3.24 Chiridius subgracilis Park 1975
Chirdius subgracilis Park, 1975: p. 285, figs.
9, 10 - Bradford and Jillett, 1980: p. 23, fig.
12.
Body length -
females: 2.35-2.72mm (12 specimens)
males: 2.00-2.16mm (5 specimens)
Female. Same body shape as C. gracilis with
the same proportional lengths between the
cephalothorax and abdomen (77: 23).
Proportional lengths of abdominal somites
and furca 39:23:17:8:13 = 100. In P2,
outer margin of Re3 with 3 strong spines
bordered by wing-like processes as in C.
gracilis, but in this case the margins between
these spines are conspicuously bulged in the
middle.
Male. General shape somewhat more slender
than C. gracilis. Proportional lengths of
cephalothorax and abdomen 70: 30. In the
maxilliped, none of the setae on the last
endopodal segment bears hairs or spinules.
Proportional lengths of abdominal somites
and furca 18:26:22:20:2: 12 = 100. P5 as in
C. gracilis.
Chiridius subgracilis
143
Remarks
According to Park (1975), this species
is clearly distinct from C. gracilis in the
female which is smaller in size and bears a
posteriorly located genital swelling in dorsal
view. At first glance, our specimens do not
show any evident differences ih morphology
or size from C. gracilis. They differ only for
the presence of conspicuous lobes on the
external margin of the P2 Re3; this feature
is easier to appreciate after dissection.
The males of these two species are easier to
distinguish from one another. The male of
C. subgracilis has a longer abdomen
compared to the cephalothorax. After
dissection, it is also possible to see the
differences in the last endopodal segment of
the maxilliped (absence of spinules on the
distal setae in C. subgracilis).
Distribution
C. subgracilis was reported by Park (1975)
as the most common species belonging to
this genus in his plankton collections from
the Gulf of Mexico. Bradford and Jillett
(1980) report it as a deep-water species,
living generally below 250m, in the New
Zealand region of the SW Pacific. This
represents a first record for the Straits of
Magellan. See C. gracilis for the distribution
range in the present study.
Chirdius subgracilis Park, 1975: p. 285, figs.
9, 10 - Bradford and Jillett, 1980: p. 23, fig.
12.
Body length -
females: 2.35-2.72mm (12 specimens)
males: 2.00-2.16mm (5 specimens)
Female. Same body shape as C. gracilis with
the same proportional lengths between the
cephalothorax and abdomen (77: 23).
Proportional lengths of abdominal somites
and furca 39:23:17:8:13 = 100. In P2,
outer margin of Re3 with 3 strong spines
bordered by wing-like processes as in C.
gracilis, but in this case the margins between
these spines are conspicuously bulged in the
middle.
Male. General shape somewhat more slender
than C. gracilis. Proportional lengths of
cephalothorax and abdomen 70: 30. In the
maxilliped, none of the setae on the last
endopodal segment bears hairs or spinules.
Proportional lengths of abdominal somites
and furca 18:26:22:20:2: 12 = 100. P5 as in
C. gracilis.
Chiridius subgracilis
143
Remarks
According to Park (1975), this species
is clearly distinct from C. gracilis in the
female which is smaller in size and bears a
posteriorly located genital swelling in dorsal
view. At first glance, our specimens do not
show any evident differences ih morphology
or size from C. gracilis. They differ only for
the presence of conspicuous lobes on the
external margin of the P2 Re3; this feature
is easier to appreciate after dissection.
The males of these two species are easier to
distinguish from one another. The male of
C. subgracilis has a longer abdomen
compared to the cephalothorax. After
dissection, it is also possible to see the
differences in the last endopodal segment of
the maxilliped (absence of spinules on the
distal setae in C. subgracilis).
Distribution
C. subgracilis was reported by Park (1975)
as the most common species belonging to
this genus in his plankton collections from
the Gulf of Mexico. Bradford and Jillett
(1980) report it as a deep-water species,
living generally below 250m, in the New
Zealand region of the SW Pacific. This
represents a first record for the Straits of
Magellan. See C. gracilis for the distribution
range in the present study.