Pachybrachis othonus Species-Group

Barney, Robert J., 2016, Definition and Revision of theOthonusSpecies-Group of North AmericanPachybrachisChevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae), The Coleopterists Bulletin 70 (3), pp. 569-605 : 569-605

Pachybrachis othonus Species-Group

Group Diagnosis. Moderate to large species, length 2.09–3.57 mm; dorsum glabrous with coloration ranging from yellow to black; color patterns unstable as vittae; eyes of both male and female widely separated (0.32–0.68 mm); front without ocular lines; antennae moderately long and slender, not attaining declivity in males; protarsal claws of male not enlarged. Median lobe of male genitalia with median basal plate simple, some lateral plates adjacent to paired, sclerotized, club-like, lamellae; en-face outline with apicolateral margin broadly and evenly rounded; nodule absent to moderately distinct; ventral surface of shaft inflated without distinct keel; beard setae short in patch or in wisp; pencilli absent.

Remarks. I propose the Pachybrachis othonus species-group to include five Nearctic species: P. armbrusti Barney , P. nigricornis (Say) , P. othonus (Say) , P. pallidipennis Suffrian , and P. praeclarus Weise. Pachybrachis othonus was selected for the species-group name due to its priority and relative familiarity within the genus. External variability within and between the P. nigricornis complex and P. othonus complex often leads to confusion between complexes and with the principally black P. praeclarus and vittate P. armbrusti , respectively.

Biology. Almost nothing is known of the biology of the members of the Pachybrachis othonus species-group . Clark et al. (2004) and Barney and Hall (2009, 2011) have summarized various plant associations with adults of this species-group, and more are reported here. Larvae and larval habitats are unknown.