Ocellularia arachchigei Weerakoon, Lücking & Lumbsch, sp. nov.
MycoBank number: MB 815548, Facesoffungi number: FoF 02026, Fig. 1a
Etymology: In honor of the collector of the type specimen, Mr. Omal Selika Arachchige.
Holotype: O. S. Arachchige 107A (PDA).
Diagnosis: Differing from Ocellularia papillata and O.rongklaensis in the grey thallus with large internal clusters of calcium oxalate crystals and the whitish cover of the columella.

Thallus corticolous, epiperidermal, up to 5 cm diam., continuous; surface smooth to uneven, light grey; prothallus absent. Thallus in section 70 – 100 μm thick, with prosoplectenchymatous cortex, 15 – 20 μm thick, photobiont layer 30 – 50 μm thick, and medulla 30 –50 μm thick, strongly encrusted with numerous clusters of calcium oxalate crystals, thicker near apothecial margin (up to 100 μm). Photobiont Trentepohlia; cells rounded to irregular in outline, in irregular groups, yellowish green, 8 – 10 × 5 – 7 μm. Ascomata immersed – erumpent, with complete thalline margin, 0.8 – 1.2 mm diam.; disc covered by 0.2 – 0.5 mm wide pore; proper margin distinct, entire, visible as thin, white rim around the pore; thalline margin entire, smooth, white. Excipulum entire, yellowish to orange-brown (difficult to separate from modified periderm), together with periderm 50 – 100 μm wide, fused with thalline margin; laterally covered by algiferous, corticate thallus containing periderm and large crystals of calcium oxalate crystal layers up to 100 – 150 μm. Columella present, finger-like to barrel-shaped, becoming irregular, 150 – 200μm broad, yellowish brown with whitish cover. Hypothecium prosoplectenchymatous, 10 – 15 μm high, colourless. Hymenium 150 μm high, colourless, clear. Epithecium indistinct, 10–15 μm high, colourless. Paraphyses unbranched, apically smooth; periphysoids absent. Asci cylindrical, 120 – 140 × 20 – 25μm. Ascospores 8 per ascus, ellipsoid, 7 – 9 – septate, 30 – 35 × 9 – 10 μm, 3 – 4 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, Central Province, Matale District, Gammaduwa; 7° 31′ N, 80° 40′ E, 360 m; low altitude, on tree bark of home garden; January 2015, O. S. Arachchige 107A (PDA holotype and F Isotype).

Distribution and ecology: The new species was collected from a home garden in the central region of Sri Lanka. It is thus far only known from the type locality.

Notes: This new species keys out close to Ocellularia papillata (Leight.) Zahlbr. and O. rongklaensis (Homchant. & Coppins) Lücking. All three agree in lacking secondary metabolites, having a non-carbonized excipulum, a smooth to uneven thallus, immersed to erumpent ascomata, and ascospores over 20 μm long. However, O. papillata differs in the pale olive thallus lacking large clusters of calcium oxalate crystals, the completely immersed apothecia, and the distinctly brown apothecial rim and columella, with the columella becoming more distinctly irregular. In contrast, O. ronklaensis has a pale olive, indistinctly verrucose thallus, due to clustered distribution of calcium oxalate crystals, more erumpent apothecia, and the columella appears dark with only a thin whitish pruina. Other similar species are O. laeviusculoides Sipman & Lücking, differing chiefly in its carbonized columella, and O. bonplandii (Fée) Müll. Arg. and O. auberianoides (Nyl.) Müll. Arg., which both produce protocetraric acid and the columella becomes distinctly irregular in the latter.

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