Pachybrachis texanus Bowditch 1909
Creators: name: Barney, Robert J.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Pachybrachis
Pachybrachis texanus

description: 2. Pachybrachis texanus Bowditch, 1909
(Fig. 2)
Pachybrachys texanus Bowditch 1909: 316. Fall 1915: 362 (taxonomy).
Pachybrachis texanus: Riley et al. 2003: 163 (catalog).
Type. Bowditch (1909) described P. texanus based upon a series of beetles from Brownsville, Texas collected by Wickham.A male specimen from this series in Fall’s collection, hereby designated lectotype, labeled “Brownsville / Texas / Wickham [printed, white paper] // ♂ // texanus / cotype Bw [hand-inked, white paper] // H. C. FALL / COLLECTION [printed, white paper] // [circular blue disc signifying dissection by RJB] // LECTOTYPE / Pachybrachys / texanus Bowditch / R. J. Barney 2023 [printed, red paper]”, was examined, dissected, and photographed (Fig. 2).
Redescription. Male.Yellow with brown maculae, eyes almost touching; L = 2.38–2.83 mm (mean = 2.60 mm, n = 10); W = 1.22–1.44 mm (mean = 1.34 mm, n = 10); L/W = 1.87–1.98 (mean = 1.94, n = 10). Head: Slightly wider than thoracic apex, HW = 0.88–0.99 mm (mean = 0.93 mm, n = 10); eyes narrowly separated, almost touching, IOD = 0.05– 0.12 mm (mean = 0.09 mm, n = 10), IOD/HW = 0.06–0.12 (mean = 0.10, n = 10); face yellow with brown macula between eyes; no ocular lines; punctation dense in dark areas, sparser in pale areas, antennae yellow-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 = 0.74–0.94 mm (mean = 0.83 mm, n = 10); PW = 1.13–1.29 mm (mean = 1.21 mm, n = 10); PL/PW = 0.64–0.73 (mean = 0.68, n = 10). Elytra: Yellow with brown maculae; striae especially confused in baso-sutural region, most 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 tibial spur. Genitalia: Median lobe in en-face view wide, large, oval OS with extended, triangular POL; medial lobe in lateral view narrowed at base, then expanded, then narrowing to terminal, edged with setae. Thirteen males fromArizona, New Mexico, Texas, and Mexico were dissected.
Female. As in male, except L = 2.52–3.20 mm (mean = 2.78 mm, n = 10); W = 1.33–1.77 mm (mean = 1.49 mm, n = 10); L/W = 1.79– 1.94 (mean = 1.87, n = 10); HW = 0.86–1.20 mm (mean = 1.01 mm, n = 10); IOD = 0.09–0.21 mm (mean = 0.14 mm, n = 10); IOD/HW = 0.10– 0.18 (mean = 0.14, n = 10).
Remarks. Pachybrachis texanus 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 with an 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. texanus only from Texas and Mexico. Arizona and Nevada represent new state records.
Biological Notes. Large series of P. texanus were taken from Vachellia farnesiana (L.) Wight & Arn. [= Acacia farnesiana L.] (Fabaceae) in Texas. Clark et al. (2004) also reported specimens in association with Vachellia constricta (Benth.) Seigler & Ebinger [= Acacia constricta Benth.] in Texas. Some beetles were captured at lights in Arizona and Texas.
Specimens Examined. Lectotype plus 74 specimens. MEXICO: TAMAULIPAS: Sierra Tamaulipas, 18 mi W of Soto La Marina, 26.vii.2011, D. J. Cavan and D. W. Sundberg [1♂ 1♀, DJCC]. USA: ARIZONA: Cochise Co., 7 mi W of Sunsites, 30.vii.2009, at light, F. W. Skillman, Jr. [1♂, RJBC]; Bowie, 28.vii.1970, UV light, S. Kozlooski [1♂, UAIC]; Pima Co., Green Valley, UV light, 26.vii.2011, C. W. O’Brien [1♂ 1♀, RJBC]; 8 mi SE Continental, 28–29.vii.1996, UV light, M. A. Goodrich [1♂, RJBC]; Santa Cruz Co., Pajarito Mts., Sycamore Canyon, 31.4322°N 111.1880°W, 1,248 m, 21.vii.2018, C. Ramsey, D. Cavan and J. Quist [1♂, CWRC]. NEVADA: Clark Co., NE Las Vegas, 10.vii.2005, D. J. Cavan [3♂♂ 3♀♀, DJCC]. TEXAS: Cameron Co., Brownsville, H. F. Wickham [1♂, LECTOTYPE, 1♀, MCZ-FALL]; Sabal Palm Grove Wildlife Refuge, 18–19.x.2002, UV, E. G. Riley [1♂ 1♀, RJBC]; Sabal Palm Sanctuary, 25.8512°N 97.4171°W, 3–4.xi.2013, ex huisache, R. J. Barney and E. G. Riley [13♂♂ 31♀♀, RJBC]; Hidalgo Co., Santa Ana NWR, 26.0762°N 98.1448°W, 6.xi.2013, R. J. Barney, S. M. Clark and M. Quinn [3♂♂ 5♀♀, RJBC]; San Patricio Co., Welder Wildlife Refuge, Big Lake Area, 28.1206°N 97.3736°W, 2.xi.2013, ex huisache, R. J. Barney [2♂♂ 4♀♀, RJBC].
description: Published as part of 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, pp. 61-68 in The Coleopterists Bulletin 78 (1) on pages 65-66, DOI: 10.1649/0010-065X-78.1.61, http://zenodo.org/record/13243665