400
Amphistomatous Parasites of Indian Food Fishes
The body is plump, elongated, with convex dorsal and concave ventral sur-
faces. There are no cuticular spines but cutaneous gland cells are well deve-
loped, specially along the sides. In permanent mounts the body measures
2.5 to 4.76* in length and 0.9 to 1.44 in maximum breadth which occurs at
about the middle of the body. The oral sucker is an oval structure of
0.3—0.34 × 0.18—0.22 in size and opens subterminally on the ventral surface.
It is followed by a long, tubular and characteristically coiled oesophagus
measuring 1.8 to 3.0 in length and 0.1 to 0.14 in width. It is surrounded
by prominent gland cells all along its course. The oesophageal bulb is well
developed and measures 0.26—0.28×0.22—0.24 in size. The intestinal
caeca are two elongated oval structures of 0.66—0.94×0.4—0.44 in size
extending posteriorly almost up to the base of the middle fifth of body
length. The acetabulum is situated on the ventral surface a little removed
from the posterior end and is of 0.36—0.5 in diameter.
The testes, two in number, are obliquely situated, but at times they are
found overlapping each other. The posterior testis, 0.42—0.48×0.38,
lies usually in level with the acetabulum. The anterior testis, 0.38—0.54
×O.42—0.58, lies obliquely in front of the posterior testis and partly over-
lapping the latter. The vesicula seminalis is a fairly long, wide tube of
0.5—0.56 × 0.12—0.18 in size and is divided into two parts by a constriction.
It opens anteriorly into a small, swollen, pars prostatica of 0.1—0.16× 0.08
—0.1 in size, which is surrounded by numerous prominent and closely aggre-
gated prostate gland cells. The ductus ejaculatorius is a 0.1—0.14 broad
tube of 0.22—0.3 in length and is lined internally with irregular, cuticular
plaques. The genital sinus is a peculiar, spherical, eversible structure of
0.42—0.6×0.3—0.5 in size, with its mouth guarded by several fairly broad,
triangular, chitinous processes. The genital pore lies in level with the middle
of the intestinal caeca.
The small, spherical ovary of 0.12—0.2 in diameter occupies varying
positions in the neighbourhood of the anterior testis. It is usually situated
obliquely in front, but may be lateral or partly overlapping the anterior
testis occasionally. The receptaculum seminis, 0.34—0.48×0.12—0.26,
lies between the ovary, anterior testis and the body wall. A small Laurer's
canal is present. The vitellaria consist of a large number of oval follicles
arranged in the form of an inverted U, extending from half the distance
between the anterior end and the posterior extremity of the intestinal caeca
to a little distance beyond the latter. The follicles never overlap the
intestinal caeca. The vitelline ducts are as in the type species. The uterus
is confined to the space between the testes and the intestinal caeca. Rarely
it may extend to the hinder level of the posterior testis. The eggs are
numerous and measure 0.076—0.087×0.041—0.049 in size.
Of the two hitherto recorded species of the genus Gyliauchen, G. ozakii,
n. sp. resembles the type species in the general shape of body, topography of
the gonads, peculiarities of the digestive system, course of the vitelline ducts
*All measurements are in mm.