SYSTEMATIC ACCOUNT 25 



Perhaps related to M. subliirideUa (Vain.) Zahlbr. (Brazil), but differing in the much thicker, 

 verrucose, lighter coloured thallus, larger fertile verrucae, and larger spores. From the f. terrestris (Hue) 

 Zahlbr. of M. mtiscorum (Fr.) Th. Fr. it is distinguished by the thicker thallus, colourless excipulum, 

 number of spores in the ascus, and saxicolous habitat. 



M. antarctica grows in small patches among other crustaceous lichens {Caloplaca, Buellia, etc.), and 

 appears to be a rather ornithocoprophilous species. 



Family DERMATOCARPACEAE 



Genus Dermatocarpon Eschweiler, 1824 



Section Endopyrenium Stizenberger 



Dermatocarpon lachneum (Acharius) A. L. Smith (Fig. 3?*) 



191 1, p. 270, pi. 37; Vainio, 1921, p. 18; Lynge, 1928, p. 37. 



Lichen lachneiis Acharius, 1798, p. 140. 



Dermatocarpon hepaticiim var. lachneum Zahlbruckner, 1921, p. 217; Zschacke, 1934, p. 605. 



Endocarpon nifescens Acharius, 1810, p. 304. 



Dermatocarpon nifescens Th. Fr., 1861, p. 354; Zschacke, 1934, p. 602. 



East Graham Land. Crozvn Prince Gtistav Channel: St. 28; west side of island, altitude c. 25 m., 

 on sandy detritus on ledges in agglomerate cliffs; F.I.D.S., 16. xi. 1945 (no. 2792). St. 29; summit 

 plateau of island, altitude c. 130 m., on detritus between rocks and stones; F.I.D.S., 13. xi. 1945 

 (no. 2828). 



The reddish brown squamules are 2-8 mm. across, becoming at maturity contiguous and variously 

 lobate, slightly concave and with conspicuously raised margins, which are for the most part eroded and 

 grey-whitish where the tissue has been killed off by exposure. Most of the black spots on the upper 

 surface are pycnidia, but a few perithecia are present; immersed, pyriform, up to 225// across and 

 360// deep, with faintly pink excipular wall. Involucrellum almost obsolete, dome-shaped, dark brown 

 in section, merging at the sides into the thalline cortex. No paraphyses. Asci cylindrical, with bluntly 

 pointed ends, 80-115 X9-i5/<, with gelatinous wall about 3// thick, becoming thinner at maturity. 

 Spores 8, uniseriate in ascus, ellipsoid, i3-5-i8-o x 6-0-8-5 fi. Mucilage of hymenium faintly pink with 

 iodine. Pycnidia immersed, globose, up to 33o(-48o)// diam., without distinct wall, filled with spongy 

 canaliculate sporogenous tissue consisting of the massed endobasidial fulcra ; pycnoconidia bacillar, 

 4X I//. 



One of the few lichens which were present on the bleak summit plateau of St. 29, where there can 

 be no protecting snow cover during the winter on account of the completely exposed situation. It is 

 hardly surprising, therefore, to find necrosis of the raised margins of the squamules, due probably to 

 the eroding action of wind-blown powder snow, which can act like a sandblast in these regions. 



Geographical Distribution. New to the Antarctic. A widely distributed species in the northern 

 hemisphere, where it has a very broad range of latitude : North Africa, the Ukraine, southern, central 

 and northern Europe, Iceland, North America from New Mexico to New England, and the Arctic 

 (Greenland, Spitsbergen, and Novaya Zemlya). It has also been recorded from northern India. I do 

 not know of any previous record from the southern hemisphere, but the closely related D. hepaticuni 

 has been recorded from Western Australia and New Zealand by Muller Arg., and it is possible that some 

 of the material may refer to the present species. 



