Scolytus quadrispinosus Say, 1824

Smith, Sarah M. & Cognato, Anthony I., 2014, A taxonomic monograph of Nearctic Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae), ZooKeys 450, pp. 1-182 : 28-30

Taxon classification Animalia Coleoptera Curculionidae

Scolytus quadrispinosus Say, 1824 Fig. 22

Scolytus quadrispinosus Say, 1824: 182.

Scolytus carya Riley, 1867: 68. LeConte 1876: 371.

Scolytus caryae Walsh, 1867: 58. LeConte 1876: 371.

Diagnosis.

The Scolytus quadrispinosus male is easily distinguished by the autapomorphic features of the abdominal venter which include: the apical margin of ventrite 3 armed by three acute spines (two lateral and one medial), the apical margin of ventrite 4 armed by one median tooth, ventrite 1 apically descending, ventrite 2 deeply concave, with the basal margin produced and bearing a median tubercle. The female is distinguished by the flattened and moderately, finely longitudinally aciculate frons, bearing long, fine, incurved setae on the lateral and dorsal margins.

Description (male).

2.8-4.8 mm long (mean = 4.0 mm; n = 20); 1.8-2.25 times as long as wide. Color red-brown to dark red-brown. Pronotum typically darker than elytra.

Head. Epistoma weakly emarginated; epistomal process strongly produced, moderately elevated, smooth, shining; median area above mandibles bearing a dense patch of long, yellow, hair-like setae. Frons appearing strongly flattened when viewed laterally; strongly, densely, coarsely, aciculate-punctate; aciculations converging at epistoma; punctures small, coarse; surface moderately covered by long, fine, yellow, erect hair-like setae, these longer than width of midpoint of eye, setae on lateral and dorsal margins longer, thicker, incurved. Antennal scape short, elongate; club flattened, irregularly ovoid, setose with partial septum, two arcuate sutures visible.

Pronotum wider than long; apical margin broadly rounded, median area between eyes lined with scales; sides distinctly arcuate, strongly constricted near apex, forming a weak transverse impression near apical margin; surface smooth, shining, punctures on disc fine, shallow, moderately abundant, larger and more abundant laterally and on apical constriction; apical and anterolateral margins bearing sparse, erect, golden setae; base weakly bisinuate.

Elytra with sides sub-parallel on apical half, narrowing to weakly rounded, serrate apex; apex entire at suture. Margin of apical edge bearing large, coarse punctures.. Disc smooth, shining; interstriae weakly impressed, twice width of striae, punctures large, uniseriate, smaller than those of striae, interstrial punctures bearing sparse, long, semi-erect yellow hair-like setae (may be abraded); striae moderately impressed. Declivity bearing sparse, short, erect yellow setae. Metepimeron half-length of metanepisternum.

Venter. Apical margin of ventrite 1 descending, strongly, acutely produced; ventrite 2 deeply concave, basal margin produced, bearing median tubercle. Ventrite 2 nearly perpendicular to ventrite 1; surface shagreened, dull, finely, obscurely punctate with small, fine, shallow punctures; apical margin armed with broad median denticle, occasionally absent. Apical margin of ventrite 3 armed by three acute spines (two lateral and one medial); apical margin of ventrite 4 armed by one median tooth. Ventrite 5 carinate ridge closer to basal margin of segment; length of ventrite 5 less than combined lengths of ventrites 3 and 4; median depression absent, apical half of segment pubescent.

Female.

2.9-5.0 mm long (mean = 3.9 mm; n = 20); 1.8-2.4 times as long as wide. Similar to male except epistoma feebly emarginated, frons less strongly flattened when viewed laterally, moderately and finely aciculate, setae shorter, less than width of eye and uniformly distributed. Apical margin of ventrite 1 weakly elevated above base of ventrite 2. Ventrite 2 surface flattened, nearly perpendicular to ventrite 1; setae erect, short, about half length of segment 3. Venter unarmed.

Specimens examined.

143.

Type material.

Holotype Scolytus quadrispinosus Say: male, Missouri (ANSP, lost). Holotype Scolytus carya Riley, location unknown. Holotype Scolytus caryae Walsh, location unknown.

Non-type material.

CANADA:ONTARIO: Queenston, 15.VII.1938, D.F. Patterson, ex. Carya ovata (CNCI-2); Z17 E464 N4820, 20.VII.2004, Seaforth, ex. handpicked from eastern white pine [= Pinus strobus ], 04-5-0265 (CNCI-1). UNITED STATES:GEORGIA: 1.IX.[19]45 (CASC-4). ILLINOIS: [Cook Co.]: Edgebrook (CNCI-2). [Unspecified County]: Willow Springs, 21.VIII.[19]04 (FMNH-1), 13.V.[19]05, A.B Wolcott (FMNH-4). KANSAS: [Shawnee Co.]: Topeka, 16.VI.[?], Popenoe (USNM-1). MASSACHUSSETS: [Unspecified County]: (CASC-1). MICHIGAN: [Ingham Co.]: East Lansing, 15.VII.1932, (MSUC-4). Wayne Co.: Detroit, 18.VIII.1902 (MSUC-3). [Unspecified County]: Lansing, 9.IX.1929 (MSUC-36). MISSOURI:Dent Co.: 28.VIII.1973, M.P. Rolling (USNM-1), 31.VIII.1973 (USNM-3). [Unspecified County]: (FMNH-1). MINNESOTA: [Sherburne Co.]: Elk River, 8.VII.1959, E.J. Kingsley (CNCI-2). Mississippi: [Madison Co.]: Canton, 16.VI.[19]04 (CUIC-1). [Oktibbeha Co.]: [Starkville], Agriculture College of Mississippi [= Mississippi State University], 15.IV.1922, F.M. Hull (CUIC-1). New jersey: [Middlesex Co.]: Dunellen (CUIC-1). NEW YORK:Onondaga Co.: 10.VI.1942, N.M. Downie (FMNH-2), 14.VII.1946 (FMNH-1). Syracuse, C.J. Drake, ex. Hickoria glabra [= Carya glabra ] (USNM-1). [Orange Co.]: Highland Falls, 20.VI.1920, F. Schott (CUIC-1). Middletown (CUIC-1). [Queens Co.]: Long Island Aqueduct, 14.VII.1912 (MSUC-4). [Tompkins Co.]: Groton, 7.VII.1946, N.M. Downie (FMNH-1). Ithaca, 4.VIII.1928, P.P. Babiy (CUIC-1). [Westchester Co.]: Mount Vernon, VII.1913, ex. from hickory [= Carya sp.] (CASC-14). Yonkers, 28.V.1935, P.A. Readio, H. Dietrich, ex. taken on air trap (CUIC-1). [Unspecified County]: New York City, 15.V.1912, (CNCI-1), 13.V.1912 (CUIC-1). north carolina: [Buncombe Co.]: Asheville, Bent Creek, 17.VI.[19]29 (FMNH-1). Pennsylvania: [Allegheny Co.]: Allegheny [= Pittsburgh] (FMNH-3), 24.VI.[18]93 (CUIC-1). [Armstrong Co.]: Ford City, 28.VIII.[19]11 (USNM-1). [Blair Co.]: Tyrone, VII.[19]12, lot 367, ex. Fraxinus alba [= Fraxinus americana ] (CASC- 7). Cumberland Co.: Roadway Dr @ Schneider Dr, 40.229030°N, -77.111580°W, 26.VI.2009, L.R. Donovall (MSUC-1). [Dauphin Co.]: Harrisburg, 19.IV.1911 (CASC-1), VI.1911 (CASC-3); 1.III.[19]11, emerged 7.IV.[19]11, Champlain (CASC-12); Hopk. U.S. 10935-E, 13-14.VII.[?], W.S. Fisher, ex. Hicoria [= Carya sp.] (CUIC-1). Hummelstown, 20.VI.[19]15 (CUIC-1). Linglestown, 8.VI.1912, W.S. Fisher (CNCI-1, CUIC-2). [Philadelphia Co.]: Angora [= Philadelphia], IX.[19]15, H.A. Kaeber, ex. Hickory bark [= Carya sp.] (USNM-7). [Westmoreland Co.]: Jeannette, H.G. Klages (CASC-2). TENNESSEE: [Hamilton Co.]: Chattanooga, 2.VI.[19]19, Leach (FMNH-1).

Distribution.

CANADA: Ontario, Quebec. UNITED STATES: Alabama, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachussets, Michigan, Minnesota, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, West Virginia, Washington, D.C., Wisconsin (Fig. 23).

Hosts.

Primary hosts: Carya spp. (hickory) including Carya illinoinensis (Wangenh.) K. Koch (pecan). Incidental hosts: Juglans cinerea L. (butternut).

Common name.

Hickory bark beetle.

Biology.

Scolytus quadrispinosus is one of the most destructive pests of hardwoods in the US and the most important pest of hickory ( Doane et al. 1936; Baker 1972). The species generally attacks and kills single trees, or solely treetops. However, outbreaks can develop during periods of drought, killing large tracts of hickory. Scolytus quadrispinosus kills its host by mass attack in which a multitude of broods develop in the phloem and cambium, effectively girdling the host tree ( Blackman 1922).

Adult galleries are parallel to the grain of the wood and deeply score the sapwood; a nuptial chamber is not constructed. The adult gallery is short (2.5-5.0 cm), and consists of a single egg gallery ( Blackman 1922). Eggs are deposited singly in niches on each side of the egg gallery with 20-60 niches per gallery ( Blackman 1922). After the eggs have been laid, the female constructs a postovipositional feeding tunnel parallel to the egg gallery ( Goeden and Norris 1965b). Larval mines are excavated in the cambium. From the egg gallery, the larval mines are first perpendicular to the grain of the wood and then gradually turn and diverge creating a fan shaped appearance. The larvae bore into the inner bark to overwinter. Larvae pupate the following spring and emerge as adults the following summer ( Blackman 1922). Upon emergence, adults feed at twig crotches and leaf petioles before selecting a host ( Baker 1972; Goeden and Norris 1964b). There is one generation per year in the north with larvae completing their development in March and April and emergence in May. There may be two generations per year in the south with the brood overwintering as larvae ( Doane et al. 1936). See Goeden and Norris (1964a, b, 1965a, b) for more information regarding the biology of this species.

Remarks.

The holotype of Scolytus quadrispinosus is lost ( Wood 1982), however Say’s (1824) description is unambiguous as to the characteristics of this species. The holotype of Scolytus caryae Walsh was likely deposited in Walsh’s type collection, which was housed in the Chicago Academy of Science Museum. This collection burned in the Great Chicago Fire and the holotypes were lost ( Sheppard 2004; J. Colby, pers. comm.).