3.30 Microcalanus pygmaeus
Sars1900
Pseudocalanus pygmaeus Sars, 1900: p. 73,
pI. 21 figs.1-14-Giesbrecht, 1902: p. 20, pI.
2 figs. 1-5.
Microcalanus pygmaeus Rose, 1933: p. 80,
fig. 35 - Brodskii, 1950: p. 116, fig. 37 -
Farran and Vervoort, 1951c: p. 3, figs. 3, 4Tanaka, 1956b: p. 385,fig. 12; 1960a:p. 35,
pI. 13 figs. 1-9 - Bradford, 1971b: p. 16, figs.
10-11 - Brodskii et aI., 1983: p. 226, fig.
106.
Spinocalanus longicornis (male) Sars, 1900:
p. 77, pI. 22 figs. 13, 14.
Body length -
females: 0.69-0.86 (20 specimens)
males: 0.64-0.84 (17 specimens)
Female. Body small in size. Cephalothorax
2.3 times longer than wide, widest in anterior
third and tapering towards head which is
somewhat triangular. Postero-Iateral comers
of last thoracic somite with short rounded
processes. Ai reaching half genital somite.
Proportional lengths of cephalothorax and
abdomen 75: 25; proportional lengths of
abdominal somites and furca 33: 19: 16: 17: 15
= 100. Genital somite conspicuously dilated
in middle with distinct pear-shaped seminal
receptacles in dorsal view. Exopods of P2P4 with serrated apical spine. P5 absent.
Male. Body shape slightly different from
female, with more pronounced triangular
head and more slender urosome. Cephalothorax 2.2 times longer than wide. Proportionallengths of cephalothorax and abdomen
70: 30; proportional lengths of abdominal
somites and furca 12 : 30 : 20 : 14: 13 : 11 = 100.
P5 asymmetrical, uniramous; left leg 5, 6jointed, right leg 2, 3-jointed, almost half as
long as left. Last joint of both right and left
legs ending with two spines; left joint also
bears long, sparse bristles.
Microcalanus pygmaeus
171
Remarks
The genus was created by Sars (1903) to
accommodate a small calanoid collected
along the Norwegian coast, Microcalanus
pusillus. He later added a second species, M.
pygmaeus, which had been described as
Pseudocalanus pygmaeus, sampled north of
the New Siberian Islands. These two species
resemble each other so closely that the distinction between them is very unclear (Farran
1929; Tanaka 1956b). According to Farran
and Vervoort (1951c), the two species of
Microcalanus described by Sars can best be
regarded as forms of a variable M. pygmaeus.
This is the view we adopt here since, in our
specimens, although the Ai is sbort, as that
reported for M. pusillus, all intermediate
forms occur.
Distribution
M. pygmaeus is a cosmopolitan species,
recorded from the Arctic, where it is widely
distributed (Sars 1900; With 1915; Jespersen
1934), and from the Antarctic (Giesbrecht
1902; Farran 1929; Vervoort 1957; Bradford
1971b) Oceans. Vervoort (1957) summarized
the Arctic and Antarctic occurrence of M.
pygmaeus. In temperate and Antarctic
regions, the species inhabits deep waters.
Tanaka (1956b) recorded it in Sagami Bay
(Japan) from 300-500 m. It was sampled
from 1000-3000 m in the Indian Ocean
(Grice and Hiilsemann 1967) and from 1002500 m in the NE Atlantic (Grice and
Hiilsemann 1965). Peterson et ai. (1988)
reported a "Microcalanus species" from
Bahia de Concepcion (Chile). Fagetti (1962)
reported M. pusillus for the Chilean coast.
The species was previously reported as M.
pusillus in the Straits of Magellan (Mazzocchi
and lanora 1991). In the present study, M.
pygmaeus was sampled at all depths, mainly
at Pacific and partly at Central stations.
Sars1900
Pseudocalanus pygmaeus Sars, 1900: p. 73,
pI. 21 figs.1-14-Giesbrecht, 1902: p. 20, pI.
2 figs. 1-5.
Microcalanus pygmaeus Rose, 1933: p. 80,
fig. 35 - Brodskii, 1950: p. 116, fig. 37 -
Farran and Vervoort, 1951c: p. 3, figs. 3, 4Tanaka, 1956b: p. 385,fig. 12; 1960a:p. 35,
pI. 13 figs. 1-9 - Bradford, 1971b: p. 16, figs.
10-11 - Brodskii et aI., 1983: p. 226, fig.
106.
Spinocalanus longicornis (male) Sars, 1900:
p. 77, pI. 22 figs. 13, 14.
Body length -
females: 0.69-0.86 (20 specimens)
males: 0.64-0.84 (17 specimens)
Female. Body small in size. Cephalothorax
2.3 times longer than wide, widest in anterior
third and tapering towards head which is
somewhat triangular. Postero-Iateral comers
of last thoracic somite with short rounded
processes. Ai reaching half genital somite.
Proportional lengths of cephalothorax and
abdomen 75: 25; proportional lengths of
abdominal somites and furca 33: 19: 16: 17: 15
= 100. Genital somite conspicuously dilated
in middle with distinct pear-shaped seminal
receptacles in dorsal view. Exopods of P2P4 with serrated apical spine. P5 absent.
Male. Body shape slightly different from
female, with more pronounced triangular
head and more slender urosome. Cephalothorax 2.2 times longer than wide. Proportionallengths of cephalothorax and abdomen
70: 30; proportional lengths of abdominal
somites and furca 12 : 30 : 20 : 14: 13 : 11 = 100.
P5 asymmetrical, uniramous; left leg 5, 6jointed, right leg 2, 3-jointed, almost half as
long as left. Last joint of both right and left
legs ending with two spines; left joint also
bears long, sparse bristles.
Microcalanus pygmaeus
171
Remarks
The genus was created by Sars (1903) to
accommodate a small calanoid collected
along the Norwegian coast, Microcalanus
pusillus. He later added a second species, M.
pygmaeus, which had been described as
Pseudocalanus pygmaeus, sampled north of
the New Siberian Islands. These two species
resemble each other so closely that the distinction between them is very unclear (Farran
1929; Tanaka 1956b). According to Farran
and Vervoort (1951c), the two species of
Microcalanus described by Sars can best be
regarded as forms of a variable M. pygmaeus.
This is the view we adopt here since, in our
specimens, although the Ai is sbort, as that
reported for M. pusillus, all intermediate
forms occur.
Distribution
M. pygmaeus is a cosmopolitan species,
recorded from the Arctic, where it is widely
distributed (Sars 1900; With 1915; Jespersen
1934), and from the Antarctic (Giesbrecht
1902; Farran 1929; Vervoort 1957; Bradford
1971b) Oceans. Vervoort (1957) summarized
the Arctic and Antarctic occurrence of M.
pygmaeus. In temperate and Antarctic
regions, the species inhabits deep waters.
Tanaka (1956b) recorded it in Sagami Bay
(Japan) from 300-500 m. It was sampled
from 1000-3000 m in the Indian Ocean
(Grice and Hiilsemann 1967) and from 1002500 m in the NE Atlantic (Grice and
Hiilsemann 1965). Peterson et ai. (1988)
reported a "Microcalanus species" from
Bahia de Concepcion (Chile). Fagetti (1962)
reported M. pusillus for the Chilean coast.
The species was previously reported as M.
pusillus in the Straits of Magellan (Mazzocchi
and lanora 1991). In the present study, M.
pygmaeus was sampled at all depths, mainly
at Pacific and partly at Central stations.