3.28 Ctenocalanus citer
Heron and Bowman 1971
Ctenocalanus citer Heron and Bowman,
1971: p. 163, figs. 1, 16-18, 31-36, 54-58,
71-77,94-99, 130-150.
Body length -
females: 1.06-1.45mm (60 specimens)
males: 1.1O-1.45mm (30 specimens)
Female. Body slender with cephalothorax
2.7 times longer than wide. Proportional
lengths of cephalothorax and abdomen
75: 25; proportional lengths of abdominal
somites and furca 34: 18: 14: 16: 18 = 100. In
lateral view, ventral surface of genital somite
with small protuberance or lapett-like structure overhanging seminal receptacles. P4
with 3-jointed endopod and exopod. Rei,
Re2 with one outer spine; Re3 with 1 long
terminal spine, 4 inner setae and 3 outer
spines, first 2 of these spines with comb-like
teeth on medial margin. P5 vestigial.
Male. Cephalothorax 2.3 times longer
than wide. Proportional lengths of
cephalothorax and abdomen 65: 35; proportional lengths of abdominal somites and
furea 12:32:18:14:10:14 = 100. P5
asymmetrical and uniramous. Left P5 4jointed with group of long bristles on
inner margin of last joint; distal margin of
penultimate joint with tuft of long bristles.
Right P5 i-jointed with 2 small terminal
spines.
Ctenocalanus citer
161
Remarks
C. citer is very similar to C. vanus, differing
mainly for the shorter Ai which reaches the
posterior margin of the caudal rami (Ai of C.
vanus exceeds the caudal rami by several
segments) and for the male with a i-jointed
right P5 (male of C. vanus without right P5)
(Heron and Bowman 1971). The left P5 of
our male specimens is consistently similar in
morphology whereas the right P5 is highly
variable in size, either rounded or pointed
with one or two small apical spines. Our
specimens concord with the description of
Heron and Bowman; the only difference is in
the number of teeth on the external spine of
P4 Re3. Also, our female and mate specimens
are somewhat larger than those reported by
these authors.
Distribution
C. citer is very similar to the tropical, subtropical congeneric species C. vanus which
has a circumglobal distribution. The species
was first described in samples collected in
the Pacific sector of the Antarctic and subAntarctic regions. It has since been cited by
Boysen-Ennen and Piatkowski (1988)
as a common species in the Weddell Sea,
Antarctica. It is probable that its presence in
the Southern Oceans has often been confused
with that of C. vanus. Mazzocchi and lanora
(1991) reported it as quite frequent in
previous collections from the Straits of
Magellan. In the present study, C. citer was
one of the most frequently sampled species
throughout the Straits of Magellan. It was
found at all depths but was most abundant
in the upper 150m.
Heron and Bowman 1971
Ctenocalanus citer Heron and Bowman,
1971: p. 163, figs. 1, 16-18, 31-36, 54-58,
71-77,94-99, 130-150.
Body length -
females: 1.06-1.45mm (60 specimens)
males: 1.1O-1.45mm (30 specimens)
Female. Body slender with cephalothorax
2.7 times longer than wide. Proportional
lengths of cephalothorax and abdomen
75: 25; proportional lengths of abdominal
somites and furca 34: 18: 14: 16: 18 = 100. In
lateral view, ventral surface of genital somite
with small protuberance or lapett-like structure overhanging seminal receptacles. P4
with 3-jointed endopod and exopod. Rei,
Re2 with one outer spine; Re3 with 1 long
terminal spine, 4 inner setae and 3 outer
spines, first 2 of these spines with comb-like
teeth on medial margin. P5 vestigial.
Male. Cephalothorax 2.3 times longer
than wide. Proportional lengths of
cephalothorax and abdomen 65: 35; proportional lengths of abdominal somites and
furea 12:32:18:14:10:14 = 100. P5
asymmetrical and uniramous. Left P5 4jointed with group of long bristles on
inner margin of last joint; distal margin of
penultimate joint with tuft of long bristles.
Right P5 i-jointed with 2 small terminal
spines.
Ctenocalanus citer
161
Remarks
C. citer is very similar to C. vanus, differing
mainly for the shorter Ai which reaches the
posterior margin of the caudal rami (Ai of C.
vanus exceeds the caudal rami by several
segments) and for the male with a i-jointed
right P5 (male of C. vanus without right P5)
(Heron and Bowman 1971). The left P5 of
our male specimens is consistently similar in
morphology whereas the right P5 is highly
variable in size, either rounded or pointed
with one or two small apical spines. Our
specimens concord with the description of
Heron and Bowman; the only difference is in
the number of teeth on the external spine of
P4 Re3. Also, our female and mate specimens
are somewhat larger than those reported by
these authors.
Distribution
C. citer is very similar to the tropical, subtropical congeneric species C. vanus which
has a circumglobal distribution. The species
was first described in samples collected in
the Pacific sector of the Antarctic and subAntarctic regions. It has since been cited by
Boysen-Ennen and Piatkowski (1988)
as a common species in the Weddell Sea,
Antarctica. It is probable that its presence in
the Southern Oceans has often been confused
with that of C. vanus. Mazzocchi and lanora
(1991) reported it as quite frequent in
previous collections from the Straits of
Magellan. In the present study, C. citer was
one of the most frequently sampled species
throughout the Straits of Magellan. It was
found at all depths but was most abundant
in the upper 150m.