Scolytus silvaticus Bright, 1972

Smith, Sarah M. & Cognato, Anthony I., 2014, A taxonomic monograph of Nearctic Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae), ZooKeys 450, pp. 1-182 : 50

Taxon classification Animalia Coleoptera Curculionidae

Scolytus silvaticus Bright, 1972 valid sp. Fig. 54

Scolytus silvaticus Bright, 1972: 1489.

Diagnosis.

The male is distinguished from other species by having the apical margin of ventrite 4 thickened, forming a broad carina with a blunt median tubercle. The female is distinguished from the morphologically similar male of Scolytus hermosus by having the apical margin of ventrite 1 produced, forming a carinate lip along the basal margin of ventrite 2 that is about half as produced as thick and by the host and is distinguished from the Scolytus hermosus female by having a strongly developed epistomal process.

Description (male).

3.0 mm long (mean = 3.0 mm; n = 1); 2.1 times as long as wide. Color dark red-brown to black. Pronotum same color as elytra.

Head. Epistoma moderately, broadly emarginate; epistomal process weakly developed; median area above mandibles bearing dense patch of long, yellow, hair-like setae. Frons appearing flattened when viewed laterally, slightly transversely impressed just above epistoma; moderately, coarsely, aciculate-punctate; aciculations converging at epistoma; punctures small, coarse; moderately, uniformly covered by long, fine, erect, yellow-brown, hair-like setae, these longer than width of midpoint of eye. Antennal scape short, elongate; club flattened, almost subquadrate, setose with partial septum, two broadly 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, dark yellow-brown setae; base weakly bisinuate.

Elytra with sides sub-parallel on apical half, narrowing to subquadrate, smooth apex; apex moderately emarginated at suture. Margin of apical edge bearing small, fine punctures. Disc smooth, shining; interstriae not impressed, more than twice width of striae, punctures uniseriate, smaller than those of striae; bearing sparse, recumbent, long, dark yellow-brown setae; striae weakly impressed. Declivity bearing abundant, long, erect dark yellow-brown hair-like setae. Metepimeron half-length of metanepisternum.

Venter. Apical margin of ventrite 1 moderately elevated above base of ventrite 2, ventrite 2 appearing impressed. Ventrite 2 nearly perpendicular to ventrite 1; surface smooth, shining, finely punctate; punctures small, fine, shallow; setae small, about two diameters of a puncture in length; surface flattened; lateral margins of ventrites 2-3 unarmed. Apical margin of ventrite 4 thickened forming a broad carina with blunt median tubercle. Ventrite 5 carinate ridge closer to apical margin of segment; length of ventrite 5 greater than combined lengths of ventrites 3 and 4; setal patch and median depression absent.

Female.

3.3-3.6 mm long (mean = 3.4 mm; n = 3); 2.2-2.8 times as long as wide. Similar to male except epistomal process more strongly developed, frons convex when viewed laterally, weakly aciculate, setae sparse, shorter, less than width of eye; weakly transversely impressed between inner apices of eye. Second ventrite unarmed.

Specimens examined.

4.

Type material.

Holotype Scolytus silvaticus Bright: male, labeled "MEX., N.L., Cerro Potosi, V.3.[19]71, 1100', D.E. Bright, Pseudotsuga menziesii , CNC No. 12603" (CNCI). Allotype, female, identical data as holotype. Paratypes, identical data as holotype (CNCI-2).

Non-type material.

None examined.

Distribution.

MEXICO: Nuevo León (Fig. 32).

Hosts.

Pseudotsuga menziesii (Mirb.) Franco (Douglas fir).

Biology.

Scolytus silvaticus is only known from a single collecting event from broken branches of Pseudotsuga menziesii ( Bright 1972). The gallery and biology of this species are unknown but the gallery structure is presumably similar to that of other Pseudotsuga feeding Scolytus , parallel to the grain of the wood.

Remarks.

Wood (1975: 22) placed Scolytus silvaticus in synonymy with Scolytus hermosus because it occured on the same mountain as Scolytus silvaticus . Wood reasoned that only one Scolytus species could occur in the same location and that the observed morphological variation was due to intraspecific differences. In addition, he stated that Bright’s image of the Scolytus silvaticus male was a normal male of Scolytus hermosus . We here remove Scolytus silvaticus from synonymy with Scolytus hermosus because of the many distinct morphological and host differences originally noted by Bright (1972). In the male of Scolytus silvaticus , the apical margin of ventrite 1 is moderately thickened and weakly produced, the posterior margin of ventrite 3 is slightly medially thickened and the posterior margin of ventrite 4 is in strongly produced and thickened medially, forming a broad carina with a blunt median tubercle. In the male of Scolytus hermosus ventrite 1 apical margin is thickened and strongly produced and ventrites 3-4 are flat and Scolytus hermosus colonizes Abies species rather than Pseudotsuga . It is also not uncommon for multiple Scolytus species to have overlapping distributions.