Ticks of Domestic Animals in Africa - Alan R Walker - Science Writer

10
Caudal to Chelicerae
Caudal depression: in Hyalomma males the posterior of the conscutum
may be broadly convex (caudal depression is absent) or it may be
broadly concave (caudal depression is present).
Central festoon: festoons are a regular series of bulges in the posterior
margin of many adult ixodid ticks. The central festoon may also be
called the parma. It is pale coloured, or dark coloured.
Cervical fields depression: cervical fields are areas on the scutum or
conscutum, below and lateral to the cervix (neck). At the points closest
to the cervix they have cervical pits. These fields may have a depression
which is not apparent relative to the surface of the scutum, or
conscutum, or the field has a depression which is apparent.
Cervical fields shape: in Rhipicephalus females the cervical fields are
usually apparent as paired depressions (marked by an asterisk on the
illustrations) on either side of the intercervical field. The outer scapular
grooves and inner cervical grooves at their margins form the characteristic
shapes of the cervical fields. The fields are either absent or
small, or large and curved, or large and straight.
Cervical field texture: the cervical fields are the paired depressions
on either side of the centre of the scutum or conscutum. In female and
male Rhipicephalus the surface may have a characteristic texture in
addition to the punctations. This texture is formed in the flat integument
between the punctations. There are either no wrinkles, or wrinkled
areas occur. (Other names for various states of these wrinkles are
shagreen, reticulation and rugosity.)
Cervical grooves: these are paired depressions near the central anterior
part of the scutum of both sexes, they go down from the raised
intercervical field into the cervical fields. (Also known as mesial
grooves.)
Chelicerae: paired structures of the mouthparts. They are within a
cheliceral sheath and are long moveable rods with teeth at the end which
cut into the skin of the host. In Rhipicephalus (Boophilus) species it is
important not to mistake the cheliceral teeth for the columns of teeth
on the ventral surface of the hypostome which need to be counted to
differentiate species.