Dinoxyleborus, Smith, 2017

Smith, Sarah M., 2017, Dinoxyleborus Smith, a new genus of Neotropical xyleborine ambrosia beetle (Coleoptera, Curculionidae: Scolytinae), Zootaxa 4303 (1), pp. 131-139 : 132-133

Dinoxyleborus , gen. nov.

(Figs 1–2)

Type species. Dinoxyleborus cognatoi sp. nov.

Description. Female. Length 2.2–3.5 mm and 3.1–3.7 times as long as wide. Body color ferruginous apically and transitioning to dark red brown posteriorly with the elytral declivity and spines the darkest. Legs and antennae ferruginous.

Head. Epistoma entire, transverse, lined with a row of hair-like setae. Frons slightly convex from epistoma to upper level of eyes; surface shagreened, dull, punctate; punctures above epistoma small, coarse, shallow, punctures increasing in size, coarseness, and depth from epistoma to upper level of eyes. Eyes moderately emarginated above level of antennal insertion, upper portion of eyes smaller than lower part. Submentum flat, slightly impressed below genae, broadly triangular. Scape narrow, elongate, about 3/4 length of club. Antennal funicle four segmented, segments equal in size. Pedicle longer than funicle. Club approximately circular, club type 4 ( Hulcr et al. 2007), flattened, round; segments 1 and 2 strongly procurved, corneus, segment 3 slightly procurved, corneous, visible on both sides of club.

Pronotum. Pronotum prolonged posteriorly (Type 8a, Hulcr et al. 2007), 1.1–1.4 times as long as wide. Anterior margin basic, elongate, parallel-sided, rounded when viewed dorsally (Type 9, Hulcr et al. 2007), lacking a row of serrations. Surface shagreened, anterior half finely asperate, asperities close, arranged in concentric rings from midpoint of pronotum to anterior and anteriolateral areas; disc finely and evenly punctate. Lateral margins rounded, slightly carinate on basal quarter. Base transverse.

Legs. Procoxae contiguous, prosternal posterocoxal piece short, triangular. Protibia slender, broadest at apical third, posterior face inflated, tuberculate; three small denticles present on outer margin of apical third. Meso- and metatibia with evenly rounded outer margin, flattened, posterior face unarmed.

Elytra. 2.0–2.3 times as long as wide. Elytral base transverse, humeral angles rounded. Scutellum small, triangular, flat, flush with elytra. Sides straight from base to apical half of declivity; apex entire. Disc at least as long as declivity. Disc smooth, shining, finely punctate; each interstrial puncture bearing a single erect, fine, golden, hair-like seta 1.5–3.0 times the distance between punctures (may be abraded); interstriae two times width of striae. Interstriae parallel near base and broadened towards elytral apex. Declivity deeply sulcate, separated from disc by large elevated margin bearing denticles and spines. Declivital face densely shagreened, dull, sparsely, shallowly punctate, glabrous or setose. Declivital margin armed by at least three large spines. Declivital interstriae armed with granules dorsad to the margin of the sulcate area.

Diagnosis. Dinoxyleborus can be distinguished from all other Xyleborini genera by the following combination of characters: posterior face of protibia inflated and tuberculate (Fig. 1), the antennal club flattened, sutures 1 and 2 strongly procurved (Fig. 2), pronotum prolonged posteriorly (Type 8a, Hulcr et al. 2007), anterior margin of pronotum basic, elongate, parallel-sided, rounded when viewed dorsally (Type 9, Hulcr et al. 2007), anterior half finely asperate, lateral margin only carinate near base, and by the anterior margin lacking two a row of serrations.

Dinoxyleborus most closely resembles Sampsonius Eggers, 1935 with which it shares the same protibia, antennal club and pronotal shape. It can be distinguished by the lateral margin of the pronotum only carinate near base rather than the entire length and by the anterior margin of pronotum lacking the two coarse serrations which are present in most Sampsonius .

Etymology. Dino (G) = terrible, xyleborus (G) = woodborer.

Comments. A five gene molecular phylogenetic analysis recovered Dinoxyleborus as sister to Sampsonius and Dryocoetoides Hopkins 1915 , both of which also exhibit the protibia inflated and tuberculate on posterior face (Fig. 1) (Cognato and Smith in prep).

PLATE 1. 1. Dinoxyleborus cognatoi sp. nov. posterior face of protibia. 2. Dinoxyleborus sexnotatus antennal club.