3.43 Oncaea coni/era Giesbrecht 1891
Oncaea coni/era Giesbrecht, 1891: p. 471;
1892: p. 591, pI. 2 fig. 10, pI. 47 figs. 4, 16,21,
23,28,34-38,42,55, 56-Mori, 1937: p. 120,
pI. 66 figs. 10-13 - Tanaka, 1960a: p. 66,
pI. 29 figs. 1-8 - Owre and Foyo, 1967:
p. 111, figs. 807-811- Ramirez, 1969: p. 89,
pI. 17 figs. 139, 140, 142, 147, pI. 18 fig. 150.
Body length -
females: 1.12-1.33mm (20 specimens)
males: 0.88-1.00mm (20 specimens)
Female. Prosome twice as long as wide.
Rostral area with thickened, rounded ventral
margin, like a fold. Second thoracic somite
bearing conspicuous dorsal projection,
characteristic in lateral view. Proportional
lengths of prosome and urosome 64: 36;
proportional lengths of urosomites and furca
16: 48: 5: 5: 10: 16 = 100. Genital somite with
two setules in mid-region of dorsal surface.
Caudal rami almost three times longer than
wide. Second segment of maxilliped with two
spines on inner surface and long row of
setules. Terminal segment bearing long claw
with row of denticules on concave surface. P4
endopod terminates in conical projection
with patch of hairs and two spines of about
the same length, with serrated, hyaline
flange. P5 free segment elongated, with one
seta almost twice as long as the other.
Male. Prosome more slender than female,
2.2 times longer than wide, lacking dorsal
protrusion on third thoracic somite. Proportional lengths of prosome and urosome
66: 34; proportional lengths of urosomites
and furca 8:51:14:2:2:11:12 = 100.
Genital somite with postero-Iateral flap
on ventral surface, ending with pointed
posterior corners. Flap bearing denticulated
margin on ventral side and minute, hyaline
denticules on both ventral and dorsal
surfaces.
Oncaea conifera
229
Remarks
Giesbrecht (1902) distinguished this species
as three varieties: "variety I", the specimens he originally described from the
Mediterranean Sea and Pacific Ocean;
"variety II" , specimens from the Arctic
Ocean; and "variety III", specimens from
the
Antarctic-Pacific
Ocean
area.
Giesbrecht's Antarctic "variety III" has been
elevated to full species status as O. antarctica
by Heron (1977). This author discussed all
morphological details distinguishing O.
coni/era from O. antarctica. Malt (1983)
summarized in a table (p. 458) the characters
distinguishing O. coni/era females from
specimens of other Oncaea species having the
same dorsal projection. The same author
reported and widely discussed polymorphic
forms of O. coni/era found in the North
Atlantic (Malt 1983). Our specimens do not
show the characteristics of O. antarctica and
agree in main features with Giesbrecht's
"variety I". However, in our specimens,
the terminal lanceolate spines in P4 Ri3
are almost of the same length, whereas in
Giesbrecht's (1892) fig. 38 (pI. 47) the terminal spine on the external side is longer.
A more detailed morphological study is
necessary to verify if polymorphism characterizes also co-occurring populations in the
Straits of Magellan.
Distribution
This species is reported as cosmopolitan. It
has an almost world-wide distribution, ranging from Arctic to Antarctic waters and is
also distributed over the Atlantic, Pacific and
Indian Oceans as well as the Mediterranean
Sea. Farran (1929) found it in samples collected from New Zealand, southwards to the
Antarctic continent, also in hauls beneath the
ice. Vervoort (1951) reported O. coni/era in
the Atlantic sector of the Antarctic, Bradford
(1971b) in the Ross Sea (Antarctica). Takana
(1960a) reported o. coni/era from the
Japanese Antarctic Expedition, in regions
south of 66°S. This species has been reported
from Argentine waters (Ramirez 1969) and
from Chilean fjords (Marin and Antezana
Oncaea coni/era Giesbrecht, 1891: p. 471;
1892: p. 591, pI. 2 fig. 10, pI. 47 figs. 4, 16,21,
23,28,34-38,42,55, 56-Mori, 1937: p. 120,
pI. 66 figs. 10-13 - Tanaka, 1960a: p. 66,
pI. 29 figs. 1-8 - Owre and Foyo, 1967:
p. 111, figs. 807-811- Ramirez, 1969: p. 89,
pI. 17 figs. 139, 140, 142, 147, pI. 18 fig. 150.
Body length -
females: 1.12-1.33mm (20 specimens)
males: 0.88-1.00mm (20 specimens)
Female. Prosome twice as long as wide.
Rostral area with thickened, rounded ventral
margin, like a fold. Second thoracic somite
bearing conspicuous dorsal projection,
characteristic in lateral view. Proportional
lengths of prosome and urosome 64: 36;
proportional lengths of urosomites and furca
16: 48: 5: 5: 10: 16 = 100. Genital somite with
two setules in mid-region of dorsal surface.
Caudal rami almost three times longer than
wide. Second segment of maxilliped with two
spines on inner surface and long row of
setules. Terminal segment bearing long claw
with row of denticules on concave surface. P4
endopod terminates in conical projection
with patch of hairs and two spines of about
the same length, with serrated, hyaline
flange. P5 free segment elongated, with one
seta almost twice as long as the other.
Male. Prosome more slender than female,
2.2 times longer than wide, lacking dorsal
protrusion on third thoracic somite. Proportional lengths of prosome and urosome
66: 34; proportional lengths of urosomites
and furca 8:51:14:2:2:11:12 = 100.
Genital somite with postero-Iateral flap
on ventral surface, ending with pointed
posterior corners. Flap bearing denticulated
margin on ventral side and minute, hyaline
denticules on both ventral and dorsal
surfaces.
Oncaea conifera
229
Remarks
Giesbrecht (1902) distinguished this species
as three varieties: "variety I", the specimens he originally described from the
Mediterranean Sea and Pacific Ocean;
"variety II" , specimens from the Arctic
Ocean; and "variety III", specimens from
the
Antarctic-Pacific
Ocean
area.
Giesbrecht's Antarctic "variety III" has been
elevated to full species status as O. antarctica
by Heron (1977). This author discussed all
morphological details distinguishing O.
coni/era from O. antarctica. Malt (1983)
summarized in a table (p. 458) the characters
distinguishing O. coni/era females from
specimens of other Oncaea species having the
same dorsal projection. The same author
reported and widely discussed polymorphic
forms of O. coni/era found in the North
Atlantic (Malt 1983). Our specimens do not
show the characteristics of O. antarctica and
agree in main features with Giesbrecht's
"variety I". However, in our specimens,
the terminal lanceolate spines in P4 Ri3
are almost of the same length, whereas in
Giesbrecht's (1892) fig. 38 (pI. 47) the terminal spine on the external side is longer.
A more detailed morphological study is
necessary to verify if polymorphism characterizes also co-occurring populations in the
Straits of Magellan.
Distribution
This species is reported as cosmopolitan. It
has an almost world-wide distribution, ranging from Arctic to Antarctic waters and is
also distributed over the Atlantic, Pacific and
Indian Oceans as well as the Mediterranean
Sea. Farran (1929) found it in samples collected from New Zealand, southwards to the
Antarctic continent, also in hauls beneath the
ice. Vervoort (1951) reported O. coni/era in
the Atlantic sector of the Antarctic, Bradford
(1971b) in the Ross Sea (Antarctica). Takana
(1960a) reported o. coni/era from the
Japanese Antarctic Expedition, in regions
south of 66°S. This species has been reported
from Argentine waters (Ramirez 1969) and
from Chilean fjords (Marin and Antezana