166
Systematic Account
3.29 Drepanopus jorcipatus
Giesbrecht 1888
Drepanopus forcipatus Giesbrecht, 1888: p.
335 - Ramirez, 1969: p. 55, pI. 8 fig. 56, pI. 9
fig. 63; 1970: p. 476, fig. 2 - Bjornberg, 1973:
p. 317, figs. 13, 14 - Hiilsemann, 1985: p.
911, figs. 2-4,6-8, 10, 12, 14, 16-20,23,24,
27-29, 32, 33; 1991: p. 199, figs. 1-107.
Drepanopus pectinatus Giesbrecht, 1892: pI.
10 figs. 23-25, 27-30, pI. 36 figs. 36-38 -
Scott, 1914: p. 8, pI. 2, figs. 10, 11 - Hardy
and Gunther, 1935: p. 153, figs. 56, 73, 74,
100, 102 - Ramirez, 1966: p. 11, pI. 2 figs.
9-16-Arcos, 1975: p. 13, pI. 3 figs. 22-27.
Body length -
females: 1.39-1.78mm (35 specimens)
males: 1.12-1.35mm (10 specimens)
Female. Body slender with elongated
abdomen. Cephalothorax 2.4 times longer
than wide. Last thoracic somite with short,
rounded postero-Iateral corners. Proportionallengths of cephalothorax and abdomen
65 : 35; proportional lengths of abdominal
somites and furca 41: 19: 13: 11: 16 = 100. In
dorsal view, genital somite swollen laterally
in anterior half, with clearly visible seminal
receptacles. In lateral view, swelling produced into evident bulge enveloping genital
aperture on ventral side. P5 with bulbous
base; terminal spine of P5 bent distally and
ornated with 30 or more small teeth.
Male. Cephalothorax 2.2 times longer than
wide, ending anteriorly with flat forehead.
Last thoracic somite with short rounded
postero-Iateral corners as in female. Proportionallengths of cephalothorax and abdomen
63 : 37; proportional lengths of abdominal
somites and furca 9:37:18:14:10:12 = 100.
Al with 3 conspicuous patches of long
spinules at base. A2 with a row of curved
spines at the base of its inner side. P5
asymmetrical and uniramous. Right P5 with
bent, long terminal spine; left P5 3-jointed
with 2 patches of spines on inner margin of
ReI. Re2 with a strong spine on external
margin; Re3 greatly reduced, bearing hairs
and ending in thin terminal spine.
Remarks
Our specimens are similar in size and proportional lengths of the cephalothorax and
abdomen to the Patagonian shelf specimens
described by Hiilsemann (1985). They differ
only in the male left P5 which bears 2 distinct
patches of spines on the inner margin of the
ReI in our specimens. D. forcipatus is very
similar to D. pectinatus. Differences in the
morphology of the two species are given by
Hiilsemann (1985). Females are more similar
than males. In the male of D. pectinatus, the
Al lacks conspicuous patches of spinules and
the P5 has a small, I-jointed endopod on
either side.
Distribution
According to Hiilsemann (1985), D. forcipatus is confined to Atlantic and Pacific
coastal shelf areas of southern South
America. South of the Antarctic Convergence, the same author reports other
populations of this species as limited geographically to a small area around South
Georgia. The Convergence therefore divides
the distribution range of D. forcipatus from
that of D. pectinatus which lives in inshore
waters south of the Antarctic Polar Front. D.
forcipatus has been reported by many
authors as widely distributed in shelf areas
off Chile and Argentina. In the Straits of
Magellan, Mazzocchi and lanora (1991)
recorded its occurrence at all stations but
one, with highest densities at the three most
Atlantic sites. In the present study, the
species was widely distributed throughout the
Straits. It was sampled up to 500 m but
reached maximum abundances in the upper
100 m at Pacific and Central stations.
Systematic Account
3.29 Drepanopus jorcipatus
Giesbrecht 1888
Drepanopus forcipatus Giesbrecht, 1888: p.
335 - Ramirez, 1969: p. 55, pI. 8 fig. 56, pI. 9
fig. 63; 1970: p. 476, fig. 2 - Bjornberg, 1973:
p. 317, figs. 13, 14 - Hiilsemann, 1985: p.
911, figs. 2-4,6-8, 10, 12, 14, 16-20,23,24,
27-29, 32, 33; 1991: p. 199, figs. 1-107.
Drepanopus pectinatus Giesbrecht, 1892: pI.
10 figs. 23-25, 27-30, pI. 36 figs. 36-38 -
Scott, 1914: p. 8, pI. 2, figs. 10, 11 - Hardy
and Gunther, 1935: p. 153, figs. 56, 73, 74,
100, 102 - Ramirez, 1966: p. 11, pI. 2 figs.
9-16-Arcos, 1975: p. 13, pI. 3 figs. 22-27.
Body length -
females: 1.39-1.78mm (35 specimens)
males: 1.12-1.35mm (10 specimens)
Female. Body slender with elongated
abdomen. Cephalothorax 2.4 times longer
than wide. Last thoracic somite with short,
rounded postero-Iateral corners. Proportionallengths of cephalothorax and abdomen
65 : 35; proportional lengths of abdominal
somites and furca 41: 19: 13: 11: 16 = 100. In
dorsal view, genital somite swollen laterally
in anterior half, with clearly visible seminal
receptacles. In lateral view, swelling produced into evident bulge enveloping genital
aperture on ventral side. P5 with bulbous
base; terminal spine of P5 bent distally and
ornated with 30 or more small teeth.
Male. Cephalothorax 2.2 times longer than
wide, ending anteriorly with flat forehead.
Last thoracic somite with short rounded
postero-Iateral corners as in female. Proportionallengths of cephalothorax and abdomen
63 : 37; proportional lengths of abdominal
somites and furca 9:37:18:14:10:12 = 100.
Al with 3 conspicuous patches of long
spinules at base. A2 with a row of curved
spines at the base of its inner side. P5
asymmetrical and uniramous. Right P5 with
bent, long terminal spine; left P5 3-jointed
with 2 patches of spines on inner margin of
ReI. Re2 with a strong spine on external
margin; Re3 greatly reduced, bearing hairs
and ending in thin terminal spine.
Remarks
Our specimens are similar in size and proportional lengths of the cephalothorax and
abdomen to the Patagonian shelf specimens
described by Hiilsemann (1985). They differ
only in the male left P5 which bears 2 distinct
patches of spines on the inner margin of the
ReI in our specimens. D. forcipatus is very
similar to D. pectinatus. Differences in the
morphology of the two species are given by
Hiilsemann (1985). Females are more similar
than males. In the male of D. pectinatus, the
Al lacks conspicuous patches of spinules and
the P5 has a small, I-jointed endopod on
either side.
Distribution
According to Hiilsemann (1985), D. forcipatus is confined to Atlantic and Pacific
coastal shelf areas of southern South
America. South of the Antarctic Convergence, the same author reports other
populations of this species as limited geographically to a small area around South
Georgia. The Convergence therefore divides
the distribution range of D. forcipatus from
that of D. pectinatus which lives in inshore
waters south of the Antarctic Polar Front. D.
forcipatus has been reported by many
authors as widely distributed in shelf areas
off Chile and Argentina. In the Straits of
Magellan, Mazzocchi and lanora (1991)
recorded its occurrence at all stations but
one, with highest densities at the three most
Atlantic sites. In the present study, the
species was widely distributed throughout the
Straits. It was sampled up to 500 m but
reached maximum abundances in the upper
100 m at Pacific and Central stations.