Pachybrachis parvus 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 : 29-32

11. Pachybrachis parvus Fall, 1915 ( Fig. 11 , Map 2B)

Pachybrachys cephalicus, var. parvus Fall 1915: 419 . Fattig 1948: 10 (regional species list); Wilcox 1954: 391 (taxonomy). New status.

Pachybrachis cephalicus, var. parvus: Downie and Arnett 1996: 1317 (catalogue); Balsbaugh and Hays 1972: 33 (taxonomy); Riley et al. 2003: 156 (catalogue).

Type Material. Fall’ s male type, herein designated as lectotype and labeled “vicinity / N.Y.City [hand-written, white paper] // 7.24 / 92 [handwritten, grey paper] // TYPE / var- [printed, white paper] / parvus [hand-written] // M.C.Z. / Type [printed] / 24960 [hand-written, red paper] //H.C. FALL / COLLECTION // LECTOTYPE 24960 / Pachybrachys / parvus Fall 1915 / R. J. Barney 2017 [printed, red paper]”, was examined, photographed, and dissected ( Fig. 11 ) .

Redescription. Male. Yellow with brown punctures, standard maculae diffuse; L = 1.74–1.93 mm (mean = 1.80 mm, n = 11); W = 0.90–1.03 mm (mean = 0.97 mm, n = 11); L/W = 1.80– 1.90 (mean = 1.86, n = 11). Head: Slightly wider than thoracic apex, HW = 0.60–0.71 mm (mean = 0.65 mm, n = 11); eyes narrowly separated, IOD = 0.15–0.20 mm (mean = 0.18 mm, n = 11), IOD/HW = 0.24–0.30 (mean = 0.27, n = 11); face yellow with brown, W-shaped macula connecting the vertex and bases of antennae and up to base of upper lobes of eyes, often diffuse and heavily punctate; antennae yellow-brown, almost reaching elytral declivity. Pronotum: Yellow, brown, M-shaped macula broadly diffuse, often only leaving small, scattered, yellow spots, punctate to lateral margins, PL = 0.53–0.64 mm (mean = 0.59 mm, n = 11); PW = 0.74–0.87 mm (mean = 0.83 mm, n = 11); PL/PW = 0.65–0.75 (mean = 0.71, n = 11). Elytra: Punctation broadly confused, marginal interspace numerously punctate, striae irregular or fragmental and lightly impressed. Pygidium: Brown with 2 oval, yellow maculae. Venter: Dark brown to black, upper sides of last ventrite yellow. Legs: Brown with standard yellow spots. Genitalia: Median lobe in en-face view with shaft narrowest at base, widest at ALM, then gently rounding to terminus, with sclerotized, lateral basal plates and reduced PRL. POL, best seen in the lateral view, with ALA near 65°. Base wide, with mid-keel or ridge eventually narrowing at ALA. Long setae present along edges of deflexation, but no denticles present at ALM ( Fig. 11 ). Forty-eight males from 13 states and provinces were dissected.

Female. As in male, except L = 1.90–2.22 mm (mean = 2.01 mm, n = 9); W = 1.02–1.24 mm (mean = 1.10 mm, n = 9); L/W = 1.79– 1.86 (mean = 1.82, n = 9); HW = 0.70–0.80 mm (mean = 0.74 mm, n = 9); IOD = 0.21–0.28 mm (mean = 0.25 mm, n = 9).

Remarks. Fall (1915) described P. parvus as a variation of P. cephalicus . Dissection of the P. parvus and P. cephalicus lectotypes revealed P. parvus to be quite distinct. Therefore, I am elevating it to full species status.

Distribution. This species is found from Québec and Michigan to Alabama and South Carolina (Map 2B). New state records are confirmed for six states and provinces that were not reported for P. cephalicus ( Riley et al. 2003) : Ontario, Québec, Connecticut, Michigan, Ohio, and Pennsylvania.

Biological Notes. Labels cited potential host plants as Potentilla sp. (Rosaceae) in Ontario, Alnus sp. (Betulaceae) in Alabama, and Desmodium lineatum (Michx.) DC. (Fabaceae) in West Virginia.

Specimens Examined. See Appendix 11.

Figures

Fig. 11. Pachybrachis parvus, lectotype. 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.