ANTARCTIC BENTHOS
81
before the moult which ushers in maturity for the female. After
fertilization the female deposits the eggs in the marsupium where
further development takes place. The total number of eggs produced
varies, largely with the size of the female. Dearborn recorded from 356
to 1 020, mean 746 at McMurdo Sound. White gave a mean of 512 for
Signy Island in the South Orkneys. Within the marsupium the development from egg to larvae to final release took from 577 to 626 days
(White). Most adult females studied in the South Orkneys died shortly
after the brood had been released, and most males died after fertilization.
In contrast to many other Antarctic animals studied in detail, there
appears to be no fixed general breeding season neither at McMurdo Sound,
nor at the South Orkneys, the species breeding throughout the year.
6. Decapoda
The Antarctic decapod fauna is sparse. Three species of natants are
known from the Antarctic continent.
Two of these, Chorismue antarcticus (Pfeffer) and Notocrangon
antarcticus (Pfeffer) were originally described by Pfeffer (1 887) and
have since been recorded by most Antarctic expeditions. They are
both apparently circum-Antarctic. A third species, Spirontocaris
antarcticus Hale was described by Hale (1941) from off Adelie Land. A
subspecies of Notocrangon antarcticus has been described from East
Antarctica as Notocrangon antarcticus gracilis Borradaile. The two common species of Chorismus and Notocrangon have been recorded from
various Antarctic localities by Calman (1907), Borradaile (1916), Coutihre
(1917), Bage (1938) and Hale (1941).
Yaldwyn (1965) has summarized all records of Decapoda from
Antarctic and Subantarctic waters. Chorismus antarcticus also extends
to the Magellan region, the other two species Notocrangon antarcticus
and Spirontomris being confined to Antarctic waters. These genera are
widespread in other areas. Yaldwyn has indicated that the record of
the hymenosomid crab, Halicarcinus planatus (Fabricius), from the
South Orkneys (Stebbing, 1914) should be disregarded although it is a
widespread Subantarctic species. The fact that it is still unknown from
South Georgia which would be a much more congenial habitat for a
hymenosomid rather rules against the South Orkney record.
The anomuran crab Paralomis spectabilis Hansen, has been recorded
from the Antarctic waters (Birstein and Vinogradov, 1967). This
species occurs elsewhere only in the North Atlantic, and if the identification in this difficult group is correct this is a new piece of evidence for
bipolarity.
81
before the moult which ushers in maturity for the female. After
fertilization the female deposits the eggs in the marsupium where
further development takes place. The total number of eggs produced
varies, largely with the size of the female. Dearborn recorded from 356
to 1 020, mean 746 at McMurdo Sound. White gave a mean of 512 for
Signy Island in the South Orkneys. Within the marsupium the development from egg to larvae to final release took from 577 to 626 days
(White). Most adult females studied in the South Orkneys died shortly
after the brood had been released, and most males died after fertilization.
In contrast to many other Antarctic animals studied in detail, there
appears to be no fixed general breeding season neither at McMurdo Sound,
nor at the South Orkneys, the species breeding throughout the year.
6. Decapoda
The Antarctic decapod fauna is sparse. Three species of natants are
known from the Antarctic continent.
Two of these, Chorismue antarcticus (Pfeffer) and Notocrangon
antarcticus (Pfeffer) were originally described by Pfeffer (1 887) and
have since been recorded by most Antarctic expeditions. They are
both apparently circum-Antarctic. A third species, Spirontocaris
antarcticus Hale was described by Hale (1941) from off Adelie Land. A
subspecies of Notocrangon antarcticus has been described from East
Antarctica as Notocrangon antarcticus gracilis Borradaile. The two common species of Chorismus and Notocrangon have been recorded from
various Antarctic localities by Calman (1907), Borradaile (1916), Coutihre
(1917), Bage (1938) and Hale (1941).
Yaldwyn (1965) has summarized all records of Decapoda from
Antarctic and Subantarctic waters. Chorismus antarcticus also extends
to the Magellan region, the other two species Notocrangon antarcticus
and Spirontomris being confined to Antarctic waters. These genera are
widespread in other areas. Yaldwyn has indicated that the record of
the hymenosomid crab, Halicarcinus planatus (Fabricius), from the
South Orkneys (Stebbing, 1914) should be disregarded although it is a
widespread Subantarctic species. The fact that it is still unknown from
South Georgia which would be a much more congenial habitat for a
hymenosomid rather rules against the South Orkney record.
The anomuran crab Paralomis spectabilis Hansen, has been recorded
from the Antarctic waters (Birstein and Vinogradov, 1967). This
species occurs elsewhere only in the North Atlantic, and if the identification in this difficult group is correct this is a new piece of evidence for
bipolarity.