138
Systematic Account
3.23 Chiridius gracilis Farran 1908
Chiridius gracilis Farran, 1908: p. 30, pI. 2
figs. 1-3 - Scott, 1909: p. 42, pI. 11 figs. 1-9
- With, 1915: p. 85, fig. 21 - Farran, 1929:
p. 229, fig. 6 - Tanaka, 1957: p. 48, fig. 30Park, 1975: p. 283, figs. 7, 8; 1978: p. 122,
fig. 13.
Body length -
females: 2.65-2.88mm (13 specimens)
males: 2.29-2.43 mm (5 specimens)
Female. Body less robust than other species
belonging to this genus. Cephalothorax 3
times longer than wide, shouldered anteriorly
with rounded forehead. Last thoracic somite
bearing straight, spiniform processes
extending beyond middle of genital somite.
Proportional lengths of cephalothorax and
abdomen 77: 23; proportional lengths of
abdominal somites and furca 37: 22: 19: 8: 14
= 100. Genital somite as wide as long and
swollen at mid-length. P2 B1 produced into
bulge on inner distal end, bearing row of
long hairs and one strong spine. Re2 with
row of small teeth along distal outer margin.
Re3 with 3 strong outer spines with winglike processes on either basal side. Between
these spines, margins of joint moderately
bulged in the middle as compared to C.
subgracilis. Terminal spine of exopod bearing
about 24 teeth on external edge.
Male. Same body shape as female, with
shorter spiniform processes on posterolateral comers of last thoracic somite. Proportional lengths of cephalothorax and
abdomen 76: 24. Abdomen 4-segmented;
proportional lengths of abdominal somites
and furca 17:27:22: 19:2: 13 = 100.
Maxilliped with last endopodal segment
bearing strong seta ornated with two rows
of small teeth. P5 long and slender,
asymmetrical, uniramous. Right leg 4jointed; last joint longer than preceding and
styliform. Fourth joint of left leg ornated
with tufts of hairs at distal end; last joint
with row of hairs along inner border
and small spine and small spatula-shaped
protuberance at apex.
Remarks
C. gracilis closely resembles C. poppei. The
differences between these two species are
discussed by Vervoort (1957).
Distribution
C. gracilis is widely distributed in temperate
waters of the Southern hemisphere. Farran
(1929) reported its occurrence off New
Zealand and Park (1978) recorded it north of
the Antarctic convergence in sub-Antarctic
waters of the Pacific Ocean. It has also been
reported south of Tasmania (Vervoort 1957).
Marin and Antezana (1985) have recently
recorded it for the first time in Chilean fjords.
Only one female specimen was sampled
previously in the Straits of Magellan
(Mazzocchi and lanora 1991). In the present
study, C. gracilis and C. subgracilis are
grouped together in the distribution maps.
They were only found at Pacific stations
where they were sampled at all depths
except the surface layer. The two species
were also sporadically sampled off Cape
Froward.
Systematic Account
3.23 Chiridius gracilis Farran 1908
Chiridius gracilis Farran, 1908: p. 30, pI. 2
figs. 1-3 - Scott, 1909: p. 42, pI. 11 figs. 1-9
- With, 1915: p. 85, fig. 21 - Farran, 1929:
p. 229, fig. 6 - Tanaka, 1957: p. 48, fig. 30Park, 1975: p. 283, figs. 7, 8; 1978: p. 122,
fig. 13.
Body length -
females: 2.65-2.88mm (13 specimens)
males: 2.29-2.43 mm (5 specimens)
Female. Body less robust than other species
belonging to this genus. Cephalothorax 3
times longer than wide, shouldered anteriorly
with rounded forehead. Last thoracic somite
bearing straight, spiniform processes
extending beyond middle of genital somite.
Proportional lengths of cephalothorax and
abdomen 77: 23; proportional lengths of
abdominal somites and furca 37: 22: 19: 8: 14
= 100. Genital somite as wide as long and
swollen at mid-length. P2 B1 produced into
bulge on inner distal end, bearing row of
long hairs and one strong spine. Re2 with
row of small teeth along distal outer margin.
Re3 with 3 strong outer spines with winglike processes on either basal side. Between
these spines, margins of joint moderately
bulged in the middle as compared to C.
subgracilis. Terminal spine of exopod bearing
about 24 teeth on external edge.
Male. Same body shape as female, with
shorter spiniform processes on posterolateral comers of last thoracic somite. Proportional lengths of cephalothorax and
abdomen 76: 24. Abdomen 4-segmented;
proportional lengths of abdominal somites
and furca 17:27:22: 19:2: 13 = 100.
Maxilliped with last endopodal segment
bearing strong seta ornated with two rows
of small teeth. P5 long and slender,
asymmetrical, uniramous. Right leg 4jointed; last joint longer than preceding and
styliform. Fourth joint of left leg ornated
with tufts of hairs at distal end; last joint
with row of hairs along inner border
and small spine and small spatula-shaped
protuberance at apex.
Remarks
C. gracilis closely resembles C. poppei. The
differences between these two species are
discussed by Vervoort (1957).
Distribution
C. gracilis is widely distributed in temperate
waters of the Southern hemisphere. Farran
(1929) reported its occurrence off New
Zealand and Park (1978) recorded it north of
the Antarctic convergence in sub-Antarctic
waters of the Pacific Ocean. It has also been
reported south of Tasmania (Vervoort 1957).
Marin and Antezana (1985) have recently
recorded it for the first time in Chilean fjords.
Only one female specimen was sampled
previously in the Straits of Magellan
(Mazzocchi and lanora 1991). In the present
study, C. gracilis and C. subgracilis are
grouped together in the distribution maps.
They were only found at Pacific stations
where they were sampled at all depths
except the surface layer. The two species
were also sporadically sampled off Cape
Froward.