3.13 Calanus australis Brodskii 1959
Calanus australis var. atlanticus Brodskii,
1959: p. 1939, pI. 1 figs. 11, 12, pI. 2 fig. 11,
pI. 3 fig. 14, pI. 4 figs. 8, 9.
Calanus australis Vidal, 1968: p. 13, pI. 1 figs.
1-10 - Grice and Hiilsemann, 1967: p. 20,
fig. 3 - Arcos, 1975: p. 7, pI. 1 figs. 1, 2.
Body length -
females: 2.47-3.04mm (30 specimens)
male:
2.78 mm (1 specimen)
Female. Body slender and gradually tapering
anteriorly; head slightly rounded in dorsal
view. Cephalothorax more than 3 times
longer than wide. Last thoracic somite with
rounded postero-Iateral corners reaching 113
length of genital somite. Proportional lengths
of cephalothorax and abdomen 78: 22;
proportional lengths of abdominal somites
and furca 36:19:13:16:16 = 100. P5 B1
ornated with 14-20 slightly curved, triangular
teeth. Number of teeth along margins of left
and right P5 rarely the same.
Male. Same body shape as female. Proportionallengths of cephalothorax and abdomen
77: 23; proportional lengths of abdominal
somites and furca 12: 30: 17: 12: 11 : 18 = 100.
P5 B1 with asymmetrical left and right sides
ornated with 12-18 teeth. Endopods of both
right and left P5 3-jointed. Left endopod
short and stout, reaching 113 length of Re2 of
same leg. Last joint of left exopod about 112
length of preceding joint and ending with two
spines of different length; this joint ornated
with long hairs and bearing one small spine
Calanus australis
95
on external margin. Exopod of right P5 about
2/3 the length of the left.
Remarks
Brodskii (1959) describes two morphotypes
for this species, C. australis var. atlanticus
and C. australis var. pacijicus, the former
occurring in the Atlantic Ocean off Argentina
and the latter sampled in New Zealand
waters and along the Pacific coast off Chile.
Our specimens resemble the former in that
they are slender and have a length/width
ratio of the cephalothorax that varies from
1: 3.1 to 1: 3.3 in accordance to the key
reported by the same Author.
Distribution
Brodskii (1959) suggested that this species
occurs in temperate latitudes in the Southern
hemisphere where it has been reported by
several Authors (Grice and Hiilsemann 1967
and others). It has been collected repeatedly
off the Argentine (Ramirez 1969,1970,1971)
and Chilean (Fagetti 1962; Vidal 1968; Arcos
1975; Marin and Antezana 1985) coasts. The
species seems to be more abundant in
northern Chilean and Argentine shelf waters
and Vidal (1968) and Ramirez (1970) report
it as one of the most common species in their
collections. Not much information is available
on the vertical distribution of this species but
Arcos (1975) maintains that it undergoes
wide vertical migrations. In the present
study, C. australis was uniformly distributed
throughout the Straits of Magellan, with
maximum abundances in the upper 200 m.
Calanus australis var. atlanticus Brodskii,
1959: p. 1939, pI. 1 figs. 11, 12, pI. 2 fig. 11,
pI. 3 fig. 14, pI. 4 figs. 8, 9.
Calanus australis Vidal, 1968: p. 13, pI. 1 figs.
1-10 - Grice and Hiilsemann, 1967: p. 20,
fig. 3 - Arcos, 1975: p. 7, pI. 1 figs. 1, 2.
Body length -
females: 2.47-3.04mm (30 specimens)
male:
2.78 mm (1 specimen)
Female. Body slender and gradually tapering
anteriorly; head slightly rounded in dorsal
view. Cephalothorax more than 3 times
longer than wide. Last thoracic somite with
rounded postero-Iateral corners reaching 113
length of genital somite. Proportional lengths
of cephalothorax and abdomen 78: 22;
proportional lengths of abdominal somites
and furca 36:19:13:16:16 = 100. P5 B1
ornated with 14-20 slightly curved, triangular
teeth. Number of teeth along margins of left
and right P5 rarely the same.
Male. Same body shape as female. Proportionallengths of cephalothorax and abdomen
77: 23; proportional lengths of abdominal
somites and furca 12: 30: 17: 12: 11 : 18 = 100.
P5 B1 with asymmetrical left and right sides
ornated with 12-18 teeth. Endopods of both
right and left P5 3-jointed. Left endopod
short and stout, reaching 113 length of Re2 of
same leg. Last joint of left exopod about 112
length of preceding joint and ending with two
spines of different length; this joint ornated
with long hairs and bearing one small spine
Calanus australis
95
on external margin. Exopod of right P5 about
2/3 the length of the left.
Remarks
Brodskii (1959) describes two morphotypes
for this species, C. australis var. atlanticus
and C. australis var. pacijicus, the former
occurring in the Atlantic Ocean off Argentina
and the latter sampled in New Zealand
waters and along the Pacific coast off Chile.
Our specimens resemble the former in that
they are slender and have a length/width
ratio of the cephalothorax that varies from
1: 3.1 to 1: 3.3 in accordance to the key
reported by the same Author.
Distribution
Brodskii (1959) suggested that this species
occurs in temperate latitudes in the Southern
hemisphere where it has been reported by
several Authors (Grice and Hiilsemann 1967
and others). It has been collected repeatedly
off the Argentine (Ramirez 1969,1970,1971)
and Chilean (Fagetti 1962; Vidal 1968; Arcos
1975; Marin and Antezana 1985) coasts. The
species seems to be more abundant in
northern Chilean and Argentine shelf waters
and Vidal (1968) and Ramirez (1970) report
it as one of the most common species in their
collections. Not much information is available
on the vertical distribution of this species but
Arcos (1975) maintains that it undergoes
wide vertical migrations. In the present
study, C. australis was uniformly distributed
throughout the Straits of Magellan, with
maximum abundances in the upper 200 m.