Taxonomic study on the montanellus species-group of genus Cyclommatus (Coleoptera: Lucanidae) from Borneo Island, Malaysia and Indonesia

Abstract Cyclommatus Parry, 1862 is a genus in the family Lucanidae that consists of 62 species. In this study, six species of the montanellus species group in the genus Cyclommatus Parry from mountainous regions in Borneo Island were recognized and reviewed. Taxonomic redescription, one changed status, and key to male species were provided for the first time in this group. As a result, the following six species are reviewed: Cyclommatus montanellus Mollenkamp, 1904; Cyclommatus magnificus Nagel, 1926 stat. rev.; Cyclommatus murutiorum Ikeda and Katsura, 2001; Cyclommatus chewi Mizunuma, 1994; Cyclommatus giraffa Mollenkamp, 1904; and Cyclommatus dooseokyii Kim, 2018, and distributional maps, photographs of adult habitus, and male genitalia are provided.