3.20 Rhincalanus nasutus
Giesbrecht 1888
Rhincalanus nasutus Giesbrecht, 1888: p.
334; 1892: p. 152, pI. 3 fig. 6, pI. 9 figs. 6,
14, pI. 12 figs. 9-12, 14, 16, pI. 35 figs.
46, 49-Sars, 1903: p. 15, pIs. 6, 7 - Esterly,
1905: p. 136, fig. 10 - Wilson, 1932: p.
34, fig. 18 - Sewell, 1947: p. 59, fig. 19 -
Brodskii, 1950: p. 105, fig. 32 - Farran and
Vervoort, 1951b: p. 3, fig. 4 - Marques,
1956: p. 9, pI. 1 figs. a, b - Fish, 1962: p. 9,
fig. 4 - Grice and Hart, 1962: pI. 3.
Body length -
females: 5.63-6.08mm (5 specimens)
Female. Body slender and elongated; beaklike projection on forehead bearing long,
slender bifid rostrum. Rostral filaments not
visible in dorsal view. Cephalothorax 3.5
times longer than wide. Proportional lengths
of cephalothorax and abdomen 84: 16. Head
separated from thorax; thorax 5-segmented.
Second-fourth thoracic somites bear two
small lateral spines. Third and fourth thoracic
somites with two dorsal spines on posterior
margins. The 3-segmented abdomen is due
to fusion of the anal somite with the furca.
Proportional lengths of abdominal somites
and furca 38: 11: 51: = 100. Two large
spines visible on dorsal side of genital somite.
Caudal rami slightly asymmetrical bearing 2
tufts of hairs on ventral side of anal region.
P5 uniramous, symmetrical, with one seta
on the second joint and three on third.
Rhincalanus nasutus
125
Remarks
In our specimens, the head is clearly
separated from the first thoracic somite. By
contrast, other authors report that the head
is fused with the first thoracic somite. We
found only 1 male specimen in our samples.
Since it was heavily damaged, it was not
considered for this study.
Distribution
Giesbrecht (1888) described this species
from specimens also collected from Punta
Arenas, Chile. R. nasutus is widely distributed throughout cold and temperate
waters of the Northern and- Southern
hemispheres. In the south, it overlaps with
the Antarctic species R. gigas at its extreme
southern limit. The species has been reported
both for the Chilean coast (Arcos 1975;
Marin and Antezana 1985; Peterson et aI.
1988) and Argentinian offshore waters
(Ramirez 1969,1970, 1971). It was previously
reported for the Straits of Magellan by
Mazzocchi and lanora (1991), who recorded
mainly juvenile specimens only at Pacific
stations. The species has a wide distribution
range from the surface to 1000-1500 m in
the Indian Ocean, but to lesser depths in the
Atlantic and Pacific Oceans (Sewell 1947).
In the Mediterranean Sea, it has been
recorded from 0-800 m (Scotto di Carlo et
al. 1984). In the present study, R. nasutus
was present throughout the water column in
the Pacific and Central areas of the Straits of
Magellan. It was also sampled in low
numbers in the Atlantic area up to the
entrance of the Primera Angostura.
Giesbrecht 1888
Rhincalanus nasutus Giesbrecht, 1888: p.
334; 1892: p. 152, pI. 3 fig. 6, pI. 9 figs. 6,
14, pI. 12 figs. 9-12, 14, 16, pI. 35 figs.
46, 49-Sars, 1903: p. 15, pIs. 6, 7 - Esterly,
1905: p. 136, fig. 10 - Wilson, 1932: p.
34, fig. 18 - Sewell, 1947: p. 59, fig. 19 -
Brodskii, 1950: p. 105, fig. 32 - Farran and
Vervoort, 1951b: p. 3, fig. 4 - Marques,
1956: p. 9, pI. 1 figs. a, b - Fish, 1962: p. 9,
fig. 4 - Grice and Hart, 1962: pI. 3.
Body length -
females: 5.63-6.08mm (5 specimens)
Female. Body slender and elongated; beaklike projection on forehead bearing long,
slender bifid rostrum. Rostral filaments not
visible in dorsal view. Cephalothorax 3.5
times longer than wide. Proportional lengths
of cephalothorax and abdomen 84: 16. Head
separated from thorax; thorax 5-segmented.
Second-fourth thoracic somites bear two
small lateral spines. Third and fourth thoracic
somites with two dorsal spines on posterior
margins. The 3-segmented abdomen is due
to fusion of the anal somite with the furca.
Proportional lengths of abdominal somites
and furca 38: 11: 51: = 100. Two large
spines visible on dorsal side of genital somite.
Caudal rami slightly asymmetrical bearing 2
tufts of hairs on ventral side of anal region.
P5 uniramous, symmetrical, with one seta
on the second joint and three on third.
Rhincalanus nasutus
125
Remarks
In our specimens, the head is clearly
separated from the first thoracic somite. By
contrast, other authors report that the head
is fused with the first thoracic somite. We
found only 1 male specimen in our samples.
Since it was heavily damaged, it was not
considered for this study.
Distribution
Giesbrecht (1888) described this species
from specimens also collected from Punta
Arenas, Chile. R. nasutus is widely distributed throughout cold and temperate
waters of the Northern and- Southern
hemispheres. In the south, it overlaps with
the Antarctic species R. gigas at its extreme
southern limit. The species has been reported
both for the Chilean coast (Arcos 1975;
Marin and Antezana 1985; Peterson et aI.
1988) and Argentinian offshore waters
(Ramirez 1969,1970, 1971). It was previously
reported for the Straits of Magellan by
Mazzocchi and lanora (1991), who recorded
mainly juvenile specimens only at Pacific
stations. The species has a wide distribution
range from the surface to 1000-1500 m in
the Indian Ocean, but to lesser depths in the
Atlantic and Pacific Oceans (Sewell 1947).
In the Mediterranean Sea, it has been
recorded from 0-800 m (Scotto di Carlo et
al. 1984). In the present study, R. nasutus
was present throughout the water column in
the Pacific and Central areas of the Straits of
Magellan. It was also sampled in low
numbers in the Atlantic area up to the
entrance of the Primera Angostura.