Epexochus mongolicus 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 : 64-66

Epexochus mongolicus Meregalli & Talamelli , sp. n.

Leucochromus consobrinus sensu Ter Minasyan, 1972: 543 (non Faust, 1904).

Diagnosis. An Epexochus species of large size, convex body, bell-shaped pronotum with straight base, large elytra with curved sides and flat intervals also at base, slightly curved hind tibiae and aedeagus with short, round apex.

Description. Dimensions. Body length excluding rostrum: 21.20 mm. Rostrum: length 3.89 mm, width 1.98 mm (ratio 1.96). Pronotum: length 5.64 mm, width 6.60 mm (ratio 0.85). Elytra: length 14.48 mm, width 9.48 mm (ratio 1.53). Ratio of elytral to pronotal length 2.57 (holotype).

Habitus. Body black, integument smooth, glossy, covered with simple sub-acuminate scales and with short setae (Figs. 69–71).

Rostrum robust, relatively short, with sides subparallel, dorso-lateral margins completely rounded; median triangular plate developed, raised, broadening from base to antennal insertion; median keel hardly distinct, obtuse, extending towards apex beyond antennal insertion; longitudinal-oblique furrows deep, shortly interrupted at antennal insertion and extending beyond antennae towards apex; upper margin of scrobes sinuate, reaching underside of eye; lower margin parallel to upper margin, not diverging at base on underside; scrobes narrow, glossy, deep; rostrum in lateral view straight, median keel visible, evenly and moderately convex, maximum height at antennal insertion; keels on underside linearly divergent from base to apex. Vestiture consisting of yellowish, aciculate, simple, glossy scales, progressively more slender and lanceolate towards apex (Figs. 72–73, 75, 77).

Antennae not studied (lost in both specimens examined).

Head transverse, interocular distance as long as rostral width at base, forehead flattened laterally and slightly convex in middle; interocular pit very small. Vestiture consisting of scales similar to those of rostrum, simple, directed towards middle. Eyes large, upper part broadened, lower margin rounded.

Pronotum bell-shaped, base rectilinear, medially not lobed towards scutellum, sides slightly sinuate from base to apex, maximum width at base, postocular lobes small, slightly angulate, upper part weakly expanded above head; dorsum flat, lacking median glossy line, densely punctulate on entire surface except for two small, round, glossy dorso-lateral patches; isolated, glossy, slightly larger punctures barely distinct, more numerous on sides. Vestiture consisting of lanceolate, glossy, ivory and brownish scales, brown scales mainly present on dorsum, sides with usually trifid light scales; setae extremely short, barely visible (Fig. 74).

Scutellum small, triangular.

Elytra broad, distinctly wider than pronotum, base nearly straight, sides curvilinear, maximum width in middle of length, evenly rounded to apex; in lateral view convex, evenly and progressively curved on declivity. Intervals completely flat, also at base, odd ones as wide as even ones. Striae narrow, deep, with distinct small punctures. Vestiture consisting of whitish and brown oval or elliptical scales, faintly acuminate, about three times as long as wide, brown scales usually more abundant along striae, forming scattered and FIGURES 69–81. Epexochus mongolicus , structural details (69, 71–72, 74, 76–81: holotype; 70, 73, 75: paratype). 69–70: habitus, dorsal view; 71: habitus, lateral view; 72–73: rostrum, dorsal view; 74: pronotum; 75, 77: rostrum, lateral view; 76: aedeagus, lateral view; 78: aedeagus, dorsal view; 79–81: apex of aedeagus, ventral, dorsal and lateral views. Scale bars: 69–71: 10 mm; 72–75, 77: 2 mm; 76, 78: 1 mm; 79–81: 500 μm.

irregular patches and short stripes; pale scales predominant along intervals, forming an irregularly oval, nearly white patch on interval 6 in middle of its length; setae short, semi-erect, stiff, relatively abundant on entire surface ( Fig. 39 ).

Legs slender. Femora very slightly thickened in middle, with dense vestiture of lanceolate scales and raised whitish setae. Tibiae with fore tibia slightly sinuate on inner side, middle tibia short, robust, hind tibia slightly but distinctly curved; all tibiae with thick coating of pale, slender, acuminate scales, at least 5 times as long as wide, and dense erect, whitish, stiff setae. Tarsi with segments slightly widened, segment 2 at least as long as wide, lobes of 3 slightly broadened; all densely scaly, lateral tuft of setae short.

Ventrites. Ventrite II slightly narrower than I, III and IV 2 /3 as long as II, V transverse, apex sinuate; scales on all ventrites dense, very long, bifid or, rarely, simple, whitish with very narrow basal brown stripes.

Genitalia. Aedeagus evenly, moderately curved; apical lamella broad, well developed, rounded at apex, slightly sinuate in lateral view (Figs. 76, 78–81). Female genitalia unknown (abdomen in only female examined empty).

Variation. The two available specimens are very similar to each other, although the collecting localities are about 150 km apart; the elytra are slightly more curved in the paratype but this may also be due to the sex of the specimen.

Material examined. Holotype ɗ: MONGOLIA: “ Mongolia, 10 km S Uzitsh-Somona, Kobdoskij Ajmak [48°01'N 91°38'E], Arnoldi, 2– 3 VIII.[1]968 ( ZIN). Paratype ΨΨ: " Mongolia, Gobi Altaj aimak, zwischen Biž gol und Bodončijn gol, cca 50 km NW von Biž gol [45°46'N 92°10'E], 1600 m, Exp. Dr. Kaszab 1966" ( HNHM) (specimen incomplete).

Distribution ( Fig. 82 ). Both known specimens were collected in the Mongolian Altai mountains.

Etymology. The species named is formed after the country of the species’ origin.

Remarks. Epexochus mongolicus is morphologically more similar to E. lehmanni than to the other two species and differs from it principally in the intervals being flat for their entire length, including at the base, the pronotum less transverse, with slightly sinuate base, curved backwards near the lateral margin, the rostrum shorter and more robust, the hind tibiae curved and more densely squamose and the apex of the aedeagus larger and rounded (Figs. 79–80 vs. 32–35). The paucity of available material of E. mongolicus does not allow assessment of other seemingly differential characters from E. lehmanni , such as the larger size and the apparently typical whitish spot on elytral interval 6. The other two species, occurring at the opposite limits of the range of the genus, are more differentiated from E. mongolicus , in that E. korotyaevi has the base of the pronotum medially lobed towards the scutellum (Fig. 74 vs. 42) and E. voriseki is smaller, with flat elytra, slightly convex intervals and hair-like, flexible setae on the entire body (Figs. 69–71 vs. 54–55).

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.