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

Chapter 4. Species of Ticks.
This page describes Steps 2 and 3 of identifying ticks. Information
on geographical distribution of ticks can be very helpful
for identifying ticks. Step 2 therefore uses the data on the distribution
of ticks in Africa given in the map below and the table
overleaf to indicate to the user which species a tick is likely to
be, according to the area in which it was collected. Step 3 uses
the drawings of female and male ticks belonging to 48 species
of ticks that infest domestic animals to find the correct species.
The 48 species of ticks are presented in alphabetical order of
genus and species within each genus. However, the sub-genus
Boophilus is listed separately at the start of the section on Rhipicephalus
genus in which it now belongs. There are also four
species partially described in conjunction with the main 48 species.
We have followed the naming of ticks given in the Ticks of
the World by Camicas et al. (1998), with recent revisions listed
in Horak et al. (2002). With each full description of each species,
the author and date for the original description is given. If
this is in parentheses ( ) it indicates that the original description
has been revised at a later date. For each illustration there is a
selection of the characters and their states relevant to that illustration.
Some comments are in parentheses to indicate either
modifications of the basic description of the character state or
to provide additional information other than the character states.
Step 2 of identification - which geographical area?
When you know the genus to which your tick belongs (see Chapter
3) consult the map below which shows Africa divided into
seven areas relevant to tick distribution. Then consult the table
overleaf showing the distribution of ticks in different areas of
Africa and find the column that lists the ticks from the same
area as your tick. These ticks are candidate species for your
tick. To confirm which of these species are found in the country
in which you found your tick, check the distribution and host
data in their species profiles. This step should help to reduce to
the minimum the number of tick species you have to consider.
Please note that the maps are intended only as an aid to identification;
they are derived from confirmed records and expert opinion
but are not supported here by the original references so they
should not be used as definite statements of tick distribution.
Step 3 of identification - which species?
When you have selected candidate species for your tick go to
the illustrations of these species. Compare your tick with the
drawings of these species of the relevant sex. The labels below
the drawings list the unique combinations of character states
that identify a tick species. Character states are sometimes difficult
to see or too variable to be sure of. For this reason it is
important to check the specimen for the complete list of character
states given. Important note: it is the unique combination
of character states that defines a species and that needs to be
checked against your specimen. For very similar species there
will be only one or two differences in the combination of the
character states. At this stage you will find it helpful to read the
Areas of Africa relevant to tick distribution.
NORTH
SAHARA & SAHEL
45
section on differential diagnosis in the species profiles of the
species you are considering. Once you have chosen a possible
identification for your specimen, compare what you know about
your specimen with the species profile of your chosen tick species.
Check the information on biology, hosts and distribution of
the tick. Do not identify a specimen to species unless it fits the
majority of character states listed; it may not be described here.
An example of Steps 2 and 3.
Suppose you are in Morocco and have made a collection there
of ticks from cattle. You have gone through Step 1 and the information
in Chapter 3 to identify the specimen as belonging to
the genus Rhipicephalus, but not in the sub-genus Boophilus.
Step 2 consists of consulting the map below of tick distribution
areas for the name - North Africa. Then in the table overleaf, in
the column for North Africa you will find the following species
of Rhipicephalus listed: Rh. bursa, Rh. camicasi, Rh.
praetextatus, Rh. sanguineus and Rh. turanicus. Step 3 takes
you directly to the species profiles and drawings of these five
species only. When you check the biological information in the
species profiles you will find that Rh. praetextatus has never
been recorded from Morocco. Rhipicephalus sanguineus is only
rarely found on cattle. Rhipicephalus bursa is a very distinctive
Rhipicephalus species, as shown in the drawings. Suppose your
tick is clearly not Rh. bursa, then finally concentrate on comparing
your specimens against the drawings and labelled character
states for the differences between Rh. camicasi and Rh.
turanicus, but also consider that it could be Rh. sanguineus if
dogs were present.
WEST NORTH EAST
CENTRAL
SOUTHERN
EAST