Phylogeny of carabid beetles as inferred from 18S ribosomal DNA (Coleoptera: Carabidae) DAVID R. MADDISON, MICHAEL D. BAKER and KAREN A. OBER Department of Entomology, University of Arizona, Tucson, Arizona, U.S.A. Abstract. The phylogeny of carabid tribes is examined with sequences of 18S ribosomal DNA from eighty-four carabids representing forty-seven tribes, and ®fteen outgroup taxa. Parsimony, distance and maximum likelihood methods are used to infer the phylogeny. Although many clades established with morphological evidence are present in all analyses, many of the basal relationships in carabids vary from analysis to analysis. These deeper relationships are also sensitive to variation in the sequence alignment under different alignment conditions. There is moderate evidence against the monophyly of Migadopini + Amarotypini, Scaritini + Clivinini, Bembidiini and Brachinini. Psydrini are not monophyletic, and consist of three distinct lineages (Psydrus, Laccocenus and a group of austral psydrines, from the Southern Hemisphere consisting of all the subtribes excluding Psydrina). The austral psydrines are related to Harpalinae plus Brachinini. The placements of many lineages, including Gehringia, Apotomus, Omophron, Psydrus and Cymbionotum, are unclear from these data. One unexpected placement, suggested with moderate support, is Loricera as the sister group to Amarotypus. Trechitae plus Patrobini form a monophyletic group. Brachinini probably form the sister group to Harpalinae, with the latter containing Pseudomorpha, Morion and Cnemalobus. The most surprising, well supported result is the placement of four lineages (Cicindelinae, Rhysodinae, Paussinae and Scaritini) as near relatives of Harpalinae + Brachinini. Because these four lineages all have divergent 18S rDNA, and thus have long basal branches, parametric bootstrapping was conducted to determine if their association and placement could be the result of long branch attraction. Simulations on model trees indicate that, although their observed association might be due to long branch attraction, there was no evidence that their placement near Harpalinae could be so explained. These simulations also suggest that 18S rDNA might not be suf®cient to infer basal carabid relationships. Introduction Carabidae, with more than 30 000 described species (Reichardt, 1977), is one of the largest families of organisms, and includes almost all terrestrial members of the suborder Adephaga. Most of these beetles belong to the subfamily Harpalinae (sensu Erwin, 1985), a relatively recent radiation (Cretaceous to Recent; Ponomarenko, 1992) which contains the most speciose carabid clades, especially in tropical regions. Although most non-harpaline tribes have relatively few species (more than half of the tribes have sixty or fewer species, Kryzhanovskiy, 1976), they represent the breadth of phyloge- netic diversity within the family. Many of these tribes appear to be remnants of early radiations in the Triassic and Jurassic (Ponomarenko, 1992). The pattern of these early radiations is the focus of this paper, which examines relationships of carabid tribes outside of Harpalinae. A suite of exoskeletal characters has traditionally been used to infer phylogenetic structure within carabids (Jeannel, 1941; Ball, 1979; Kavanaugh & Erwin, 1991). The most recent common ancestor of carabids is thought to have had a mandible with a scrobal seta, procoxa open behind (not R Correspondence: David R. Maddison, Department of Entomology, University of Arizona, Tuscon, AZ 85721, U.S.A. Fax: +1 520 621 1150. E-mail: beetle@ag.arizona.edu # 1999 Blackwell Science Ltd 103 Systematic Entomology (1999) 24, 103±138 Systematic Entomology (1999) 24, 103±138