LICHENS AND LICHEN. PARASITES

DODGE--LICHENS AND LICHEN PARASITES
GEOGRAPHICAL UISTRIHI1TTIr)N.
The lichens herewith reported, represent three distinct floras, apparently unrelated and
will be discussed separately.
MACQUARIE ISLAND. (For a complete account of the geography and geology, see Mawson,
1943). This flora 'seems very uniform with that of the islands of the New Zealand Submarine
Plateau (Auckland and Campbell Islands and usually the mountains of the South Island of New
Zealand). Only five fragmentary specimens of conspicuous species from the Australasian
*4ntarctic Exhibition, collected by Mr. H. Hamilt on, were received,* the rest of the specimens cited
being from the British, Australian, and New Zealand Antarctic Research Expedition, collected
in two days in the v'cinity of Hasselborough and Buckle's Bays. Hence the sampling error is
\
very large, as only four localities are represented, all in the north end of the island from the
younger basic group of rocks, most of the material coming from Featherbed Flats (Mawson, 1943,
47). Our knowledge of the Aucklaad fslands is almost wholly based on collection's of Sir. J. D.
Hooker (Voy. "Erebus & Terror") over a century ago (Hook. f. & Tayl., 1844, 1845, 1847).
The lichens of Campbell Island are known from collections of Hooker f. (loc. cit.) and of Filhol
on the French Transit of Venus Expedition Ny lander, 1876). Some collections have been made
since, but have not been published so far as I can learn. The literature on the lichens of the
South Island of New Zealand is extensive but very scattered. In the genera concerned, I have
read all the descriptions of New Zealand, Tasmanian and Australian species listed in Zahlbruckner
(1921-1940) before describing Macquarie Island species as new.
About one-third of the species have been described as endemic, although I expect many if
not most of them will later be found on other islands of the New Zealand Submarine Plateau,
as we have more knowledge of their floras. Fifteen families, twenty-three genera and thirtyeight
species are represented in Macquarie Island, five of the latter in such fragmentary state
as to be unidentifiable beyond genus.
~h; present flora is of comparatively recent origin as the present Island seems to have been
completely denuded by an ice sheet during the Glacial Epoch (Mawson, 1943, 92). Since, the
lichens df Macquarie Island seem wholly unrelated to those of Antarctica (except for Mastodia
sp. with another species in MacRobertson Land), they furnish no ancillary evidence that Mac-.
quarie Island was "land coextensive with Antarctica, and that it was the Antarctic ice sheet
that over-rode it" as Blake suggested (Mawson, 1943, 92, footnote), although a submarine ridge
extends most of the way to South Victoria Land via the Balleny Islands.
The source of the species for re-population, presents a difficult problem. The submarine
' ridge connecting the island to the New Zealand Submarine Plateau is submerged about 1,200,.
fathoms, if one can rely on the relatively few soundings available along the ridge. Probably i6
did not supply a land bridge or a chain of islands by which Macquarie Island could be re-popu,
latcd from the Auckland Islands. Unless wind direction has reversed in recent times, there
seems little likelihood that it has served to re-populate Macquarie Island. Wind might have
served to bring in species from Tasmania, and five of the thirty-eight species also occur in Tasmania.
Four of these are wide ranging species, also occurring in New Zealand and the Auckland
group and the fifth is so fragmentary that it can only be referred to a species group, members
of which also occur in New Zealand and the Auckland group, hence there is no clear evidence
that Tasmania has been the source.
Hamilton 'a collection, erroneously labelled "algae ", was included by mistake with the Expedition 'a main
botanical collection which was forwarded to the British &iuseum for report. Ui~fortunately the lichens thus forwarded
in error have not been recoverable for reference to Dr. Dodge for they were destroyed by bomb blast during
the blitz.