Pachybrachis nubilus, Bowditch, 1909

Barney, Robert J., 2021, Redescription of Five Species of Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae) of the Western USA, Including New Synonymies, Records of Greatly Expanded Ranges into the Eastern USA, and New Plant Associations, The Coleopterists Bulletin 75 (2), pp. 485-496 : 491-492

2. PACHYBRACHIS nuBIluS Bowditch, 1909

( Figs. 3 , 4 , 6 )

Pachybrachys nubilus Bowditch 1909: 312 ; Fall 1915: 444 (taxonomy).

Pachybrachis nubilus : Riley et al. 2003: 161 (catalog).

Pachybrachis conspirator Fall 1915: 445 . New synonymy.

Pachybrachis conspirator : Riley et al. 2003: 156 (catalog).

Type. Bowditch (1909) described P. nubilus from two Arizona males and a female from Utah. One of the males, hereby designated lectotype, labeled “ ♂ // Bill Williams Fork / Ariz. Sept. [printed, white paper] // TYPE / F. C. B. Coll. [printed, pink paper] // TYPE [printed] / 8765 [hand-inked, red paper] // P. nubilus BW / Type [hand-inked, white paper // [circular blue disc signifying dissection by RJB] // LECTOTYPE / Pachybrachys / nubilus Bowditch / R. J. Barney 2020 [printed, red paper]”, was examined, dissected, and photographed ( Figs. 3A–D ). The other male, now a paralectotype due to the above lectotype designation, labeled “ ♂ // Bill Williams Fork / Ariz. Sept. [hand-inked, white paper] // So. Arizona / F. H. Snow [printed, white paper] // P. nubilus Bowd. [hand-inked] / Det. H. C. Fall. [printed, white paper with black-lined border] // [circular blue disc signifying dissection by RJB] // PARALECTOTYPE / Pachybrachys / nubilus Bowditch / R. J. Barney 2020 [printed, yellow paper]”, was examined, dissected, and photographed ( Figs. 3E–F ). The female, labeled “ St. George / Utah, July / Wickham [printed, white paper]”, was characterized by Fall (1915) as “almost certainly identical” and cannot be confirmed as P. nubilus with complete confidence.

Fall (1915) described P. conspirator from four specimens of unknown locality in Arizona. The lone male in the Fall type collection, hereby designated lectotype, labeled “Ariz [printed, white label] // Coll / Schaeffer [printed, white paper] // ♂ // TYPE / conspira - / tor [hand-inked, white paper] // M.C.Z. / Type [printed] / 24927 [hand-inked, red paper] // [circular blue disc signifying dissection by RJB] // LECTOTYPE / Pachybrachys / conspirator Fall / R. J. Barney 2020 [printed, red paper]”, was examined, dissected, and photographed ( Fig. 4 ).

Redescription. Male. Yellow, pale brown punctate, elytra often with brown maculation ( Figs. 3 , 4 ); L = 3.11–3.25 mm (mean = 3.17 mm, n = 4); W = 1.55–1.59 mm (mean = 1.57 mm, n = 4); L/W = 2.56–2.68 (mean = 2.63, n = 4). Head: Distinctly wider than thoracic apex, HW = 1.12–1.25 mm (mean = 1.17 mm, n = 4); IOD = 0.27–0.34 mm (mean = 0.30 mm, n = 4); IOD/HW = 0.31–0.38 (mean = 0.34, n = 4); face yellow with thin brown macula descending from vertex to between eyes; ocular lines wanting; antenna not reaching elytral declivity. Pronotum: Yellow, M-shaped macula broadly diffuse to almost imperceptible, three basal spots often well defined; incomplete punctation, side margins smooth; PL = 0.91–1.03 mm (mean = 0.96 mm, n = 4); PW = 1.30–1.39 mm (mean = 1.35 mm, n = 4); PL/PW = 0.90–0.96 (mean = 0.92, n = 4). Elytra: Yellow, baso-sutural punctation confused, striae mostly regular, five and six much confused, punctures brown, standard maculae brown, diffuse to wanting. Pygidium: Yellow, with base, a median and two side spurs black. Venter: Black, upper sides of last ventrites yellow. Legs: Yellow, front claws not enlarged. Genitalia: Median lobe in en-face view rectangular, with very prominent terminus extended from “level” DEO ( Fig. 3E ). In lateral view the edge of lobes is sinuous to the extended terminus, with a small rounded keel or knob near base. Four males from Arizona were dissected.

Female. As in male, except, L = 3.32–3.51 mm (mean = 3.41 mm, n = 2); W = 1.76–1.78 mm (mean = 1.77 mm, n = 2); L/W = 2.42–2.60 (mean = 2.51, n = 2); HW = 1.35–1.43 mm (mean = 1.39 mm, n = 2); IOD = 0.44–0.48 mm (mean = 0.47 mm, n = 2); IOD/HW = 0.40–0.47 (mean = 0.44, n = 2).

Remarks. Fall’s (1915) speculation that P. conspirator “is not at all unlikely that this is only an extreme form of nubilus ” rings true. The very pronounced terminus arising from a somewhat “flat” DEO is distinctive. In en-face view, the median lobe of P. nubilus appears as a more extreme version of P. laevis .

Distribution. Riley et al. (2003) reported P. nubilus from Arizona, Utah, and Mexico. Riley et al. (2003) reported P. conspirator from Arizona. The female P. nubilus identified from Kansas would appear to be an outlier ( Fig. 6 ).

Specimens Examined. Lectotypes, paralectotypes + 1 specimen. USA: ARIZONA: Mohave Co., Bill Williams Fork, ix, F. H. Snow [ 1♂, nubilis LECTOTYPE, MCZ-BOW; 1♂, det. H. C. Fall nubilus, SEMC ]; unknown county, Ariz., Schaeffer [ 1♂, conspirator LECTOTYPE, MCZ-FALL]; same data, except M. L. Linell [ 1♂ 1♀, Fall 1915 Revis conspirator PARATYPES, USNM]. KANSAS: Douglas Co., F. H. Snow [ 1♀, det. H. C. Fall nubilus, SEMC ].

Figures

Fig. 3. Pachybrachis nubilus, lectotype, Bill Williams Fork, Arizona. Habitus: A) Dorsal, B) Lateral. C) Face. D) Pygidium. Median lobe of aedeagus: E) En-face view, F) Lateral view.

Fig. 4. Pachybrachis conspirator, lectotype, Arizona. Habitus: A) Dorsal, B) Lateral. C) Face. D) Pygidium. Median lobe of aedeagus: E) En-face view, F) Lateral view.

Fig. 6. Distribution of Pachybrachis species, based upon specimens examined.P.laevis (black); P. nubilus (orange), and P. alticola (purple).