Phylogenetic relationships and biogeographic considerations of four new species of Cnemalobus (Coleoptera: Carabidae) from Patagonia

ROIG JUÑENT, SERGIO; CARRARA, R.; E. RUIZ MANZANOS; AGRAIN, F.; SACKMANN, P.; TOGNELLI, M.

Insect Systematic and Evolution

Brill, Leiden, The Netherlands

Lugar: Copenhagen; Año: 2007 vol. 38 p. 267 - 292

1399-560x

ABSTRACT. New species of Cnemalobus Guérin-Ménéville (Coleoptera: Carabidae) their phylogenetic relationships, and considerations about a possible pattern of speciation. New prospections in the northern steppe of Patagonia and extra-Andean mountains reveal the presence of several new species of insects, some newly described carabids among them. Four new species of Cnemalobus Guérin-Ménéville are described in this work, two from the most northern region of Patagonia, the Payunia (Argentina): Cnemalobus nevado sp. n. and Cnemalobus diamante sp. n., one from the vicinity of  Somuncurá plateau: C. somuncura sp. n., and one from the northwestern steppe: Cnemalobus troll sp. n.. Illustrations and keys for the identification of these new species are provided. In order to establish the phylogenetic relationships of the new species a cladistic analysis is performed for the genus Cnemalobus based on 56 characters of the external morphology and male and female genitalia. The cladogram shows that C. nevado sp. n. and C. diamante sp. n. constitute a monophyletic group that is the adelphotaxon of an apical clade of species mainly inhabiting mountain habitats in central Chile. Cnemalobus somuncura sp. n. and C. troll sp. n. are also sister species and constitute the apical group of the Patagonian species. Cnemalobus nevado and C. diamante occur in northern Patagonia, the Payunia, and have a restricted distribution in mountains that are isolated from one another. It is not possible to establish a dispersal pattern from one mountain to the other for the big and apterous Cnemalobus species, since these mountains are at least 200 km apart. The ancestral species might have been broadly distributed and due to habitat changes got isolated and stayed in restricted habitats at the upper regions of each mountain where speciation happened. The other two new species, C. somuncura and C. troll, are placed in the group of Patagonian species that inhabit the lowlands or plateaus. Distributional data, together with phylogeny, show that the sister species of Cnemalobus have allopatric distribution. Strict sympatry (same locality) occurs in the northwestern region of the Patagonian steppe. Nevertheless, ecological studies show that sometimes this strict sympatry is a problem of geographical scale, since in the same place some species are more associated with grasslands next to forests, while others inhabit strictly steppe areas. KEY WORDS. Carabidae. Cnemalobus. Phylogeny. patagonian steppe Pattern of distribution.