Astrocystis cocoes (Henn.) Laessøe & Spooner, Kew Bull.

Wu, You-Peng, Pi, Yin-Hui, Long, Si-Han, Lin, Yan, Long, Qing-De, Kang, Ji-Chuan, Kang, Ying-Qian, Shen, Xiang-Chun, Wijayawardene, Nalin N., Zhang, Xu & Li, Qi-Rui, 2021, Morphological and phylogenetic study of five species of Astrocystis and Collodiscula on bamboo, Phytotaxa 522 (4), pp. 265-284 : 280

Astrocystis cocoes (Henn.) Laessøe & Spooner, Kew Bull. 49(1): 27 (1994) ( Fig. 6 )

≡ Rosellinia cocoes Henn., Hedwigia 47(4): 256 (1908)

MycoBank: MB580660

Saprobic on the surface of dead bamboo stalk, visible as black raised spots on the host. Sexual morph: Stromata erumpent, solitary or gregarious, not or somewhat confluent, black, carbonaceous, containing 1 ascoma, almost conical with a round apex, 0.4–0.6 mm diam., 0.5–0.8 mm high, with an outer stellate layer; persistent pale squamules from host cuticle, apex smooth and sometimes almost annulate with a minutely papillate ostiole. Asci 118–129 × 6.6–8.5 μm (mean 123 × 7.6 μm, n = 30), 8-spored, spore bearing part cylindrical, stipe short and tapering, apically rounded, with a discoid, subapical, J+ apical apparatus, with sides tapering to the base, blue staining in Melzer’s reagent, 2.4–3.5 μm (mean 2.8 μm, n = 30) high, 2.0–3.2 μm (mean 2.8 μm, n = 30) wide. Ascospores 18.1–22.8 × 5.5–6.0 μm (mean 19.8 × 6.2 μm, n = 30), overlapping uniseriate, aseptate, dark reddish brown, inequilaterally fusiform, with one or both ends beaked, flattened side slightly convex, with a germ slit on flattened side, less than full spore-length, with thin mucilaginous sheath and pad-like polar appendages. Asexual morph: undetermined.

Specimens examined:— CHINA. Hainan Province: Wuzhishan City, Wuzhishan Nature Reserve (18.541959°N, 109.405444°E), elev. 767 m, on dead bamboo culms, 11 October 2020, Q.R. Li 2020WZS64-3 (GMB0037; KUN-HKAS 112701; living culture, GMBC0037) .

Culture characteristics:— Ascospores germinated on PDA within 24 hours at 25 °C, colonies, dense but thinning towards the edge, edge irregular, white from above, reverse similar in colour. No conidia were observed on PDA or OA media.

Habitat/Distribution:— Known to inhabit dead bamboo, Brazil, China, India, Philippines.

Notes:— Astrocystis cocoes was described on dead branches of Cocos nucifera ( Laessøe & Spooner 1994) collected from Philippines. Our new collection (GMB0037) morphologically resembles A. cocoes . Astrocystis cocoes is distinct from A. sublimbata by its size of ascospores (15–19 × 6.5–8.5 μm vs 17–22 × 7.5–9.5 μm). Moreover, the ascospores of A. sublimbata do not possess a mucilaginous sheath and pad-like polar appendages ( Smith & Hyde 2001). Phylogenetic analyses of the combined ITS, RPB2, β-tubulin and α-actin genes show that GMBC0037 groups with A. cocoes with high support (100% ML, 1.00 BYPP; Fig. 1 ). This is the first report of A. cocoes from China.

Figures

FIGURE 1. RAxML tree based on analysis of a combined dataset of ITS- RPB2-β-tubulin-α-actin sequence dataset from selected species of Xylariales. Bootstrap support values for maximum likelihood (ML) greater than 75%, and Bayesian posterior probabilities (BYPP) greater than 0.90 are given at the nodes. Strain numbers are noted after the species names. The tree is rooted to the outgroup of Daldinia loculatoides (CBS 113279), D. macaronesica (CBS 113040) and Hypoxylon rickii (MUCL 53309).

FIGURE 6. Astrocystis cocoes (GMB0037). A–C. Stromata on the surface of host. D. Transverse section of stroma. E. Longitudinal section of stroma. F. Ascus apex with a J+, apical apparatus (stained in Melzer’s reagent). G–I. Asci with ascospores. J–Q. Ascospores. Scale bars: B–E = 200 μm, F–Q = 10 μm.