Pyxine pseudokeralensis Kalb, Mongkolsuk & Buaruang, 2012

Mongkolsuk, Pachara, Meesim, Sanya, Poengsungnoen, Vasun & Kalb, Klaus, 2012, The lichen family Physciaceae in Thailand-I. The genus Pyxine, Phytotaxa 59 (1), pp. 32-54 : 49

15. Pyxine pseudokeralensis Kalb, Mongkolsuk & Buaruang , sp. nov. ( Fig. 3C )

Mycobank MB 800694

Similar to Pyxine keralensis Awasthi , but differing in having a white medulla (pale yellow to yellow-orange in P. keralensis ).

Holotype:— THAILAND. Sukhothai; Ramkhamhaeng National Park , in a dry evergreen forest, on Tetrameles nudiflora , 553 m, 16°53'00'' N, 99°43'00'' E, 23 October 1997, N. Homchantara 9575 ( RAMK 17617 ).

Thallus corticolous and saxicolous, 2–8 cm wide, firmely adnate to adnate, subdichotomously lobate. Lobes radiating, discrete to ± imbricate, plane to slightly convex, 0.3–0.7 mm wide, subrotund to truncate at the apices. Upper surface pale yellowish white to yellowish grey or pale grey, epruinose; polysidiangia and soralia absent. Pseudocyphellae distinct, marginal and laminal, irregular and linear, seldom becoming reticulate. Isidia starting marginally, then spreading to the surface, cylindrical, simple or sparingly branched, ± clustered, 0.2–0.5 mm tall, 0.05–0.1 mm thick. Medulla uniformly white. Lower surface brown-black in the centre, paler towards the margin; rhizines ± dense, short, simple or furcate. Apothecia obscurascens - type, 0.5–1.1 mm wide; disc epruinose. Internal stipe distinct, orange, K+ wine red, P-. Ascospores 12–18 × 6–7 µm. Pycnidia not seen.

Chemistry: Cortex K+ yellow, C-, KC-, P+ yellow, UV-; medulla K-, C-, KC-, P+ orange; containing atranorin (major), chloroatranorin (minor), testacein (major), unknown terpenes (minor).

Distribution and habitat:—Very rare on bark of Tetrameles nudiflora and rocks in a dry evergreen forest.

Notes:— Pyxine pseudokeralensis is characterized by the cylindrical isidia, the white medulla and the presence of atranorin, testacein and terpenes. P. cylindrica , P. keralensis and P. lyei Swinscow & Krog (1975a: 57) , the only other isidiate species on a world level, are morphologically similar, particularly P. keralensis . P. lyei is easily separated by the presence of lichexanthone (thallus UV+ yellow), while P. keralensis has a pale yellow to yellow-orange medulla. P. cylindrica is distinguished by the presence of medullary norstictic acid. Furthermore, all four species display different arrays of terpenes on TLC.

Material from Thailand examined:— Nakhon Ratchasima; Khao Yai National Park , on rock in a dry evergreen forest, 760 m, 14°26' N, 101°25' E, 23 April 2000, K . Buaruang & W . Polyiam 18686 ( RAMK) .

Figures

FIGURE 3. A. Pyxine boonpragobiana (hb. K. Kalb 36928), thallus with polysidiangia; Scale: 3 mm. B. Pyxine dactyloschmidtii (holotype), thallus with polysidiangia; Scale: 3 mm. C. Pyxine pseudoceralensis (holotype), thallus with isidia; Scale 2 mm. D. Pyxine subcoralligera (holotype), thallus with polysidiangia; Scale 3 mm. E. Pyxine cylindrica (hb. K. Kalb 36836), thallus with marginal and partly laminal isidia; Scale 2 mm. F. Pyxine cognata (hb. K. Kalb 12344), thallus with obscurascens-type apothecia and patchy priuna; Scale 3 mm.