Scolytus Geoffroy, 1762

Smith, Sarah M. & Cognato, Anthony I., 2014, A taxonomic monograph of Nearctic Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae), ZooKeys 450, pp. 1-182 : 20-21

Taxon classification Animalia Coleoptera Curculionidae

Scolytus Geoffroy, 1762

Scolytus Geoffroy, 1762: 309

Type species.

Bostrichus scolytus Fabricius, 1775.

See Alonso-Zarazaga and Lyal (2009) for complete taxonomic history.

Diagnostic characters.

Scolytus is easily distinguished from all other Nearctic scolytines by the unarmed protibia with a single curved uncus at the outer apical angle, by the flattened antennal club with 0-1 septate procurved sutures, by the seven-segmented funicle, by the slightly declivous elytra, the depressed scutellar notch and scutellum and by the abruptly ascending abdominal ventrites 2-5 (except Scolytus rugulosus ).

Description

(modified from Wood 1982). Length 1.7-6.0 mm, 1.7-2.9 times as long as wide. Color variable, red-brown to black. Teneral adults are often light brown.

Head visible from above. Frons flattened to convex, sexually dimorphic (discussed below for each species group or clade). Eye elongate, sinuate to shallowly emarginated, finely faceted. Antennal scape club shaped, shorter than four funicle segments; funicle seven-segmented; club larger than funicle, flattened, oval to obovate, minutely pubescent and with 3 strongly procurved sutures, suture 1 partially to completely septate and with or without a surface groove. Pronotum large, wider than long; lateral and basal margins marked by a fine elevated line; disc finely punctate. Scutellum triangular, deeply depressed below elytral surface. Elytra depressed around scutellum and along basal one-fifth to half-length of elytral suture. Elytra wider than pronotum, flattened; striae punctate; interstriate punctate, with or without setae. Venter either gradually ascending from apical margin of ventrite 1 to elytral apex, or ventrite 2 abruptly ascending, sexually dimorphic, with or without tubercules and/or carinae; remaing ventrite usually unarmed, may have various armature or elevated margins, especially in males. Procoxae narrowly separated. Protibia rectangular; sides straight, nearly parallel, without denticles; outer distal angle produced into a curved uncus.

Species descriptions.

Species are redescribed and treated alphabetically by clade or group beginning with the introduced group, native hardwood clade and conifer clade. Common names listed are the official common names of the Entomological Society of America and Canada.

Introduced species group.

The introduced species group (1.9-4.2 mm long) ( Scolytus mali , Scolytus multistriatus , Scolytus rugulosus and Scolytus schevyrewi ) is not monophyletic and consists of a morphologically diverse group of Palearctic species that encompasses three formerly recognized subgenera ( Butovitsch 1929; Balachowsky 1949). This diversity is reflected in the sexual dimorphism exhibited by the group. Scolytus multistriatus and Scolytus schevyrewi exhibit the typical frons dimorphism as discussed above. The venter lateral teeth are identical in both sexes of Scolytus multistriatus and the spine on ventrite 2 is smaller in the female compared to the male. Sexual dimorphism of Scolytus mali and Scolytus rugulosus is much more subtle and differentiating the sexes can be challenging. Scolytus mali males have the medial area of the frons and epistomal regions impressed and the lateral margins of the epistoma are lightly covered with more abundant erect setae than the female. Scolytus rugulosus males have the medial area of the frons and epistoma slightly more impressed and the frons bears longer and more abundant, erect setae.