LICHENS AND LICHEN. PARASITES

DODGE-LICHENS AND LICHEN PARASITES
USNEA PUSTULATA Dodge, sp. nov.
Type: Queen Mary Land, Possession Nunatak, C. T. Harrisson, A.A.E. 85-1.
Thallus ad 4-5 cm. altitudine, subdichotomeramosus, ramis flexuosis, adscendentibus, rigidis,
ramis ultimis longis capillaribus, frequenter nigris, raro nigro-maculatis, rarissime nigroannulatis
sed non fractis, inferne ochraceo-aurantiacus ad ochraceo-alutaceus superne ; ramis majoribus
laevibus rare subfoveolatis aut rugosis, ramis secundariis laevibus cum tuberculi~ humilibus sparsis,
raro in parvis sorediis punctiformibus, 0.1 mm. diametro vel minoribus ruptis; ramis penulti-
\
mis cum sorediis palli&e\ olivaceis granulo-isidioideis in soraliis orbicularibus, primum subconvexis
ad 0.5 mm. diametro mox erosis, apotheciis minutis cum disco plano vel subconcavo, similibus
; soralia in ramis ultimis immarginath'in maculis irregularibi~s erosie confluentia; cortex 55-
110p crassitudine, gelifactus, strato extero 10-2'Jp crassitudine, flavido, reliqua parte hyphis ramosis,
contortisque pachydermeis; medulla 35-5 5p crassitudine, hyphis conglutinatis pachydermeis,
periclinalibus cum cellulis algarnm singulis vel in coloniis parvis sparsis ; axis chondroideus
- 680-750p diamtro, hyphis conglutinatis, longitudinalibus, pachydermeis.
Thallus 4-5p cm. tall, branching essentially dichotomous, but often one branch larger than
the other, branches flexuous, ascending, rigid, ultimate branches long, capilliform, usually wholly
black, rarely black maculate and very rarely black annulate, not cracked, ochraceous-orange below,
shading to ochraceous buff above; larger branches smooth, rarely slightly foveolate or rugose, secondary
branches smooth with scattered, low tubercles which occasionally rupture as small, punctiform
soredia, 0.1 mm. in diameter or smaller, perhaps only breathing pores; the penultimate
branches producing many pale olive buff granulo-isidioid soredia in circular soralia, slightly convex
at first, up to 0-5 mm. in diameter, soon eroded, and appearing as small apothecia with plane
or slightly
,
concave discs; on the ultimate branches, soralia similar but not margined, confluent ,
in irreguvr eroded patches; cortex 55-110p thick, gelified, the outer 10-20p yellowish, netrly
structureless, the rest hyaline, composed of branched and contorted, thick-walled periclinal hyphm
not arranged in a palisade ; medulla 35-55p thick, of conglutinate, thick-walled, periclinal hyphae a
with scattered algal cells, 5-7,~ in diameter or small colonies, scattered throughout ; chondroid
axis 680-75OP in diameter, of conglutinate, thick-walled, longitudinal hyphae.
This species is evidently related more closely to U. aurantia;coatra than to other members of
rthe
i
group. The medulla is extremely thin and compact, and the structure of the cortex is quite
i
.' f different from the usual type in Usnda. The thickness of the cortex varies considerably i11 the
same section, but i11 general is much thicker than the medulla. This is the commonest form in our
' - region. A shorter, somewhat stouter and less branched form with a rather thicker cortex, occurs
but there as so many intermediate conditions that I have been unable to separate it. In general,
this form is more soredime.
King George V Land : Horn ["Dreadnought "1 Bluff, [ca. 68" 25' S., 149" 45' E.], A. L. Mc-
Lean, A.A.E. 46; Penguin Point [ca. 67" 35' S., 146" E.], A. L. McLean, A.A.E. 86; vicinity of
Cape Denison, Commonwealth Bay, 67" S. [ca. 142" 40' E.], J. G. Hunter, A.A.E. 1, 5, 18, 19,
20, 45 on gneissic rocks, Sta. 88, B.A.N.Z.A.R.E. 536-38, 536-39 ; [McKellar Islets], Commonwealth
Bay [ca. 67" s., 142" 45' E.], A. L. McLean, A.A.E. 90-3.
Queen Mary Land : Hippo Nunatak, C. T. Harrisson, A.A.E. 82-1 ; David Island, C. T.
Harrisson, A.A.E. 83 ; Possession Nunatak, C. T. Harrisson, A.A.E. 85-1, 85-2, type; Alligator
Nunatak, C. T. Harrisson, A.A.E. 72. i