Astrothelium conjugatum Weerakoon & Aptroot, 2016

Weerakoon, Gothamie & Aptroot, André, 2016, Nine new lichen species and 64 new records from Sri Lanka, Phytotaxa 280 (2), pp. 152-162 : 153

Astrothelium conjugatum Weerakoon & Aptroot , sp. nov. ( Fig. 1A–B )

Mycobank No.: MB 817608

Astrothelium with ascomata pyriform, arranged astrothelioid with 2–8 chambers joined with eccentric, fused ostioles; 3–10 fused ascomata grouped within one pseudostroma; pseudostromata c. 1–5 mm diam., erumpent to prominent, with irregularly lobate to linear outline, completely covered by a thallus layer that is thick and opaque at the sides, and can be similar on top or thinner and translucent; ascospores 3-septate, 20–25 × 6.5–7.5 μm.

Type: — SRI LANKA. Rilhena, on bark of tree, 9 February 2015, G.Weerakoon & P.Wolseley Ri01F (holotype PD, isotypes ABL & F).

Thallus corticate, pale yellowish brown, rather smooth, covering an area of up to 7 cm diam., without prothallus. Ascomata c. 0.5–0.7 mm diam., pyriform, astrothelioid, 2–8 chambers joined with eccentric, fused ostioles; 3–10 fused ascomata grouped within one pseudostroma; pseudostromata c. 1–5 mm diam., erumpent to prominent, with irregularly lobate to linear outline, completely covered by a thallus layer that is thick and opaque at the sides, and can be similar on top or thinner and translucent, in which case the black ascoma wall is visible through it; with tiny brown ostioles. Hamathecium clearly but sparsely inspersed with hyaline oil droplets. Ascospores 8/ascus, hyaline, 3-septate, fusiform-ellipsoid, 20–25 × 6.5–7.5 μm, hyaline, IKI–, lumina diamond-shaped when mature. Pycnidia not observed. Chemistry. Thallus and pseudostroma UV–, K–. TLC: No substances detected.

Distribution and habitat: —On tree in wet lowland tropical rain forest. Only known from Sri Lanka.

Discussion: —This species is close to Astrothelium straminicolor (Nyl.) Aptroot & Lücking (2016 ,in press), which is known from India, Malaysia and Sarawak and differs by the absence of thallus on top of the pseudostromata.

Figures

FIGURE 1. A–B, Astrothelium conjugatum, A, habitus, B, ascospores; C–E, Heterodermia fragmentata, C, apothecium, D–E, thallus; F–G, Lecanactis minutissima, F, apothecia, G, ascospores; H–I, Megalotremis cylindrica, H, conidiomata, I, conidia and conidiophores. Scale:A, H = 0.5 mm, B = 25 μm, C = 2 mm, D–E = 1 mm; F = 0.2 mm, G = 20 μm, I = 10 μm.