Pachybrachis luridus (Fabricius, 1798)

Barney, Robert J., LeSage, Laurent & Savard, Karine, 2013, Pachybrachis (Coleoptera, Chrysomelidae, Cryptocephalinae) of Eastern Canada, ZooKeys 332, pp. 95-175 : 118-119

Pachybrachis luridus (Fabricius, 1798) Habitus 7 ; Map 7 ; Figure 7g

Cryptocephalus luridus Fabricius, 1798: 109.

Cryptocephalus femoratus Say, 1824: 439.

Cryptocephalus aesculi F. E. Melsheimer, 1847: 171.

Pachybrachys moerens Stål, 1857: 63.

Pachybrachys luridus var. Pachybrachis nigrinus Blatchley, 1910: 1130.

Pachybrachys luridus var. Pachybrachis festivus Fall, 1915: 470.

Recognition.

Body dull black, densely, coarsely punctured; pronotum black with anterior median line and sides red or reddish yellow, varying to almost entirely red; elytra mottled with yellow, especially toward sides, varying to entirely yellow to entirely black ( Habitus 7 ); front claws of male much enlarged (as in Figure 4a ); male size medium: length 2.65 ± 0.23 mm, width 1.45 ± 0.12 mm.

Distribution.

Occuring in the eastern half of the United States ( Riley et al. 2003) to the Rocky Mountains, but in Canada restricted to the Carolinian Life Zone of southern Ontario ( Map 7 ).

Material examined.

ONTARIO: Essex Co., Ojibway, 9.VI.1943, S. D. Hicks [1♀, CNC]; Lambton Co., Grand Bend, 20.VII.1930, G. E. Shewell [1♀, CNC]; Simcoe Co., 19.VI.1939, G. S. Walley [1♀, CNC]; Toronto Co., Toronto, 26.VI.1896, C. T. Hills [2♂ 2♀, LEM]; same data, except 15-30.VI.1927, L. J. Milne [1♀, UNHC]; same data, except F. Knab [29♂ 20♀, USNM]; Toronto, High Park, 4.VI.1897 [3♂ 2♀, ROM]; Unknown Co., Black Creek, 14.VI.1897 [1♀, ROM]; Springfield [2♀, ROM]; Can., G. M. Greene [1♂, USNM].

Host plants.

No plant association records were available from Canadian specimens. In the United States, the false indigos ( Baptisia leucantha T. & G., Baptisia tinctoria (L.) R. Br.) ( Fabaceae ) were the associations most often cited by authors ( Frost 1945, details in Clark et al. 2004). However, these plants are not present in Québec ( Marie-Victorin 1995), and extremely rare in southern Ontario ( Scoggan 1978). Barney et al. (2011) stated that recently collected specimens in Kentucky were probably from oak ( Quercus spp., Fagaceae ).

Comments.

Fall (1915) observed specimens from Ontario: Toronto (Wickham). However, no specimens of Pachybrachis luridus have been collected from the province in the last 68 years, and one of its potential hosts ( Baptisia spp.) were always extremely rare in southern Ontario ( Scoggan 1978). Consequently, Pachybrachis luridus is likely extirpated from the eastern Canadian fauna.

Figures

Figure 4. Claws: a, b front claws enlarged c, d normal.

Habitus 7. Dorsal habitus of Pachybrachis luridus. Scale bar, 1 mm.

Map 7. The known distribution of Pachybrachis luridus in eastern Canada. Carolinian Zone in dark beige.

Figure 7. Elytral punctures and coloration: a in rows in deep striae, Pachybrachis luctuosus b confused in basal half, in rows in apical half, Pachybrachis calcaratus c all confused, Pachybrachis hepaticus d confused and mottled, Pachybrachis spumarius e vittate with marginal vitta interrupted, Pachybrachis bivattatus f black, margined with yellow, Pachybrachis nigriconis carbonarius g entirely black, Pachybrachis luridus.