Ocellularia ratnapurensis Weerakoon, Lücking & Lumbsch, sp. nov.
MycoBank number: MB 815549, Facesoffungi number: FoF 02027, Fig. 1b
Etymology: Referring to the type locality.
Holotype: G. Weerakoon 1005 (PDA).
Diagnosis: Differing from Ocellularia guptei in the larger ascospores and the only partially (upper half) carbonized columella.

Thallus corticolous, epiperidermal, up to 5 cm diam., continuous; surface uneven to verrucose, brownish yellow; prothallus absent. Thallus in section 50 – 80 μm thick, with paraplectenchymatous cortex, 5 – 10 μm thick, photobiont layer 30 – 60 μm thick, and medulla 30 – 50 μm thick, strongly encrusted with clusters of calcium oxalate crystals, near apothecial margins much thicker, up to 150 μm; in addition with numerous small, grey granules. Photobiont Trentepohlia; cells rounded to irregular in outline, in irregular groups, yellowish green, 8 – 11 × 5 – 8 μm. Ascomata rounded, erumpent to prominent, with complete thalline margin, 0.7 – 1.2 mm diam., 0.2 – 0.3 mm high; disc covered by 0.15 – 0.25 mm wide pore; proper margin distinct, entire, visible as brownish rim around the pore; thalline margin entire, smooth, light yellowish. Excipulum entire, yellowish to orange-brown, upper half carbonized, 50 – 70 μm thick, covered by periderm layer, 70 – 100μm thick, orange, fused with thalline margin. Columella present, finger-like to barrel-shaped, 100 μm broad, upper half carbonized; hypothecium prosoplectenchymatous, 10 – 15 μm high, colourless. Hymenium 300 μm high, colourless, clear; epithecium indistinct, 10 – 15 μm high, colourless. Paraphyses unbranched, apically smooth; periphysoids absent. Asci cylindrical, 200 – 250 × 50 – 70 μm. Ascospores 1 – 2 per ascus, muriform, 200 – 250 × 40 – 50 μm, about 5 times as long as wide, hyaline, distoseptate with lens-shaped lumina, I+ violet-blue. Secondary chemistry: No substances detected by TLC.

Material examined: SRI LANKA. Sabaragamuwa Province: Ratnapura District, Coolbone Tea Estate, on tree bark, 7° 02′ N, 80° 23′ E, 1288 (PDA holotype and F Isotype).

Distribution and ecology: The new species was collected from montane forest patches in a Tea estate in the Sabaragamuwa region of Sri Lanka. It is thus far only known from the type locality.

Notes: Ocellularia ratnapurensis belongs in a small group of species with carbonized excipulum and columella, large, muriform ascospores, and absence of secondary substances. Among these, the neotropical O. sanfordiana Zahlbr. differs by the carbonization of the excipulum and columella reaching down to the base, the larger apothecia, and the smaller ascospores (130 – 170 × 25 – 35 μm). The paleotropical Ocellularia kalbii Mangold also differs in the basal carbonization of excipulum and columella and in addition has less erumpent apothecia with gently sloping sides and much longer ascospores (300 – 600 × 25 – 50 μm). Ocellularia guptei (Nagarkar, Sethy & Patw.) D. D. Awasthi, from India, apart from a fully carbonized columella, differs in its smaller ascospores (100 – 180 × 15 – 30 μm). All other similar species differ in their chemical components, mostly producing hypoprotocetraric or isonotatic and norisonotatic acid.

Fig. 1 Ocellularia arachchigei (holotype) a Thallus with ascomata. Ocellularia ratnapurensis (holotype) b Thallus with ascomata. Rhabdodiscus albodenticulatus (c holotype, d paratype) c, d Thallus with ascomata. Scale bars: a – d = 1 mm.