Platygramme subcolubrosa J. Kalb & Kalb, 2017

Kalb, Jutarat & Kalb, Klaus, 2017, New lichen species from Thailand, new combinations and new additions to the Thai lichen biota, Phytotaxa 332 (2), pp. 141-156 : 150

Platygramme subcolubrosa J. Kalb & Kalb , sp. nov. ( Fig. 2 H )

Mycobank MB823630

Similar to Platygramme colubrosa (Nyl.) Staiger , but differs in having non-pruinose discs and in ascospore septation (21–30 × 1–7-septate in P. colubrosa ).

Type:— THAILAND. Phang Nga province: Takua Pa district, tambon Khuek Khak, Samnaksong Bandokdang, at Phetkasem Road (Road Nr. 4), a few km S of Bangsak village, on bark of a deciduous tree in a secondary forest, 45 m, 8°45’35’’ N, 98°19’13’’ E, 8 June 2015, J. Sutjaritturakan 5008 & K. Kalb (RAMK, holotype).

Etymology:—The species epithet refers to the similarity with P. colubrosa .

Thallus corticolous, pale greenish or brownish grey, 5 cm diam., 100–150 μm thick, corticate, continuous, smooth, slightly brilliant. Thallus in section with scattered irregular clumps of crystals. Photobiont Trentepohlia . Lirellae black, erumpent to sessile with constricted base when mature, thin lateral thalline margin, flexuous, single or stellately branched, up to 3 × 0.5 mm, disc first concealed, soon widely open, labia striate, divergent, not pruinose. Exciple with thick apical, wedge-shaped carbonization, up to 75 μm wide. Hymenium hyaline, densely inspersed, 150–200 μm high. Hypothecium hyaline above, pale brown below, 20–30 μm high. Asci 2(–4)-spored. Ascospores brown, muriform, 65–100 × 14–20 μm, 20–25 × 1–4-septate, I+ red-brown. Pycnidia not seen.

Chemistry: no lichen substances by TLC.

Distribution and habitat:—The new species is known from a single collection obtained from the bark of a deciduous tree in a secondary forest in southern Thailand.

Remarks:—In the world key to Platygramme presented by Seavey et al. (2017), P. subcolubrosa would key out as P. colubrosa (Nyl.) Staiger , but this species differs by larger, especially broader ascospores with more longitudinal septa (80–115 × 18–34 μm, 21–30 × 1–7-septate). It should be mentioned that in that key, there is a regrettable error: P. australiensis keys out as a species with one ascospore/ascus, but actually it has 6–8/ascus.

Figures

FIGURE 2. A. Graphis indica (J.K. & K.K, KJK 41769; scale 1 mm); B. Leucodecton occultum (J.K. & K.K, KJK 41952; scale 0.25 mm); C. Phaeographopsis palaeotropica, ascomata with a distinct black mazaedium (J.K. & K.K, KJK 41398; scale 0.5 mm); D. Phaeographopsis palaeotropica, ascomata lacking a mazaedium (J.K. & K.K, KJK 41395; scale 0.4 mm); E. Platygramme australis (J.K. & K.K, KJK 41279; scale 0.5 mm); F. Platygramme commutabilis (Sutjaritturakan 4225, KJK 42227; scale 1 mm); G. Platygramme discurrens (Sutjaritturakan 4895, KJK 42217; scale 0.3 mm); H. Platygramme subcolubrosa (J.S. & K.K., KK 41534; scale 0.5 mm).