22 DISCOVERY REPORTS 



This State was described by Nylander on material from Fox Bay in West Falkland as ' Vernicaria 

 dermoplaca' and for practical purposes may be distinguished as V. tesselatula f. dermoplaca (Nyl.) 

 M. Lamb, n.comb. The South Orkneys specimen no. 1094-2 belongs to this form. 



Apart from these differences in external habitus, the variability of this species is not great. The thallus 

 varies in colour from pale glaucescent buff (Ridgway, 1912, pi. xl, 19'"^) to a pinkish brown (pi. xlvi, 

 13""/), usually yellowish buff or brown-buff (pi. xl, ly'" li). Upper cortex present: brown, 9-15// 

 deep, composed of il rounded, thin-walled cells 3-0-4-5// diam. Fungal tissue between gonidial algae 

 hyaline, paraplectenchymatic. Perithecia up to 0-25 mm. diam., varying on the same thallus from 

 slightly convex-emergent to hemispherical. Excipulum variable in size, 165-270 (-300) /i diam., always 

 with hyaline wall at base and sides. Usually there is no trace of paraphyses, but occasionally a few 

 isolated hyphae are present in the mucilage around the asci. Asci up to 50 • 20//, with diaphanous 

 gelatinized walls up to 5/< thick. Spores 11-15 x 6-5-9-o/z. Hymenial gelatine rose-pink with 

 iodine. 



V. tesselatula, like the related V. ceiithocarpa, is a marine species of the spray zone. I saw it at Port 

 Louis, East Falkland, forming extensive patches on shoreline rocks 0-5-1 -o m. above high-water level, 

 associated with V. maiira. The South Orkneys specimens occur together with Caloplaca cirrochrooides 

 (Vain.) Zahlbr., which is also a species characteristic of the upper spray zone. 



Geographical Distribution. Subantarctic-antarctic, perhaps circumpolar; Kerguelen, Falklands, 

 Fuegia, South Orkneys. 



Verrucaria sp. 



South Orkneys. Inaccessible Islands: on schistose rock, together with V. tesselatula Nyl. ; Discovery 

 193 1-3. 25- i- 1933 (no. iog4-2 pr. p.). 



A small patch of olive-blackish, rimose, minutely black-punctate thallus. Unfortunately, no mature 

 perithecia are present. The thallus indicates that it belongs to the antricola-aractina-Erichsenii-scotina- 

 Zschackeana group, none of which have as far as I know been recorded from the southern hemisphere. 



EXCLUDED SPECIES 

 Vernicaria exqiiisita Darbishire, 1912, p. 17. 

 Re-examining the type material from South Georgia, I found it to be Lecidea Dicksonii (Gmel.) Ach. 

 in a very poorly developed condition, with minute juvenile apothecia about o-i mm. in diameter, in 

 their unexpanded state resembling perithecia. The upper part of the thecium was characteristically 

 aeruginose, and two spores were seen, 10-12 x 5-7 /<• 



Genus Thelidium Massalongo, 1855 



Three species attributed to this genus were found in Marie Byrd Land by the second Byrd Antarctic 

 Expedition, and described by Dodge and Baker (1938). One of them, Th. Caloplacae Dodge and Baker, 

 is a lichen-parasite with numerous spores in the ascus, and should hence be excluded from the genus. 

 The others, Th. inaequale Dodge and Baker, p. 524, pi. 38, figs. 1-5, and Th.parvum Dodge and Baker, 

 p. 526, pi. 62, figs. 393-395, the first occurring on schistose rocks and the second over the thallus of a 

 Parmelia on sandy loam, show some spore characters unusual in this genus. In Thelidium inaequale the 

 spores are dark coloured, i -septate with frequently unequal cells, 10-13 x 5-7 /<; in Th. parvum colour- 

 less, i-septate with unequal cells, 7*5-9'OX 3-0-3-5//. The thallus in both these species is extremely 

 reduced or evanescent, and the perithecia are of simple structure with entire dark walls of only a few 

 cell layers in thickness. 



