Eggersanthus, Sittichaya & Smith, 2020

Sittichaya, Wisut & Smith, Sarah M., 2020, Eggersanthus Sittichaya & Smith gen. nov., a new Oriental ambrosia beetle genus (Coleoptera: Curculionidae: Scolytinae: Xyleborini), Zootaxa 4779 (2), pp. 282-288 : 283-284

Eggersanthus , gen. nov.

( Fig. 1 A–G)

Type species: Webbia sublaevis Eggers, 1927

Material examined. Holotype, female: USNM, PHILIPPINES, Mindanao , Provinz Surigao , Surigao ; Nontypes : females, lowland tropical rain forest of the Ton Nga Chang Wildlife Sanctuary , Songkhla province, Thailand (6°59’32.1”N 100°08’57.8”E) (3, WST).

Diagnosis: Eggersanthus is most similar to Arixyleborus ( Figure 2 and Table 1) and can be separated from other xyleborine genera by the following combination of characters: pronotum in dorsal view rectangular (type a in Hulcr et al. 2007), anterior margin weakly concave, without a median row of serrations, corners sharply quadrate, anterolateral corners asperate with 4–5 serrations forming a 90° angle; pronotum in lateral view with disc longer than anterior slope (type 7 in Hulcr et al. 2007); antennal funicle 4-segmented, club obliquely truncate type 2 ( Hulcr et al. 2007), approximately circular, as long as wide, segment 1 corneous, nearly encircling anterior face, segment 2 pubescent, visible on anterior face only; elytral declivity with granulate striae and interstriae; protibiae very slender, distinctly triangular, posterior face flat and unarmed; scutellum large, triangular, clearly visible from dorsal view; elytra attenuate; and no mycangial tufts present.

Description: Female. Length 2.05–2.2 mm and 2.73–2.90 times as long as wide (n = 4). Body color light brown to brown, darker in appearance on pronotum anterior slope and elytral declivity.

Head. Mandibular base broad, mandibles short. Epistoma with long yellowish setae arranged in a single row. Frons flat, shagreened, with an indistinct small flat median line; vestiture of fine hairs of variable length. Eye comparatively large, shallowly emarginate at antennal insertion, lower portion distinctly larger than upper. Submentum shallowly impressed, shaped as a very narrow triangle. Antennal scape short and thick; pedicel cup-shaped, longer than funicle; funicle 4-segmented, antennal club type 2 ( Hulcr et al. 2007), moderate in size, approximately circular, as long as wide, segment 1 prominent, distinctly corneous, its margin convex, costate, nearly covering posterior face; second segment not sclerotized, soft, visible on anterior face only.

Pronotum. Robust, in dorsal view rectangular (type a in Hulcr et al. 2007), anterior margin weakly concave, without a median row of serrations, corners sharply quadrate, anterolateral corners asperate with 4–5 serrations forming a 90° angle, asperities on anterior slope short, moderately sized and coarse; disc shagreened; basal margin bisinuate; no mycangial tuft; pronotum in lateral view with disc longer than anterior slope (type 7 in Hulcr et al. 2007).

Scutellum. Clearly visible in dorsal view, comparatively large, triangular, flat, flush with elytra, impunctate.

Elytra. 1.53–1.63 times longer than wide; 1.53–1.63 times longer than pronotum, sides parallel from base to apical for three-fourths of length and then becoming gradually attenuate, apex acuminate. Base slightly bisinuate. Disc shining, striae and interstriae uniseriate punctate, striae with long setae, interstriae with minute shallow punctures and a row of shorter setae. Declivity rugose, dull, striae and interstriae granulate; striae uniseriate granulate, granules rhomboidal, very closely arranged; interstriae broader than striae, covered with one or two rows of irregular minute granules.

Legs. Protibiae very slender, distinctly triangular, outer margin straight, widest at apical margin, armed with 4 medium denticles clustered at apical quarter, one or two additional spines may be present on apical half, posterior side flat, finely setose. Procoxae contiguous. Prosternal posterocoxal process flat.

Etymology: Masculine, Eggers + Greek anthos = glory, meaning “glory of Eggers”. The name honors the late Dr. Hans Eggers, a prolific German bark beetle taxonomist who described the type species and has had a significant impact on bark and ambrosia beetle classification.

Distribution: PHILIPPINES, Mindanao; THAILAND, Songkhla province.

Biology: Unknown but probably similar to that of Arixyleborus and Webbia species which are specialized on Dipterocarpaceae and Fagaceae in Asia ( Browne 1958, 1961), though Papua New Guinean species are host generalists ( Hulcr & Cognato 2013).

Figures

FIGURE 1. Eggersanthus sublaevis (Eggers, 1927) comb. nov. A dorsal view, B lateral view, C posterolateral view, D front, E declivity, and metatibia, F protibia posterior face, G protibia anterior face.

FIGURE 2. Morphological appearance of Eggersanthus sublaevis (Eggers, 1927) (A,B,C,G,H,I), Arixyleborus rugosipes Hopkins, 1915 (type species of Arixyleborus) (D,E,F,J,K,L).