Pachybrachis wickhami Bowditch, 1909

Barney, Robert J., 2019, Definition and Revision of the Pubescens Species-Group of North American Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae), Including Descriptions of Three New Species, The Coleopterists Bulletin 73 (4), pp. 1017-1048 : 1023-1025

2. Pachybrachis wickhami Bowditch, 1909 ( Fig. 2 ; Map 1B)

Pachybrachys wickhami Bowditch 1909: 238 . Fall 1915: 330 (taxonomy).

Pachybrachis wickhami: Riley et al. 2003: 165 (catalogue).

Types. Bowditch’ s ( MCZ-BOW) male P. wickhami labeled “ ♂ // Tucson, Ariz / Wickham / Aug. 12-14 [printed, white paper] // wickhami / Type ♂ [hand-inked, white paper] // TYPE / F. C. B. Coll. [printed, pink paper] // Type [printed] / 8655 [handinked, red paper] // [circular blue disc signifying dissection by RJB] // LECTOTYPE / Pachybrachys / wickhami Bowditch 1909 / design. R. J. Barney 2019 [printed, red paper]”, was examined, dissected, and photographed and is hereby designated lectotype to stabilize the epithet ( Fig. 2 ). Bowditch’ s ( MCZ-BOW) female P. wickhami labeled “ ♀ // Tucson, Ariz / Wickham / Aug. 12-14 [printed, white paper] // TYPE / F. C. B. Coll. [printed, pink paper] // PARALECTOTYPE / Pachybrachys / wickhami Bowditch 1909 / design. R. J. Barney 2019 [printed, yellow paper]”, was examined and is hereby designated paralectotype .

Redescription. Male. Short and stout, head and thorax black obscured by dense, white pubescence, elytra luteous with grey maculae; L = 1.91–2.25 mm (mean = 2.08 mm, n = 10); W = 1.00– 1.18 mm (mean = 1.06 mm, n = 10); L/W = 1.91–2.04 (mean = 1.96, n = 10). Head: Distinctly wider than thoracic apex, HW = 0.77–0.94 mm (mean = 0.85 mm, n = 10); eyes narrowly separated, IOD = 0.13–0.19 mm (mean = 0.16 mm, n = 10); IOD/HW = 0.17–0.20 (mean = 0.19, n = 10); face primarily black with dense, white, recumbent pubescence; antennae yellow, not reaching elytral declivity. Pronotum: Black, completely covered with dense, white, recumbent pubescence; PL = 0.65–0.77 mm (mean = 0.70 mm, n = 10); PW = 0.87–1.04 mm (mean = 0.95 mm, n = 10); PL/PW = 0.73–0.77 (mean = 0.74, n = 10). Elytra: Dull luteous with white pubescence and variable, indistinct dark maculae. Pygidium: Black with white pubescence. Venter: Black with white pubescence. Legs: Luteous with dark areas and white pubescence; front claws not enlarged. Genitalia: Median lobe in enface view distinctly narrowed before oval OS, rounded with visible setae on each side of a nodule, which is often obscured by eversible endophallus. Narrowing pre-OS distinctive in lateral view. Six males from one USA state and one Mexican state were dissected.

Female. As in male, except L = 2.13–2.41 mm (mean = 2.30 mm, n = 10); W = 1.09–1.31 mm (mean = 1.19 mm, n = 10); L/W = 1.84–2.00 (mean = 1.93, n = 10); HW = 0.87–1.00 mm (mean = 0.94 mm, n = 10); IOD = 0.20–0.29 mm (mean = 0.24 mm, n = 10); IOD/HW = 0.22–0.29 (mean = 0.26, n = 10).

Remarks. Pachybrachis wickhami is a relatively unusual species for the genus in that the pubescence and coloring of the head and thorax is distinctly different from the elytra. Externally, P. wickhami can be confused with P. baja . However, P. baja is larger, less densely pubescent, and red rather than black. Also, in my experience, P. baja has only been found on the Baja California Peninsula of Mexico.

Distribution. This species is found in southeastern Arizona and Baja California Sur (Map 1B).

Biological Notes. Specimens were collected via UV blacklight in Arizona. A specimen was caught on A. constricta in Arizona. Clark et al. (2004) reported this species in association with Prosopis sp. on the Baja California Peninsula.

Specimens Examined. See Appendix 2.

Figures

Fig. 2. Pachybrachis wickhami, lectotype. A–B) Dorsal and lateral habitus, respectively, C) Face, D) Pygidium, E–F) Median lobe of aedeagus, lateral and en-face views, respectively.