Hister

Abstract: Spilodiscus Lewis, a Nearctic group of Histerini, is polyphyletic as presently constituted. Morphological analyses indicate that the following species should be removed from the taxon to Hister: militaris Horn, lucanus Horn, patagiatus Lewis, sarcinatus Lewis, penulatus Lewis, tunicatus Lewis, humilis Fall, bilobatus Casey, and quadratulus Casey. Based on cladistic character evidence, Spilodiscus contains eight valid species (new junior synonyms in brackets). Morphological data supports exclusive, full-species status for S. arcuatus (Say), S. sellatus (LeConte), S. flohri (Lewis), and S. floridanus Ross. The remaining four taxa are ferespecies, which are putatively reproductively isolated entities whose phylogenetic exclusivity is not well-supported: S. ‘ulkei’ (Horn) [= Hister sculpticauda Casey, H. subcruentus Casey, H. coruscans Casey, H. iowensis Casey], S. ‘gloveri’ (Horn), S. ‘biplagiatus’ (LeConte), and S. ‘instratus’ (LeConte) [= Hister semiruber Casey, H. solaris Carnochan]. Over time the lineage...

Abstract: Pantostictus burmanicus Poinar and Brown, a new genus and new species of hister beetles (Coleoptera: Hydrophiloidea: Histeridae) are described from Cretaceous Burmese amber. The new genus is characterized by the following: small size (under 2 mm), prognathous head; head, pronotum and elytra covered with deep punctures; a 9- segmented geniculate antenna terminated with a 1-segmented asymmetrical club; tarsal formula 5-5-5; pairs of spines on all tarsal segments, fused elytra covering most of the abdomen, and a postocciput bearing paired triangular-shaped sclerotized apophyses. This represents the first Cretaceous member of the family.

Abstract: The most common predaceious hister beetles (Coleoptera: Histeridae) found associated with Ips engraver beetles (Coleoptera: Scolytidae) in southern Louisiana were Platysoma attenuata LeConte, P. cylindrica (Paykull), P. parallelum (Say), and Plegaderus transversus (Say). The seasonal abundance of histerids caught in flight traps coincided with Ips spp. activity in the area. Histerid adults were initially caught in sticky traps on Ips-infested loblolly pine logs 1 wk after Ips spp. attacks had begun. As a group, histerids emerged from logs in a bimodal pattern with the first peak occurring during Ips. spp. emergence and a second 4 wks later. The abundance of P. parallelum and P. transversus indicates that they likely fed on bark beetles and organisms arriving later in the colonization sequence. Visual orientation appeared to play a role in attraction of histerids to logs colonized by bark beetles. Platysoma attenuata preferred vertically-positioned logs to horizontal logs, while P. parallelum was the opposite. These results suggest that some histerids may be visually attracted to horizontal silhouettes, such as pine trees, that have been blown down or felled and often are infested by Ips spp. Other hister beetles may prefer vertical silhouettes, such as standing pines, which tend to be colonized by the southern pine beetle, Dendroctonus frontalis Zimmermann.