Epexochus korotyaevi Meregalli & Talamelli

Meregalli, Massimo & Talamelli, Fabio, 2009, Revision of the genus Epexochus Reitter, with description of three new species (Coleoptera: Curculionidae: Lixinae: Cleonini), Zootaxa 2011, pp. 47-68 : 58-61

Epexochus korotyaevi Meregalli & Talamelli , sp. n.

Diagnosis. An Epexochus species characterised by: base of pronotum medially distinctly lobed towards scutellum; scales narrow, lanceolate, ivory-greyish, with vague, slightly darker stripes on odd intervals; median triangular plate of rostrum slightly raised, barely visible; median part of the pronotum convex; elytra with slightly broadened sides; aedeagus with faintly sinuate apex.

Description. Dimensions. Body length excluding rostrum: 16.72 mm. Rostrum: length 3.45 mm, width 1.84 mm (ratio 1.87). Pronotum: length 4.58 mm, width 4.95 mm (ratio 0.93). Elytra: length 11.90 mm, width 7.36 mm (ratio 1.62). Ratio of elytral to pronotal length 2.60 (holotype).

Habitus. Body black, shortly elliptical, completely covered with usually simple scales but often imbricate, lanceolate, acuminate at apex (Figs. 40–41).

Rostrum straight, less than twice as long as wide, weakly conical, dorso-lateral sides rounded, median part with a triangular, slightly raised and barely distinct plate; median line narrow, not sharply keeled, extending from vertex to antennal insertions, lowered in its anterior part; apex flat; epistoma prominent, straight; dorsal furrows very shallow, barely distinct; upper margin of scrobes weakly curved downwards in basal third, straight anteriorly, interrupted before lower margin of eye; lower and upper margins parallel; scrobes narrow, shallow, distinctly broadened at base; rostrum in lateral view nearly straight, nearly as thick at base as at apex, median line very weakly and evenly curved, subsinuate at base beyond head; underside with U-shaped keels, moderately converging from apex to base. Vestiture very thick, consisting of yellowish, oval, finely trifid scales directed towards median part in basal half and progressively turned anteriad in apical half, median tooth progressively more developed and lateral teeth reduced, scales at apex simple, elongate to lanceolate, seta-like on apical plate; on sides above scrobes short, sparse, mainly trifid, below scrobes lanceolate, acutely pointed; setae moderately distinct, yellow-orange, not raised (Figs. 44–45).

Antenna slender. Scape straight, slightly thickened towards apex, with digitate scales. Funicle segment 1 globose, slightly bigger than 2, this twice as long as 1, cylindrical and slightly widened to apex; 3–5 moderately transverse; 6 larger than previous; 7 fused to club; all segments with elongate grey scales and hairlike setae. Club elliptical, finely setose, as long as previous 4 funicle segments combined (Fig. 47).

Head transverse, flattened anteriorly between eyes, with a narrow, interocular, short, glossy median keel, densely coated with short, bifid and trifid yellowish scales; distance between eyes slightly broader than rostrum at base; vertex slightly convex. Eyes big, flat, broadly elliptical, lower margin rounded.

Pronotum nearly as long as wide, base oblique, medially distinctly lobed towards scutellum, sides moderately and very evenly convergent from base to apex; dorsum medially weakly but distinctly convex from centre to apex, with barely visible median line, flat and lacking any raised sculpture from centre to base; in lateral view faintly convex, maximum height in middle; sculpture consisting of minute, dense punctures and sparse, scattered, barely larger, isolated punctures becoming denser towards sides, completely hidden by dense vestiture of ivory-greyish and very pale brownish, simple or trifid short scales, directed towards centre, with median tooth more developed and lateral teeth small, acute, sometimes indistinct; sides with very thick, in part imbricate, more distinctly trifid, usually paler yellow-whitish scales; setae short, hair-like, inserted in isolated larger punctures, hardly distinct (Fig. 42).

Scutellum microscopic.

Elytra broad, oval-elliptical, sides slightly broadened, maximum width behind middle of length, evenly rounded towards apex; in lateral view convex, declivity sharply sloping. Intervals 3, 5, 7 and 9 slightly but clearly convex, more raised and forming a distinct low hump near base; 6 reaching base of elytra, 7 and 9 fused at base; even intervals usually as wide as odd ones. Striae very narrow, shallow and generally indistinct. Vestiture consisting of dense, imbricate, simple, lanceolate, pale ivory scales, acutely pointed at one edge and rounded on other side, finely digitate only on interval 11 (lateral margin); scales on odd intervals slightly darker, very light brownish, particularly at base; setae distinct, stiff, hair-like, light brownish, semi-erect, inserted in two irregular rows on even and odd intervals ( Fig. 37 ).

FIGURES 40–53. Epexochus korotyaevi , structural details (40–42, 44–45, 48, 50–52: holotype; 43, 46–47, 49, 53: paratype). 40–41: habitus, dorsal and lateral views; 42: pronotum; 43, ventrites; 44–45, rostrum, lateral and dorsal views; 46: hemisternites; 47: antenna; 48: aedeagus, lateral view; 49: spermatheca; 50: aedeagus, dorsal view; 51–52: apex of aedeagus, dorsal and ventral views; 53: sternum VIII. Scale bars: 40–41: 5 mm; 42–45: 2 mm; 46–48, 50, 53: 1 mm; 51–52: 500 μm; 49: 400 μm.

Legs slender. Femora slightly thickened medially, with generally trifid, lanceolate scales and erect, stiff, white setae. Tibiae rectilinear, densely coated with whitish scales and long sparse setae. Tarsi as typical of genus, with lateral setae directed downwards, segment 3 with lobes elongate, slightly widened; claws narrow, divergent, connate at base.

Venter. Ventrite I curved at apex, II narrower, III half as long as II, IV longer than III, V shortly transverse; all very densely coated with whitish, imbricate, finely digitate scales and erect, stiff, whitish setae; base of II, III and IV with two very narrow stripes of dark brownish scales forming a narrow, barely distinct median basal stripe on V (Fig. 43).

Genitalia. Aedeagus similar to that of E. lehmanni , slightly less curved and with a slightly conical median lobe; lamella longer and with weakly sinuate sides (Figs. 48, 50–52). Sternite VIII of Ψ with arms not fully connate at base, lamina conformed as in E. lehmanni (Fig. 53). Spermatheca with basal ramus (Fig. 49).

Variation. The specimens examined are very uniform, in particular regarding the most significant discriminative traits, such as the base of the pronotum prominently extended towards the scutellum and the shape of the elytral scales; the ivory-greyish scales are always predominant but in some specimens the pale brown scales are more frequent, usually on the disc of the pronotum and the odd intervals, particularly on the basal low hump. The size is uniform, varying between 16.5 and 18.2 mm.

Material examined. Holotype ɗɗ: TAJIKISTAN: "Beshkentskaja dol., Tadzh., r-i Shaar-tuza [37°18'N 67°58'E], Lopatin, 5.IV. [19]58 ( ZIN). Paratypes: same data, 1 ɗ 1 Ψ (1 ɗ MER; 1 Ψ ZIN) " Tadzhikistan, Tschilitschor, Tshesherin, 30.III.1982 ", 1 ɗ 2 Ψ (1 ɗ 1 Ψ CSNV; 1 Ψ MER); "Tschilitshor-Tschashta W, Shaartuza, Tadzh. 22.IV. [1]962, Krizhakovskij, 1 ɗ ( ZIN); "Beshkentskaja dol., Tschilu sor Sashta, Tschukajukov, 13.III. [19]64, 1 Ψ ( ZIN); same data, 23.VI. [19]63, Soboleva, 2 ɗ i Ψ ( ZIN); " Tadzhikistan distr., Shaartuz vil, Beshkent. dol, 24.IV. [19]63", 1ɗ 1 Ψ ( ZIN); same data, 14.III. [19]62, 2 ɗ ( ZIN); "r. Vakhsh, okr. Kyzyl-Kala [37°53'N 68°39'E], 4.IV. [19]58", 1 ɗ ( ZIN).

Distribution ( Fig. 82 ). The type locality, Beshkentskaja dolina, is in southern Tajikistan, and the species is apparently restricted to the southernmost part of Tajikistan.

Etymology. With great pleasure we name this species after our friend Boris Korotyaev, acknowledging his help and contribution to this paper and to our studies of Russian weevils.

Remarks. This species is closely related to E. lehmanni , from which it is consistently differentiated in the shape of the pronotum, with the base distinctly curved towards the elytra and the median part weakly but distinctly convex in the anterior half, in the lanceolate elytral scales, about 5 times as long as wide (2–3 times as long as wide in E. lehmanni ) ( Figs. 37 vs. 36), in the rostrum being moderately conical, broader at the base than between the antennae (Figs. 45 vs. 12), and in the very narrow stripe of brown scales at the base of the ventrites (Figs. 43 vs. 11).

Figures

FIGURE 82. Distribution of the genus Epexochus [map taken from Encarta World Atlas 2000 (Microsoft Corporation), elaborated with Photoshop 7.0 (Adobe Systems Incorporated)].

FIGURES 21 – 39. Epexochus, genitalia, claws and scales. Female genitalia (21 – 23: specimen from Kzyl-Dzhar; 24 – 25: specimen from Aulie-ata). 21, 24, sternum VIII; 22, 25, spermatheca; 23, hemisternites. Claws. 26, specimen from Borokhoro. Aedeagus, dorsal and lateral views and detail of apex. 27, 30, 35, specimen from Koibun; 28 – 29, 32, specimen from Elton lake; 31, specimen from Dzharkentsk; 33, specimen from Betpak; 34, specimen from Borokhoro. Elytral scales. 36, holotype of E. lehmanni; 37, holotype of E. korotyaevi; 38, holotype of E. voriseki; 39, paratype of E. mongolicus. Scale bars: 21, 23 – 24, 27 – 31: 1 mm; 26, 32 – 35: 500 μm; 36 – 39: 100 μm.