LICHENS AND LICHEN. PARASITES

DODGE--LICHENS AND LICHEN PARASITES 205
Thallus mostly 2 cm. (one plant 3 em.) tall, branching essentially dichotomous, but one
branch often larger than the other, not widely divergent, ascending, rigid, buff yellow to maize
yellow, ultimate branches relatively short, wholly blackened; primary branches smooth, not
cracked below, slightly rugose and subfoveolate with small, scattered papillae above, not con-
stricted at the base; soralia slightly convex, very small, confined to the ultimate branches, occa-
sionally several confluent along the axis, soredia granular, not conspicuously eroded, slightly
yellowish; cortex 60-65cl thick, outer 20p a hyaline gel, rest of palisade of hyphae with isodia-
metric cells, heavily nubilated with small, acicular, yellowish crystals in a yellowish gel ; medulla
K-, 100p thick, compact with small air spaces quite uniformly distributed; algae in small
colonies or singly, irxqgularly distributed in the outer third of medulla, cells mostly 10p or
smaller, a few up to 15p; chondroid axis about 250p in diameter, round or slightly hexag-
onal in cross section, of slender, conghtinate, longitudinal, thick-walled hyphae. Apothecia
and spermogonia not seen.
Macroscopically this species appears intermediate between 77. scabridda and U. pstulala.
Microscopically it is closer to the former, from which it differs in its soredia, more sparse papilla-
tion, more slender, blacker ultimate branches and axis circular in cross section. So far known
only from Queen Mary Land.
Queen Mary Land : Hippo Nunatak, C. T. Harrisson, A.A.E. 82-3, type ; 71-2.
USNEA PICATA (Lamb) Dodge, comb. nov.
Neuropogm acronzelana (Stirton) Lamb, var. inactivlls f. picatzls Lamb, Jour. Linn. Soc. Bot.,
52, 220 ; 1939.
Type : S. Victoria Land, Cape Adare on Sastrugi, Brit. Antarct. (Terra Nova) Exp., not
seen. The following description based on material from Queen Mary Land.
Thallus about 3 cm. tall, base 1 mm. in diameter, repeatedly dichotomously branched near
the base, f orming a dense, erect tuft, ultimate branches 1 cm. or more long, very slender, often
wholly dlackened, more rarely annulate blackened, intermediate portion between antimony yeilow
and ochraceous buff, sometimes slightly rugose and subfoveolate, with occasional annular cracks,
which may be blackened as in U. montela~na but without the characteristic longitudinal cracks
of that species ; soredia minutely tubercular, beconling granular and finally partly eroded, leaving
circular, almost flat soralia, resembling minute apothecia on the ultimate branches; cortex 40-45cl
('thick, highly gelified, the outer 7-8r, hyaline, the rest a palisade of vertical branched, loosely
ascending hyphae about lp in diameter, with very minute yellowish crystals; algal cells 6-7r,
I' in diameter, scattered or in small, loose groups in the outer portion of the medulla; medulla
' dense, K-, about 150p thick, of densely woven hyphae about 4p in diameter with moderately
thickened walls; chondroid axis nearly square in cross section, about 34OP on a side, of very
densely conglutinate, slender, thick-walled hyphae. Apothecia and spermogonia not seen.
I have been unable to satisfy myself whether the blackening in the cracks of this species is
due to chemical or to morphological changes ir. the lichen itself. It seems rather due to the
invasion of a parasite, perhaps mycelium of a Phacopsis. I have seen no reproductive structures -
of the supposed parasite, although in some seclions, a palisade, suggestive of the base of the
apothecium of Phacopsis, has been noted.
The systematic relationship of this species is not clear. It is erect, not subdecumbent and
in its microscopic characters and chemical reactions, it is closer to U. mtarctica than to
U. acromelmw. @
Queen Mary Land : Hippo Nunatak, C. T. arki is son, A.A.E. 71.