ANTARCTIU BENTHOS
119
this kind of environment. Other species of the Pyuridae and Styelidae
and species from the families Corellidae and Ascidiidae have modified
the shape of their attachment area for attachment to stones or shells,
or have developed stalks.
Kott’s distributional data can be presented with a different emphasis. Taking the boundaries of the Antarctic region in the sense they
have generally been accepted in the present work (including South
Georgia) and excluding abyssal forms, it would appear that some 73
species are now known. Of these 41 (56%) are known from nowhere
else.
Ten species seem to be known only from East Antarctica, eight of
these being endemic and two having a wide distribution elsewhere in
the Southern Hemisphere. A further 10 species which occur in East
Antarctica extend as far as West Antarctica but do not extend beyond
the Antarctic Peninsula (eight are Antarctic endemics, two have wider
distribution outside the area). An additional three endemic species
also occurring in East Antarctica extend as far north as the South
Orkneys, while another seven endemic species reach South Georgia.
Four more reach the Magellan area (two of them widely distributed
Southern Hemisphere forms). A further eight species extend from East
Antarctica to the Magellan region and the Subantarctic Islands (two
are also more widely distributed in the Southern Hemisphere). Two
more have a similar distribution in the Antarctic and Subantarctic but
have not yet been recorded from the Magellan area.
The rest of the Antarctic species are not known from East Antarctica. One species seems to be confined to the Weddell Sea, with another
four endemic to the Antarctic Peninsula. Pive endemic species are
shared between the Antarctic Peninsula and the South Shetlands. The
South Shetlands has one endemic species, plus the sole representative
known in the Antarctic for another widely distributed Southern Hemisphere species. One species extends from the Antarctic Peninsula to
South Georgia, one species is confined to the South Orkneys and South
Shetlands.
South Georgia seems to have two endemic forms, shares two species
with Subantarctic Islands, three species with the Magellan area and two
species with the Subantarctic Islands and the Magellan area.
Many Antarctic species appear to be circumpolar, e.g. Sycozoa
georgiana (Michaelsen), Distaplia cylindrica (Lesson), D . colligans
Sluiter, Tyiobranchion speciosum Herdman, Aplidium radiatum (Sluiter),
A. circumvolutum (Sluiter), Ascidia challengeri Herdman, Caenagnesia
bocki Anback, Cnemidiocarpa verrucosa (Lesson), Styela nordenskjoldi
Michaelsen, S. insinuosa (Sluiter), S. pfefferi Michaelsen, Pyura
119
this kind of environment. Other species of the Pyuridae and Styelidae
and species from the families Corellidae and Ascidiidae have modified
the shape of their attachment area for attachment to stones or shells,
or have developed stalks.
Kott’s distributional data can be presented with a different emphasis. Taking the boundaries of the Antarctic region in the sense they
have generally been accepted in the present work (including South
Georgia) and excluding abyssal forms, it would appear that some 73
species are now known. Of these 41 (56%) are known from nowhere
else.
Ten species seem to be known only from East Antarctica, eight of
these being endemic and two having a wide distribution elsewhere in
the Southern Hemisphere. A further 10 species which occur in East
Antarctica extend as far as West Antarctica but do not extend beyond
the Antarctic Peninsula (eight are Antarctic endemics, two have wider
distribution outside the area). An additional three endemic species
also occurring in East Antarctica extend as far north as the South
Orkneys, while another seven endemic species reach South Georgia.
Four more reach the Magellan area (two of them widely distributed
Southern Hemisphere forms). A further eight species extend from East
Antarctica to the Magellan region and the Subantarctic Islands (two
are also more widely distributed in the Southern Hemisphere). Two
more have a similar distribution in the Antarctic and Subantarctic but
have not yet been recorded from the Magellan area.
The rest of the Antarctic species are not known from East Antarctica. One species seems to be confined to the Weddell Sea, with another
four endemic to the Antarctic Peninsula. Pive endemic species are
shared between the Antarctic Peninsula and the South Shetlands. The
South Shetlands has one endemic species, plus the sole representative
known in the Antarctic for another widely distributed Southern Hemisphere species. One species extends from the Antarctic Peninsula to
South Georgia, one species is confined to the South Orkneys and South
Shetlands.
South Georgia seems to have two endemic forms, shares two species
with Subantarctic Islands, three species with the Magellan area and two
species with the Subantarctic Islands and the Magellan area.
Many Antarctic species appear to be circumpolar, e.g. Sycozoa
georgiana (Michaelsen), Distaplia cylindrica (Lesson), D . colligans
Sluiter, Tyiobranchion speciosum Herdman, Aplidium radiatum (Sluiter),
A. circumvolutum (Sluiter), Ascidia challengeri Herdman, Caenagnesia
bocki Anback, Cnemidiocarpa verrucosa (Lesson), Styela nordenskjoldi
Michaelsen, S. insinuosa (Sluiter), S. pfefferi Michaelsen, Pyura