Pachybrachis uncinatus Fall, 1915

Barney, Robert J., 2024, Redescriptions and Figures of the Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae) of Arizona, Including New State Records, Plant Associations, and Description of a New Species: The Tibial Spur Species, The Coleopterists Bulletin 78 (1), pp. 61-68 : 66-67

3. Pachybrachis uncinatus Fall, 1915

( Fig. 3 )

Pachybrachys uncinatus Fall 1915: 363 .

Pachybrachis uncinatus : Riley et al. 2003: 164.

Type. Fall (1915) described P. uncinatus based upon five (4♂♂ 1♀) specimens from an unknown location in Arizona. Fall’s type male, hereby designated lectotype, labeled “Ariz [printed, white paper] // TYPE [printed] / uncinatus [hand-inked, white paper] // M.C.Z. / Type [printed] / 24985 [hand-inked, red paper] // H.C. FALL / COLLECTION [printed, white paper] // [circular blue disc signifying dissection by RJB] // LECTOTYPE / Pachybrachys / uncinatus Fall / R. J. Barney 2023 [printed, red paper]”, was examined, dissected, and photographed ( Fig. 3 ).

Redescription. Male. Yellow with brown maculae, eyes almost touching; L = 2.73–3.17 mm (mean = 2.97 mm, n = 7); W = 1.35–1.53 mm (mean = 1.47 mm, n = 7); L/W = 1.95–2.09 (mean = 2.02, n = 7). Head: Slightly wider than thoracic apex, HW = 0.92–1.03 mm (mean = 0.98 mm, n = 7); eyes narrowly separated, IOD = 0.05–0.10 mm (mean = 0.07 mm, n = 7), IOD/HW = 0.05–0.11 (mean = 0.11, n = 7); face yellow with brown macula between eyes; no ocular lines; punctation dense in dark areas, sparser in pale areas; antennae yellow to brown, almost reaching elytral declivity. Pronotum: Yellow with brown, M-shaped macula, not sharply defined; punctation dense in dark areas, more sparsely placed in pale areas; PL = 0.94–1.01 mm (mean = 0.98 mm, n = 7); PW = 1.24–1.39 mm (mean = 1.33 mm, n = 7); PL/PW = 0.69–0.78 (mean = 0.74, n = 7). Elytra: Yellow with extensive brown maculae; striae especially confused in baso-sutural region, mostly regular laterally and apically. Pygidium: Brown with yellow maculae. Venter: Brown, upper sides of last ventrite yellow. Legs: Yellow with brown spots; front claws enlarged, foreleg with enlarged tibial spur. Genitalia: Median lobe in en-face view shows a wide, round OS, with slight indentations at the ALA, opening to a broad, scoop-like DEO; medial lobe in lateral view with inflated base and prominent mid-lobe projection based within a recessed area. Twelve males from Arizona, New Mexico. and Texas were dissected.

Female. As in male, except L = 3.11–3.30 mm (mean = 3.20 mm, n = 8);W = 1.57–1.77 mm (mean = 1.66 mm, n = 8); L/W = 1.87–2.03 (mean = 1.93, n = 8); HW = 1.09–1.20 mm (mean = 1.13 mm, n = 8); IOD = 0.10–0.17 mm (mean = 0.14 mm, n = 8); IOD/HW = 0.09–0.15 (mean = 0.13, n = 8).

Remarks. Pachybrachis uncinatus is one of two species with very closely spaced eyes, male front tibial spur, and enlarged claws. The aedeagal median lobe of P. texanus is narrowed at the base with a rounded keel and extended, triangular POL, while the median lobe of P. uncinatus is not narrowed at the base, has an obvious rear-facing projection, with a rounded POL ending in a scoop-like DEO.

Distribution. Riley et al. (2003) reported P. uncinatus only from Arizona. New Mexico and Texas are new state records.

Biological Notes. A series was collected in New Mexico with Prosopis juliflora (Sw.) DC. [= P. glandulosa Torr. ] ( Fabaceae ) listed on the labels. Some specimens were collected at UV light in Texas.

Specimens Examined. Lectotype plus 55 specimens. USA: ARIZONA: Cochise Co., Benson, 12.vii.1932, R. H. Beamer [1♂, SEMC]; Jct. Hwy. 186 and Kansas Settlement Road , 3.viii.1990, B. F. and J. L. Carr [2♂♂, CNC]; Kansas Settlement, 2.v.1956, F. Werner and G. Butler [1♂, UAIC]; Hereford, 1.viii.1948, Nutting and Werner [1♂, UAIC]; Pima Co., Tucson , 21.iv, Hubbard and Schwarz [1♂, USNM]; Pinal Co., Sawtooth Mts. , 490 m, 32.5671°N 111.7583°W, 28.vii.2022, MV/ UV light, D. J. Cavan and J. W. Quist [10♂♂ 6♀♀, DJCC]; Santa Cruz Co., Rio Rico , 1,023 m, 31.4751°N 111.0023°W, 14.viii.2019, D. Cavan, C. Ramsey and J. Quist [1♂, CWRC]; 18 mi E Douglas , 3,804 ft., 31.33729°N 109.28762°W, 12.vii.2010, A. J. Gilbert and N. J. Smith [3♂♂ 7♀♀, AJGC]; Unknown county, Ariz. [1♂, LECTOTYPE, MCZ-FALL]. NEW MEXICO: Hidalgo Co., 12.2 mi W of Animas , ex Prosopis juliflora [= P. glandulosa ], 29.vii.1987, F. Andrews and T. Eichlin [2♂♂ 1♀, BYUC]; 9 mi N Cotton City, Rt. 338, 4,170 ft., 32.9141°N 108.1308°W, 7.viii.2022, R. J. Barney [3♂♂ 3♀♀, RJBC]; San Simon Valley , 32°52.3′N 109°03.0′W, 12.viii.2001, S. M. Clark and R. E. Acciavatti [1♂ 2♀♀, BYUC]; Hachita Valley , 31°46.3′N 108°22.8′W, 11.viii.2001, S. M. Clark and R. E. Acciavatti [1♂ 3♀♀, BYUC]; Rt. 10, mm 11–20, 8.vii.2012, J. Huether and C. O’Brien [2♂♂ 2♀♀, BYUC]. TEXAS: Brewster Co., Health Canyon Ranch , UV light, 3.vii.1999, E. G. Riley [1♂ 1♀, RJBC].

Figures

Fig. 3. Pachybrachis uncinatus, Arizona, lectotype. 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.