Leucodecton occultum

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 : 146

Leucodecton occultum (Eschweiler in Martius et al. 1833: 174) Frisch (2006: 157). ( Fig. 2B )

This species can be recognized by its grey, dull thallus, immersed to slightly emergent ascomata with a free proper exciple, brown (sub-) muriform ascospores, 3–7 x 0–2-septate, 16–30 x 9–11 μm. Our TLC results revealed a greater variation in the concentration of the lichen compounds than we could find in the literature, viz. norstictic acid (major), stictic acid (major to minor), α- acetylconstictic acid (minor to trace), connorstictic acid (minor to trace), hypostictic acid (minor to trace).

Distribution and habitat:—This pantropical species is here reported for the first time from three provinces in central and northern Thailand where it was found growing on bark of deciduous trees in ± open, well-lit situations from 200– 550 m.

Material from Thailand examined:— Chiang Mai province: Chiang Dao district ; tambon Chiang Dao, at the edge of Doi Chiang Dao Wildlife Sanctuary, on freestanding deciduous trees along the road, 510 m. 19°24’13’’ N, 98°55’20’’, 2 December 2016, J. &. K. Kalb 42046 (Hb. K. & J. Kalb )— Chiang Mai province: Doi Saket district ; tambon Mae Pong, on the way to Mae Kampong Waterfall ; in a light, secondary forest, on bark of Mangifera indica , 550 m. 18°54’02’’ N, 99°14’36’’ E, 13 December 2016, J. &. K. Kalb 41952 (Hb. K. & J. Kalb )— Kanchanaburi province: Sangkhlaburi district ; parking area of Wat Wang Wiwegkaram (Wat Mon), in a light deciduous forest on bark, 210 m, 15°07’55’’ N, 98°26’48’’ E, 17 December 2015, J. Sutjaritturakan & K. Kalb 41381 ( Hb. K. & J. Kalb )— Ratchaburi province: Suan Phueng district ; tambon Suan Phueng, trail to Kaew Chan Waterfall (Nine-Level Waterfall), bamboo scrub with scattered deciduous trees along a creek (mixed deciduous forest), 200–250 m. 13°31’31’’ N, 99°14’23’’ E, 11 December 2015, J. Sutjaritturakan & K. Kalb 41303 ( Hb. K. & J. Kalb ) .

Remarks:—A possible co-occurrence of norstictic and stictic acids as major substances could cause difficulties with identification when either of the two acids are used as an alternative in the key, e.g. in Rivas Plata et al. (2010). In this case, the occurrence of norstictic acid is distinctive. Leucodecton occultum is a new addition to the Thai lichen biota.

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).