Amasa tropidacron, Smith & Beaver & Cognato, 2020

Smith, Sarah M., Beaver, Roger A. & Cognato, Anthony I., 2020, A monograph of the Xyleborini (Coleoptera, Curculionidae, Scolytinae) of the Indochinese Peninsula (except Malaysia) and China, ZooKeys 983, pp. 1-442 : 1

Amasa tropidacron sp. nov. Fig. 10A, B, G

Type material.

Holotype, female, Japan: Okinawa, Iriomote-jima, Isd. Code. 1, 9.xi.2012, Kajimura (MSUC). Paratypes, female, as holotype (MSUC, 1); as previous except: Yona, 1.xi.2010, J. Hulcr, ex Castanopsis , uffeID 7348 (UFFE, 2), uffeID 7389 (UFFE, 4); Vietnam: Ninh Binh, Cuc Phuong N.P., Mac Lake, 20°15'29.0"N, 105°42'27.5"E, 155 m, 4-7.v.2009, J.B. Heppner, ex blacklight trap (FSCA, 1).

Diagnosis.

2.5-2.8 mm long (mean = 2.65 mm; n = 2); 2.5-2.54 × as long as wide. This species is distinguished by the pronotum appearing basic (type 2) when viewed dorsally, anterior margin serrate; declivital surface glabrous, smooth, strongly shiny; small size; declivital face flattened; and interstriae 1 carinate, weakly inflated from apex to near midpoint of declivity; declivital striae 1-3 approximately equidistant.

Similar species.

Amasa concitata , A. gibbosa , A. lini , A. youlii .

Description

(female). 2.5-2.8 mm long (mean = 2.65 mm; n = 2); 2.5-2.54 × as long as wide. Body light red-brown. Head, legs, and antennae light brown. Head: epistoma entire, transverse, with a row of hair-like setae. Frons weakly convex to upper level of eyes; median impression between eyes; surface shagreened, impunctate, alutaceous, asperate; asperities longitudinal, smaller, rounder, denser above epistoma, increasing in length and decreasing in width and density dorsally and laterally. Eyes deeply emarginate just above antennal insertion, upper part smaller than lower part. Submentum triangular, deeply impressed. Antennal scape regularly thick, as long as club. Pedicel as wide as scape, shorter than funicle. Funicle 4-segmented, segment 1 shorter than pedicel. Club approximately circular and flat, type 4; segment 1 corneous, convex on anterior face, occupying approximately basal 1/5; segment 2 broad, larger than segment 1, corneous; segments 1-3 present on posterior face. Pronotum: 1.13 × as long as wide. In dorsal view basic, type 2, sides parallel in basal 1/2, rounded anteriorly; anterior margin with a row of 6-8 serrations. In lateral view basic, type 0, disc flat, summit at midpoint. Anterior slope shagreened with densely spaced, fine asperities, becoming lower and more strongly transverse towards summit; bearing long, fine, semi-recumbent hair-like setae. Disc shiny, alutaceous, impunctate, glabrous. Lateral margins obliquely costate. Base transverse, posterior angles narrowly rounded. Elytra: 1.4 × as long as wide, 1.23 × as long as pronotum. Scutellum moderately sized, broad, linguiform, flush with elytra, flat, shiny. Elytral base transverse, edge oblique, humeral angles rounded, parallel-sided in basal 3/4, then sharply angulate to apex. Disc ascending posteriorly, shiny, glabrous; striae and interstriae laterally diverging from base to declivital summit; striae not impressed, punctures separated by 1-4 diameters of a puncture; interstriae flat, finely punctate, punctures 1/5 size of strial punctures, strongly confused. Declivity truncate, face flattened, strongly shiny, smooth, glabrous; three striae present, striae weakly impressed, equidistant, strial punctures strongly shiny, very large, deep, much larger and deeper than on disc, punctures subcontiguous to spaced by one diameter of a puncture; interstriae impunctate, convex, interstriae 1 weakly inflated from apex to below declivital midpoint, interstriae 1 uniseriate granulate, 2-4 multiseriate granulate, granules strongly confused; apical 1/4 of interstriae 1 and 2 costate with a row of rugae. Posterolateral margin forming a circumdeclivital carina; carina setose, setae short, erect, hair-like. Legs: procoxae contiguous; prosternal coxal piece flat, inconspicuous. Protibiae slender, broadest at apical 1/3; posterior face inflated, finely granulate; apical 1/2 of outer margin with five small socketed denticles, their length as long as basal width. Meso- and metatibiae broad, flattened, outer margins evenly rounded with 11 and ten small socketed denticles, respectively; posterior faces unarmed; anterior faces finely granulate.

Etymology.

G. tropis = keel, ridge; akron = end. In reference to the inflated costate apex of the declivity. Noun in apposition.

Distribution.

Japan, Vietnam.

Host plants.

This species has been recorded from Castanopsis ( Fagaceae ).

Figures

Figure 10. Dorsal, lateral and declivital view of Amasa tropidacron holotype, 2.5 - 2.8 mm (A, B, G), A. versicolor, 2.5 - 2.6 mm (C, D, H), and A. youlii holotype, 2.9 - 3.0 mm (E, F, I).