Invertebrate Zoology

Collection Manager Robert L. "Bob" Davidson

Amazing New Ground Beetle from Mexico Discovered rawlinsius 

Based on structural and ecological features of adults and larvae, an extraordinary carabid beetle from the Sierra Madre del Sur of Guerrero, Mexico, was described as a new monobasic genus and species by Carnegie Museum of Natural History coleopterist Bob Davidson and Research Associate George Ball (Edmonton, Alberta). The remarkable new genus is placed in the tribe Broscini, subtribe Broscina, and Bob and George have written a key that distinguishes it from the other New World genera of Broscini.

The new species is Rawlinsius papillatus, the generic name in honor of John Rawlins, Carnegie entomologist and collector of the first known specimen of this unusual beetle.

Separated widely both morphologically and geographically from other New World Broscina, the new taxon is postulated to be relictual, with its present isolation indicating past connections to a broscine lineage more broadly distributed in the Northern Hemisphere. The new species evinces some character states that are quite unusual within Carabidae, and its habitat requirements are extraordinary for this family of beetles. It lives under thin sheets of running water of mountain streams, foraging both above and below the water, and spending at least some, perhaps all, of its time on vertical rock faces. It has lost nearly all the normal fixed setae typical of carabid beetles on the dorsal surface and legs, presumably because of its torrential habitat.

In the paper in Annals of Carnegie Museum, 67(4):349-378 (1998), other unusual insects unique to this region of Mexico, and the importance of habitat conservation there is also discussed.

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