Xenoastrosphaeriella aquatica D.F. Bao, H.Y. Su & Z.L. Luo, 2022

Luo, Zong-Long, Bao, Dan-Feng, Li, Long-Li, Luan, Sha & Su, Hong-Yan, 2022, Xenoastrosphaeriella aquatica sp. nov. from freshwater habitat in Yunnan Province, China, Phytotaxa 544 (2), pp. 193-200 : 196-198

Xenoastrosphaeriella aquatica D.F. Bao, H.Y. Su & Z.L. Luo , sp. nov. FIGURE 2

Index Fungorum number: IF558599; Facesoffungi number: FoF 09922

Etymology: Referring to the aquatic habitat of this fungus.

Holotype: KUN-HKAS 115792

Saprobic on decaying submerged wood. Sexual morph: Ascomata 470–580 μm high, 405–545 μm diam., carbonaceous, easily broken, dark brown to black, solitary to gregarious, erumpent through the outer layers of the host tissue, superficial, conical to mammiform, with host cortex persisting as ruptured, stellate, uni-loculate, ostiolate, with a minute papilla. Peridium 50–120 μm wide, carbonaceous, comprising two zones, outer layers composed several dark, brown cells of textura prismatica, while the inner zone with hyaline cells of textura prismatica. Hamathecium comprising 1–2 μm wide, filiform, trabeculate pseudoparaphyses, anastomosing at the apex, embedded in a hyaline gelatinous matrix. Asci 105–195 × 12–15 μm (= 148 × 13 μm, n = 20), 8-spored, bitunicate, fissitunicate, cylindrical to cylindric-clavate, shortly pedicellate, apically rounded, with an ocular chamber. Ascospores 55–70 × 6–7 μm (= 61 × 6 μm, n = 30), 1–2-seriate, overlapping, narrowly elongate fusiform, tapering at both ends, hyaline when young, becoming dark olivaceous to brown after maturing, paler at the end cells, 1–5-septate, mostly 5-septate, slightly constricted at the septa, smooth-walled, with a mucilaginous sheath surrounded ascospores. Asexual morph: Undetermined.

Material examined: CHINA, Yunnan Province, on decaying wood submerged in Lancang River , December 2017, S-1525, Z.L Luo (KUN-HKAS 115792, holotype), ex-type culture, CGMCC 3.206 83 = DLUCC 1525 , additional sequence rpb2: MZ 442702 ; ibid, on decaying wood submerged in Nujiang River , October 2016, S-869, Z.L Luo (KUN-HKAS 115797, isotype), living culture, DLUCC 0869 , additional sequence rpb2: MZ 442703 .

Notes: Xenoastrosphaeriella aquatica resembles X. tornata in having similar shapes of ascostromata, asci and ascospores. However, X. aquatica can be distinguished from X. tornata by the ascospores color (dark olivaceous to brown vs. brown to reddish-brown), size (55–70 × 6–7 vs. 48–52 × 7–8 μm) and numbers of septa (3-septate vs. 5- septate). Xenoastrosphaeriella aquatica is closely related to X. trochus ( FIGURE 1 ). Morphologically, X. aquatica resembles X. trochus in having conical to mammiform, superficial, carbonaceous ascomata, cylindric-clavate asci and broadly fusiform ascospores, but differs from the latter in the ascospores color (dark olivaceous to brown vs. brown to reddish-brown) and dimension (55–70 × 6–7 vs. 45–55 × 4.5–6 μm). Moreover, the comparison of the tef1-α sequence data between X. aquatica and X. trochus showed 25 base pair differences, which also indicates that X. aquatica and X. trochus are different.

Figures

FIGURE 1. Phylogram generated from maximum likelihood analysis based on combined LSU, SSU and tef1-α sequence data. Bootstrap values for maximum likelihood (ML) equal to or greater than 75% and clade credibility values greater than 0.95 from Bayesian-inference analysis were labelled on the branches. The ex-type strains are in bold. The newly generated sequences are indicated in red.

FIGURE 2. Xenoastrosphaeriella aquatica (KUN-HKAS 115792, holotype). a, b Appearance of ascomata on host substrate. c Pseudoparaphyses. d Vertical section through ascoma. e, f Parts of peridium. g–l Asci. m–r Ascospores. Scale bars: d = 200 μm, e = 50 μm, f–l = 30 μm, c, m–r = 20μm.