Pachybrachis jacobi Barney

Barney, Robert J., 2018, Definition and Revision of the Atomarius Species-Group of North American Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae), Including Descriptions of Nine New Species, The Coleopterists Bulletin 72 (1), pp. 9-74: 23-24

publication ID 10.1649/0010-065X-72.1.9

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Pachybrachis jacobi Barney

new species

6. Pachybrachis jacobi Barney   , new species ( Fig. 6 View Fig , Map 1C)

Holotype. Male, labeled “ KENTUCKY: Logan  

Co. / R. Athey Barrens SNP / 36.8521 o N,

- 86.7936 o W /, R. J. Barney [printed, white paper] // [circular blue disc signifying dissection by RJB] // HOLOTYPE / Pachybrachis   / jacobi   / R. J. Barney 2017 [printed, red paper]”. Deposited in MCZ. The specimen is point-mounted with genitalia affixed to a second point. It is in excellent condition with all appendages intact. There are 42 paratypes (2066 22♀♀) having identical collecting data as the holotype.  

Paratypes. 23866 242♀♀. See Appendix 6.

Description. Male. Yellow with fuscous punctures, standard maculae diffuse; L = 1.87–2.18 mm (mean = 2.01 mm, n = 11); W = 0.99–1.18 mm (mean = 1.09 mm, n = 11); L/W = 1.75– 1.89 (mean = 1.84, n = 11). Head: Slightly wider than thoracic apex, HW = 0.69–0.82 mm (mean = 0.75 mm, n = 11); eyes moderately separated, IOD = 0.20–0.28 mm (mean = 0.24 mm, n = 11); IOD/HW = 0.26–0.37 (mean = 0.32, n = 11); face yellow with black, W-shaped macula connecting vertex and bases of antennae and up to base of upper lobes of eyes, often expanded to cover almost entire face; punctation dense in black areas, sparser in pale areas; antennae brown to black, not reaching elytral declivity ( Fig. 6 View Fig ). Pronotum: Yellow with black, M-shaped macula broad, not sharply defined; punctation dense in black areas, more sparsely placed in pale areas, especially along lateral margins, anterior width slightly less than basal width, lateral margin arcuate basally, PL = 0.56–0.68 mm (mean = 0.63 mm, n = 11); PW = 0.85–1.03 mm (mean = 0.92 mm, n = 11); PL/ PW = 0.66–0.72 (mean = 0.68, n = 11). Elytra: Yellow with black in equal proportion to yellow in no particular pattern; punctation confused in basosutural region, striae weak and incomplete basally, mostly regular laterally and apically. Pygidium: Finely punctate, weakly convex; black with small yellow maculae. Venter: Black. Legs: Black with brown and yellow femoral and tibial spots; front claws not distinctly enlarged. Genitalia: Median lobe in en-face view near equal width but narrowing slightly to ALM, then gently curved to terminus; OS ca. 2 times as long as wide, basal plates lightly pigmented; pre- and post-orificial lengths very small; median lobe very narrowed in lateral view, DEO deflexed at near 30° angle, without denticles or beards ( Fig. 6 View Fig ). Sixty-two males from 10 states were dissected.

Female. As in male, except L = 2.18–2.36 mm (mean = 2.26 mm, n = 10); W = 1.17-– 1.31 mm (mean = 1.24 mm, n = 10); L/W = 1.77–1.90 (mean = 1.82, n = 10); HW = 0.81–0.88 mm (mean = 0.85 mm, n = 10); IOD = 0.28–0.32 mm (mean = 0.30 mm, n = 10); IOD/HW = 0.33–0.37 (mean = 0.36, n = 10).

Etymology. This species is named in recognition of Jacob Nathaniel Barney, PhD, Associate Professor of Invasive Plant Ecology, Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech University, Blacksburg, Virginia.

Remarks. Undissected males of P. jacobi   can possibly be confused with very dark, punctured specimens of P. gibsoni   and several other similar looking species. However, the slender, upright median lobe is definitive for this species.

Distribution. This species is found, often in long series, in scattered distributions across 11 states from Illinois to Kansas south to Texas and Florida (Map 1C).

Biological Notes. Labels cited potential host plants as Amorpha canescens Pursh   ( Fabaceae   ) in Illinois and Balduina angustifolia (Pursh) B. L. Rob.   ( Asteraceae   ) in Florida, and from Malaise traps in longleaf pine-turkey oak Florida habitats.

Specimens Examined. See Appendix 6.