ANTAROTIC BENTHOS
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Some families only just gain entry into Antarctic faunal lists with
either single species or single genera. The family Arcidae usually includes
many medium sized species. The only Antarctic genus is the minute
Bathyarca with two species in East Antarctica. The family of the
mussels (Mytilidae) has only one genus (Dacrydium) with three minute,
closely allied species in Antarctica. The enormous family of the
Veneridae has a single representative of the genus Gomphina in the
Scotia Arc while the Tellinidae has two species in the same area. Other
families with only one species or at most one genus in the Antarctic
are : Lyonsiidae, Pholadomyidae, Verticordiidae, and Poromyidae.
Two other families in this category supply two of the most characteristic Antarctic bivalves. Thracia meridionalis Smith (Thraciidae) is a
common species around the Continent extending through the Scotia
Arc to the Falklands, and to the shelf areas surrounding Kerguelen,
Marion and Prince Edward Islands. Laternula elliptica (King and
Broderip), the sole representative of the Laternulidae is one of the most
surprising Antarctic species. Species of the genus Laternula are distributed over a wide area of tropical and subtropical waters from the Red
Sea to Japan and Australia. Two species reach Tasmania, the only
other incursion by the genus into even cold-temperate waters.
The essentially Northern Hemisphere family, Astartidae, has a pair
of species in Antarctic-Subantarctic waters. Astarte longirostris
Orbigny occurs off Kerguelen, Prince Edward and Marion Islands, the
Magellan Region and South Georgia (Dell, 1964b) and has recently been
recorded from East Antarctica (Nicol, 1966). The second species, A .
antarctica Thiele occurs in East Antarctica. The family Carditidae has a
single genus which extends into the Antarctic, Cyclocardia. There are
several species in this genus in southern South America and two poorly
understood forms, C. antarctica (Smith) and C. intermedia (Thiele), have
been described from East Antarctica, in addition to the widely distributed species, C. astartoides (Martens). This latter is one of the commonest, and most widely distributed of Antarctic bivalves, occurring
around the Continent, off Bouvet Island, through the Scotia Arc to
South Georgia and into the Subantarctic at Kerguelen.
The family Limopsidae supplies a very characteristic element to the
bivalve fauna. The distribution of the Antarctic species of Limopsis
has been detailed by the writer (Dell, 1964b, 1969), the very variable,
most widely distributed species Limopsis marionensis Smith reaching a
very large size for this genus, a specimen up to 80 mm in length having
been reported by Powell (1958).
The family Philobryidae is predominantly a southern family, with
three Antarctic genera, Philobrya, Adacnarca and Lissarca. Probably
!xJ
Some families only just gain entry into Antarctic faunal lists with
either single species or single genera. The family Arcidae usually includes
many medium sized species. The only Antarctic genus is the minute
Bathyarca with two species in East Antarctica. The family of the
mussels (Mytilidae) has only one genus (Dacrydium) with three minute,
closely allied species in Antarctica. The enormous family of the
Veneridae has a single representative of the genus Gomphina in the
Scotia Arc while the Tellinidae has two species in the same area. Other
families with only one species or at most one genus in the Antarctic
are : Lyonsiidae, Pholadomyidae, Verticordiidae, and Poromyidae.
Two other families in this category supply two of the most characteristic Antarctic bivalves. Thracia meridionalis Smith (Thraciidae) is a
common species around the Continent extending through the Scotia
Arc to the Falklands, and to the shelf areas surrounding Kerguelen,
Marion and Prince Edward Islands. Laternula elliptica (King and
Broderip), the sole representative of the Laternulidae is one of the most
surprising Antarctic species. Species of the genus Laternula are distributed over a wide area of tropical and subtropical waters from the Red
Sea to Japan and Australia. Two species reach Tasmania, the only
other incursion by the genus into even cold-temperate waters.
The essentially Northern Hemisphere family, Astartidae, has a pair
of species in Antarctic-Subantarctic waters. Astarte longirostris
Orbigny occurs off Kerguelen, Prince Edward and Marion Islands, the
Magellan Region and South Georgia (Dell, 1964b) and has recently been
recorded from East Antarctica (Nicol, 1966). The second species, A .
antarctica Thiele occurs in East Antarctica. The family Carditidae has a
single genus which extends into the Antarctic, Cyclocardia. There are
several species in this genus in southern South America and two poorly
understood forms, C. antarctica (Smith) and C. intermedia (Thiele), have
been described from East Antarctica, in addition to the widely distributed species, C. astartoides (Martens). This latter is one of the commonest, and most widely distributed of Antarctic bivalves, occurring
around the Continent, off Bouvet Island, through the Scotia Arc to
South Georgia and into the Subantarctic at Kerguelen.
The family Limopsidae supplies a very characteristic element to the
bivalve fauna. The distribution of the Antarctic species of Limopsis
has been detailed by the writer (Dell, 1964b, 1969), the very variable,
most widely distributed species Limopsis marionensis Smith reaching a
very large size for this genus, a specimen up to 80 mm in length having
been reported by Powell (1958).
The family Philobryidae is predominantly a southern family, with
three Antarctic genera, Philobrya, Adacnarca and Lissarca. Probably