Systematic Parasitology 53: 101–107, 2002. © 2002 Kluwer Academic Publishers. Printed in the Netherlands. 101 A new subfamily, Bothriocrotoninae n. subfam., for the genus Bothriocroton Keirans, King & Sharrad, 1994 status amend. (Ixodida: Ixodidae), and the synonymy of Aponomma Neumann, 1899 with Amblyomma Koch, 1844 Hans Klompen 1 , Susan J. Dobson 2 & Stephen C. Barker 2 1 Acarology Laboratory, Department of Entomology, Ohio State University, Columbus, Ohio 43212-1192, USA 2 Department of Microbiology and Parasitology, and Institute for Molecular Biosciences, University of Queensland, Brisbane, 4072 Queensland, Australia Accepted for publication 21st February, 2002 Abstract Evidence suggesting polyphyly of the traditionally recognised tick genus Aponomma Neumann, 1899 is summa- rized. Continued recognition of this genus in its current concept leaves a polyphyletic genus Aponomma and a paraphyletic genus Amblyomma Koch, 1844. To improve the correlation between our understanding of phyloge- netic relationships in metastriate ticks and their classification, a few changes in classification are proposed. The members of the ‘indigenous Australian Aponomma’ group (sensu Kaufman, 1972), A. auruginans Schulze, 1936, A. concolor Neumann, 1899, A. glebopalma Keirans, King & Sharrad, 1994, A. hydrosauri (Denny, 1843) and A. undatum (Fabricius, 1775), are transferred to Bothriocroton Keirans, King & Sharrad, 1994, which is raised to full generic rank. The remaining members of Aponomma are transferred to Amblyomma. Uncertainty remains on relationships of Bothriocroton to other metastriate lineages and on the systematic position of the two species formerly included in the ‘primitive Aponomma’ group, A. elaphense Price, 1959 and A. sphenodonti Dumbleton, 1943. Introduction Generic classification in the hard ticks, family Ixo- didae, has been remarkably stable over the last 50 years. Although a few new genera have been proposed (Anomalohimalaya Hoogstraal, Kaiser & Mitchell, 1970, Dermacentonomma Dias 1978); only Anomalo- himalaya is generally recognised. Apart from some discussion on the validity of Anocentor Schulze, 1937, as part of, or separate from, Dermacentor Koch, 1844 (e.g. Borges et al., 1998; Crosbie et al., 1998), ixodid classification has not really been challenged. However, a recent upsurge in interest in tick systematics, fuelled in part by the use of more rigid methodology and the addition of molecular data sets, is prompting a re- assessment of ixodid generic classification. One of the most challenging problems involves Aponomma Neu- mann, 1899. Neumann (1899) created this genus for ticks of reptiles with the following characteristics: ‘Pas d’yeux. Base du rostre ordinairement pentagonal, à bords latéraux très courts du côté dorsal. Palpes longs’ (Neumann, 1899, p. 180). Of these characteristics the shape of the basis capituli and the long palps are shared with, respectively, most and all Amblyomma, leaving the lack of eyes as the defining character for Aponomma. Although some authors (Camicas & Morel, 1977; Nuttall & Warburton, 1911) suggested that its constituent species should be included in Am- blyomma Koch, 1844, most recent studies have recog- nized Aponomma at the generic level (Dias, 1993; Filippova, 1997; Keirans, 1992; Keirans & Rob- bins, 1999). The main motivation for recognition of Aponomma as a genus separate from Amblyomma appears to be common usage, rather than phyloge- netic relationships (Camicas & Morel, 1977). A close relationship between Aponomma and Amblyomma is acknowledged by the grouping of the two genera in the subfamily Amblyomminae (see Hoogstraal &