Pachybrachis saguaro, Barney, 2021

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 : 730-732

4. PACHYBRACHIS SAgUARo Barney , new species zoobank.org/ urn:lsid:zoobank.org:act:3242C62B-20AD-46D4-9716-A425B9AF2D72 ( Figs. 4 , 14B )

Holotype. Male labeled “ USA: ARIZONA / Pima Co., Sonoran Desert/ N.Kinney Rd. 2800′/ 32.2386°N 111.1561°W / 18.iv.2017 R. J. Barney [printed, white paper]//[circular blue disc signifying dissection by RJB]// HOLOTYPE / P a c h y b r a c h i s / s a g u a ro Barney/R. J. Barney 2021 [printed, red paper]”. Deposited in MCZ. The specimen is point-mounted with the genitalia affixed to a second point. It is in excellent condition.

Paratypes. Fourteen specimens (6♂♂ 8♀♀), including seven (2♂♂ 5♀♀) from the holotype series, are labeled “ PARATYPE / Pachybrachis / saguaro Barney /R. J. Barney 2021 [printed, yellow paper]”.

Description. Male. Large, yellow with brown maculae ( Fig. 4 ); L = 3.67–4.39 mm (mean = 3.98 mm, n = 7); W = 1.87–2.46 mm (mean = 2.17 mm, n = 7); L/W = 1.79–1.95 (mean = 1.84, n = 7). Head: Not wider than thoracic apex; HW = 1.27–1.52 mm (mean = 1.39 mm, n = 7); eyes very closely separated, without ocular lines, IOD = 0.17–0.30 mm (mean = 0.22 mm, n = 7); IOD/HW = 0.13–0.21 (mean = 0.16, n = 7); face yellow with 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 reduced M-shaped brown macula, densely punctate, less so at margins and median line, strongly narrowed apically; PL = 1.21–1.50 mm (mean = 1.34 mm, n = 7); PW = 1.78–2.17 mm (mean = 2.00 mm, n = 7); PL/PW = 0.59–0.70 (mean = 0.67, n = 7). Elytra: Yellow with brown maculae on each elytron prior to declivity, thus appearing as a trans-elytral stripe, densely punctate in baso-sutural area, striae irregular. 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 OS, with large POL ending in projecting T, bounded on each side by extensions of the DEO, thus appearing as a three-pronged T. The lateral view reveals that the large POL is bounded by large wisps, with a smaller set of setae beards behind the side “prongs” of the T. A large keel projects from the base to the wisps. The sub view of the median lobe shows that the keel has a darkened sharp edge. Seven males from two USA states were dissected.

Female. As in male, except L = 4.23–4.64 mm (mean = 4.42 mm, n = 8); W = 2.38–2.60 mm (mean = 2.47 mm, n = 8); L/W = 1.74–1.88 (mean = 1.79, n = 8); HW = 1.51–1.72 mm (mean = 1.61 mm, n = 8); IOD = 0.33–0.51 mm (mean = 0.42 mm, n = 8); IOD/HW = 0.21–0.30 (mean = 0.26, n = 8).

Etymology. Pachybrachis saguaro is named for the iconic saguaro cactus, Carnegiea gigantea (Engelm.) Britton & Rose ( Cactaceae ). The beetle and cactus share the same Sonoran Desert habitat, but there is no suspected plant association.

Remarks. Externally, P. saguaro is very similar to P. cylindricus , P. huachuca , and P. ashfork . However, the three-pronged terminus and extended POL of the median lobe are very distinctive.

Distribution. Specimens were found in the Sonoran Desert of Arizona and southern California ( Fig. 14B ).

Biological Notes. Many of the specimens were collected at lights.

Specimens Examined. Holotype + 15 paratypes. USA: ARIZONA: Maricopa Co., Lost Dutchman State Park, restroom light, 2,059′, 33°27.14′N 111°28.59′W, 6.viii.2016, M. Kippenhan [1♂ 1♀, RJBC]; Pima Co. , Coronado National Forest , Redington Road , E Tucson, 32°15′47′′N, 110°39′11′′W, 9.viii.2003, UV, E. G. Riley [1♂ 1♀, EGR#24 , RJBC]; Lower Tanque Verde Canyon , 32.25465°N 110.66471°W, parking lot, 18.vii.2012, 3,150′, UV light, Barney, Clark & Riley [1♂, RJBC]; Sonoran Desert, N. Kinney Rd, 2,800′, 32.2386°N 111.1561°W, 18.iv.2017, R. J. Barney [3♂♂ (HOLOTYPE) 5♀♀, RJBC]; Green Valley , 13.vi.2009, at light, C. W. O’Brien [1♂, BYUC]. CALIFORNIA: Imperial Co. , 9 mi S Walter Camp, 28.ix.1980, blacklight, A. R. Hardy and F. G. Andrews [1♂ 1♀, RJBC].

Figures

Fig. 4. Pachybrachis saguaro, new species, Pima Co., Arizona, 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.

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).