*THE SYSTEMATIC POSITION OF ORNITHODORUS CROSSI BRUMPT
(1921)
By S. N. SAPRE, B.Sc., G.B.V.C., Research Scholar, Imperial Veterinary Research Institute, Mukteswar
(Received for publication on 5 June 1943)
(With Plates VII and VIII)
THE name Ornithodorus crossi was proposed by
Brumpt [1921] for a species of tick occurring in
the Punjab. In 1930 Pavlovsky, working in
Russia, produced evidence to show that the name
was antedated by O. papillipes Birula. He also
forwarded to Nuttall and Warburton in Cambridge
for examination a consignment of Russian forms
of O. papillipes, and these were found by them to
be identical with O. crossi Brumpt. Brumpt
himself later agreed that O. crossi Brumpt was
synonymous with O. papillipes Birula.
The writer, during the course of his studies on
the morphology of the Indian form of O. papillipes,
found that it lacked certain characters which had
been reported by Pavlovsky [1930] in O. papillipes
and which had been utilized by him in distinguish-
ing the latter from O. cholodkovskyi Pavlovsky
(1930) and O. tholozani (Laboulbene and Megnin
1882). The most important of these characteristics
is the tuft of denticulated hairs arising from the
conical antero-ventral surface of the body in
front of the camerostome. In the Indian form
the male hypostome has nearly parallel sides,
while the female hypostome shows some widening
at the base. In the Russian form, the hypostome
has parallel sides in both sexes. In the two forms
there is also a marked difference in the disposition
of the hypostomal teeth and in the size of the anus,
vulva and basis capituli. The differences
between the two forms are summarized in the
table on the next page.
It will be seen from the table that the Indian
form of O. papillipes differs in several fundamental
characters from the Russian form as described by
Pavlovsky [1930] and should be considered a
separate species and that the name O. crossi should
be regarded as valid. Unfortunately Brumpt's
description [1936] of O. crossi is inadequate, and
the species is therefore redescribed below.
Female. When fed, body dark grey slightly
tinged with green, or slate colour. Unfed speci-
mens, pale yellow. Form, more or less eliiptical,
the anterior end being a little drawn out, forming
a beak-like protuberance. Engorged specimens
measure 5.0 × 4.0 to 9.0 × 5.0 mm. (average
8.0 × 4.5 mm.). The arrangement of the dorsal
dises is as in the Russian form. Corresponding
depressions occur in unfed ticks. The cuticle
shows a reticulate structure with irregular pro-
tuberances interspersed, these being largest margi-
nally; it appears wrinkled in the unfed specimens,
the centre of each mesh of network-pattern
appears (Plate VII, fig. 7) to be occupied by a
single hair.
The arrangement of the furrows on the ventral
surface is similar to that in the Russian form of
O. papillipes. Eyes are absent. The anal ring
measures 0.2 to 0.3 mm., each anal plate bearing
nine to ten hairs. The vulva is 0.65 to 0.7 mm.
wide. The capitulum lies in the camerostome,
with its posterior and lateral margins protruding.
The latter terminate where the slightly movable
' cheeks' begin. The denticulated hairs on the
conical protrusion of the ventral body surface are
absent. There is, however, a tuft of short denti-
culated hairs on the roof of the camerostome, visible
only when the camerostome is raised. The basis
capituli measures 0.5 mm. The hypostome differs
in the sexes, being longer than it is broad in the
male and spatulate with parallel sides. The crown
of small teeth is followed by two rows of big teeth,
the border row consisting of three teeth, the
median one of two only. In the female it is longer
than the base and lanccolate, with a border row
of three teeth and the median row of two only.
In both the sexes, the hypostome has a slightly
bulging end. Two long hairs arise at the sides
of the hypostomal base, as in all Argasidae.
Plate VII, fig. 6 shows the lateral view of the
palp, with its dense growth of fine, smooth hairs.
The articles show different relative lengths, parti-
cularly article No. 1 which is longer than that in the
Russian form. The structure of the cuticle re-
sembles that of O. tholozani (Plate VII, fig. 7, and
Plate VIII, fig. 2). Tarsus 1 has a wavy dorsal
contour, the dorsal spur not being as pointed as
in the Russian form (Plate VIII, fig. 8). The
Haller's organ is clongate oval. T. 4 has practi-
cally no papillao on the ventral border, and
of O. papillipes. Male : size 4.5 × 2.5 to 5.5 ×
3.0 mm. (average 5.0 × 2.8 mm.). The hypostome
is shorter than in the female and has smaller teeth.
* Paper read under the title, ' Ornithodorus crossi Brumpt [1921] as a valid species and not a synonym of
Ornithodorus papillipes Birula (1895)', at the 26th session of the Indian Science Congress 1939. Revised and re-
written.
54