Definition and Revision of theOthonusSpecies-Group of North AmericanPachybrachisChevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae) Author Barney, Robert J. text The Coleopterists Bulletin 2016 2016-09-30 70 3 569 605 http://dx.doi.org/10.1649/0010-065x-70.3.569 journal article 10.1649/0010-065X-70.3.569 5339378 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.