An international journal of the Systematic and Applied Acarology Society, published since 1996
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Systematic & Applied Acarology (2002) 7, 91-108
Morphological comparison of the adult and larval stages of the Australian ticksIxodes holocyclus Neumann, 1899 and I. cornuatus Roberts, 1960 (Acari : Ixodoidea)
J. JACKSON, I. BEVERIDGE, N.B. CHILTON, R.H. ANDREWS * & B. DIXON *
Department of Veterinary Science, University of Melbourne, Parkville, Victoria 3052,
*Department of Environmental Studies, University of Adelaide, South Australia 5000, Australia
Morphological methods of distinguishing the adult and larval stages of the ticks Ixodes cornuatus and I.
holocyclus were examined, using specimens whose identity had been determined using multilocus enzyme
electrophoresis. Individual morphological characters identified most, but not all specimens. The only character
which unequivocally distinguished males of the two species was the shape of the epimeral plate. Statistical
analyses of metric characters revealed significant differences between the two species and among populations
of I. holocyclus. However, no single metric character permitted unequivocal identification of all specimens.
Discriminant function analyses were employed, resulting in the differentiation of all specimens of both males
and females of the two species. In the larval stages, the numbers of marginal dorsal setae and supplementary
setae, as well as the lengths of posterior marginal dorsal setae, allowed identification of the two species. The
results highlight the advantages of utilising morphological methods in conjunction with genetic techniques to
provide markers for accurate identification and characterisation in instances in which taxonomic confusion
Key words: Ixodes holocyclus, Ixodes cornuatus, identification, discriminant functions
Copyright 1999-2002 Systematic and Applied Acarology Society
Last updated 15 Jul. 2002
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