Pachybrachis chaoticus, 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 : 727-730

3. PACHYBRACHIS CHAotICUS Fall, 1915 ( Figs. 3 , 14A )

Pachybrachys chaoticus Fall 1915: 367 . Pachybrachis chaoticus Fall : Riley et al. 2003: 156

(catalog).

Type. Fall’s (1915) male type, hereby designated lectotype, labeled “Ari. [printed, white paper]// Comp. with/Lec. Coll. [hand-inked, white paper]// ♂ [printed, white paper]//TYPE [printed]/ chaoticus [hand-inked, white paper]//M.C.Z./Type [print- ed]/24924 hand-inked, red paper]//H.C. FALL / COLLECTION [printed, white paper]//[circular blue disc signifying dissection by RJB]// LECTOTYPE / Pachybrachys / chaoticus Fall /R. J. Barney 2021 [printed, red paper]”, was examined, dissected, and photographed ( Fig. 3 ).

Redescription. Male. Large, yellow with reduced punctures and standard brown maculae ( Fig. 3 ); L = 3.63–3.97 mm (mean = 3.80 mm, n = 10); W = 2.04–2.33 mm (mean = 2.19 mm, n = 10); L/W = 1.67–1.79 (mean = 1.74, n = 10). Head: Not wider than thoracic apex, HW = 1.27–1.40 mm (mean = 1.35 mm, n = 10); eyes closely separated, without ocular lines, IOD = 0.22–0.29 mm (mean = 0.25 mm, n = 10); IOD/HW = 0.16–0.24 (mean = 0.19, n = 10); 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 = 1.26–1.40 mm (mean = 1.36 mm, n = 10); PW = 1.90–2.16 mm (mean = 2.02 mm, n = 10); PL/PW = 0.66–0.72 (mean = 0.68, n = 10). Elytra: Yellow with standard brown maculae, 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 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, darkened, sharp-edged keel, projecting between the bases of the wisps. A sub view of the median lobe shows that the keel ridge is not grooved or split. Ten males from two USA states were dissected.

Female. As in male, except L = 3.98–4.34 mm (mean = 4.16 mm, n = 7); W = 2.31–2.54 mm (mean = 2.43 mm, n = 7); L/W = 1.68–1.73 (mean = 1.71, n = 7); HW = 1.44–1.65 mm (mean = 1.57 mm, n = 7); IOD = 0.31–0.52 mm (mean = 0.38 mm, n = 7); IOD/HW = 0.20–0.31 (mean = 0.25, n = 7).

Remarks. The sparsely punctate pronotum and irregular elytral striae are characteristic of P. chaoticus . The median lobe is very similar to P. turgidicollis , but P. chaoticus does not have a groove or split in the keel ridge as does P. turgidicollis . This species is also very similar to P. hybridus , but the keel on P. hybridus extends further to the base of the median lobe. The median lobe of P. pinguescens appears to be identical to P. chaoticus .

Distribution. Riley et al. (2003) reported P. chaoticus from Arizona, New Mexico, and Texas ( Fig. 14A ).

Biological Notes. A specimen was labeled as collected on catclaw, Uncaria tomentosa (Willd. Ex Schult.) DC. ( Rubiaceae ) in Texas. Several specimens were collected via ultraviolet (UV) lights.

Specimens Examined. Lectotype, paratype + 21 specimens. USA: ARIZONA: Cochise Co., Dragoon Mts., Middlemarch Pass , 31.vii.2000, F. W. Skillman Jr. [1♂, BYUC]; 18 mi E Douglas, 3,804 ft., 31.33729°N 109.28762°W, 12.vii.2010, A. J. Gilbert & N. J. Smith [1♂, AJGC]; Rt. 186 ,

vic Dos Cabezas, 7.vii.2012, J. Huether [2♂♂ 1♀, BYUC]; Pima Co., Green Valley, 13.vi.2009, at light, C. W. O’Brien [1♂, BYUC]; Lower Tanque Verde Canyon , 32.25465°N 110.66471°W parking lot, 3,150′, UV light, 18.vii.2012, Barney, Clark & Riley [6♂♂ 5♀♀, RJBC; 1♂, BYUC]; Lower Madera Canyon , 15.vii.2013, J. & M. Huether [1♂, BYUC]; Santa Rita Mts. , 31.vii.1950, J. G. Rozen [1♂, SEMC]; Pinal Co. , Oracle, 6–15.vii, Hubbard & Schwarz [1♂ 1♀, Fall 1915 Revis. PARATYPE, USNM]; unknown county, Ari. [1♂, LECTOTYPE, MCZ-FALL]. TEXAS: Presidio Co. , Presidio , 6.iv.1950, on catclaw, J. H. Russell [1♂, CDFA] .

Figures

Fig. 3. Pachybrachis chaoticus, 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).