Morphometric study of the species <i>Hypocoprus latridioides</i> Motschulsky, 1839 and <i>H. quadricollis</i> Reitter, 1877 (Coleoptera: Atomariinae)

Phenotypic variability is an observable characteristic of all animal species. Somatometric studies aid assessment of the extent to which the observed variability should be considered intraspecific, as opposed to interspecific and thus of value for species discrimination (Prat 1985). Furthermore, they can reveal geographic patterns of morphometric variation (Casteig & Escala 1988), and in some cases — in comparisons of populations of sympatric species — detect niche variation (Martin Cantarino & Seva Roman 1991). It is thus not surprising that numerous studies of this type exist in the literature (e.g. Bach & Cardenas 1985, Cardenas et al. 1998, Desender & Crappe 1983, Prat 1985, Savage & Saponis 1983, Reyes 1986). In the genus Hypocoprus, there is some uncertainty as regards the taxonomic status of the species H. latridioides Motschulsky, 1839 and H. quadricollis Reitter, 1877. Some authors argue for their consideration as two separate species (Reitter 1911, Jansson 1940), while others consider them as synonyms (Vogt 1967, Silfverberg 1992, Jelinek 1993). Reitter (1911) distinguishes between the two on the basis of pronotum-toelytron length ratio, while Jansson (1940) adds other diagnostic characters: pilosity coloration and thickness, and geographic distribution (H. latridioides in Finnish and Swedish Lapland, H. quadricollis in southern Scandinavia, France and Madeira). The present study is a morphometric analysis of specimens collected in Finnish and Swedish Lapland, southern Sweden, Siberia, and central and southern Europe, with the aim of assessing patterns of variation and identifying possible species groups. In addition, a new description of H. latridioides Motsch. is provided, since the existing description is incomplete.