LICHENS AND LICHEN. PARASITES

DODQE-LICHEN8 AND LICHEN PARABITEB
RINODINA SORDIDA Dodge & Baker.
Rinoddna sordidu Dodge & Baker, Ann. Mo. Bot. Gard., 25,657 ; 1938.
Type : Marie Byrd Land, Edsel Ford Range, Skua Gull Peak, P. Siple & S. Corey 72W-6.
Thallus up to 3 cm. in diameter ; non assimilative portion scant, black, dull ; cortex capitate fatigiate,
cells brewn and thick walled ; medulla hyaline to pale brown ; assimilative areoles up to 1
mm. in diameter, angular, white to grey, the margins often blackened; cortex fastigiate, well
developed laterally and in places on the upper surface, often with a conspicuous zone of dead cells;
algae protococcoid, celh up to 1 8 in ~ diameter, scattered in the upper half of the thallus ; medulla of
loosely woven hypbae ; basal layer of small, dark cells merging laterally with the fastigiate cortex.
Apothecia up to 1-35 mm. in diameter, angular, sinuous or hemispheric, convex, flattened with
a faint margin or umbilicate, surface cracked, scattered or gregarious, sessile on the areoles; amphi.
cium 100~ thick, cortex 20~ thick, of spgeFical, subhyaline cells, algal layer of scattered cells
in diameter, no medulla nor parathecium; hypothecium up to 230,~ thick, thinning toward thc
margin, hyaline, of compact, small cells; thecicm up to 7 0 thick; ~ paraphyses lP in diameter,
branched or unbranched, conspicuously septate, thick-walled, tips 4-tip in diameter with dark
spherical caps; asci 8-spored, 47-54-63 X 16-19~, slender clavate, thick-walled when young,
the mature asci shorter and stouter as the spores fill them; ascospores bilocular, slightly constricted
at the septum, acute or obtuse, dark brown, 11-13.5 X 6-8,~.
Our material is very old with the thecia largely disintegrated. Such cliaracters as are still
visible agree with this species, although the habit and colour approach that of R. olivaeeobrunnea
Dodge & Baker.
King George V Land : Cape Denison, A.A.E. 194.
RI~TODINA FRIGIDA (Darbishire) Dodge, comb. nov.
Buellia frigida Darbishire, Brit. Nat. Antarct. "Discovery" Exp., Nat. Hist., 5, Lich. ; 7, 1910.
T~&: South Victoria Land, Granite Harbour, McMurdo Bay, British National Antarctic
"Discovery " Expedition.
Thallus crustose, effigurate, up to 7 cm. in diameter, mostly much smaller; hypothallus black,
carbonaceous, extending 5-7.5 mm. beyond the assimilative thallus, margin somewhat fimbriate,
sornctimes much narrower and scarcely visible; assimilative portion deeply rimose radially,
giving the appearance of radiating marginal lobes, with shallower cracks cutting up the whole sur-
/ face into angular areoles, surface more or less verrucose, so that the individual areoles are subcere-
,' briform, colour variable, bufTy brown to grey, marginal areoles often nearly black; amorphous
layer highly developed, often 3,540~ thick, upper cortex 6-7~ thick, capitate-fastigiate, but appearing
as a single layer of dark, thick-walled, isodiametric cells, the hyphae bearing them thickerwalled
but not otherwise differentiated from those of the medulla; algal layer variable in thickness,
protococcoid, cells small, 4-7,~ in diameter; medulla variable in thickness, of loosely woven thinwalled
hyphae, somewhat vertically arranged ; basal layer brownish, about thick, of compact,
dark brown, more or less isodiametric cells elongating upward and merging with the medullary
hyphae.
Apothecia carbonaceous, somewhat shining, sessile or subsessile on the assimilative areoles, flat
to convex and almost spherical, up to 0.75 mm. in diameter, lecanorine (clearly so when young) ;
amphithecial cortex 15-17,~ thick, a palisade of isodiametric cells; algae between the medullary
hyphae, early disappearing ; medulla of vertical brown hyphae, loosely woven and continuous with
those of the thslline medulla ; parathecium not differentiated; hypothecium brown, 3&80cr thick ill