i8 DISCOVERY REPORTS 



Verrucaria mucosa Wahlenberg (Fig. i c) 



apud Acharius, 1803, suppl. p. 23; Zschacke, 1934, p. 192; Santesson, 1939, p. 4. 



West Graham Land. Mainland coast : Cape Renard ; on non-calcareous rocks at about normal high- 

 tide level, constantly drenched by wave action during rough weather; F.I.D.S., 22. iii. 1944 (no. 1172 

 pr. p.). 



Quite typical, although poorly developed. Thallus thin, in scattered irregular patches, continuous 

 or with a few sporadic cracks probably due to post mortem drying. Spores 9-13 ■: 6-7//. 



Geographical Distribution. New to the Antarctic. Occurs on the Atlantic seaboard of Europe, 

 Iceland, Greenland, North America, Siberia; also in the subantarctic (Fuegia, Auckland Island, 

 Campbell Island); possibly in New Zealand (Santesson, 1939, p. 17). 



Verrucaria psychrophila M. Lamb, n.sp. (Fig. 3^; PL I, figs, i, 3) 



West Graham Land. Palmer Archipelago : Port Lockroy, Goudier Islet ; on granodiorite rocks and 

 boulders in the boat harbour and on the south side of the islet, intermittently submerged by the tide ; 

 F.I.D.S., 25. iii. 1944 (no. 1178, holotype); 21. iv. 1944 (no. 1219); 23. iv. 1944 (no. 1220). 



Description. Thallus epilithicus, olivaceo-nigricans aut nigricans, madef actus leviter gelatinosus, con- 

 tiguus, late expansus, ejfusus, modice incrassatus (o-20-o-25 mm. crassus), laevigatiis, vix nitidus, reticulato- 

 rimosus vel plerumque grosse areolatus, areolis i •0-2-5 ^^- l^ii^> irregulariter angidosis, planis vel levissime 

 convexis, rimis acutis ad o-i mm. latis separatis; ad peripheriam tenuior, anguste pallidus (olivaceo-albidus), 

 hypothallomdlo ; stratum basale thalli hand fuliginosum. Gonidia laete vel fiavidoviridia, S-i ^{-20) ^diam., 

 in seriebus verticalibus disposita. Perithecia immerosa, in quavis areola 2-20, immersa, apice alro, hand vel 

 paullum nitido, subconvexo, o- i-o-2 mm. lata leviter emergenti; ostiolo necpapillato nee impresso, indistincto. 

 Excipulum globosiim aut depresso-globosiim, 165-180 /^ diam., omfiino incoloratum, superne involucrello 

 carbonaceo-fiiligineo, later ibus leviter producto, 20-40// crasso, 210-245 ju lato obducttim. Paraphyses mox 

 dissolutae. Asci clavati, 40-50x12-18//, pariete aequaliter tenui. Sporae 8nae, in asco irregulariter 

 biseriatim dispositae, simplices, incolores, ellipsoideae, Ii-i3(-i5) x 6-7//. Pyctiidia numerosa, peritheciis 

 intermixta, maculis punctiformibus atris circ. 0-05 mm. diam. indicata, haud prominentia; pycnoconidia 

 bacillaria, recta aut rarius leviter curvata, 3-4X o-6-^o-7//. Thallus extus intusque KHO-, CaCljOg-, 

 C6H4(NH2)2-, 1-; gelatina hymenialis I + leviter roseo-rubescens vel-, ascis sporisque lutescentibus, strato 

 ascigero pallide caerulescenti . 



The thallus has a rudimentary brown or olive-brown cortex J-iZju deep, formed from the pigmented, 

 concrete ends of the vertical thalline hyphae; the cells are thin- walled, 3 •0-4-5// diam. The gonidial 

 algae occupy the entire depth of the thallus, but are more concentrated and larger in the upper half; 

 arranged in distinct vertical rows ; bright green in living material, subglobose or irregularly angulose, 

 often ± horizontally flattened, thin-walled, multiplying by fission into 2's, 4's and 8's. Fungal tissue 

 between algae colourless, hyaline, compact, entirely paraplectenchymatic, with oblong, upright, 

 or ± cubical thin-walled cells 3-0-4-5 x 2-5-3-0//. Excipulum colourless, of even thickness all round 

 (18-30//), formed of tangentially elongated thin-walled cells. Involucrellum brown-black, slightly 

 convex, about 20 // thick round ostiole, 35-40 // thick at margin. Periphyses crowded on upper inner wall 

 of excipulum, simple, 12-30 x i -5-2^5//. Spores thin-walled, often with granulose contents but no 

 large guttules. Pycnidia globose or flask-shaped, 75-120// across, ioo(-30o)// deep, with colourless 

 perifulcrium ; ostiole surrounded by brown-black tissue like a small involucrellum. Fulcra exobasidial, 

 subulate. 



This species appears to be related to V. ceuthocarpa, from which it differs in the much larger thallus- 

 areolae, extensive growth-habitus, and somewhat longer spores. From V. tesselatula Nyl. it is distin- 

 guished by the blackish, more regular areolae without darker edges. It is also ecologically distinct from 



