Pachybrachis quadrioculatus Fall, 1915

Barney, Robert J., 2018, Definition and Revision of the Atomarius Species-Group of North American Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae), Including Descriptions of Nine New Species, The Coleopterists Bulletin 72 (1), pp. 9-74 : 20

2. Pachybrachis quadrioculatus Fall, 1915 ( Fig. 2 , Map 1A)

Pachybrachys quadrioculatus Fall 1915: 429 .

Pachybrachis quadrioculatus: Fattig 1948: 10 (regional species list); Kirk 1969: 89 (regional species list); Riley et al. 2003: 163 (catalogue); Ciegler 2007: 181 (taxonomy).

Type Material. Fall’ s male type, herein designated as lectotype and labeled “TYPE [printed] / 4- oculatus [hand-inked, white paper] // H. C. FALL / COLLECTION [printed, white paper] // Ga. [printed, white paper] // Pachybrachys / 4- oculatus / Fall. [hand-inked, white paper with pink-lined border] // M.C.Z. / TYPE [printed] / 24975 [hand-inked, red paper] // LECTOTYPE 24975 / Pachybrachys / quadrioculatus Fall 1915 / R. J. Barney 2017 [printed, red paper]”, was examined and photographed ( Fig. 2 ) .

Redescription. Male. Small, head and prothorax rufo-testaceous, elytra pale yellow, each with a small humeral and subapical spot; L = 1.79–2.12 mm (mean = 1.89 mm, n = 10); W = 0.90–1.20 mm (mean = 1.07 mm, n = 10); L/W = 1.70–1.86 (mean = 1.77, n = 10). Head: Slightly wider than thoracic apex, HW = 0.65–0.79 mm (mean = 0.69 mm, n = 10); eyes narrowly separated, IOD = 0.12–0.20 mm (mean = 0.17 mm, n = 10); IOD/HW = 0.17–0.27 (mean = 0.25, n = 10); face yellow with brown, W-shaped macula connecting the vertex and bases of antennae and up to base of upper lobes of eyes; antennae yellow to brown, not reaching elytral declivity. Pronotum: Rufo-testaceous, M-shaped macula brown, broadly diffuse to almost imperceptible; incomplete punctation to lateral margins; PL = 0.57–0.78 mm (mean = 0.68 mm, n = 10); PW = 0.88–1.04 mm (mean = 0.91 mm, n = 10); PL/PW = 0.72–0.77 (mean = 0.74, n = 10). Elytra: Yellow, striae mostly regular, baso-sutural punctures confused, punctures brown, standard maculae reduced to a small humeral and subapical spot on each elytron. Pygidium: Brown with 2 large, oval, yellow maculae. Venter: Brown, upper sides of last ventrite yellow. Legs: Yellow and brown. Genitalia: Median lobe in en-face view parallelsided, abruptly narrowing at ALM to extended tip; in lateral view, ALA 40° with setae along edges ( Fig. 2 ). Nine males from two states were dissected.

Female. As in male, except L = 2.04–2.20 mm (mean = 2.13 mm, n = 9); W = 1.13–1.24 mm (mean = 1.20 mm, n = 9); L/W = 1.72– 1.82 (mean = 1.77, n = 9); HW = 0.74–0.81 mm (mean = 0.77 mm, n = 9); IOD = 0.20–0.32 mm (mean = 0.26 mm, n = 9); IOD/HW = 0.27– 0.42 (mean = 0.33, n = 9).

Remarks. Pachybrachis quadrioculatus was obviously named to reflect the four spots on the otherwise pale elytra. Interestingly, Fall referred to this species in three ways: quadrioculatus , quadrioculatus , and on the lectotype label, 4-oculatus. This species is relatively rare; only 53 specimens were available for examination, yet two potential host plant species were referenced on labels.

Distribution. Pachybrachis quadrioculatus is only found in two states, Georgia and Florida, with Florida being a new state record (Map 1A).

Biological Notes. The following potential host plants were listed on labels: Quercus inopina Ashe in Florida and Licania michauxii Prance (= Geobalanus oblongifolius (Michx.) Small ) ( Chrysobalanaceae ) in Georgia. Malaise and flight traps were cited on labels, as were scrub and xeric dune habitats.

Specimens Examined. See Appendix 2.

Figures

Fig. 2. Pachybrachis quadrioculatus. A) Dorsal habitus, B) Lateral habitus, C) Face, D) Pygidium, E) Median lobe of aedeagus, lateral view, F) Median lobe of aedeagus, en-face view.