Revista Chilena de Historia Natural 77 (3): 491-500, 2004
RESEARCH ARTICLE
Geographical distribution of the genus Gyriosomus Guérin-Méneville, 1834
(Coleoptera: Tenebrionidae): a biogeographic approach
A parsimony analysis of areas of endemism for the monophyletic genus
Gyriosomus, an eremic and endemic element of the northern coast of Chile, was performed. We tested that: (i)
distributional patterns of Gyriosomus species are determined by environmental heterogeneity, and that (ii) discontinuities
in the distribution of Gyriosomus species will reflect areas of endemism. We identified areas of endemism for
Gyriosomus species, relating them with vegetational formations, and establishing biogeographical patterns among
different ecosystems from northern Chile. The study area corresponded with the distributional limits of the genus from where data on
the presence or absence of 34 species in grid cells half degree longitude by one quarter degree were registered on a matrix. The
analysis was undertaken using NONA 2.0 and Winclada softwares. A strict consensus tree allowed us to establish a pattern of nested
areas for Gyriosomus, where two areas of endemism were recognized; coastal ecosystems of Paposo and Carrizal Bajo.
Taltal coastal desert was determined for G. angustus and G. curtisi and the Huasco coastal desert with
G. planatus and G. kingi. The Huasco coastal desert followed by the coastal steppe shrub ecosystems were
the richest areas in terms of Gyriosomus species. A cladogram revealed disjunction of faunistic components in two
biogeographic units: the coastal desert and the steppe shrub, although several species are widely distributed along the intermediate
depression. The results of this study along with a phylogenetic reconstruction of the genus might explain vicariant events behind the
biogeographic disjunction of Gyriosomus.
Key words:
biogeography,
Tenebrionidae, Gyriosomus, areas of endemism, coastal desert
