Cryptic species diversity and character congruence: review of the tribe Anthracini (Diptera : Bombyliidae) in Australia

doi:10.1071/IT97019

Cryptic species diversity and character congruence: review of the tribe Anthracini (Diptera : Bombyliidae) in Australia

David K. Yeates and Christine L. Lambkin

Abstract

The Australian Anthracini are revised. In all, 28 new species are described, bringing the total fauna to 34 species. The previously described species of Anthrax Scopoli – A. maculatus Macquart, A. incomptus Walker, A. confluensisRoberts, A. lepidiotus Roberts and A. proconcisus Hardy – are diagnosed and the following eight new species of Anthrax are described: A. argentia, A. asciculus, A. clinatus, A. crenatus, A. dolabratus, A. funestus, A. opacus and A. torulus. This taxonomic study reveals a group of at least 20 cryptic species previously included in collections under the name Anthrax angularis Thomson. A new genus, Thraxan, is erected to contain this cryptic group of species and the following 20 new species are described: T. acutus, T. abditus, T. caligneus, T. cinctus, T. cornuatus, T. depressus, T. echinatus, T. ebenus, T. emicatus, T. hamulus, T. luteus, T. misatulus, T. nodus, T. norrisi, T. obstipus, T. patielus, T. planus, T. prolatus, T. simulatusand T. spiculus. Many of these cryptic species have been collected sympatrically, hill topping together in eastern Australia. A key is provided to the species of Anthrax and Thraxan, genitalia drawings are presented for most species and distribution maps of all species are presented. A cladistic analysis of the species of Anthrax and Thraxan is also presented. A total of 26 of the species is compared for 125 synapomorphies in 39 adult morphological characters. Three species-groups were found: Thraxan, and two species-groups within Anthrax, the A. proconcisus species-group and the A. maculatusspecies-group.

Previous authors divided Anthrax into species-groups on the basis of wing patterns, but found that these species-groups were not confirmed when other characters were taken into consideration. We studied the congruence of seven different character sets within the clade comprising Anthrax and Thraxan – antennae, venation, wing patterns, vestiture, genitalia, male genitalia and female genitalia – using several incongruence indices. Significance of incongruence was measured using a randomisation procedure. Results of these studies indicate that the wing-pattern character set is significantly incongruent with the other morphological data. These quantitative cladistic results explain the difficulty previous authors experienced in finding suites of characters to support species-groups in Anthrax on the basis of wing patterns. A relationship is found between the level of incongruence and the distance over which mate-recognition signals operate.