Four New Diclidophorid Gill Parasites — Unnithan 
89 
from the base of the damp to the center of the 
haptor. Clamp structure (Figs. 19 and 20) more 
or less that of Choricotyle elongata (Goto) 
Llewellyn, 1941, but in a higher stage of evolu- 
tion; median spring very broad and distally ex- 
panded horizontally so as to provide articulation 
for the lateral jaw sclerites; distal half of clamp 
with numerous transverse cuticular thickenings, 
basal half of the clamp capsule with a large 
bilobed muscular pad to which are connected 
the axial fibers of the peduncles, and the lip 
of the clamp capsule is fleshy and glandular. 
Terminal lappet and anchors absent. 
Testes 19-22, small and spherical, 21-42 g, 
in diameter, and confined to the small intercaecal 
area between the ovary and the posterior crural 
confluence; vas deferens long and narrow, arises 
from the anterior row of the testes, runs forward 
ventrally along the median plane and opens into 
the male genital pore; male genital pore median 
ventral, situated at the level of intestinal bifurca- 
tion and armed with a circlet of eight small, 
elongately conical, cuticularized spines converg- 
ing to the center of the pore (Fig. 21); each 
spine with a fleshy basal cushion embedded in 
the circular rim of the pore; penis and cirrus 
absent. 
Ovary median, highly convoluted (Fig. 22), 
curved at right angles to the long axis of the 
body, and occupying an area 168 X l68g-315 X 
210 g of the intercrural space in front of the 
testes; proximal ovary slightly lobed on the 
right side of the median line close to the ootype; 
oviduct arises from the distal end of the ovary 
and runs obliquely backward to open into the 
vitelline ampulla; uterus arises from the an- 
terior end of the vitelline ampulla, proceeds 
ventrally along the median plane parallel to the 
vaginal duct, and is traceable up to the mass of 
gland cells surrounding the vaginal region; egg 
spindle-shaped and operculate, operculum 21 g 
long and 42 g broad, body 210 X 63 g, anterior 
filament 126 g long, and posterior filament 168 
H long. 
Vitellaria coextensive with the crura and its 
branches from the level of intestinal bifurcation, 
and terminates slightly in front of the intestinal 
confluence; follicles large and spherical, 21 g in 
diameter, not confluent posteriorly. Transverse 
vitelline ducts almost empty; median vitelline 
duct large and filled with vitelline follicles, in 
irregular dilatations especially at the anterior 
end, posteriorly the median vitelline duct opens 
into the vitelline ampulla; vitelline ampulla 
small, oval, or spherical and slightly embedded 
in the anterior margin of the receptaculum 
seminis, into which it opens. 
Ootype apparently absent, but a genito- 
intestinal canal is present, which arises from the 
right posterior margin of the receptaculum 
seminis, runs obliquely forward, and opens into 
the right intestinal crus (Fig. 22 ). 
Vagina median dorsal and unarmed, situated 
in the angle of intestinal bifurcation, and sur- 
rounded by a cluster of deeply staining small 
spherical gland cells (Figs. 17 and 18) which 
almost obliterate the vaginal opening; vaginal 
duct median dorsal, runs backwards as a straight 
tube, and opens into the receptaculum seminis; 
the receptaculum seminis is median, irregularly 
oval, 84 X 36 g, and situated close to the pos- 
terior margin of the ovary. 
HOST: Opisthopterus turdoore ( Cuv. ) , on 
the gills and inner opercular wall. 
LOCALITY: Trivandrum (southwest coast of 
India). Seven specimens, three collected on 22 
December 1954, and four on 26 July 1955. 
DISCUSSION 
The genus Keralina closely resembles Chori- 
cotyle Van Ben. and Hesse, 1863, but differs in 
the shape of the body disposition of the clamps 
and in the structure of the clamp sclerites. More- 
over, terminal lappet and anchors are absent. Of 
the various species of Choricotyle, the recently 
recorded American species Choricotyle aspina- 
chorda Hargis, 1955, shows the closest resem- 
blance to Keralina opisthopterus. They resemble 
each other in the shape of the body and the hap- 
tor, but differ markedly in the distribution of the 
testes and ovary. Keralina closely resembles 
Cyclohothrium Cerf., 1895, in the arrangement 
of the clamps, but the par- and pre-ovarian testes 
of Cyclohothrium are absent. Moreover, the size 
and relative position of the testes, the convoluted 
condition of the ovary, and the comparatively 
large size of the receptaculum seminis clearly 
distinguish the present species from Cyclo- 
