A reappraisal of the 'fracticornis–opacicollis' taxonomic complex of the genus Onthophagus Latreille using allozymes (Coleoptera, Scarabaeoidea)

The present taxonomic status of the so called fracticornis–opacicollis complex of the genus Onthophagus , Onthophagus fracticornis (Preyssler, 1790), Onthophagus similis (Scriba, 1790) and Onthophagus opacicollis Reitter, 1892 is still controversial. Discrepancies mainly involve the status of O. similis and O. opacicollis . A genetic analysis of nine populations of this complex using eight loci is presented, indicating that: (i) O. fracticornis is a good species, and (ii) the genetic distances between O. opacicollis and O. similis populations as a function of the biogeographic scenery (allopatry versus sympatry), indicate that they are not completely reproductively isolated across their entire geographic range, thus suggesting a still unfinished speciation in different areas. The data demonstrate both the existence of some gene flow between O. opacicollis and O. similis in one place ('El Barraco'; Central Spain) and isolation in others ('S^a Nevada'; South-east Spain). Geographic areas hosting populations of both taxa with intermediate genetic distances ('Doñana'; South-west Spain) also exist in the Iberian Peninsula.