Pachybrachis cephalicus 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 : 40-43

18. Pachybrachis cephalicus Fall, 1915 ( Fig. 18 , Map 3A)

Pachybrachys cephalicus Fall 1915: 419 .

Pachybrachis cephalicus: Fattig 1948: 10 (regional species list); Downie and Arnett 1996: 1317 (catalogue); Balsbaugh and Hays 1972: 33 (taxonomy); Riley et al. 2003: 156 (catalogue); Ciegler 2007: 178 (taxonomy); Barney et al. 2013: 116 (taxonomy).

Type Material. Fall’ s male type of P. cephalicus , herein designated as lectotype and labeled “Mobile, Ala. / VI-5-08 [hand-inked, white paper] H. P. Loding [printed, white paper] // 6 // TYPE [printed] / cephalicus [hand-inked, white paper] // Type 24923 [hand-inked, red paper] // H. C. FALL / COLLECTION // LECTOTYPE 24923 / Pachybrachys / cephalicus Fall 1915 / R. J. Barney 2017 [printed, red paper]”, was examined, photographed, and dissected ( Fig. 18 ).

Redescription. Male. Fuscous and dull yellow mottled; L = 2.18–2.19 mm (mean = 2.19 mm, n = 2); W = 1.17–1.21 mm (mean = 1.19 mm, n = 2); L/W = 1.81–1.87, mean = 1.84, n = 2). Head: Slightly wider than thoracic apex, HW = 0.85–0.86 mm (mean = 0.86 mm, n = 2); eyes moderately separated, IOD = 0.23–0.28 mm (mean = 0.26 mm, n = 2); HW/IOD = 0.27–0.32 (mean = 0.30, n = 2); face yellow with large, dark brown to black, W-shaped macula connecting the vertex and bases of antennae and up to base of upper lobe of eyes, punctation dense in dark areas, which may be extensive, antennae yellow-brown, not reaching elytral declivity. Pronotum: Yellow, with dark brown to black, M-shaped macula broadly diffuse, punctation dense in dark areas, extending to margins, PL = 0.67–0.72 mm (mean = 0.70 mm, n = 2); PW = 0.96–0.98 mm (mean = 0.97 mm, n = 2); PL/PW = 0.69–0.75 (mean = 0.71, n = 2). Elytra: Dull yellow, with dark brown to black punctures, striae confused in baso-sutural region, forming irregular lines towards sides and apex, feebly impressed, marginal interspace punctate. Pygidium: Finely punctate, weakly convex; dark brown with 2 small, oval, yellow maculae. Venter: Dark brown to black, yellow spot on last ventrite. Legs: Yellow with brown to black femoral and tibial spots. Genitalia: Median lobe in en-face view with large, oval OS with shaft widest near the midpoint, PRL reduced. POL, best seen in the lateral view, deflexed at near 75° ALA, thereby creating a triangular, arrowhead-shaped area with a gently rounded terminus and 2 posteriorly projecting denticles. Arrowhead in dorsal view with a third, middle denticle that arises from distinct ridge along the edge of inflated keel. Long setae present on rounded ALM and lateral edges of arrowhead-shaped POL ( Fig. 18G ). EFW = 0.26–0.27 mm (mean = 0.27 mm, n = 2); AAM = 0.07–0.08 mm (mean = 0.08 mm, n = 2); AAL = 0.09–0.10 mm (mean = 0.10 mm, n = 2); AAW = 0.11–0.12 mm (mean = 0.12 mm, n = 2); AAL/AAW = 0.79–0.91 (mean = 0.85, n = 2). Three males from two states were dissected.

Female. As in male, except L = 2.51–2.55 mm (mean = 2.53 mm, n = 3); W = 1.38–1.45 mm (mean = 1.43 mm, n = 3); L/W = 1.75–1.82 (mean = 1.78, n = 3); HW = 1.00– 1.03 mm (mean = 1.02 mm, n = 3); IOD = 0.28–0.35 mm (mean = 0.30 mm, n = 3).

Remarks. In Fall’ s (1915) discussion of P. cephalicus , he recognized that he had “several more or less distinct types”, two of which he gave varietal names. Upon my dissection of the male lectotypes of P. dixianus and P. parvus , it was very obvious that neither possessed the arrowheadshaped structure and, therefore, were not P. cephalicus . Therefore, P. dixianus and P. parvus are elevated to full species status.

The three female P. cephalicus measured above, although not accompanied by males, were all collected by Loding from Mobile, Alabama and identified by Fall in his personal collection ( MCZ- FALL) .

Distribution. There are only six confirmed specimens of this species, five from Alabama and one from Georgia (Map 3A).

Biological Notes. No information is available.

Specimens Examined. See Appendix 18.

Figures

Fig. 18. Pachybrachis cephalicus, 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, G) Median lobe of aedeagus, dorsal view.