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6.2 Discoconchoecia aff. elegans
Sars, 1865
Conchoecia elegans Sars, 1865: p. 117 - Miiller,
1906a: p. 69, pl. 13 figs. 10, 11, 19-26 - Skogsberg, 1920: pp. 624-636, figs. 117, 118 - Angel,
1981: p. 558, fig. 194/41.
Paraconchoecia gracilis Claus, 1890: p. 15.
Conchoecia quadrangularis Aurivillius, 1898:
p.42.
Paraconchoecia elegans Poulsen, 1973: pp. 45-47,
fig. 18.
Conchoecia (Paraconchoecia) elegans Deevey,
1978: pp. 51, 52, fig. 5- Deevey, 1982: p. 147,
fig. 16.
Discoconchoecia aff. elegans Martens, 1979:
p. 344.
Carapace length -
females: 1.56-1.67 mm
males: 1.66-1.71 mm
Female. Adult shell elongate and rectangular; the
height:length ratio for most adults about 0.43 -
0.45; rostrum rather short and slightly curved;
incisure deep; dorsal margin straight below welldeveloped shoulders; posterior margin almost
straight; postero-dorsal terminus indistinctly
pointed in the right but not in the left val ve; ventral margin regularly convex. Asymmetric
glands in the usual places; lateral corner glands
and dorsomedial glands absent; medial glands
prominent, about 9-10 posteriorly and numerous along the ventral margin; about 6 elongate
anterior glands below the incisure. Shell sculpture observed to be finely reticulate on many
specimens. Cap of the frontal organ thickened in
the middle and rounded in front. Al without a
dorsal bristle; of the 5 end bristles, the 'e' bristle
is slender, long and carries spinules, the 4 sensory'pipe' bristles are short and simple. Furca with
8 claws separated from the lamella and reducing
in size rearwards; no posterior unpaired bristle.
Male. Carapace similar to that of the female, except for the occurrence of a postero-dorsal dorsomedial gland on each val ve. Cap of the frontal
organ clearly jointed and produced frontally; ornament of scattered stiff ventral hairs and numerous minute follicles. The 'e' bristle of the Al
carries a disc-like expansion (principal generic
character) and below this 1-2 stout spinules. A2
clasping joints dimorphic; the right one more
strongly recurved than the left one. P2 larger
than in the female ( although bearing shorter
bristles). Penis with a backwards-curving
rounded tip; about 5 transverse muscle bands;
seminal tube simple and broadened at its base.
Remarks
In our specimens, the mean length of mature
males is a little greater than that of mature females. This is unusual among planktonic ostracods, in which females are generally larger, as
noted by Poulsen (1973). The size range of our
material is more restricted than the 1-2 mm cited by Angel (1981) for adult females; but he also
notes that there are severa! different 'forms' for
this species, those from lower latitudes being
smaller than those from high latitudes. For Koch
(1992), who also works on Antarctic ostracods,
this difference can be characterized at the subspecific level and he refers to D. elegans gracilis
as equal to the 'southern form' of Angel (1972).
Chavtur (1993) considers that a number of new
species are hidden under the old species names
in this genus. However, no author as yet has been
6.2 Discoconchoecia aff. elegans
Sars, 1865
Conchoecia elegans Sars, 1865: p. 117 - Miiller,
1906a: p. 69, pl. 13 figs. 10, 11, 19-26 - Skogsberg, 1920: pp. 624-636, figs. 117, 118 - Angel,
1981: p. 558, fig. 194/41.
Paraconchoecia gracilis Claus, 1890: p. 15.
Conchoecia quadrangularis Aurivillius, 1898:
p.42.
Paraconchoecia elegans Poulsen, 1973: pp. 45-47,
fig. 18.
Conchoecia (Paraconchoecia) elegans Deevey,
1978: pp. 51, 52, fig. 5- Deevey, 1982: p. 147,
fig. 16.
Discoconchoecia aff. elegans Martens, 1979:
p. 344.
Carapace length -
females: 1.56-1.67 mm
males: 1.66-1.71 mm
Female. Adult shell elongate and rectangular; the
height:length ratio for most adults about 0.43 -
0.45; rostrum rather short and slightly curved;
incisure deep; dorsal margin straight below welldeveloped shoulders; posterior margin almost
straight; postero-dorsal terminus indistinctly
pointed in the right but not in the left val ve; ventral margin regularly convex. Asymmetric
glands in the usual places; lateral corner glands
and dorsomedial glands absent; medial glands
prominent, about 9-10 posteriorly and numerous along the ventral margin; about 6 elongate
anterior glands below the incisure. Shell sculpture observed to be finely reticulate on many
specimens. Cap of the frontal organ thickened in
the middle and rounded in front. Al without a
dorsal bristle; of the 5 end bristles, the 'e' bristle
is slender, long and carries spinules, the 4 sensory'pipe' bristles are short and simple. Furca with
8 claws separated from the lamella and reducing
in size rearwards; no posterior unpaired bristle.
Male. Carapace similar to that of the female, except for the occurrence of a postero-dorsal dorsomedial gland on each val ve. Cap of the frontal
organ clearly jointed and produced frontally; ornament of scattered stiff ventral hairs and numerous minute follicles. The 'e' bristle of the Al
carries a disc-like expansion (principal generic
character) and below this 1-2 stout spinules. A2
clasping joints dimorphic; the right one more
strongly recurved than the left one. P2 larger
than in the female ( although bearing shorter
bristles). Penis with a backwards-curving
rounded tip; about 5 transverse muscle bands;
seminal tube simple and broadened at its base.
Remarks
In our specimens, the mean length of mature
males is a little greater than that of mature females. This is unusual among planktonic ostracods, in which females are generally larger, as
noted by Poulsen (1973). The size range of our
material is more restricted than the 1-2 mm cited by Angel (1981) for adult females; but he also
notes that there are severa! different 'forms' for
this species, those from lower latitudes being
smaller than those from high latitudes. For Koch
(1992), who also works on Antarctic ostracods,
this difference can be characterized at the subspecific level and he refers to D. elegans gracilis
as equal to the 'southern form' of Angel (1972).
Chavtur (1993) considers that a number of new
species are hidden under the old species names
in this genus. However, no author as yet has been