Hexachaetus vietnamensis Tian & Deuve, 2016, n. sp.
Creators: name: Tian, Mingyi
name: Deuve, Thierry
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Carabidae
Hexachaetus
Hexachaetus vietnamensis

description: Hexachaetus vietnamensis n. sp.
(Figures 9, 18–19)
Material. Holotype male, “ Annam, Kontum, R. P. C. Corompt, 1914”, from Central Vietnam, in MNHN; paratypes: 1 male, “Tonkin, Than-Moi, Juni-Juli, H. Fruhstorfer”, northern Vietnam, in SCAU; 1 male: “ Coll. I. R. Sc. N. B. / Vietnam: Dak Lak Province, env. Buon Ma Thuot / IX. 2008 / Leg. Local collectors”, in IRSNB.
Diagnosis. Large sized, reddish brown; body moderately stout, smooth, polish; head and pronotum impunctate, elytra covered fine and sparse punctures; palps dilated, clypeus bisetose; pronotum transverse, widest at about middle, hind angle broadly round off; middle tibia not dilated medially in male, though stout; fore tarsi slightly stouter than middle ones, both much thicker than hind tarsi.
Length: 16.0–17.0 mm; width: 6.5 mm. Habitus as in Fig. 9.
Description. Reddish yellow to brown, tibiae and tarsi of legs, antennae, apex of mandibles, frons, clypeus and middle labrum dark brown, femora and vertex lighter; strongly shiny; surface glabrous, especially on pronotum; microsculptural engraved meshes irregularly striate on head and pronotum, isodiametric on elytra.
Head convex, longer than wide, HL/HW=1.13; glabrous, frontal impressions well-marked, long and deep, extending to level between anterior and posterior eyes; clypeus bisetose, labrum straight at front, eyes large and prominent; palps stout; labial palpomere 2 with three setae on inner margin; maxillary palpomere 4 obliquely truncate at subapex; ligula very broad at apex, 12-setose, median two (normal length) much longer than others, three pairs shorter, and two pairs shortest, closed to median ones and at outer sides, respectively. Antennae short, antennomere 3 shorter than 4, but as long as 5.
Pronotum moderately transverse, PL/PW=1.62; bordered at base and front, widest at about middle, lateral expanded margins broad and distinctly reflexed; both fore and hind angle round off, transversal impressions partly faint, basal foveae narrow, striate; median line clear.
Elytra elongate-ovate, EL/EW=1.58; shoulders nearly quadrate, widest at middle, parallel-sided, apex obliquely truncated, inner apical angle pointed, outer one round off; striae deep, intervals slightly convex, intervals 2, 4 and 5 slightly wider than 3 and 6, or subequal in length; intervals 3, 5 and 7 with fine, indistinct punctures; interval 3 with basal and apical setiferous pores.
Legs moderate, fore tibia slightly dilated at apex, with a moderate outer angle nearly rectangular, apical margin sinuate, outer margin distinctly serrate; middle tibia not dilate in male, hind tibia slender; apical tibial spurs of hind leg short and blunt, broadly sword-like, hind tarsomeres 3–4 subequal, tarsomere 4 bilobed at apex, asymmetrically; tarsal claws moderately pectinate.
Male genitalia (Figs. 18–19): The median lobe of aedeagus short and stout, distinctly enlarged medially, ventral margin bisinuate, strongly expanded near base, gradually narrowed towards apex; in dorsal view, the apical lamella very short and broad, apical margin nearly straight.
Remarks. This species is probably a representative of a unique lineage within the genus Hexachaetus. The peculiar character states of H. vietnamensis n. sp. include dilated palps, plurisetose ligula, and stout aedeagus which is broadly rounded at apex.
Etymology. Referred to the type locality.
Distribution. Vietnam (Fig. 20 g).
description: Published as part of Tian, Mingyi & Deuve, Thierry, 2016, Re-definition and review of the Oriental genus Hexachaetus Chaudoir, 1871 (Coleoptera: Carabidae: Orthogoniini), pp. 540-554 in Zootaxa 4169 (3) on pages 550-551, DOI: 10.11646/zootaxa.4169.3.7, http://zenodo.org/record/258027