Pyxine cocoës (Sw.) Nyl. , Mém. Soc. Imp. Sci. Nat. Cherbourg (Sw.)

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 : 41

5. Pyxine cocoës (Sw.) Nyl., Mém. Soc. Imp. Sci. Nat. Cherbourg 5: 108 (1857).

Type:— Lichen cocoës Sw. , Nova gen. spec. plant.: 146 (1788);— Coccocarpia pellita var. cocoës (Sw.) Zahlbr., Cat. lich. univ. 3: 286 (1925). Holotype:— Jamaica, on Cocos, Swartz ( S!; isotype:—H-ACH 379!).

Thallus usually corticolous, rarely also saxicolous, 1–3 (–10) cm wide, adnate. Lobes radiating, discrete to ± contiguous, plane to slightly convex or concave, 0.4–0.8 mm wide, subrotund to truncate at the apices. Upper surface white to yellowish white, pale yellow-brown or grey, patchily pruinose; pruina glistening; polysidiangia and isidia absent. Pseudocyphellae usually restricted to the margins, rarely laminal or becoming reticulately confluent, developing into soralia with age. Soralia marginal and laminal, orbicular to linear, ± coalescing into extensive patches; soredia granular. Medulla uniformly white. Lower surface black in the centre, paler towards the periphery; rhizines ± dense, furcate. Apothecia rare, cocoës - type, 0.4–1.4 mm wide; disc epruinose. Internal stipe distinct, reddish brown in the upper part and K + purple, P-; lower part white, K-, P-. Ascospores 15–18 × 6–7 μm. Conidia bacilliform, 3–4 × ca. 1 μm.

Chemistry: Cortex K-, UV + yellow; medulla K-, C-, KC-, P-; containing lichexanthone (major), ± unknown terpenes (traces).

Distribution and habitat:—This very common, mainly pantropical lichen grows on rock, wood and bark in dry dipterocarp and mixed deciduous forests.

Notes:— Pyxine cocoës is characterized by the cortical lichexanthone, marginal pseudocyphellae developing into coalescing soralia with rather coarsely granular soredia, the white medulla and apothecia of the cocoës - type with an internal stipe that is reddish brown (K+ purple) in the upper part and the patchy pruina covering large parts of the lobe tips.

Selected material from Thailand examined:— Chiang Mai; Mae Rim, along a big pond called ' Huay Tueng tao Reservoir', ca. 6 km NNW of Chiang Mai , on bark in a dry dipterocarp forest, 360 m, 18°52'11'' N, 98°56'28'' E, 16 March 2008, K . Kalb (hb. Kalb 37099).— Loei; Phu Luang Wildlife Sanctuary, Nam Chan Forest Ranger Station , on rocks in mixed deciduous forest, 397 m, 17°20'49'' N, 101°33'29'' E, 28 July 2009, S . Meesim & K . Buaruang MSPL 308 , 309 ( RAMK).— Loei; Phu Luang Wildlife Sanctuary, Phu Ho Forest Ranger Station , on the trunk of Bambusa bambos in mixed deciduous forest, 569 m, 17°07'13'' N, 101°34'30'' E, 29 July 2009, S . Meesim & K . Buaruang 427 ( RAMK).— Nakhon Ratchasima; Khao Yai National Park, Khao Noi , on the bark of Wrightia lecomtei in dry dipterocarp forest, 300 m, 14°10' N, 101°30' E, 2 April 1998, P . Mongkolsuk 12917 ( RAMK).— Nakhon Ratchasima; Khao Yai National Park, the trail “Kang Kao” cave Khao Lookchang site, on the bark of Pterospermum aceritolium in mixed deciduous forest, 1100 m, 14°32' N, 101°40' E, 6 April 1999, P . Mongkolsuk 13781 ( RAMK).— Chonburi; Panutnikom district, Tung Kwang , on the trunk of Phyllanthus acidus in plantation, 50 m, 13 April 2001, P . Mongkolsuk 30000 ( RAMK) .