Systematic revision of Neotropical Achalcus and a related new genus (Diptera: Dolichopodidae, Achalcinae) with comments on their phylogeny, ecology and zoogeography

Abstract

A revision of the species of the subfamily Achalcinae of the Neotropical region is presented. A new genus, Australachalcus gen. nov., is erected based on the presence of six dorsocentral bristles and synapomorphies in the hypopygium. Eight new Achalcus species (bilineatus, brevicornis, costaricensis, cyanocephalus, maculipennis, micromorphoides, niger, tibialis) and eight new Australachalcus species (acornis, browni, cummingi, incisicornis, pseudorobustus, robustus, setosus, variabilis) are described, and Achalcus albipalpus Parent, A. brevinervis Van Duzee, A. longicornis Van Duzee and Enlinia edwardsae (Van Duzee) are newly referred to Australachalcus and redescribed. A key to males of all species and females of eight species is provided. One Palaearctic species, Achalcus melanotrichus Mik, and nine New Zealand Achalcus species (chaetifemoratus, luteipes, medius, minor, minusculus, minutus, nigroscutatus, relictus, separatus) described by Parent are also transferred to Australachalcus. In Neotropical Achalcinae, three Achalcus and more than four different Australachalcus species groups can be distinguished, whereas all Holarctic Achalcus species belong to the single A. flavicollis species group. In the Neotropics, Australachalcus is nearly entirely confined to Chile, whereas Achalcus is recorded from Costa Rica, Venezuela, Ecuador, Colombia, Peru and Chile, with no or little overlap in distribution between the separate species groups. Beyond Chile, most achalcine species treated here were collected at higher altitudes. Most Chilean species are only active during the southern summer, whereas in Costa Rica achalcine representatives are encountered throughout the year. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 143, 27–73.