Discoelius aurantiacus Nguyen

Nguyen, Lien Thi Phuong, 2016, A new record of the genus Discoelius Latreille, 1809 (Hymenoptera: Vespidae: Eumeninae) from Northern Vietnam with description of two new species, Zootaxa 4154 (5), pp. 589-594 : 590-592

Discoelius aurantiacus Nguyen , sp. nov.

( Figs 1–5 )

Diagnosis. Clypeus with basal margin nearly straight and close to antennal sockets, with median carina from near base to area between antennal socket, apical margin nearly truncated; first metasomal segment petiolate, short and thick, T1 with swollen part in dorsal view nearly 1.6 × as long as wide, abruptly widening at one-fourth of tergum from base, then slightly narrowing to apical margin; T2-T3 with well developed apical lamella.

Material examined. HOLOTYPE, ♀, “ VIETNAM, Seomity, Sa Pa , Lao Cai, 1700 m, 9.vii.2009, LTP Nguyen & PH Pham [ IEBR].

Description. Female. Holotype. Body length 12 mm; fore wing length 11.3 mm. Head in frontal view oval, about 1.1 × as wide as high ( Fig. 1 ). Vertex behind ocelli strongly produced behind eye. Distance from posterior ocelli to apical margin of vertex 1.8 × as long as distance from posterior ocelli to inner eye margin ( Fig. 2 ). Gena slightly narrower than eye, in lateral view 0.9 × as wide as eye. Occipital carina developed only laterally. Inner eye margins not distinctly convergent ventrally, in frontal view slightly further apart from each other at vertex than at clypeus. Clypeus in lateral view convex from base to apical margin, in frontal view 1.3 × as wide as high ( Fig. 1 ), with basal margin nearly straight and close to antennal sockets, with a median carina from near base of clypeus to supraclypeal area; apical margin nearly truncated ( Fig. 1 ); width of truncation 0.4 × width of clypeus between inner eye margins. Mandible with four prominent teeth. Antennal scape 3 × as long as its maximum width, F1 1.2 × as long as its maximum width, F2–F9 wider than long, F10 bullet-shaped, about as long as its basal width.

Mesosoma longer than wide in dorsal view, 1.5 × as long as wide. Pronotal carina slightly raised and reaching ventral corner of pronotum. Mesoscutum with notauli from scutellum to lateral margin of mesoscutum, in lateral view weakly convex dorsally near anterior margin, then dorsally straight to apical margin, about 1.1 × as long as wide between tegulae; anterior margin broadly rounded. Scutellum flattened, slightly medially depressed at basal half, in lateral view at same level as mesoscutum. Metanotum slightly sloping down to apical margin, strongly depressed along anterior margin. Propodeum with median part slightly concave, with distinct median carina from near base to apex, with fovea at base ( Fig. 3 ).

First metasomal segment petiolate, short and thick ( Fig. 4 ), T 1 in dorsal view abruptly widening at one-fourth of the tergum from base, then slightly narrowly to apical margin, with maximum width about 3.3 × its basal width, tergum and sternum fused, with a distinct suture between them throughout the segment, with some short striae at anterior area and irregular rugose at posterior area of the sternum, the widening part in dorsal view nearly 1.6 × as long as wide, strongly transverserly depressed near apical margin, in lateral view abruptly dorsally swollen from near base, then depressed near apical margin ( Fig. 4 ). Second segment petiolate at base ( Fig. 3 ). T 2 in dorsal view 1.1 × as long as wide, in lateral view slightly convex then nearly straight to apical margin. T2–T3 with well developed apical lamella, T4 without apical lamella. S 2 in lateral view slightly convex from base then nearly straight to apical margin ( Fig. 4 ).

Body with rather long, ferruginous setae; setae on clypeus, frons, vertex and propodeum longer than those in other parts of the body, length greater than 1.5 × as long as posterior ocellus diameter. Clypeus with coarse punctures, interspaces between punctures narrow, arranged in weak longitudinal striations at medial part. Mandible with smaller and sparser punctures. Frons with dense, deep and large punctures, interspaces between punctures raised to form reticulation. Vertex and gena with dense, deep, and well defined punctures, interspaces between punctures smooth. Pronotum with coarse and dense punctures, interspaces between punctures narrow, strongly raised to form reticulation. Mesocutum with dense and coarse punctures, interspaces narrow, raised to form longitudinal striae at medial part. Punctures on scutellum similar to those on frons. Punctures on metanotum similar to those on the vertex and gena. Mesepisternum with punctures on dorsal part as those on pronotum, punctures on ventral part as on vertex, smaller punctures anteroventrally. Metapleuron with weak and short striae in dorsal area, without punctures in ventral area. Propodeum with large and shallow punctures on dorsal and posterior surfaces, interspaces between punctures raised to form reticulation, lateral parts with weak transverse striae. T1 with dense and coarse punctures, interspaces between punctures rugose, punctures on T2 much finer and smaller, minute punctures in between them, punctures near base of T2 denser and larger than those in other part of the tergum, T3– 6 with smaller punctures, punctures on S2 larger and deeper than those on T2.

Color. Black. The following parts orange: two wide and short bands on anterior margin of pronotum, narrow band on apical margin of T1 and wider band on apical margin of T2. Propodeal valvulae dark brown. Wings dark brown, strongly infuscate, veins dark brown.

Male. Unknown.

Distribution. Northern Vietnam: Lao Cai.

Remarks. This species can be distinguished from the similar species D. nigriclypeus Zhou et al. (2013) and D. emeishanensis Zhou et al. (2013) , from China and other known species of the genus by the combination of the following characters: T1 with swollen part in dorsal view nearly 1.6 × as long as wide, T2–T3 with developed apical lamella, and color pattern.

Etymology. The specific name refers to the orange on the body.

Figures

FIGURES 1 – 5. Discoelius aurantiacus sp. nov., holotype, ♀. 1. Head, frontal view. 2. Vertex, dorsal view. 3. Propodeum and metasoma, dorsal view. 4. Metasoma, lateral view. 5. Habitus.