Pachybrachis crassus, Bowditch, 1909

Barney, Robert J., 2021, Definition and Revision of the cylindricus Species-Group of North American Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae), Including Descriptions of Six New Species, The Coleopterists Bulletin 75 (4), pp. 723-748 : 727

2. PACHYBRACHIS CRASSUS Bowditch, 1909 ( Figs. 2 , 14A )

Pachybrachys crassus Bowditch 1909: 290 . Fall 1915: 358 (taxonomy).

Pachybrachis crassus Bowditch : Riley et al. 2003: 156 (catalog).

Type. Bowditch’s (1909) female holotype, labeled “ ♀ // St. George / Utah, July/Wickham [printed, white paper]// crassus Bw /Type [hand-inked, white paper]// TYPE F. C. B. Coll. [printed, pink paper]//M.C.Z./ Type [printed]/8773 [hand-inked, red paper]”, was examined and photographed ( Fig. 2H ) .

Redescription. Male. Large, yellow with much reduced brown maculae ( Fig. 2 ); L = 3.85–4.65 mm (mean = 4.26 mm, n = 7); W = 2.09–2.56 mm (mean = 2.34 mm, n = 7); L/W = 1.80–1.84 (mean = 1.82, n = 7). Head: Not wider than thoracic apex, HW = 1.27–1.59 mm (mean = 1.43 mm, n = 7); eyes narrowly separated, without ocular lines, IOD = 0.20– 0.27 mm (mean = 0.23 mm, n = 7); IOD/HW = 0.13–0.19 (mean = 0.16, n = 7); face yellow with large, brown macula descending from the vertex and between the upper lobes of eyes, punctation dense in dark areas, antennae progressing from yellow to brown, not reaching elytral declivity. Pronotum: Yellow with diffuse M-shaped brown macula, sparsely punctate, less so at margins and median line, strongly narrowed apically; PL = 1.26–1.55 mm (mean = 1.43 mm, n = 7); PW = 1.86–2.34 mm (mean = 2.09 mm, n = 7); PL/PW = 0.66–0.70 (mean = 0.68, n = 7). Elytra: Yellow with reduced to no brown maculae, densely punctate in baso-sutural area, striae irregular and prominent as dark brown lines on yellow background. Pygidium: Brown with 2 oval conjoined yellow spots. Venter: Brown with yellow side and apical margins. Legs: Yellow with brown spots, front claws of male greatly enlarged. Genitalia: Median lobe in en-face view shows large, oval OS, with a wide projecting terminus, bounded on each side with large wisps at the ALM. The lateral view reveals a large, dark-edged keel, projecting from the base to the initiation of the wisps. A sub view of the median lobe shows that the keel ridge is very sharp. Four males from California were dissected.

Female. As in male, except L = 3.77–4.80 mm (mean = 4.29 mm, n = 11); W = 2.20–2.69 mm (mean = 2.42 mm, n = 11); L/W = 1.72–1.82 (mean = 1.77, n = 11); HW = 1.34–1.69 mm (mean = 1.51 mm, n = 11); IOD = 0.27–0.44 mm (mean = 0.34 mm, n = 11); IOD/HW = 0.19–0.29 (mean = 0.22, n = 11).

Remarks. Pachybrachis crassus was described by Bowditch (1909) based upon a single female. Fall (1915) reported that he had only seen three females. Previous experience makes me very hesitant to confirm any specimens without a male for median lobe determination. However, I find the distinctive dark brown strial punctures on the yellow background of the elytra compelling, causing me to make this tentative determination. Acknowledging this, P. crassus has a very similar median lobe to P. cylindricus but without the setal-covered extensions of the DEO on each side of the terminus, which is wide and ungrooved in P. crassus . The median lobe is also very similar to P. ashfork , but the keel is without the fissura or split at the most extended point as in P. ashfork .

Distribution. Riley et al. (2003) restricted P. crassus to Arizona and Utah and did not believe it was present in California. If my assumption is correct that this is, in fact, P. crassus , these specimens near the Arizona border would make California a new state record ( Fig. 14A ).

Specimens Examined. Lectotype + 22 specimens. USA: CALIFORNIA: Riverside Co., 25 mi N Blythe, 24.v.1985, boll weevil trap, J. Ball [4♂♂ 3♀♀, BYUC]; Mecca, 30.vii.1956, L. D. Moore [2♂♂ 4♀♀, BYUC]; same data, except 19– 22.v.1958 [1♂ 8♀♀, BYUC]. UTAH: Washington Co., St. George , vii, Wickham [1♀, LECTOTYPE, MCZ-BOW].

Figures

Fig. 2. Pachybrachis crassus, Riverside Co., California, holotype. 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, sub view, H) Female holotype.

Fig. 14. Distribution of Pachybrachis species, based only upon specimens examined in this study. A) P. hybridus (black), P. turgidicollis (red), P. texasensis, new species (green), P. chaoticus (blue), P. pinguescens (orange), P. crassus (purple), B) P. saguaro, new species (black), P. peninsularis (purple), P. cylindricus (red), P. huachuca, new species (orange), P. hurricane, new species (gray), P. ephedra, new species (blue), and P. ashfork, new species (green).