306
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
Description. Adult female (Fig. 203) total length (from anterior
terminal to tip of caudal ramus) 0.696-0.852 mm (average 0.766 mm),
greatest width 0.216-0.264 mm (average 0.230 mm) ; genital segment
a little wider than long, 0.108 mm x 0-128 mm, with smooth dorsal
surface but with several lateral spines ; ventral surface with two transverse rows of spines across anterior half of segment and with a row of
small spines along its posterior border; abdomen of three segments,
0.045, 0.057 and 0.024 mm long, without spines dorsally but with a
row of small spines ventrally along posterior border of first segment;
first antenna with seven segments, measuring (from base to tip) 0.024,
0.029, 0.013, 0.010, 0.022, 0.011 and 0.019 mm respectively; a sensory
organ on each of three basal segments ; second antenna of three segments,
third segment long and slender, with a sensory organ and a row of
indistinct bristles along interior border, a row of small spines along
basal portion of exterior border, and three thin setae and large recurved claw a t its apex ; segments of first through fourth swimming
legs like those of 0. cluvutor ; spines and setae of exopodites like those
of 0. clavator ; terminal spine on endopodite of first leg semi-gladiate,
with a row of bristles along interior margin; terminal podomere of
endopodite of second leg with a short gladiate spine on external surface,
a long semi-gladiate spine with bristles along internal border, and four
plumose setae exteriorly ; terminal podomere of endopodite of third
leg with three spines and three setae ; terminal podomere of fourth leg
with three external spines, a gladiate seta on its distal half, and a
plumose seta on its medial surface ; terminal spines on podomeres very
long and large, that on terminal podomere of exopodite of fourth leg,
for example, measures 0.056 mm long; second podomere of fifth leg
flattened, 0.098 mm x 0.078 mm, with single spine, 0.022 mm long, on
distal border of external edge and three spines on medial edge measuring
0.011, 0.024 and 0-014 mm respectively; edge of middle podomere
without spines but with small sclerified denticles along medial surface ;
groups of long spines on both edges of basal podomere ; sixth leg absent;
caudal ramus, 0.096 mm x 0.017 mm basally, 0.096 mm x 0.006 mm
distally, with dorsal seta 0.012 mm long and lateral seta about 0.030 mm
long, lateral subterminal seta 0.005 mm long, three terminal setae
0.006, 0.013 and 0.010 mm long ; egg sacs slightly orange, 0.132 mm x
0.070 mm, containing about fifty-five eggs.
Adult male (Fig. 204) with body outline like that of female ; total
length 0.540-0.648 mm (average 0.602 mm), greatest width 0.1440.192 mm (average 0.160 mm); first podomere of first leg distinctly
separated from head ; genital segment somewhat rounded, 0.092 mm
x 0.093 mm, posteroventrally divided, with group of small spines at
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
Description. Adult female (Fig. 203) total length (from anterior
terminal to tip of caudal ramus) 0.696-0.852 mm (average 0.766 mm),
greatest width 0.216-0.264 mm (average 0.230 mm) ; genital segment
a little wider than long, 0.108 mm x 0-128 mm, with smooth dorsal
surface but with several lateral spines ; ventral surface with two transverse rows of spines across anterior half of segment and with a row of
small spines along its posterior border; abdomen of three segments,
0.045, 0.057 and 0.024 mm long, without spines dorsally but with a
row of small spines ventrally along posterior border of first segment;
first antenna with seven segments, measuring (from base to tip) 0.024,
0.029, 0.013, 0.010, 0.022, 0.011 and 0.019 mm respectively; a sensory
organ on each of three basal segments ; second antenna of three segments,
third segment long and slender, with a sensory organ and a row of
indistinct bristles along interior border, a row of small spines along
basal portion of exterior border, and three thin setae and large recurved claw a t its apex ; segments of first through fourth swimming
legs like those of 0. cluvutor ; spines and setae of exopodites like those
of 0. clavator ; terminal spine on endopodite of first leg semi-gladiate,
with a row of bristles along interior margin; terminal podomere of
endopodite of second leg with a short gladiate spine on external surface,
a long semi-gladiate spine with bristles along internal border, and four
plumose setae exteriorly ; terminal podomere of endopodite of third
leg with three spines and three setae ; terminal podomere of fourth leg
with three external spines, a gladiate seta on its distal half, and a
plumose seta on its medial surface ; terminal spines on podomeres very
long and large, that on terminal podomere of exopodite of fourth leg,
for example, measures 0.056 mm long; second podomere of fifth leg
flattened, 0.098 mm x 0.078 mm, with single spine, 0.022 mm long, on
distal border of external edge and three spines on medial edge measuring
0.011, 0.024 and 0-014 mm respectively; edge of middle podomere
without spines but with small sclerified denticles along medial surface ;
groups of long spines on both edges of basal podomere ; sixth leg absent;
caudal ramus, 0.096 mm x 0.017 mm basally, 0.096 mm x 0.006 mm
distally, with dorsal seta 0.012 mm long and lateral seta about 0.030 mm
long, lateral subterminal seta 0.005 mm long, three terminal setae
0.006, 0.013 and 0.010 mm long ; egg sacs slightly orange, 0.132 mm x
0.070 mm, containing about fifty-five eggs.
Adult male (Fig. 204) with body outline like that of female ; total
length 0.540-0.648 mm (average 0.602 mm), greatest width 0.1440.192 mm (average 0.160 mm); first podomere of first leg distinctly
separated from head ; genital segment somewhat rounded, 0.092 mm
x 0.093 mm, posteroventrally divided, with group of small spines at