Biology Reference
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the basis capitulum. Segments 2 and 3 may have basodorsal and/or basoventral ret-
roverted spurs. These palpal segments are important from the identification point
of ticks especially in Haemaphysalis.
The adults are provided with four pairs of legs, which are attached to idiosoma
ventrally by immovable coxae. Each leg has six segments, namely coxa, trochanter,
femur, tibia, metatarsum, and tarsus. A pair of claws and median pad or pulvillus is
attached to the posterior side of the tarsus. Larvae have only three pairs of legs. A
sensory organ called Haller's organ is situated dorsally on the tarsus of leg no. 1.
The Haller organ consists of the posterior capsule and an anterior pit. This organ is
unique and is believed to be olfactory in nature.
Body parts of typical male and female hard ticks, including various parts of
capitulum are given in the illustrations below. Terminology used for these illustra-
tions has been used throughout this topic.
1.3 Tick Genera in India 3,86
The family Ixodidae includes 13 genera comprising approximately 650 species
known from all over the world. In India a total of 88 species belonging to the
following seven genera have been recorded.
Genus Ixodes
This is the largest genus in the family Ixodidae containing 245 species , of which
only 11 are known to occur in India. Ixodes are inornate ticks. The capitulum of
the female is considerably longer than that of male. There are no eyes or festoons.
The anal groove is placed anteriorly to the anus, whereas in all other genera the
anal groove is posterior to the anus. In the male there are seven ventral plates. In
India Ixodes species are known to occur in forests with heavy rainfall. They are
known to mate off the hosts. They are generally three-host ticks.
Genus Haemaphysalis
At present 155 Haemaphysalis species are known throughout the world, of which
41 have been recorded in India and one new species is proposed in this topic. These are
small inornate ticks with short mouthparts, that is, brevirostrate. The basis capitulum is
rectangular and the base of the second palpal segment is expanded, projecting laterally
beyond the basis capitulum. The second and third palpal segments taper anteriorly so
that the capitulum anterior to the basis capitulum appears to be triangular. There are
no eyes in either sex. Festoons are present. They are generally three-host ticks.
Genus Dermacentor
These are usually ornate, brevirostrate ticks. There are 30 species known from
all over the world of which three occur in India. The basis capitulum is rectangular
dorsally. Coxa IV is greatly enlarged in the male, which has no ventral plates.
They are generally three-host ticks.
Genus Nosomma
These are brevirostrate ticks with short palps. This genus comprises a single spe-
cies N. monstrosum, which has been recorded from India and Southeast Asia. This
is a three-host tick.
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