Collagenus dasysternus Ratcliffe and Hardy

Ratcliffe, Brett C. & Hardy, Martin, 2005, Collagenus dasysternus, A New Genus And Species Of Dynastinae From Eastern Venezuela With A Key To The New World Genera Of Pentodontini (Coleoptera: Scarabaeidae: Dynastinae), The Coleopterists Bulletin 59 (1), pp. 143-150 : 143-144

Collagenus dasysternus Ratcliffe and Hardy , new genus and species, is described from eastern

Venezuela. We include a revised key to the 26 genera of New World Pentodontini .

When the second author (Hardy) first saw this Venezuelan specimen in the Henry Howden collection, he could not readily place it to genus. When the first author (Ratcliffe) received the specimen from Hardy for examination in mid-2003, he was immediately taken with its gestalt similarity with the genus Coscinocephalus Prell that occurs in Arizona and Mexico. Unfortunately, there is only one specimen, but our examination revealed such unique character states that were indicative of a new, undescribed genus and species that we describe it here. We utilize the Phylogenetic Species Concept as outlined by Wheeler and Platnick (2000). This concept defines species as the smallest aggregation of sexual populations diagnosable by a unique combination of character states. Whether this species occurs rarely in nature remains unknown, but the area from which it was collected is readily accessible if someone wanted to make a concerted effort to find additional specimens. During a visit by one of us (Ratcliffe) to the extensive collections of the Universidad Central de Venezuela in Maracay in 1999, similar specimens were not found .

With the new genus described here, the tribe Pentodontini now contains 26 genera and a few more than a hundred species in the New World. Endrödi (1969, 1985) comprehensively reviewed and defined the Pentodontini , and this tribal concept was used by Ratcliffe (2002) in the latest generic treatment of the North American dynastines. Endrödi’s definition did not address monophyly, and we remain concerned that the Pentodontini (as currently defined) may not be monophyletic. In particular, the head and pronotal armature as well as the form of the meso- and metatibiae used to characterize the tribe are not consistently expressed.

Until such time as the monophyly of the Pentodontini is resolved, we place our new genus in the Pentodontini because it possesses the following characters: a weak tubercle on the frons, a strong frontoclypeal carina, tridentate foretibia, and a truncate metatibia with a fringe of short, spine-like setae on the apex.

The last generic keys to adults of the New World Pentodontini were by Ratcliffe (1981) and Endrödi (1985). Morón and Ratcliffe (1997) transferred the genus Coscinocephalus from the Cyclocephalini to the Pentodontini , but it has never been incorporated into a comprehensive generic key. In addition, the genus Oryctomorphus Guérin-Meneville has bounced back and forth between the Rutelinae (i.e., Machatschke 1972) and Dynastinae (i.e., Endrödi 1985). It is in the key by Ratcliffe (1981), but molecular data based on 28S and 18S DNA gene regions suggest that Oryctomorphus is a member of the subfamily Rutelinae (A. Smith and D. Hawks, unpubl. data), and so it is not included in the present key. We provide a revised key to the adults of all the New World genera of Pentodontini . Morón and Ratcliffe (1997) provided a key to nine genera of larval Pentodontini .