204
Systematic Account
3.37 Scolecithricella minor
Brady 1883
Scolecithrix minor Brady, 1883: p. 58, pI. 16
figs. 15, 16, pI. 18 figs. 1-5.
Scolecithricella minor Sars, 1903: p. 55, pIs.
37,38 - Mori, 1937: p. 51, pI. 25 figs. 1-7Brodskii, 1950: p. 269, fig. 178 - Park, 1968:
p. 554, pI. 8 figs. 9-12; 1980: p. 31, figs. 2,
3.
Scolecithrix glacialis Giesbrecht, 1902, p. 25,
pI. 4 figs. 1-7.
More complete lists of synonyms of S.
minor and S. glacialis are given in Vervoort
(1956b) and Vervoort (1957), respectively.
Body length -
females: 1.27-1.37mm (15 specimens)
males: 1.27-1.31mm (3 specimens)
Female. Cephalothorax slender, 2.5 times
longer than wide. Head fused with thorax,
narrowly rounded in dorsal view. Rostrum
bifurcated with strong rami. A1 reaching
posterior margin of genital somite. Posterolateral comers of last thoracic somite symmetrical, produced distally, forming an obtuse
angle in lateral view. Proportional lengths of
cephalothorax and abdomen 79: 21; proportionallengths of abdominal somites and furca
39:18:18:8:17 = 100. P5 foliate, 1-jointed;
apical spine short, inner spine longer, serrated; outer margin of joint with smaller
spinule, sometimes appearing as small
tubercle.
Male. Body slender; cephalothorax 2.3 times
longer than wide. Rostrum similar to that of
female. Proportional lengths of cephalothorax
and abdomen 70: 30; proportional lengths of
abdominal somites and furca 16: 26: 20: 25 :
4: 9 = 100. P5 exceeding length of abdomen,
asymmetrical; both legs biramous; right leg
with vestigial endopod. Right exopod with
spatula-like distal joint. Left exopod ending
in "bayonet-shaped" (Brodskii 1950) joint.
Remarks
Scolecithricella minor was originally described
as Scolecithrix minor by -Brady (1883) from
specimens collected in the Indian Ocean.
Sars (1903) accurately re-described this
species from Norwegian-water specimens
and established the genus Scolecithricella to
accommodate it. Park (1980) noted that it is
impossible to distinguish S. minor Brady
from S. glacialis Giesbrecht, 1902, on the
basis of the original descriptions for these
species, and considered S. glacialis as a
junior synonym of S. minor. Brodskii (1950)
distinguished two forms of S. minor mainly
for the shape of the P5 in females: f. orientalis
from the North Pacific and f. occidentalis
from the North Atlantic Ocean. Our specimens are similar to the occidentalis form.
Distribution
Scolecithricella minor is distributed worldwide. This species is known to occur in all
oceans, even though it is purely oceanic and
avoids coastal waters (Vervoort 1965b). It
seems to be absent in the Mediterranean Sea.
Park (1980) found this species as the most
common of the genus in Antarctic and subAntarctic waters during the Eltanin cruises,
from samples collected from the surface to
3750m. According to Park (1980), this
species was more common in Antarctic than
sub-Antarctic waters. It was found in Chilean
areas by Wilson (1942) and Hirakawa (1989).
In the present study, S. minor was more
widely distributed in the Straits of Magellan
than the congeneric species S. dentata. It was
sampled from the surface to 500 m with
maximum abundances from l50-200m at
Pacific stations.
Systematic Account
3.37 Scolecithricella minor
Brady 1883
Scolecithrix minor Brady, 1883: p. 58, pI. 16
figs. 15, 16, pI. 18 figs. 1-5.
Scolecithricella minor Sars, 1903: p. 55, pIs.
37,38 - Mori, 1937: p. 51, pI. 25 figs. 1-7Brodskii, 1950: p. 269, fig. 178 - Park, 1968:
p. 554, pI. 8 figs. 9-12; 1980: p. 31, figs. 2,
3.
Scolecithrix glacialis Giesbrecht, 1902, p. 25,
pI. 4 figs. 1-7.
More complete lists of synonyms of S.
minor and S. glacialis are given in Vervoort
(1956b) and Vervoort (1957), respectively.
Body length -
females: 1.27-1.37mm (15 specimens)
males: 1.27-1.31mm (3 specimens)
Female. Cephalothorax slender, 2.5 times
longer than wide. Head fused with thorax,
narrowly rounded in dorsal view. Rostrum
bifurcated with strong rami. A1 reaching
posterior margin of genital somite. Posterolateral comers of last thoracic somite symmetrical, produced distally, forming an obtuse
angle in lateral view. Proportional lengths of
cephalothorax and abdomen 79: 21; proportionallengths of abdominal somites and furca
39:18:18:8:17 = 100. P5 foliate, 1-jointed;
apical spine short, inner spine longer, serrated; outer margin of joint with smaller
spinule, sometimes appearing as small
tubercle.
Male. Body slender; cephalothorax 2.3 times
longer than wide. Rostrum similar to that of
female. Proportional lengths of cephalothorax
and abdomen 70: 30; proportional lengths of
abdominal somites and furca 16: 26: 20: 25 :
4: 9 = 100. P5 exceeding length of abdomen,
asymmetrical; both legs biramous; right leg
with vestigial endopod. Right exopod with
spatula-like distal joint. Left exopod ending
in "bayonet-shaped" (Brodskii 1950) joint.
Remarks
Scolecithricella minor was originally described
as Scolecithrix minor by -Brady (1883) from
specimens collected in the Indian Ocean.
Sars (1903) accurately re-described this
species from Norwegian-water specimens
and established the genus Scolecithricella to
accommodate it. Park (1980) noted that it is
impossible to distinguish S. minor Brady
from S. glacialis Giesbrecht, 1902, on the
basis of the original descriptions for these
species, and considered S. glacialis as a
junior synonym of S. minor. Brodskii (1950)
distinguished two forms of S. minor mainly
for the shape of the P5 in females: f. orientalis
from the North Pacific and f. occidentalis
from the North Atlantic Ocean. Our specimens are similar to the occidentalis form.
Distribution
Scolecithricella minor is distributed worldwide. This species is known to occur in all
oceans, even though it is purely oceanic and
avoids coastal waters (Vervoort 1965b). It
seems to be absent in the Mediterranean Sea.
Park (1980) found this species as the most
common of the genus in Antarctic and subAntarctic waters during the Eltanin cruises,
from samples collected from the surface to
3750m. According to Park (1980), this
species was more common in Antarctic than
sub-Antarctic waters. It was found in Chilean
areas by Wilson (1942) and Hirakawa (1989).
In the present study, S. minor was more
widely distributed in the Straits of Magellan
than the congeneric species S. dentata. It was
sampled from the surface to 500 m with
maximum abundances from l50-200m at
Pacific stations.