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A New Parasite, M. Ovocaudatum
The testes, two in number, are reniform with tri-lobed outer and regular
inner margins. They are situated almost symmetrically in front of the pos-
terior third of the body, overlapping the caeca. The right testis, 0.7 × 0.3,
is slightly larger than the left which measures 0. 58 × 0. 36 in size. The vesi-
cula seminalis lies to the right of the acetabulum and consists of a long, fairly
broad tube with three or four constrictions and twists. It extends from a
little behind the acetabulum to about one-third the distance between the
acetabulum and intestinal bifurcation. Anteriorly it continues into a small,
ill-defined, pars prostatica with a few prostate glands and a wide ductus ejacu-
latorius. The latter joins the terminal part of the uterus to form a small
genital sinus which opens in the median line, close in front of the acetabulum.
Both the genital pore and the acetabulum lie in a small depression on the
ventral body surface to which are attached a few feebly developed retractor
muscles.
The ovary measures 0.5 × 0. 52 in size and consists of a large number of
pear-shaped follicles, arranged radially in a spherical mass in the median line
a little anterior to the testes. The receptaculum seminis, 0.22 in diameter,
is a small, spherical, thin-walled sac, situated a little in front of the ovary.
A small Laurer's canal is given off from the duct of the receptaculum seminis.
The vitellaria consist of a large number of small, irregular follicles which ex-
tend from the anterior margin of the testes to the first quarter of the body
length, without meeting in the median line. The shell gland complex lies
in the space between the ovary, receptaculum seminis and the left body wall.
The uterus extends, in transversely coiled descending and ascending arms,
from the acetabulum to a little distance in front of the blind ends of the caeca.
Laterally it extends up to the body wall. The eggs are roughly triangular
in shape, operculate and measure 0. 015—0. 023×0. 0076—0. 01 in size.
They possess a fairly long polar filament at the aoperculate end. The excre-
tory bladder is Y-shaped.
Of all the genera of the family Acanthostomidae, Mehrailla ovocaudatum
gen. et. sp. nov., in its affinities stands nearest to Paracryptogonimus acanthos-
tomatus Yamaguti [1934]. It resembles the latter genus somewhat in the
topography of the gonads, shape of ovary, extent of uterus, the presence of
a genito-acetabular depression, presence of cutaneous gland cells and similar
digestive and excretory systems. It, however, differs remarkably from the
Japanese genus in the absence of oral spines, presence of receptaculum seminis,
anterior extent of vitellaria, position of testes, vesicula seminalis and genital
pore and the presence of a well-developed filament at the aoperculate end of
the egg.
GENERIC DIAGNOSIS
Body medium-sized, muscular, fusiform and spinose. Oral sucker sub-
terminal, larger than acetabulum which lies at about the first third of the body
length. Prepharynx and pharynx well -developed, oesophagus small; caeca
simple, broad, nearly reaching the hinder end. Testes two, reniform, lobed,
nearly symmetrical, overlapping caeca, situated in front of posterior third