Pachybrachis relictus Fall, 1915

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: 29

publication ID

http://doi.org/ 10.1649/0010-065X-72.1.9

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lsid:zoobank.org:pub:urn:lsid:zoobank.org:pub:69C3E6FD-3835-4B7D-BA21-76DE061F8D7D

persistent identifier

http://treatment.plazi.org/id/120C879C-FFD2-FF86-FF51-80E7FBC8C8E9

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scientific name

Pachybrachis relictus Fall, 1915
status

 

10. Pachybrachis relictus Fall, 1915   ( Fig. 10 View Fig , Map 2A)

Pachybrachys relictus Fall 1915: 424   . Wilcox 1954: 391 (taxonomy).

Pachybrachis relictus: Downie and Arnett 1996: 1319   (catalogue); Barney 1984: 141 (regional species list); Riley et al. 2003: 163 (catalogue); Clark et al. 2004: 161 (plant associations).

Type Material. Fall’ s male type, herein designated as lectotype and labeled “Frmghm. / Mass. / Frost [printed, white paper] // VIII-14-07 [handinked] // 6 // TYPE / relictus   [hand-inked, white paper] // Type 24976 [hand-inked, red paper] // H. C. FALL / COLLECTION // LECTOTYPE 24976 / Pachybrachys   / relictus Fall 1915   / R. J. Barney 2017 [printed, red paper]”, was examined, photographed, and dissected ( Fig. 10 View Fig )   .

Redescription. Male. Yellow, with dark brown to fuscous punctures, standard maculae diffuse; L = 1.97–2.28 mm (mean = 2.13 mm, n = 10); W = 1.02–1.18 mm (mean = 1.10 mm, n = 10); L/W = 1.84–2.09 (mean = 1.94, n = 10). Head: Slightly wider than thoracic apex, HW = 0.69–0.77 mm (mean = 0.72 mm, n = 10); eyes moderately separated, IOD = 0.18–0.21 mm (mean = 0.19 mm, n = 10), IOD/HW = 0.25–0.29 (mean = 0.27, n = 10); face yellow with dark brown to black, W-shaped macula connecting the vertex and bases of antennae and up to base of upper lobes of eyes, punctation dense, antennae yellowbrown, almost reaching elytral declivity. Pronotum: Yellow, dark brown to black M broadly diffuse, leaving small, scattered, yellow spots, incomplete punctation to side margins, PL = 0.62–0.71 mm (mean = 0.66 mm, n = 10); PW = 0.90–1.04 mm (mean = 0.93 mm, n = 10); PL/PW = 0.69–0.73 (mean = 0.71, n = 10). Elytra: Confused punctures in basosutural region, striae impressed, especially posteriorly and laterally, irregular in middle, marginal interspace mostly impunctate. Pygidium: Dark brown to black with 2 oval, yellow maculae. Venter: Dark brown to black, upper sides of last ventrite yellow. Legs: Dark brown to black with standard yellow spots. Genitalia: Median lobe in en-face view with wide, parallel-sided shaft, gently rounding to terminus, with sclerotized, lateral basal plates and reduced PRL. POL, best seen in the lateral view, with ALA deflexed near 60°. Base wide, with mid-keel or ridge eventually narrowing at ALA. Long setae present along edges of deflexation, but no denticles present at ALM ( Fig. 10 View Fig ). Thirty-nine males from 14 states and provinces were dissected.

Female. As in male, except L = 2.07–2.46 mm (mean = 2.26 mm, n = 9); W = 1.15–1.31 mm (mean = 1.23 mm, n = 9); L/W = 1.77– 1.91 (mean = 1.84, n = 9); HW = 0.71–0.84 mm (mean = 0.79 mm, n = 9); IOD = 0.23–0.32 mm (mean = 0.28 mm, n = 9).

Remarks. Fall (1915) believed that P. relictus   was a widely dispersed species in the northeastern USA, being found from New York to Tennessee. Dissection of many males in the MCZ-FALL and MCZ collections, each bearing a Fall identification label, revealed a mixture of four species: true P. relictus   from Massachusetts (as compared to the lectotype); P. gibsoni   from Massachusetts (labels often read “ relictus   var (?)”, some with same label as lectotype); P. mcmeansi   from Massachusetts and Tennessee; and P. luctuosus   from New Jersey. This illustrates the difficulty in separating Pachybrachis   specimens from the same collecting event to species, pre-dissection, even for an expert like Fall.

Distribution. Pachybrachis relictus   is found in the northeast from Québec and Maine to Indiana and South Carolina. New state records are confirmed for four states: Michigan, New Hampshire, North Carolina, and South Carolina (Map 2A).

Biological Notes. A label cited a specimen collected from Quercus sp.   in Ontario.

Specimens Examined. See Appendix 10.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Chrysomelidae

Genus

Pachybrachis

Loc

Pachybrachis relictus Fall, 1915

Barney, Robert J. 2018
2018
Loc

Pachybrachis relictus: Downie and Arnett 1996: 1319

Clark, S. M. & LeDoux, T. N. & Seeno, E. G. & Riley, A. J. 2004: 161
Riley, E. G. & S. M. Clark & T. N. Seeno 2003: 163
Downie, N. M. & R. H. Arnett 1996: 1319
Barney, R. J. 1984: 141
1996
Loc

Pachybrachys relictus Fall 1915: 424

Wilcox, J. A. 1954: 391
Fall, H. C. 1915: 424
1915