Diorygma sticticum Sutjaritturakan, Kalb & Lücking
Mycobank MB 517764
Thallus corticolous, up to 5 cm diam., 70–150 µm thick, continuous; surface smooth to uneven, light green; white prothallus sometimes present. Thallus in section with 10–15 µm thick loose upper cortex, irregular algal layer and clusters of calcium oxalate crystals. Lirellae in dense clusters, stellately branched, erumpent, with thick complete thalline margin, 1–3 mm long, 0.15–0.3 mm wide, 0.1 mm high; disc concealed to partly exposed, pale brown but thickly white-pruinose; labia conspicuous, white, the proper excipulum white-pruinose; thalline margin white. Excipulum entire, orange-brown, 15–30 µm thick; laterally covered by corticate algiferous thallus including clusters of crystals; hypothecium prosoplectenchymatous, 10–15 µm high, yellowish; hymenium 60–80 µm high, colourless, clear; epithecium granulose, 5–10 µm high, yellow-brown. Paraphyses unbranched; asci clavate, 60–70 x 10–12 µm. Ascospores 8 per ascus, ellipsoid, submuriform with 3 transverse and 0–1 longitudinal septa per segment, 10–13 x 6–8 µm, 1.5–2 times as long as wide, with thickened septa and rounded lumina, colourless, strongly I+ violet-blue. Secondary chemistry: stictic, hypostictic, and cryptostictic acids.
This is a second new species in the genus Diorygma, similar to the preceding one in having extremely small ascospores, but differing in the secondary chemistry and the geographic distribution.
The epithet refers to the secondary chemistry.
Diorygma sticticum is so far known from several collections from lowland rain forest in Thailand.
Type:—THAILAND: Nakhon Ratchasima Province: Khao Yai National Park, in front of Ban To Or, on unidentified tree; 1999, Sutjaritturakan 12683 (holotype RAMK).
Additional specimens examined (paratypes):—THAILAND: Nakhon Ratchasima Province: Khao Yai National Park, Sutjaritturakan 13556 (RAMK). Saraburi Province: Sutjaritturakan 20215 (RAMK). Loei: Phuluang Wildlife Sanctuary, Phuluang Animal Research Station; Poensungnoen RU-VP00413 (RAMK).
Sicut Diorygma poitaei sed ascosporis minoribus differt.