Pachybrachis tridens (F. E. Melsheimer, 1847)

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

Pachybrachis tridens (F. E. Melsheimer, 1847) Habitus 16 ; Map 16

Cryptocephalus tridens F. E. Melsheimer, 1847: 172.

Cryptocephalus flavicornis F. E. Melsheimer, 1847: 172.

Pachybrachys mollis Haldeman, 1849: 263.

Recognition.

Color pale yellow with broad, sharply limited, black markings; antennae (usually) and legs entirely yellow ( Habitus 16 ). Lustre dull. Eyes separated by about twice length of basal antennomere in male, and by two and one-half to three times length of this antennomere in female. Ocular lines fine. Front claws of male not enlarged (as in Figure 4c ); male size small: length 1.93 ± 0.10 mm, width 1.01 ± 0.04 mm.

Distribution.

Pachybrachis tridens is an eastern species distributed from Manitoba to Texas to the Atlantic Coast in the United States ( Riley et al. 2003), and restricted to the Carolinian Zone of southern Ontario in eastern Canada ( Map 16 ).

Material examined.

ONTARIO: Prince Edward Co., 21-28.VI.1950, J. F. Brimley [3♂ 5♀, CNC].

Host plants.

No records are available from the specimens examined. Poison ivy ( Toxicodendron radicans (L.) Kuntze) ( Anachardiaceae ) was given as the preferred host by Fall (1915), Blatchley (1924a), Wilcox (1954, 1979), Furth (1985), and others. A complete list of citations is found in Clark et al. (2004).

Comments.

Since Pachybrachis tridens has not been collected in the last 55 years, it can be considered as extirpated from the Canadian fauna. Formerly, it was probably restricted to the Carolinian Life Zone, which is now reduced to minute remnants. For this reason, the Manitoba record reported by LeSage (1991) and Riley et al. (2003), and the Québec record cited by Riley et al. (2003) are questionable. No specimens were available to confirm them.

Figures

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

Habitus 16. Dorsal habitus of Pachybrachis tridens. Scale bar, 1 mm.

Map 16. The known distribution of Pachybrachis tridens in eastern Canada. Carolinian Zone in dark beige.