Xylaria apiospora M. Niranjan & V.V. Sarma, sp. nov.

Index Fungorum number: IF 557848; MycoBank number: MB 557848; Facesoffungi number: FoF 08683; Fig. 1

Etymology – The ascospores having the apical cell.

Holotype – AMH-10071

Saprobic on decaying twig. Sexual morph Ascostromata superficial, solitary, black, crust 95 μm high, with brown hyphae on surface, loosely connected, hyaline, filamentous tissue and central brown tissue. Ascomata (193–)285–460×(180–)215–260 μm (x̅=242×233 μm, n=8), globose, erumpent, pullvinate, clypeate, periphysate. Necks 82–120 μm high. Peridium 39 μm wide, with brown to hyaline cell layers of textura porrecta. Hamathecium comprising 5.9 μm wide, septate, branched, longer than asci, sparsely paraphyses. Asci 91–126 × 4.5–6 μm (x̅=108×5 μm, n=25), 8–spored, unitunicate, cylindrical, apically rounded, cylindrical, with a J+an apical ring, rings 1.5–2×1.5–2 μm (x̅=2×2 μm, n=25), long pedicellate, persistent. Ascospores 12–14.5 × 4–5 μm (x̅=13 × 4 μm, n=25), overlapping uni-seriate, fusiform, hyaline to brown at maturity, germ slit curved, obtuse ends, with hyaline apical cell at one end, smooth walled. Asexual morph Undetermined.

Material examined – INDIA, Andaman and Nicobar Islands, South Andaman, Chidiya Tapu, Viewpoint Area (11°48′10″ N 92°71′08″ E). Recorded on a decaying log, 9 December 2017, M. Niranjan and V.V. Sarma (PUFNI 1766). Herbarium specimen submitted to Ajrekar Mycological Herbarium-AMH (AMH-10071, holotype) and ex-type living culture (NFCCI-4370) deposited at National Fungal Culture Collection of India (NFCCI), Agarkhar Reserch Institute, Pune, Maharasthra, India.

GenBank numbers – ITS=MT572916.

Notes – Xylaria apiospora slightly differs from X. longipes (Rogers 1983) in having smaller ascomata (285–460 × 215–260 vs. 450–650 × 400–600 µm) and asci (91–126 × 4.5–6 vs. 130–180 × 7–9 μm), and larger ascospores (12–14.5×4–5 vs. 13–15×5–7 μm) with hyaline smaller, apical cells. While X. apiospora has fusiform ascospores with hyaline, smaller cells, X. longipes has ellipsoid-inequilateral, aseptate ascospores. Phylogenetically, X. apiospora constitutes a distinct basal lineage to Xylaria multiplex (1010). Therefore, we introduce X. apiospora as a new species based on morphology and phylogenetic evidence (Figs. 1 and 2).

Figure 1 – Xylaria apiospora (NFCCI-4370, holotype). a Stromata on decaying host. b, c Horizontal section of stromata. d Paraphyses. e–h Asci. i Striations on stromatal surface. j Cross section of stroma. k Peridium. l–q Ascospores. Scale bars: b=100 μm, c, j, k=50 μm, d–h=20 μm, l–q=10 μm

Figure 2 – Maximum parsimony tree of Xylariaceae constructed by using the ITS sequence. The tree includes both ML and MP values. Rosellinia australiensis is selected as an outgroup taxon. RAxML analysis yielded a minimum scoring tree with a final ML optimization likelihood value of − 5854.053127. The matrix had 393 distinct alignment patterns with 10.20% of undetermined characters or gaps. The maximum parsimonious dataset consists of 626 characters of which 278 were constant, 233 parsimony-informative and 115 parsimony-uninformative. The parsimony analysis of the data matrix resulted in one thousand equally parsimonious trees with a length of 1041 steps (CI 0.540, RI=0.829, RC 0.447, HI=0.460) in the first tree. The overall topology of the phylogenetic trees resulted from ML and MP were similar and incongruent in with earlier studies. The phylogenetic analysis showed that Xylaria haemorrhoidalis NFCC-4369 nested with Xylaria haemorrhoidalis 89041207 with 100% MLBS and 100% MPBS support. Similarly, Xylaria apiospora NFCC-4370 branched with Xylaria multiplex 1010 with week bootstrap support of MPBS. The newly generated sequences are indicated in blue bold