Scolytus muticus Say, 1824

Smith, Sarah M. & Cognato, Anthony I., 2014, A taxonomic monograph of Nearctic Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae), ZooKeys 450, pp. 1-182 : 27-28

Taxon classification Animalia Coleoptera Curculionidae

Scolytus muticus Say, 1824 Fig. 20

Scolytus muticus Say, 1824: 182.

Diagnosis.

Scolytus muticus are differentiated from other Scolytus species by the presence of long, erect hair-like setae on the elytral interstriae and on the abdominal venter. The male is further distinguished by a pair of strongly elevated areas on the basal two-thirds of ventrite 5, each densely covered with abundant fine, long hair-like setae.

Description (male).

2.2-5.3 mm long (mean = 3.65 mm; n = 20); 1.75-2.6 times as long as wide. Head, pronotum, legs and abdominal venter dark red-brown, antennae yellow-brown, elytra usually dark red-brown but occasionally red-brown. Pronotum typically darker than elytra.

Head. Epistoma moderately, broadly emarginated; epistomal process absent; median area above mandibles bearing dense patch of long, yellow, hair-like setae. Frons appearing strongly flattened when viewed laterally; densely, finely, longitudinally aciculate; aciculations converging at epistoma; impunctate; setae on lateral and dorsal margins covered by long, thick, incurved, yellow erect hair-like setae, these longer than width of midpoint of eye, median areas covered with sparse, shorter and thinner setae. Antennal scape short, elongate; club flattened, irregularly ovoid, setose with partial septum, three very sharply 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; smooth, shining, punctures on disc fine, shallow, moderately abundant, larger, coarser and dense laterally and on apical constriction; apical and anterolateral margins bearing sparse, erect, yellow hair-like setae; base weakly bisinuate.

Elytra with sides sub-parallel on apical half, narrowing to subquadrate, smooth apex; apex entire at suture. Margin of apical edge bearing small, fine punctures. Disc reticulate, shining; interstriae faintly impressed, equal to width of striae, interstrial punctures large, uniseriate, equal in size to those of striae, bearing moderately abundant, 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 weakly elevated above base of ventrite 2. Ventrite 2 nearly perpendicular to ventrite 1; surface reticulate, shining, densely, coarsely punctured; punctures large, coarse; surface flattened; setae moderately abundant, longer than length of ventrite 3; apical margin unarmed; lateral margins of ventrites 2-3 and ventrite 4 unarmed. Ventrite 5 unarmed; length of ventrite 5 greater than combined lengths of ventrites 3 and 4; median depression absent; pair of strongly elevated areas on basal two-thirds, each densely covered with abundant fine, long hair-like setae; apical third strongly impressed.

Female.

3.1-5.1 mm long (mean = 4.0 mm; n = 20); 1.96-2.45 times as long as wide. Similar to male except epistoma feebly emarginated, epistomal process absent, frons less strongly flattened when viewed laterally, finely, narrowly longitudinally aciculate, setae shorter, less than width of eye and less abundant; weakly transversely impressed between inner apices of eyes. Second ventrite unarmed. Ventrite 5 without a pair of strongly elevated areas on basal two-thirds or setal patches.

Specimens examined.

214.

Type material.

Holotype: male, Missouri (ANSP, lost).

Non-type material.

CANADA:ONTARIO: Pelee Island, 29.VI.1940, W.J. Brown (CNCI-1). Point Pelee National Park, 23.VI.[19]31, W.J. Brown (CNCI-1); 27.IX.1989, K. Dunster, ex. Celtis tenuifolia (CNCI-1), 2.VIII.1990 (CNCI-1). UNITED STATES:COLORADO:Jefferson Co.: Evergreen, Upper Bear Creek Rd, 11.IX.1980, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-1). ILLINOIS:Alexander Co.: Pleasant Valley, 15.VI.1979, B.C. Weber, ex. Trap 6, Ht. 2 (USNM-1), 22.VI.1979, ex. Trap 14, Ht. 4 (USNM-1). Champaign Co.: 28.X.1960, ex. hackberry [= Celtis sp.] (EMEC-4). Sangamon Co.: Springfield, 29.V.2003, C. Helm (CUIC-1). Stephenson Co.: Freeport, 4.VII.[19]17 (USNM-1). INDIANA:Tippecanoe Co.: 6.VI.1971, N.M. Downie, ex. Celtis occidentalis (USNM-6). IOWA: [Story Co.]: Ames, 18.VIII.1926, H.H. Harris (DEBC-2), 1.IV.1936 (DEBC-1), 22.V.1939, E. Polderboer (DEBC-1); 22.V.1939, C. Vocom (USNM-2); E. Snead (USNM-1). KANSAS:Douglas Co.: Lawrence, 5 mi N.E., Kansas University Natural History Research Station, 9.VII.1982, D.H. Wahl (CNCI-1). Lawrence, 10.VI.[19]20, M.W. Blackman (USNM-8); 5.IX.1950, S.L. Wood (USNM-4). Riley Co.: G.A. Dean (DEBC-1); Popenoe (DEBC-1). [Unspecified County]: Manhattan, 1.VI.[19]29, F. Kruger (DEBC-1); 5.VI.[19]29, T.N. Winburn (DEBC-1); 8.V.1968, G. Hevel (USNM-1). KENTUCKY:Christian Co.: 15.VI.1960, J.M. Campbell (CNCI-1). LOUISANA:Jefferson Parish: New Orleans, 4.XII.1975, emerged II.1976, S.G. Wellso, ex. Celtis laevigata wood (MSUC-13). Saint Bernard Parish: J.N. Knull, ex. reared from Celtis mississippiensis [= Celtis tenuifolia ] (USNM-3). MARYLAND: [Cecil Co.]: Port Deposit, 26.VI.1977, D. Jump (USNM-1), 13.VII.1977 (USNM-1), 9.VI.1979 (USNM-2), 3.VII.1979 (USNM-1). Montgomery Co.: Bethesda, 25.V.1981, W.E. Steiner (USNM-1). Plummers Island, II-III.1912, E.A. Schwarz, ex. branch of Celtis sp. (USNM-30). MICHIGAN:Ingham Co.: East Lansing, Agriculture College [Michigan State University] (MSUC-8); S21 T4N R1W, VII.1970, S.G. Wellso (MSUC-12). East Lansing, IV.1972, D.K. Young (MSUC-4); 15.VI.1970, S.G. Wellso, ex. emerged from Celtis occidentalis (MSUC-7). Okemos, 12.VIII.1969, S.G. Wellso (MSUC-1), 5.VI.1976 (MSUC-1); 28.V.1970, S.G. Wellso, ex. Celtis occidentalis (MSUC-2), 10.VIII.1969 (MSUC-1). Kalamazoo Co.: Gourdneck Lake State Game Area, 19.VI.2011, A.I. Cognato, ex. funnel trap with EtOH (MSUC-1). Wayne Co.: Grosse Ile, Pke [sic! = Parke] lane, N42.17060°, W84.14496°, 23. V– 7.VI.2007, R. Mech, ex. Lindgren trap with ipslure (MSUC-1), ex. Lindgren trap with EtOH + alpha (MSUC-1), 20.VI-6.VII.2007, ex. Lindgren trap with ipslure (MSUC-1), 7-20.VI.2007 (MSUC-5). MISSISSIPPI: [Unspecified County]: 19.V.1920, M.W. Blackman (CNCI-1). MISSOURI: [Boone Co.]: Columbia, 24.IV.1954, P.J. Spangler (USNM-1). NEBRASKA:Dixon Co.: Ponca, Ponca State Park, 42.607161°N, -96.73223°W, 23.VIII.2007, T.P. Miller, ex. funnel trap with PSB alpha-pinene (MSUC-1). Knox Co.: Crofton, Lewis and Clarke Lake, 42.8321983°N -97.575555°W, 5.IX.2007, T.P. Miller, ex. funnel trap with Sirex (MSUC-1). [Lancaster Co.]: Lincoln, 29.VIII.[19]53, R. Roselle, ex. elm [= Ulmus sp.] (USNM-1). Sarpy Co.: Fontenelle Forest, 41.171478°N -95.9068166°W, 30.V.2006, N. Haxton, ex. funnel trap with ethanol lure (MSUC-1), 7.VII.2006 (MSUC-1). NEW JERSEY: [Burlington Co.]: Riverton, 12.II.1934, Wadley, ex. on Hackberry [= Celtis sp.] (USNM-1). [Essex Co.]: Newark (USNM-1). [Somerset Co.]: North Branch, 9.III.1937, C.H. Hoffman, ex. from gallery made in honey locust [= Gleditsia triacanthos ] (USNM-1). NEW YORK: [Tompkins Co.]: Ithaca, 18.VI.[19]59, ex. in Celtis occidentalis (CUIC-11). NORTH CAROLINA:Mecklenburg Co.: Charlotte, 15-20.VI.2006, J.F. Cornell, ex. FIT in vacant lot (MSUC-1). NORTH DAKOTA: [Ransom Co.]: Mcleod, 5 mi N.W., 4.VII.1968, H.F. Howden (CNCI-1). OHIO: [Franklin Co.]: Columbus (USNM-1); 11.V.[19]14 (DEBC-2). [Hamilton Co.]: Cincinnati, 6.VI.[?] (USNM-1), 24.VI.[?] (USNM-1), 9.VII.[?] (USNM-1). OKLAHOMA:Latimer Co.: V.1982, K. Stephan (USNM-2). PENNSYLVANIA: [Allegheny Co.]: Allegheny [= Pittsburgh], 7.VIII.[18]95 (CUIC-12). [Dauphin Co.]: Harrisburg, T.H. Hubbell (CUIC-1). Hummelstown, 26.VI.[19]37, J.N. Knull (CUIC-6). TEXAS:Brazos Co.: College Station, 13.IV.1964, S.G. Wellso (MSUC-1), 26.IV.1964 (MSUC-1). [Unspecified County]: Dallas, Hopk. U.S. 9929-X, F.C. Bishop, ex. hackberry [= Celtis sp.] (USNM-5). VIRGINIA:Clarke Co.: Boyne, 2 mi S., U[niversity of] Virginia Blandy Experimental Farm, 8-18.VI.1990, D.R. Smith, ex. malaise trap (USNM-1), 19-30.VI.1990 (USNM-1), 1-12.VII.1990 (USNM-1). Essex Co.: Dunnsville, 1 mi S.E., 37°52'N, 76°48'W, 29.V-9.VI.1993, D.R. Smith, ex. malaise trap (USNM-1); 24.VI-9.VII.1992 (USNM-1). Fairfax Co.: Mount Vernon, 27.VI.1915, ex. Cornus stricta (USNM-1). [Unspecified County]: Falls Church, 4.III.1921, E.A. Chapin (USNM-1). WASHINGTON, D.C.: 21.V.1908 (MSUC-5). WEST VIRGINIA:Morgan Co.: near Great Cacapon, 25.V.1985, G.F. & J.F. Hevel (USNM-2). Wood Co.: Hopk. U.S. 6675, ex. Celtis (USNM-1).

Distribution.

CANADA: Ontario. UNITED STATES: Colorado, Florida, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Mississippi, Missouri, Nebraska, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, Washington, D.C., West Virginia (Fig. 21).

Hosts.

Celtis occidentalis L. (common hackberry), Celtis tenuifolia Nutt. (dwarf hackberry), Celtis laevigata Willd. (sugar hackberry) and Gleditsia triacanthos L. (honeylocust).

Common name.

Hackberry engraver.

Biology.

Scolytus muticus prefers to colonize dead, dying or felled trees and the broken, dead and dying branches of live hackberry ( Blackman 1922; Doane et al. 1936; Bright 1976).

The biology of this species is poorly understood. Adult galleries are parallel to the grain of the wood and consist of a single egg gallery; a nuptial chamber is not constructed. The adult gallery strongly scores the sapwood and ranges in size from 2.5-5.0 cm in length ( Blackman 1922). Larval mines first radiate perpendicular to the egg gallery and later meander, giving the galleries a tortuous appearance ( Blackman 1922; Bright 1976). Larvae construct pupal chambers in burrows 2.0-3.0 cm deep within the sapwood ( Bright 1976; Smith and Cognato, pers. obs.). There are two generations per year in the southeastern US and one generation per year in the northeastern US ( Blackman 1922; Baker 1972).

Remarks.

The holotype of Scolytus muticus has been lost ( Wood 1982), however, Say’s (1824) description is unambiguous as to the characteristics of this species.

Wood (1982) reports Scolytus muticus as having a transverse gallery that is perpendicular to the grain of the wood. Other authors, including Blackman (1922), Baker (1972), and Bright (1976) report this species as having a longitudinal gallery that is parallel to the grain of the wood. After examining the literature and photographs provided by T.H. Atkinson, it appears that Wood erred in his description and the gallery is parallel to the grain of the wood.