Epexochus voriseki 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 : 61-64

Epexochus voriseki Meregalli & Talamelli , sp. n.

Diagnosis. An Epexochus species of relatively small size, characterised by its flat body, the elytra covered with predominantly brown scales and slender, long, hair-like setae, and the tarsi having very thick lateral tufts of setae.

Description. Dimensions. Body length excluding rostrum: 13.10 mm. Rostrum: length 2.63 mm, width 1.63 mm (ratio1.61). Pronotum: length 3.45 mm, width 3.97 mm (ratio 0.86). Elytra: length 9.04 mm, width 5.96 mm (ratio 1.52). Ratio of elytral to pronotal length 2.62 (holotype).

Habitus. Body oval. Integument dark reddish to nearly black, densely coated with lanceolate, usually simple scales and long, hair-like setae; antennae ferruginous (Figs. 54–55).

Rostrum straight, robust, dorso-lateral margins rounded, with very slight trace of a keel; median keel relatively sharp, high, distinct from base of rostrum to base of epistoma, slightly broadened at antennal insertion; convex triangular plate reduced, barely visible; longitudinal furrows moderately impressed, interrupted at antennal insertion and also visible, although shallower, on subapical plate, behind epistoma; rostrum in lateral view straight, median keel visible, straight from base to antennal insertion and curved towards apex; upper margin of scrobes glossy, keeled and slightly prominent, sinuate and reaching lower margin of eye; lower margin subparallel, shortly reaching underside; scrobes narrow, glossy, barely broadened basad when viewed from underside. Vestiture consisting of digitate whitish scales, densely disposed into dorsal furrows; scales smaller, trifid, whitish and brown, relatively sparse and not completely concealing integument on sides above upper margin of scrobes; scales on pregenae glossy, lanceolate, trifid, with very short lateral teeth or simple (Figs. 57–58).

Antenna slender. Scape straight, narrow, slightly thickening towards apex, with dense silvery scales. Funicle with segment 1 globose, 2 as long as wide, 3–6 transverse, 7 larger, appressed to club, all densely coated with silvery scales and long setae. Club elliptical, segments 1 and 2 together as long as 3 (Fig. 59).

Head transverse, broad, forehead between eyes as wide as rostrum at base, flat, with short median keel behind small interocular pit; vertex weakly convex. Vestiture consisting of dense, short, trifid, brownish scales. Eyes oval-triangular, nearly flat, upper part broadened, subangular at lower margin.

Pronotum transverse, base weakly and evenly arched, not lobed towards scutellum, slightly sinuate towards external margins; sides subrectilinear up to anterior quarter, then shortly constricted to apex; apex distinctly prominent above head, on sides straight, postocular lobes hardly developed; dorsum flat, smooth, densely punctulate and with sparse, round, larger punctures; median line barely visible only on disc. Vestiture consisting of acuminate scales, usually trifid with very short lateral teeth, on disc forming a dark brown pattern narrowed anteriorly and broadening basad, delimited by a dorsal whitish stripe widening apicad, followed dorso-laterally by another brownish stripe; upper part of sides mainly white, median part brown, prosternum white; setae long, erect, mainly distinct on sides, clearly visible in dorsal view, particularly on sides and forming a distinct fringe behind base (Fig. 56).

Scutellum minute.

Elytra oval, sides hardly rounded, maximum width in middle of length, dorsum flattened, in lateral view very slightly convex, declivity feeble (Fig. 55). Odd intervals weakly but distinctly convex, particularly in basal half, even intervals not completely flat; interval 6 reaching base, 7 joined to 9 but not broadened at base, 8 nearly reaching base. Striae narrow but distinctly impressed. Vestiture consisting of acuminate to lanceolate scales, usually simple, finely digitate only on basal half of interval 11, brown on suture and intervals 3, 5, 7, white alternating with brown in short longitudinal stripes on odd intervals, mainly white on intervals 8–11; setae erect, hair-like, longer than an interval width, irregularly and relatively densely inserted on whole surface, longer on sides and declivity ( Fig. 38 ).

Legs robust. Femora moderately thickened in middle, with dense, aciculate, white scales and erect setae. Tibiae cylindrical, densely scaly and with dense and long erect white setae. Tarsi with segment 1 shortly triangular, 2 triangular, widened, 3 with broad lobes, all with strongly developed lateral tuft of setae, particularly thickened on hind tarsus, and with very dense white scales and very long hair-like setae (Fig. 62); onychium slender and setose, claws narrow, divergent, connate near base.

Ventrites. Ventrites I and II relatively narrow, of similar length, III and IV slightly narrower, V transverse, evenly rounded; all with extremely thick vestiture of slender, imbricate digitate scales, teeth very long and fine, white with a brown basal stripe on segments II–V (Fig. 61).

Genitalia. Aedeagus weakly curved; lamella short, apex subacute (Figs. 63–64, 66, 68). Sternite VIII of Ψ with arms connate at base, apical sclerotisation dense and expanded (Fig. 60). Spermatheca with cornu thick, sharply curved at 90° above nodulus, ramus basal (Fig. 65). Hemisternites slightly and evenly broadened (Fig. 67).

Variation. The specimens examined are relatively uniform; the peculiar structure of the tarsi is present in all. Also the pattern of the vestiture shows limited variability, with the brown scales always predominant, sometimes covering the entire dorsum of the elytra, but some specimens have a narrow median longitudinal white line on the pronotum. All specimens are smaller than 15 mm.

Material examined. Holotype ɗ: UZBEKISTAN: “ Uzbekistan, Gazli [40°08'N 67°27'], 13.IV. (19)89, M. Janata leg.“ (MER). Paratypes: same data, 10 ex (3 ɗ 1 Ψ MER; 2 ɗ CSNV; 4 ex VOR). TURKMENISTAN: "Ozera Turkmen kel' [indication non precisely located], 28.IV. [19]54, Luppova A. N.", 2 Ψ ( ZIN).

FIGURES 54–68. Epexochus voriseki , structural details (54–59, 62–64, 66, 68: holotype; 60–61, 65, 67: paratype). 54–55: habitus, dorsal and lateral views; 56: pronotum; 57–58: rostrum, dorsal and lateral views; 59: antenna; 60: sternum VIII; 61: ventrites; 62: tarsus; 63: aedeagus, detail of apex, dorsal view; 64: aedeagus, lateral view; 65: spermatheca; 66: aedeagus, detail of apex, ventral view; 67: hemisternite; 68: aedeagus, dorsal view. Scale bars: 54–55: 5 mm; 56–57, 61: 2 mm; 58, 64, 68: 1 mm; 59–60, 62–63, 67: 500 μm.

Distribution ( Fig. 82 ). All specimens examined were collected in central Uzbekistan and in Turkmenistan. The Turkmenian record is not indicated on the map ( Fig. 82 ) since it was impossible to precisely locate it.

Etymology. We name this species in memory of the Czech entomologist J. O. Voříšek (1921–2008), with whom the senior author shared a personal friendship for more than 30 years and whose kindness, warm hospitality and help with specimens and information was always inspirational.

Remarks. This species is easily recognisable by its comparatively smaller size, the barely convex elytra with faintly oblique declivity and vestiture of predominating brown scales with narrow stripes of whitish scales, the very long, flexible setae sparsely distributed over the entire dorsum, the long tufts of setae behind the base of the pronotum and the slightly shorter tarsal segments with long lateral setae.

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.