Gnathoncus vietnamicus Kryzhanovskij, 1972: 22 [Vietnam]; Mazur, 1997: 215; Mazur and Ohara, 2004: .

Redescription. Female. Body length**: PPL, 3.17; PEL, 2.58; APW, 0.78; PPW, 1.91; PL, 0.94; EL, 1.58; EW, 2.20; ProW, 1.32; ProL, 0.39; PyL, 1.03; PTL, 0.68; MSTL, 0.71; MTTL, 0.87. Body broadly oval and convex. Cuticle shiny and black; antennae, legs and mouth parts dark reddish-brown, the antennal club rufopiceous, finely pubescent. Front moderately densely covered with round punctures, separated by 0.5 ­ 3.0 times their diameter and intermingled with very minute punctulation. Epistoma flat, its anterior margin emarginate, more finely punctured as that on front. Labrum transverse, a little emarginate anteriorly, minutely punctulate. Mandibles convex, finely and sparsely punctulate, their inner margin with a small denticle, mandibular apex long and sharp.
Pronotal sides feebly arcuate and convergent on basal 2/3, thence strongly convergent apically. Apical angles obtuse. Marginal stria carinate and complete. Disc moderately densely covered with slightly oblong punctures, separated by 1 ­ 2 times their diameter, the punctures becoming coarser and denser towards sides, being separated here by 0.5 ­1.0 times their diameter. Interspace among these punctures smooth and shiny, with occasional microscopic punctures.
Epipleura of elytra not concave, alutaceous. Marginal epipleural as well as an another epipleural stria thin but complete. Marginal elytral stria complete, carinate and its apical end attaining the elytral apex. Surface of epipleura between the marginal epipleural stria and second epipleural stria smooth, surface between marginal elytral stria and second epipleural stria moderately densely covered with elongate punctures. Inner subhumeral stria a little crenate, present on medio-apical 1/3. Oblique humeral stria present on basal 1/3 and crossed by some oblique rugae. Dorsal striae deeply impressed and crenate, all the striae a little hamate inwardly at base. First dorsal stria present on basal 3/5, the 2 ­ 4 ones progressively shortened, the 4th one extending to/or a little beyond the elytral mid length. Sutural stria present on median 1/3 only. There are also two short, semicircular striae at elytral base between the suture and the 4th dorsal stria. Surface of apical 1/2 ­ 3/5 of elytra covered with deep and oval punctures, separated by 0.5 ­ 2.0 times their diameter, surface of basal 1/2 ­ 2/5 more finely punctulate than middle of pronotal disc. Interspace among punctures with fine, alutaceous microreticulation, especially at elytral apex.
Propygidium covered densely with coarse, transversely elongate punctures, being separated by 0.2 ­ 0.5 times the diameter, and more finely and more sparsely punctured on basal half. All the interspace alutaceous. Pygidium incised laterally, densely covered with round or slightly elongate punctures, separated by about 0.5 (0.2 ­ 0.7) times the diameter, the apex more finely punctured. Interspace among the punctures smooth, only with traces of microsculpture.
Anterior margin of median portion of prosternum round. Ventral disc of keel even, sparsely and moderately punctate. Carinal striae complete, carinate and sinuate, the anterior apex of striae attaining to a large preapical fovea. Descending lateral stria shortly present on medial 1/3 of prosternum, its medio-apical end attaining to apical 1/3 of keel.
Anterior margin of mesosternum bisinuate, with a feeble median projection. Marginal stria of mesosternum complete and carinate. Disc sparsely covered with elongate and setiferous punctures, the interspace between punctures a little alutaceous. Meso-metasternal suture impressed and accompanied by a crenate line. Median area of intercoxal disc of metasternum sparsely clothed with fine and setiferous punctures, the punctures separated by 2 ­ 5 times their diameter, posterior corner evenly covered with coarse punctures which are separated by 0.5 ­ 1.5 times their diameter. Lateral metasternal stria carinate and deeply impressed on lateral 2/3 of intercoxal disc, lateral disc moderately covered with round, setiferous punctures. Metepisternum more densely covered with elongate punctures than those of lateral disc.
Intercoxal disc of 1st abdominal sternum completely striate, the stria carinate, running along postcoxal cavity on basal 1/2 and straight towards posterior margin on apical 1/2. Surface of disc sparsely covered with moderately large punctures, the punctures being finer on median and apical area.
Protibia with 3 teeth bearing spinules on outer margin as well as with two, obtuse, proximal and spinulose ones.
Female genitalia: spermatheca as shown in Fig. 3B.

Specimen examined. Thailand: Doi Inthanon, Chiang Mai, 31.VII.1987, K. Masumoto, 1 female (MO-02027).

Distribution. Described and known so far only from Vietnam. New to Thailand.