Zethus nanlingensis Nguyen & Xu

Nguyen, Lien Thi Phuong & Xu, Zai-Fu, 2017, First record of the genus Zethus Fabricius, 1804 (Hymenoptera: Vespidae, Eumeninae) from China with description of a new species, Zootaxa 4272 (4), pp. 596-600 : 598-599

Zethus nanlingensis Nguyen & Xu , sp. nov. ( Figs 6–8 )

Material examined. Holotype, ♀, pinned, CHINA: Guangdong, Nanling National Nature Reserve, 5–7.VI.2010, Zaifu Xu, No 201301125 ( SCAU).

Diagnosis. The female of new species can be distinguished from all other congeners by the following combination of characteristics: Propodeum dull, without lateral carinae, with median part deeply concave, submarginal carina produced into pointed lamella. Metasomal segment 1 petiolate, long and slender, T1 2.5 × as long as wide, in dorsal view gradually widening from one-sixth of tergum from base, then narrowly toward apical margin, in lateral view abruptly swollen from near base, then gradually convex and depressed near apical margin, with dorsal margin nearly parallel to ventral margin. Metasomal segment 2 petiolate at base. S 2 in lateral view gradually convex from base to apical margin.

Description. Female. Body length 12.5 mm; fore wing length 11.5 mm. Head in frontal view wider than high, 1.3 × as wide as high ( Fig. 6 ). Vertex slightly produced behind eye. Frontal ocellus diameter 0.6 × diameter of antennal socket. Distance from posterior ocelli to apical margin of vertex 2.2 × as long as distance from posterior ocelli to inner eye margin. Area around ocelli slightly swollen. Gena narrower than eye, in lateral view 0.7 × as wide as eye. Occipital carina complete, clearly present along entire length of gena. Inner eye margins slightly convergent ventrally; in frontal view distance of inner eye margins at vertex 1.1 × than those at clypeus. Short median carina located between antennal sockets. Clypeus in lateral view gradually convex from base to apical margin; in frontal view wider than high, 1.2 × as wide as high, with basal margin emarginated, slightly concave medially and close to antennal sockets, apical margin truncated, width of truncation 1/3 × width of clypeus between inner eye margins. Mandible with four prominent teeth. Scape 2.8 × as long as its maximum width; F1 1.5 × as long as its maximum width, F2 as long as wide, F3–F9 wider than long, F10 bullet-shaped, as long as its basal width.

Mesosoma longer than wide, 1.3 × as long as wide in dorsal view. Pronotal carina raised, produced at humeral angles, reaching ventral corner of pronotum. Mesoscutum with notaulices developed (presenting from posterior margin to lateral margin of mesoscutum), in lateral view weakly convex, as long as wide between tegulae; anterior margin broadly rounded. Scutellum flattened, slightly depressed in the middle, in lateral view at same level as mesoscutum, strongly depressed along anterior margin with 8–9 short longitudinal carinae. Metanotum slightly sloping down posteriorly. Propodeum dull, without lateral carinae, with median part deeply concave, basal fovea about one third of length of median carina from fovea to apical margin ( Fig. 7 ), submarginal carina produced into pointed lamella.

Metasomal segment 1 petiolate, long and slender ( Fig. 8 ) (but thicker than in Z. malayanus ), T1 2.5 × as long as wide, in dorsal view gradually widening from one-sixth of tergum from base, then narrowly toward apical margin, with maximum width 3 × its basal width, with medial carina from basal margin to near apical margin, tergum and sternum fused, with distinct suture between them throughout segment, in lateral view abruptly swollen near base, then gradually convex and depressed near apical margin, with dorsal margin nearly parallel to ventral margin ( Fig. 8 ). Metasomal segment 2 petiolate at base. T 2 in dorsal view gradually widen from base to half then narrowly apically, longer than wide, 1.4 × as long as wide. S 2 in lateral view gradually convex from base to apical margin ( Fig. 8 ). T2 and S2 with well developed and raised apical lamella, T3 with thick apical lamella, not raised.

Body with rather long, golden setae. Clypeus with dense, deep and large punctures, each bearing long bristle, borders between punctures with some micro punctures. Mandible with small and deep punctures, each bearing shorter and thicker bristle. Frons densely with dense deep, large and flat-bottomed punctures, border between punctures slightly raised. Vertex and gena with dense, deep, and well-defined punctures, borders between punctures smooth. Pronotum with coarse and dense punctures medially, borders between punctures raised to form reticulation, lateral part along pronotal carina with transverse striae. Mesocutum with large, dense flat-bottomed punctures, area between punctures slightly raised. Punctures on scutellum similar to those on mesoscutum posteriorly. Punctures on metanotum deeper than those on scutellum. Mesepisternum dorsally with dense, deep and large punctures, sparser ventrally, barely punctured anteroventrally. Metapleuron with strong and short striae in dorsal area, with some shallow punctures in ventral area. Propodeum with some oblique striae along each side of median carina, with sparse, small and deep punctures laterally, with shallow and large punctures dorsally and posteriorly, borders between punctures raised to form reticulation, dorsal part with smooth area. T1 with dense and coarse punctures; punctures on T2 much finer and smaller, area between punctures smooth, about 2–3 × larger than puncture diameter, punctures near base of T2 denser and larger than those in other part of tergum; T3 with dense and deep punctures near apical margin; punctures on T3–T6 smaller and sparser, punctures on disc of S2 smaller and sparser than those on T2, punctures near lateral margin denser and larger than those on disc.

Color. Black. Propodeal valvulae ferruginous. Wings slightly infuscate, veins dark brown.

Male. Unknown.

Distribution. China (Guangdong).

Etymology. The specific name refers to the type locality, Nanling, China.

Remarks. The female of new species is most similar to Zethus malayanus Gusenleitner, 2010 and Z. propodeus Nguyen & Carpenter, 2017 , but can be easily distinguished from Z. malayanus by having the metasomal segment 2 petiolate but shorter than in Z. malayanus , metasomal segment 1 in dorsal view gradually widening from one-sixth of the tergum from base, then narrowly toward apical margin (metasomal segment 1 in dorsal view nearly parallel in Z. malayanus ), and can be distinguished from Z. propodeus by submarginal carina produced into pointed lamella above propodeal valvulae (submarginal carina produced into short and round lamella above propodeal valvulae in Z. propodeus ).

Figures

FIGURES 6 – 8. Zethus nanlingensis sp. nov., holotype, ♀. 6. Head, frontal view. 7. Propodeum laterodorsal view. 8. Metasomal segments 1 – 3, lateral view. Scale bars = 1 mm.