Pachybrachis nigricornis (Say, 1824)

Barney, Robert J., LeSage, Laurent & Savard, Karine, 2013, Pachybrachis (Coleoptera, Chrysomelidae, Cryptocephalinae) of Eastern Canada, ZooKeys 332, pp. 95-175 : 120-122

publication ID	https://dx.doi.org/10.3897/zookeys.332.4753
persistent identifier	https://treatment.plazi.org/id/850884FC-4FE8-9A0B-0908-A52CA2123548
treatment provided by	ZooKeys by Pensoft
scientific name	Pachybrachis nigricornis (Say, 1824)
status

Treatment

Pachybrachis nigricornis (Say, 1824) Habitus 9a View Habitus 9a , 9b View Habitus 9b , 9c View Habitus 9c ; Map 9 View Map 9 ; Figures 6d View Figure 6 , 7f View Figure 7

Cryptocephalus nigricornis Say, 1824: 436.

Pachybrachys carbonarius Haldeman, 1849: 260.

Pachybrachys autolycus Fall, 1915: 458.

Pachybrachys autolycus var. Pachybrachis difficillis Fall, 1915: 459.

Pachybrachys autolycus var. Pachybrachis wahsatchensis Fall, 1915: 459.

Pachybrachys carbonarius var. Pachybrachis janus Fall, 1915: 462.

Recognition.

Pronotum strongly alutaceous and opaque, more finely punctate than elytra. In subspecies Pachybrachis difficilis , black stripes usually complete and distinct ( Habitus 9a View Habitus 9a ), but in some specimens fused together. In subspecies Pachybrachis carbonarius , elytra largely black ( Habitus 9b View Habitus 9b ), margined with yellow, or with yellow at edge of elytra in some females ( Habitus 9c View Habitus 9c ); male size small: length 2.20 ± 0.14 mm, width 1.21 mm ± 0.06 mm ( Pachybrachis difficilis ); length 2.10 ± 0.07 mm, width 1.17 ± 0.04 mm ( Pachybrachis carbonarius ).

Distribution.

The species Pachybrachis nigricornis is distributed across the eastern two-thirds of North America ( Riley et al. 2003). The distribution of the subspecies remains a subject of debate ( Balsbaugh and Tucker 1976; Barney and Hall 2009) ( Map 9 View Map 9 ).

Material examined.

NEW BRUNSWICK: Kent Co., Kouchibouguac National Park, 7.VII.1978, Code 7785K, H. Goulet [3♂, CNC]; same data except Code 7754F [1♂ 1♀, CNC]; same data, except 13.VII.1977, code 5599I, G.A. Calderwood [1♂ 1♀, CNC]; same data, except 4.VIII.1977, code 5779G [1♂, CNC]; same data, except 25.VIII.1977, code 5849Y, S.J. Miller [1♂ 1♀, CNC]; Queens Co., Jemseg, 18.VI.1981, ex. Potentilla simplex , L. LeSage & D. Ward [1♀, CNC].

ONTARIO: Carleton Co., Britannia, 14.VI.1949, R. de Ruette [2♀, CNC]; Constance Bay, 12.VII.1996, lot 3, B. F. & J. L. Carr [1♀, CNC]; Innis Point, 9-16.VII.1985, Interception trap, J. Denis & L. Dumouchel [1♂, CNC]; Ottawa, 17.VII.1912, G. Ouellet [1♀, IDM]; Hasting Co., Trenton, 28.V.2000, Evans [1♂, CNC]; Kenora Co., Berens River, 4-9.VII.1938, W. J. Brown [1♂ 1♀, CNC]; Hwy 17, 15 km east of Borups Corners, 23.VI.1996, lot 2, B. F. & J. L. Carr [1♀, CNC]; Leeds Co., Saint-Lawrence Island National Park, Grenadier Island Center, 27.V.1975, sweeping, E. Sigler [1♀, CNC]; Lennox - Addington Co. Kaladar, 21.VII.1996, lot 3, B. F. & J. L. Carr [1♂, CNC]; Muskoka Co., Bala, 24.VI.1956, W. J. Brown [3♂ 11♀, CNC]; Nipissing Co., Algonquin Provincial Park near Brent, 19.VIII.1980, R. Baranowski [1♀, CNC]; Hwy11, 30 km north of North Bay, 14.VII.1995, lot 3, B. F. & J. L. Carr [1♂ 1♀, CNC]; Hwy 17, 13 km west of Mattawa, 14.VI.1995, lot 1, B. F. & J. L. Carr [2♀, CNC]; Parry Sound Co., Parry Sound, 12.VII.1961, G. Brumpton [2♂, CNC]; same data, except 12.VII.1995, lot 1, B. F. & J. L. Carr [1♂, CNC]; Hwy 69, 12 km south Shawanaga, 13.VII.1995, Lot 3, B. F. & J. L. Carr [1♀, CNC]; Prescott Co., Alfred Bog, 8.VI.1982, breeding, ex. Cassandra calyculata , L. LeSage [4♂ 4♀, CNC]; same data, except 4.VI.1982, ex. Ericaceae [2♂ 4♀, CNC]; Prince Edward Co., 23.VI.1933, J. F. Brimley [1♀, CNC]; same data, except 1.VII.1936 [1♂, CNC]; same data, except 28.VI.1939 [1♂, CNC]; same data, except 19.VII.1942 [1♂, CNC]; same data, except 11-18.VI.1947 [12♂ 7♀, CNC]; same data, except 9.VI.1948 [8♂ 7♀, CNC]; same data, except 21.VI.1950 [2♀, CNC]; same data, except 17.VI.1953 [8♂ 14♀, CNC]; same data, except 19.VII.1961 [1♂, CNC]; same data, except 2.VII.2000, Evans [1♀, CNC]; Russell Co., Mer Bleue, 13.VI.1932, W. J. Brown [2♂ 1♀, CNC]; same data, except 30.VI.1932 [5♂, CNC]; same data, except 26.VII.1932 [1♂, CNC]; same data, except 30.VI.1934 [1♂, CNC]; same data, except 10.VIII.1936 [1♂, CNC]; same data, except 25.VII.1932, L. J. Milne [6♂ 3♀, CNC]; same data, except 29.VI.1954, E. C. Becker [2♂ 2♀, CNC]; same data, except 3.VII.1981, ex. Cassandra calyculata , L. LeSage [1♂ 1♀, CNC]; same data, except 30.VII.1979, sweeping, H. Goulet [1♂, CNC]; Sudbury Co., Sudbury, 1898 [1♀, CNC]; Thunder Bay Co., Manitouwadge, paper yard, 3.VII.1985, T. Baker [1♂ 1♀, CNC]; 59 km north junction of highways 516 & 599, 24.VI.1992, lot 1 B. F. & J. L. Carr [1♂, CNC].

QUÉBEC: Beauce Co., Beauceville, 21.VI.1937, Frère Étienne-Maurice [1♀, CEUM]; Bonaventure Co., Cascapédia, 22.VI.1933, W.J. Brown [1♂ CNC]; same data, except 9.VII.1933 [1♂, CNC]; same data, except 16.VIII.1933 [1♀, CNC]; Châteauguay Co., Ormstown, 12.VII.1977, E. J. Kiteley, sweeping [1♂, CNC]; Deux-Montagnes Co., La Trappe, VII.1933 [1♂ 1♀, Pachybrachis autolycus , var. Pachybrachis difficillis Fall, Fall-MCZ]; same data, except 25.V.1929, P. Leopold [4♀, CEUM]; same data, except 2-19.VI.1936 [1♀, CEUM]; same data, except 21.VI.1933, J. Ouellet [5♂ 3♀, CEUM]; same data, except 23.VII.1933 [1♂, CEUM]; same data, except 3-28.VII.1934 [2♂ 1♀, CEUM]; same data, except 3-17.VII.1935 [1♂ 1♀, CEUM]; same data, except 15.VI.1946 [1♂, CEUM]; Gatineau Co., Aylmer, 11.VI.1932, W. J. Brown [6♂ 4♀, CNC]; Gracefield, 22.VI.1937, O. Peck [1♂, CNC]; Kazabazua, 28.VIII.1928, W. J. Brown [1♀, CNC]; Lytton, 1.VII.1981, weeds, side of road, A. Larochelle [1♂, CNC]; Mont King, Parc de la Gatineau 7-14.VII.1997, L. LeSage & C. Lacroix [1♂ CNC]; Huntingdon Co., Saint-Antoine- Abbé, 16.VI.1983, fern, A. Larochelle [2♀, CNC]; Joliette Co., Joliette, 12.VII.1922, J. Ouellet [1♂ 2♀, CEUM]; Labelle Co., Nominingue, 21.VII.1932 [1♂, Pachybrachis autolycus , var. Pachybrachis difficillis Fall, Fall-MCZ]; same data, except 12-19.VII.1932, J. Ouellet [4♂ 3♀, CEUM]; same data, except 4.VII.1934, L. Daviault [1♀, CEUM]; Lac-Saint-Jean-Ouest Co., Mistassini, 28.VII.1944, A. Robert [1♂ 1♀, CEUM]; Montcalm Co., Parc du Mont-Tremblant, 22.VI.1956, A. Robert [1♀, CEUM]; same data, except 11.VII.1961 [1♀, CEUM]; Pontiac Co., Beech Grove, 10.VIII.1966, H. Goulet [1♂, CNC]; Portneuf Co., Sainte-Catherine, 3.VII.1956, J. C. Aubé [1♀, LEMC]; Territoires-du-Nouveau-Québec Co., Casa-Berardi, 22-29.VI.1997, interception trap, P. Paquin [2♂, LEM]; same data, except 6-27.VII.1997 [4♂ 2♀, LEM]; same data, except 3-24.VIII.1997 [3♂ 1♀, LEM]; Chemin Selbale, 6-27.VII.1997, interception trap, P. Paquin [1♂ 4♀, LEM].

Host plants.

Although over 200 specimens were examined, the only potential host plants recorded by collectors were Cassandra calyculata (L.) D. Don ( Ericaceae ) and Potentilla simplex Michx. ( Rosaceae ). Balsbaugh and Tucker (1976) reported that they collected series of Pachybrachis carbonarius on wild strawberry ( Fragaria sp.) ( Rosaceae ), and tick-trefoil ( Desmodium sp.) ( Fabaceae ) in Alabama. Barney and Hall (2009) reared the same subspecies on Desmodium paniculatum L. DC and Lespedeza virginica (L.) Britton ( Fabaceae ) in Kentucky.

Comments.

Balsbaugh and Tucker (1976) and Riley et al. (2003) recognized Pachybrachis nigricornis as having four subspecies in North America. Fall (1915) described Pachybrachis autolycus as a separate species with two “varieties”, and he added the variety Pachybrachis janus to Pachybrachis carbonarius , which he also recognized as a separate species. Specimens from each of the provinces of NB, ON and QC included an assortment of var. Pachybrachis carbonarius , var. Pachybrachis difficilis , and the yellow variation of Pachybrachis carbonarius as per Barney and Hall (2009). In the "Material examined" section above, the QC specimens from Fall’s personal collection (Fall-MCZ) are listed, with an indication of his identification label of Pachybrachis autolycus , var. Pachybrachis difficillis .