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

SERGIO ROIG-JUÑENT; RODOLFO CARRARA; EIDER RUIZ MANZANOS; FEDERICO AGRAÍN; PAULA SACKMANN; MARCELO TOGNELLI

Insect Systematics and Evolution

Scandinavian Society of Entomology

Año: 2007 vol. 38 p. 267 - 292

1399-560X

Four new species of Cnemalobus Guérin-Ménéville, 1838 (Carabidae) from the northern steppe of Patagonia and extra-Andean mountains are described in this work. Two of these species, Cnemalobus nevado sp. n. and Cnemalobus diamante sp. n., are from the Payunia (Argentina), the northernmost region of Patagonia. One species, C. somuncura sp. n., is from the vicinity of the Somuncurá Plateau. The other species, Cnemalobus troll sp. n., is from the northwestern steppe. Illustrations and keys for these new species are provided. The phylogenetic relationships among the new species were defined using a cladistic analysis for the genus Cnemalobus, based on 56 characters of the external morphology and male and female genitalia. The cladogram showed that C. nevado sp. n. and C. diamante sp. n. comprise a monophyletic group that is the adelphotaxon of an apical clade of species that mainly inhabit mountain habitats in central Chile. Cnemalobus somuncurasp. n. and C. troll sp. n. are also sister species and comprise the apical group of the Patagonian species. Cnemalobus nevado and C. diamante occur in the Payunia, and their distribution is restricted to different mountains and are isolated from each other. Given that these two mountains are 200 km apart, it is not likely that dispersal has occurred in these large and flightless species. The ancestral species might have been broadly distributed, and, as a result of habitat changes, they became isolated into restricted habitats in the upper part of each mountain, where speciation might have occurred. 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, showed that the sister species of Cnemalobus have an allopatric distribution. Strict sympatry (same locality) occurs in the northwestern region of the Patagonian Steppe. Nevertheless, this strict sympatry may be an artifact of geographical scale. For example, within the same area, some species may inhabit grasslands next to forests, while other species inhabit only steppe areas.