Systematic & Applied Acarology
ISSN 1362-1971
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 ticks Ixodes holocyclus Neumann, 1899 and I. cornuatus Roberts, 1960 (Acari : Ixodoidea)


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


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Last updated 15 Jul. 2002
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