Introduction

Specimens of Scolytus fagi Walsh have been rarely collected and within the past 140 years the species was only recorded from Illinois and Texas (Wood 1982). However, in 2009 specimens were collected in surprisingly large numbers from several locations in Pennsylvania. Initially, species identification of these specimens was difficult partially due to vague species descriptions, inadequate keys, a lack of illustrations and most importantly the loss of the syntypes (Walsh 1867, Blackman 1934, Wood 1982). Walsh (1867) described Scolytus fagi from a series of six syntypes collected from “southern Illinois” from what was presumably a beech tree (Fagus sp.). These specimens were stored in Walsh’s personal collection. Shortly after his death in 1869, the state of Illinois purchased his entire collection and moved it to the ‘fire-proof building’ of the Chicago Academy of Sciences (CASM). Unfortunately, the wing and nearly all of Walsh’s specimens were destroyed in the Great Chicago Fire of 1871 (Sheppard 2004). A few of Walsh’s Coleoptera and Lepidoptera specimens survived in the Chicago Academy of Sciences (Sheppard 2004), however the syntypes of Scolytus fagi were not among them (J. Colby, pers. comm.). These circumstances warrant the designation of a neotype to maintain nomenclatural stability and reduce taxonomic confusion with morphologically similar sympatric species such as Scolytus muticus Say and Scolytus quadrispinosus Say.

In this publication, we designate a neotype for Scolytus fagi, redescribe the male and female, add new distributional records and create a key for the identification of eastern Scolytus species.

Materials and methods

Scolytus specimens were examined from the following collections (following Evenhuis 2009) for the creation of the key:

MCZ Museum of Comparative Zoology, Cambridge, MA (Phil Perkins)

MSUC Albert J. Cook Arthropod Research Collection, East Lansing, MI (Gary Parsons)

NMNH National Museum of Natural History, Washington, DC (Natalia Vandenberg)

SEMC Snow Entomological Museum, Lawrence, KS (Zack Falin)

UMMZ University of Michigan Museum of Zoology, Ann Arbor, MI (Mark O’Brien).

Scolytus specimens collected by United States Forest Service Early Detection and Rapid Response Program in Missouri and Pennsylvania were also examined as part of this study.

Scolytus fagi Walsh

Scolytus fagi is known from a few specimens collected from Columbus, Texas, specimens from Illinois were difficult to locate. A single specimen of Scolytus fagi from Galesburg, Illinois was found in the collection of the MCZ (T.H. Atkinson, pers. comm.), and is here designated as the neotype. The specimen was examined by the authors and was chosen because it matches Walsh’s description, is from the same state as the type series and is in good condition.

Neotype. Male, vouchered in the MCZ and bearing the following labels:

1) “Galesburg/Ill”

2) “Liebeck/Collection”

3) “S. /fagi/Walsh”

4) “Scolytus fagi Walsh/Det. Atkinson 88”

Redescription

Male: body length 3.5–6.0 mm long (x_= 5.0 mm; n = 20); 2.1–2.5 (x_= 2.37) times as long as wide. Color dark reddish brown to black. Dorsal habitus (Fig. 1a), lateral habitus (Fig. 1b).

Frons flattened, feebly concave, more strongly concave above epistoma and weakly concave above upper level of eyes, concave surface of frons punctate-granulate and densely covered with fine, long setae with apices directed toward the median line, basal and lateral margins of concavity with fewer, shorter, finer setae; median line devoid of granules, faintly aciculate and shining (Fig. 1d). Antennae dark reddish brown, club covered by short golden hair-like setae with two strongly procurved sutures.

Pronotum slightly longer than wide. Pronotum dark brown to black, margins reddish brown; pronotal surface shining, disk shallowly and minutely punctate, punctures on basal and its lateral sides larger and deeper; median line devoid of punctures on disk. Sparse, erect hair-like setae on apical and lateral margins of pronotum. Basal and lateral margins carinate, nearly straight.

Scutellum triangular, covered by fine recumbent golden hair-like setae and deeply set in the shagreened and subopaque scutellar impression. Elytra dark reddish-brown to black, slightly narrower than pronotum. Elytral strial punctures 2–3 times the size of those on interstriae, interstriae 2–2.5 times the width of striae; elytral surface shining, glabrous. Striae impressed, interstriae not impressed. Interstriae 9 and 10 and declivital interstriae covered with sparse and irregularly spaced setae. Elytral lateral edges feebly serrate, apex smooth, weakly emarginate.

Abdomen reddish-brown to black, surface of sternite 1, smooth, shining; sternites 2–5 shagreened, subopaque. Sternite 2 vertical (face at an angle of approximately 90º to first sternite) unarmed, coarsely punctured and covered with sparse setae. Apical margin of sternites 1–4 with a faintly raised margin. Sternite 5 longer than sternites 3 and 4 combined; apical fourth of sternite 5 subvertical, transversely impressed, more closely and coarsely punctured, moderately covered with abundant fine, hair-like setae each 2–3 times the length of setae on sternite 2. Genitalia (ventral view, Fig. 1f; lateral view, Fig. 1g).

Female (lateral habitus, Fig. 1c): similar to male except frons convex, faintly aciculate and devoid of granules, frons less abundantly covered by fine, long setae, basal and lateral margins with fewer, shorter, finer setae (Fig. 1e). Abdominal sternite 5 with a strongly elevated transverse subapical carina.

Natural history

There is a single report of the life history by Packard (1890) in which Scolytus fagi was reported by Schwarz to colonize Celtis texana (=Celtis laevigata var. texana) in Texas and were “found boring in the solid wood in all stages… so numerous were the insects that the pattern of the larval burrow…was confused and undecipherable” (1890). Schwarz also reported that they did not appear to colonize healthy trees, but were very destructive to Celtis laevigata var. texana (1890).

In addition to Celtis laevigata, Scolytus fagi has been reported to colonize Celtis occidentalis (Cannabaceae), no locality given (Blatchley and Leng 1916; Chamberlin 1939), Celtis tenuifolia (Bright and Skidmore 1994) in Ontario, Fagus americana (Fagaceae) no locality given (Blatchley and Leng 1916; Chamberlin 1939), Fagus grandifolia, no locality given (Wood 1982), and Quercus sp. (Fagaceae) in Mississippi (Atkinson et al. 1991).

Distribution

Scolytus fagi was known only from Illinois (Walsh 1867), Mississippi (Atkinson et al. 1991), Texas (Packard 1890), and southern Ontario (Bright and Skidmore 1994). Here we report new state records of Scolytus fagi from Kansas, Ohio and Pennsylvania. It is likely that Scolytus fagi occurs throughout the range of its hosts and the sparse locality records are due to the inadequate sampling.

Kansas (vouchers deposited in the SEMC)

Bourbon Co.: Fort Scott, 9 mi SW, Hollister Wildlife Area, 1-14-VI-2005, canopy trap (1); 14-28-VI-2005 (3); 17-30-V-2006 (2); 30-V-7-VI-2006 (1); 7-15-VI-2006 (1); 26-VI-6-VII-2006 (1). Douglas Co.: 22-VI-2004, Lindgren trap, S. White SCW040326 (1); 14-VII-2004, Lindgren trap, S. White, SCW040430 (1); Baldwin, 2 mi NW, 9-16-VI-2005, canopy trap (1). Geary Co.: 3-VI-2004, rest stop, Lindgren trap, D. Martin, DJM040179 (1). Johnson Co.: Shawnee, 1.2 mi N of 43rd St, nr Kansas River, 2-9-VI-2005, canopy trap (2); 9-19-VI-2005 (1); 24-VI-5-VII-2005 (3). Sedgwick Co.: Derby, 0.5 mi S, NE of intersection K15 and 91st St, 21-30-VI-2005, canopy trap (1).

Ohio (voucher deposited in the MSUC)

“Ohio” (1).

Pennsylvania (vouchers deposited in the MSUC and additional specimens at the Pennsylvania Department of Agriculture)

Cumberland Co.: Roadway Dr @ Schneider Dr, 40.229030°N; 77.111580°W, 26.VI.2009, Coll. LR Donovall (25). Dauphin Co.: Wildwood on Industrial Rd, 40.316325°N; 76.888783°W, 6.VIII.2009, Coll. SE Spichiger, Ex. Lindgren-EtOH (2). Lancaster Co.: 7031 Elizabethtown Rd, 40.182583°N; 76.498783°W, 23.VII.2009, SE Spichiger, Ex. Lindgren-BEBB/EtOH (1). York Co.: 400 Mundis Race Rd, 40.030170°N; 76.705330°W, 10.vi.2009, Coll. S Rebert, Ex. Lindgren-Alpha/EtOH (4).

Key to the Scolytus Geoffroy of North America East of the Mississippi River

This key treats both sexes of Scolytus species and includes all species in America east of the Mississippi and all species known to colonize hardwoods in North America. Scolytus species are typically difficult to identify, especially females. Most current keys identify males, with females determined by association with males collected from galleries or based on a priori knowledge of the nuances of Scolytus sexual dimorphism. This key allows identification of Scolytus species regardless of the user’s familiarity with the genus. Terminology is similar to that used by Blackman (1934), Bright (1976) and Wood (1982) in their respective keys. Host records were obtained from Wood (1982) and Wood and Bright (1992) and all measurements excluding Scolytus fagi were taken from Wood (1982).