Ocellularia phatamensis Naksuwankul, Parnmen & Lumbsch

Naksuwankul, Khwanyuruan, Kraichak, Ekaphan, Parnmen, Sittiporn, Luecking, Robert & Lumbsch, H. Thorsten, 2016, Five new species of Graphidaceae (Ascomycota, Ostropales) from Thailand, MycoKeys 17, pp. 47-63 : 53

Ocellularia phatamensis Naksuwankul, Parnmen & Lumbsch sp. nov. Figure 4 A–B

Type.

THAILAND, Ubon Ratchathani Province, Pha Tam National Park, Sang Chan waterfall, 15°30'N, 105°35'E, 124 m, dry evergreen forest, on bark; 12 April 2013, K. Papong 8574 (holotype: MSUT; isotype: F).

Diagnosis.

Differing from the similar Ocellularia krathingensis in having an a grayish, thick and rimose thallus.

Etymology.

The specific epithet refers to the name of the Pha Tam National Park in Ubon Ratchathani Province, Thailand.

Description.

Thallus corticolous, epiperidermal, up to c. 5 cm diam., continuous; surface uneven-verrucose to rimose, grayish, medulla white; prothallus absent. Thallus in section 60-75 µm thick, with prosoplectenchymatous cortex, 5-8 µm thick, photobiont layer 20-25 µm thick, and medulla 35-40 µm thick, with scattered clusters of calcium oxalate crystals. Photobiont Trentepohlia ; cells rounded to irregular in outline, in irregular groups, green, 8-10 × 6-7 µm. Ascomata rounded, erumpent, with complete thalline margin, 0.4-0.7 mm diam., 0.15-0.2 mm high; disc covered by 0.07-0.1 mm wide pore more or less filled with black-tipped columella but columella often immersed; proper margin indistinct; thalline margin entire to slightly fissured, smooth, light yellowish green. Excipulum entire, prosoplectenchymatous, apically carbonized, 15-20 µm wide, fused with thalline margin and difficult to separate from the bordering periderm; laterally covered by algiferous, corticate thallus containing periderm layers; columella present, finger-like, carbonized, up to 110 µm broad and 120-135 µm high; hypothecium prosoplectenchymatous, 5-10 µm high, light brown; hymenium 120-150 µm high, hyaline, clear; epithecium indistinct, 5-10 µm high, hyaline. Paraphyses unbranched, apically smooth; periphysoids absent; asci cylindrical to narrowly clavate, 100-110 × 12-15 µm. Ascospores 8 per ascus, ellipsoid, 7-8-septate, 25-30 × 7.5-8 µm, hyaline, distoseptate with lens-shaped lumina, I+ violet-blue. Pycnidia not seen.

Secondary chemistry.

No substances detected by TLC.

Distribution and ecology.

The new species was collected in northeastern Thailand, growing on bark in a dry evergreen forest. It is known only from the type locality.

Remarks.

The new species is similar to Ocellularia krathingensis in having an apically carbonized exciple and columella, transversely septate, amyloid ascospores, and lacking secondary metabolites, but differs in having a grayish and thicker thallus ( Homchantara and Coppins 2002). Another similar species is Ocellularia klinhomii , but differs in lacking a dark apothecial rim and the ascomata are not immersed in verrucae. Molecular data support the distinction of these two species (Fig. 2). Another similar and related species is Ocellularia diacida , which is readily distinguished by the presence of the hirtifructic acid chemosyndrome. The species would key out at alternative 60 in the Ocellularia key for Thailand ( Sutjaritturakan and Kalb 2015).