slightly radiating, circular, reverse brown to dark brown at the margin ( Liu et al. 2015); while P. qujingense has clustered or scattered and glabrous ascomata, 8-spored asci, and ascospores lacking a mucilaginous sheath, the culture on PDA is white to creamy, reverse creamy ( Monkai et al. 2021). Therefore, based on morphology and molecular data, we introduce the new genus Neopalmiascoma , to accommodate N. macadamiae .

Figures

FIGURE 2. Neopalmiascoma macadamiae (ZHKU 23-0096, holotype). a. Appearance of ascomata on host substrate. b. Vertical section of an ascoma. c. Peridium. d. Hamathecium. e–g. Asci. h–k. Ascospores. l, m. Ascospore stained with Indian ink. n. A germinating ascospore. o, p. Colony on PDA from above and below after one month. Scale bars: c = 40 μm; b, d–g, n = 20 μm; j, k = 10 μm; h, i, l, m = 5 μm.