Pristacrus Chaudoir 1869

Kavanaugh, David H. & Rainio, Johanna, 2016, Twenty-six New Species of Predaceous Ground Beetles (Coleoptera: Adephaga: Carabidae) from Ranomafana National Park, Madagascar, Proceedings of the California Academy of Sciences 63 (7), pp. 201-268 : 238

Genus Pristacrus Chaudoir 1869

Jeannel (1949) recognized four species in this precinctive Malagasy genus and provided a key for distinguishing their respective members. In this key, Jeannel used two features with which we found problems. First, his statements about pronotal proportions—width in relation to pronotal length (i.e. ratio PW/PL)—appear to have been based on visual impressions only, rather than actual comparative measurements, because our measurements of these proportions in specimens (including types) of the four species have not corresponded to those stated by Jeannel. Unfortunately, this problem renders two of his three couplets (couplets 1 and 3) difficult to interpret. Second, he used shape of the sutural angle of the elytral apex (i.e., whether it is broadly rounded or sharp and toothed) as the primary comparative feature in his couplet 2. In fact, based on the examination of many more specimens than were available to Jeannel, we found that members of all species except one, Pristacrus laticollis ( Gory and Laporte 1837) have elytral apices that are sharp and toothed, including members of Pristacrus bonotatus ( Klug 1833) , which Jeannel cited as broadly rounded in his key. We point out these problems with Jeannel’s key as caution to those trying to use it, as we were, for identifications. No additional species have been described since Jeannel’s study.