Pachybrachis cephalicus Fall, 1915

Barney, Robert J., LeSage, Laurent & Savard, Karine, 2013, Pachybrachis (Coleoptera, Chrysomelidae, Cryptocephalinae) of Eastern Canada, ZooKeys 332, pp. 95-175 : 115-116

Pachybrachis cephalicus Fall, 1915 Habitus 4 ; Map 4 ; Figure 8b

Pachybrachys cephalicus Fall, 1915: 419.

Pachybrachys cephalicus var. Pachybrachis dixianus Fall, 1915: 419.

Pachybrachys cephalicus var. Pachybrachis parvus Fall, 1915: 419.

Recognition.

Pronotum and head generally fuscous, densely punctate and darker than elytra; elytra with puncturation dense and confused ( Habitus 4 ); ocular lines absent; male size small: length 1.94 ± 0.12 mm, width 1.05 ± 0.08 mm.

Distribution.

A typical eastern species distributed from Louisiana to New York to Atlantic Coast ( Riley et al. 2003), restricted to southern Ontario in eastern Canada ( Map 4 ).

Material examined.

ONTARIO: Norfolk Co., Walsingham Forest Station, 28.VII.1982, ex. Potentilla or strawberry, L. LeSage [11♂ 14♀, CNC].

Host plants.

Cinquefoil ( Potentilla sp.) and strawberry ( Fragaria sp.) (both Rosaceae ) are the first host associations reported for Pachybrachis cephalicus . The specimens were swept from these two plants growing in a sandy clearing within a dry oak-pine forest (LeSage, personal field notes). Since 1984, the previous Walsingham Forestry Station is part of the St. Williams Dwarf Oak Forest, the largest block of publicly owned forest in the Carolinian Life Zone ( NHIC 1998).

Comments.

Pachybrachis cephalicus is another of Fall’s (1915) Group C species that have "great variation in the degree of (elytral) maculation." The fairly large number of examined specimens may be misleading since they all come from only one event. In fact, Pachybrachis cephalicus is very rarely collected in eastern Canada and known from only one locality within the Carolinian Life Zone. This is also a first record of this species for Canada.

Figures

Habitus 4. Dorsal habitus of Pachybrachis cephalicus. Scale bar, 1 mm.

Map 4. The known distribution of Pachybrachis cephalicus in eastern Canada. Carolinian Zone in dark beige.

Figure 8. Pygidium: a largely yellow, Pachybrachis bivittatus b with well-defined yellow spots, Pachybrachis cephalicus c with faint reddish spots, Pachybrachis spumarius d black, Pachybrachis atomarius.