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Barney, R.J. 2017. Definition and revision of the luridus species-group of North American Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae). The Coleopterists Bulletin 71(1): 1-45.

Abstract
The luridus species-group of Nearctic Pachybrachis Chevrolat, 1836 is defined and revised.

The group is composed of ten species, including two described as new species:
Pachybrachis confusus Bowditch,
Pachybrachis dilatatus Suffrian,
Pachybrachis discoideus Bowditch,
Pachybrachis femoratus (Olivier),
Pachybrachis luridus (Fabricius),
Pachybrachis rileyi Barney,
Pachybrachis sherriae Barney, new species,
Pachybrachis shirleyae Barney, new species,
Pachybrachis subfasciatus (LeConte), and
Pachybrachis turbidus (LeConte).

Neotypes are designated for Cryptocephalus femoratus Olivier, 1808, Cryptocephalus subfasciatus LeConte, 1824, Pachybrachys impurus Suffrian, 1852, and Pachybrachys dilatatus Suffrian, 1852.
Lectotypes are designated for Cryptocephalus luridus Fabricius, 1798, Cryptocephalus aesculi Melsheimer, 1846, and Pachybrachys characteristicus Suffrian, 1852.

Pachybrachys impurus Suffrian, 1852 and Pachybrachys impurus var. umbrosus Fall, 1915 are synonymized with P. subfasciatus (new synonymies).
Pachybrachys characteristicus Suffrian, 1852 and Pachybrachys femoratus var. aquilonis Fall, 1915 are confirmed as synonymies of P. femoratus (Olivier), and
Pachybrachis luridus var. nigrinus Blatchley, 1910 and Pachybrachis luridus var. festivus Fall, 1915 are confirmed as synonymies with P. luridus.

Twenty-nine new state records are confirmed for members of this species-group. A key to species is given, and a description, figure, and range map is presented for each species.