Pachybrachis turgidicollis, Fall, 1915

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 : 742-744

11. PACHYBRACHIS tURgIDICoLLIS Fall, 1915 ( Figs. 11 , 14A )

Pachybrachys turgidicollis Fall 1915: 369 . Pachybrachis turgidicollis Fall : Riley et al. 2003:

164 (catalog).

Type. Fall’s (1915) type male, hereby designated lectotype, labeled “Green Val/VII 15 Tex [printed, white paper]//BrewsterCo/HAWenzel [printed, white paper]//TYPE [printed]/ turgidi -/ collis [hand-inked, white paper]//M.C.Z./Type [printed]/24982 [hand-inked, red paper]//H.C. FALL /COLLECTION [printed, white paper]//[circular blue disc signifying dissection by RJB]// LECTOTYPE / Pachybrachys / turgidicollis Fall /R. J. Barney 2021 [printed, red paper]”, was examined, dissected, and photographed ( Fig. 11 ).

Redescription. Male. Large, black or fuscous and yellow maculate ( Fig. 11 ); L = 3.64–4.00 mm (mean = 3.77 mm, n = 5); W = 1.99–2.21 mm (mean = 2.07 mm, n = 5); L/W = 1.78–1.86 (mean = 1.82, n = 5). Head: Not wider than thoracic apex, HW = 1.26–1.35 mm (mean = 1.31 mm, n = 5); eyes closely separated, without ocular lines, IOD = 0.22–0.30 mm (mean = 0.26 mm, n = 5); IOD/ HW = 0.16–0.23 (mean = 0.20, n = 5); face yellow with large, brown W-shaped macula connecting the vertex and bases of antennae and up to bases of upper lobes of eyes, punctation dense in dark areas, antennae progressing from yellow to brown to apically black, not reaching elytral declivity. Pronotum: Yellow with broad, diffuse M-shaped brown macula, densely punctate, less so at margins and median line, strongly narrowed apically; PL = 1.20–1.37 mm (mean = 1.26 mm, n = 5); PW = 1.82–2.02 mm (mean = 1.92 mm, n = 5); PL/PW = 0.62–0.70 (mean = 0.66, n = 5). Elytra: Yellow with standard brown maculae, densely punctate in baso-sutural area, striae irregular. Pygidium: Dark brown with 2 oval conjoined yellow spots. Venter: Dark 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 a large, oval OS, with a wide projecting terminus, bounded on each side with large wisps at the ALM. The lateral view reveals a medium-sized keel, projecting between the bases of the wisps. A sub view of the median lobe shows that the keel ridge is grooved or split. Five males from two USA states were dissected.

Female. As in male, except L = 3.85–3.94 mm (mean = 3.90 mm, n = 3); W = 2.08–2.26 mm (mean = 2.16 mm, n = 3); L/W = 1.74–1.87 (mean = 1.81, n = 3); HW = 1.34–1.42 mm (mean = 1.37 mm, n = 3); IOD = 0.31–0.40 mm (mean = 0.36 mm, n = 3); IOD/HW = 0.23–0.29 (mean = 0.26, n = 3).

Remarks. Pachybrachis turgidicollis appears to have the same median lobe as P. chaoticus and P. pinguescens . However, the keel of P. turgidicollis has a groove or split in the keel ridge which P. chaoticus and P. pinguescens do not. These three species must be very closely related.

Distribution. Riley et al. (2003) reported P. turgidicollis from New Mexico and Texas. Oklahoma is a new state record ( Fig. 14A ).

Biological Notes. Two specimens were labeled as found on Quercus sp. ( Fagaceae ) in Texas. Clark et al. (2004) referenced specimens labeled from New Mexico and Texas in association with Vachellia constricta (Benth.) Seigler & Ebinger ( Fabaceae ).

Specimens Examined. Lectotype + 8 specimens. USA: OKLAHOMA: Roger Mills Co., 7 mi W Cheyenne, 35.609°N 99.806°W, 2.vi.2019, S. M. Clark [1♂, BYUC]. TEXAS: Brewster Co., Green Valley , H. A. Wenzel [1♂, LECTOTYPE, MCZ]; Big Bend National Park , 4,000 –5,300 ′, Panther Jct., 29.iv-26.v.1939, ex. Quercus sp. , Howden and Becker [1♂ 1♀, RJBC]; Crosby Co. , White River Lake , 33°29′09′′N 101°06′17′′W, 12.v.2002, E. G. Riley [1♂ 1♀, EGR#11 , RJBC]; Jeff Davis Co. , Davis Mts. , 14.vi.1935, J. N. Knull [1♂, OSUC]; Randall Co. , Palo Duro State Park , 3.vi.1959, Howden and Becker [1♂ 1♀, RJBC].

Figures

Fig. 11. Pachybrachis turgidicollis, Green Valley, Texas, 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).