Pachybrachis calcaratus Fall, 1915

Barney, Robert J., LeSage, Laurent & Savard, Karine, 2013, Pachybrachis (Coleoptera, Chrysomelidae, Cryptocephalinae) of Eastern Canada, ZooKeys 332, pp. 95-175 : 115

Pachybrachis calcaratus Fall, 1915 Habitus 3 ; Map 3 ; Figures 5c , 7b

Pachybrachys calcaratus Fall, 1915: 389

Recognition.

Color dull yellow, with diffuse brown markings on pronotum, with more contrasting markings on elytra ( Habitus 3 ); ocular lines absent; front tibiae of male with subapical rectangular tooth on inner margin, due to abrupt narrowing of tibia, and with long stout curved terminal spur ( Figure 5c ); terminal spur of front tibia of female reduced to narrow spine; male size small: length 2.09 ± 0.07 mm, width 1.106 ± 0.04 mm.

Distribution.

Pachybrachis calcaratus has been found across the central portion of the United States but only in small numbers (Barney, unpublished data). Within the area of this study, it is restricted to the Carolinian Life Zone in southern Ontario ( Map 3 ).

Material examined.

ONTARIO: Essex Co., Roseland, 24.VI.1942, 'compared with type’, J. A. Wilcox [1♂, CDFA]; same data, except 24.VI.1944, S. D. Hicks [1♂, CNC].

Host plants.

No information was recorded on the specimens collected in southern Ontario. Clark et al. (2004) reported Pachybrachis calcaratus nibbling purple loosestrife, Lythrum salicaria L. ( Lythraceae ), in Ohio.

Comments.

Pachybrachis calcaratus is another of Fall’s (1915) Group C species that have "great variation in the degree of (elytral) maculation." The tibial spur ( Figure 5c ) is a defining character. Pachybrachis calcaratus was very likely associated with the Carolinian Life Zone in southern Ontario in the past. However, it has not been seen from there for the last 68 years.

Figures

Habitus 3. Dorsal habitus of Pachybrachis calcaratus. Scale bar, 1 mm.

Map 3. The known distribution of Pachybrachis calcaratus in eastern Canada. Carolinian Zone in dark beige.

Figure 5. Tibial spurs: a absent from front leg, Pachybrachis atomarius b minute on front leg, Pachybrachis spumarius c large on front leg, Pachybrachis calcaratus d small and pointed on middle legs in most species.

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.