Pachybrachis subfasciatus (J. E. LeConte, 1824)

Barney, Robert J., LeSage, Laurent & Savard, Karine, 2013, Pachybrachis (Coleoptera, Chrysomelidae, Cryptocephalinae) of Eastern Canada, ZooKeys 332, pp. 95-175 : 131-132

Pachybrachis subfasciatus (J. E. LeConte, 1824) Habitus 15 ; Map 15

Cryptocephalus subfasciatus J. L. LeConte, 1824: 173.

Pachybrachys biguttatus Suffrian, 1852: 167.

Pachybrachys impurus Suffrian, 1852: 186.

Pachybrachys xanthias Suffrian, 1852: 199.

Pachybrachys impurus var. Pachybrachis umbrosus Fall, 1915: 379.

Recognition.

Color dark, pronotum with sides narrowly yellow; elytra with red or yellow, more or less broad, irregular or indented transverse median fascia often interrupted at suture, and with red or yellow apical spot ( Habitus 15 ); Disc of pronotum often, and head more rarely, variegated with reddish yellow; male size small: length 2.21 ± 0.09 mm, width 1.18 ± 0.06 mm.

Distribution.

Eastern species distributed from Kansas to Louisiana to Atlantic Coast in the United States ( Riley et al. 2003), restricted to the Carolinian Zone in southern Ontario in eastern Canada ( Map 15 ).

Material examined.

ONTARIO: Essex Co., Leamington, 6.VII.1931, G. S. Walley [1♀, CNC]; same data, except 9.VI.1937 [1♀, CNC]; Hastings Co., 19.VII.1938, J. F. Brimley [2♀, CNC]; Lennox & Addington Co., 16.VII.1938, J. F. Brimley [1♂, CNC]; Norfolk Co., Normandale, 5.VI.1931, W. J. Brown [1♀, CNC]; Walsingham, 3.VI.1944, W. J. Brown [3♀, CNC]; same data, except 11.VII.1956 [2♀, CNC]; Northumberland Co., Hamilton, 15.VII.1981, M. Sanborne [1♂, CNC]; Toronto Co., Toronto, 15.VI.1896 [3♀, LEM]; same data, except 30.V.1897, C. T. Hills [1♂ 1♀, LEM].

Host plants.

No records are available from the specimens examined. Downie and Arnett (1996) reported Pachybrachis subfasciatus from black walnut ( Juglans nigra L.) ( Juglandaceae ).

Comments.

Pachybrachis subfasciatus is another possible example of a species once living in the Carolinian Zone which may have been extirpated from the Canadian fauna. No specimens were collected in the last 55 years. If its association with black walnut is correct, this may explain its rarity, or even extinction, since Fox and Soper (1953) reported this tree occurring naturally only in rich woods in southernmost Ontario and considered recent trees above these limits to have been planted.

Figures

Habitus 15. Dorsal habitus of Pachybrachis subfasciatus. Scale bar, 1 mm.

Map 15. The known distribution of Pachybrachis subfasciatus in eastern Canada. Carolinian Zone in dark beige