Pararrhynchium sparsum Nguyen & Ljubomirov, 2021

Nguyen, Lien Thi Phuong, Tran, Ngat Thi, Bui, Dien Trong & Ljubomirov, Toshko, 2021, Contribution to the genus Pararrhynchium de Saussure (Hymenoptera: Vespidae Eumeninae), with description of two new species from Vietnam, Zootaxa 5082 (2), pp. 159-168 : 163-166

Pararrhynchium sparsum Nguyen & Ljubomirov , sp. nov.

Diagnosis. This species can be distinguished from all other known species of the genus Pararrhynchium by the following combination of characters: clypeus with flattened part well defined, in frontal view almost as high as wide, with sparse punctures, borders between punctures smooth, shining, and with micropunctures; propodeum with the carina produces to blunt tubercles behind metanotum and at lower lateral corner; T1 with distinct basal transverse carina; T2 almost as long as wide in dorsal view; and S2 strongly depressed at base, in lateral view almost straight from base to half, then straight to apical margin.

Material examined. Holotype, female, Vietnam: Cham Chu NR, Cao Duong, Yen Thuan, Ham Yen , Tuyen Quang, way to waterfall, 22°17’32.5”N, 104°59’28”E, alt. 643 m, 16 May 2019, LTP Nguyen & CQ Nguyen, deposited in IEBR.

Paratypes: 4 females, same data as holotype, deposited in IEBR .

Description. Female ( Fig. 20 ). Body length 13.2–13.5 mm (holotype: 13.5 mm); fore wing length 12.8–13.0 mm (holotype: 13.0 mm).

Head in frontal view subcircular, slightly wider than high ( Fig. 13 ). Vertex with cephalic foveae situated close to each other, distance between them about one-fourth distance between posterior ocelli ( Fig. 14 ). Distance from posterior ocelli to apical margin of vertex 2 times distance from posterior ocelli to inner eye margin ( Fig. 14 ). Gena almost as wide as eye; occipital carina complete, present along entire length of the gena, somewhat weak at dorsal part. Inner eye margins convergent ventrally; in frontal view nearly 1.25 times further apart from each other at vertex than at clypeus. Clypeus with flattened part well defined, in frontal view almost as high as wide ( Fig. 13 ), with basal margin strongly convex medially and distinctly separated from antennal sockets; apical margin emarginate medially forming a blunt tooth on each side, width of the truncation slightly greater than 1/3 width of clypeus between inner eye margin. Mandible with four prominent teeth. Antennal scape about 3.8 times as long as its maximum width, slightly curved; F1 about 1.7 times longer than wide, F2 and 3 slightly longer than wide, F4 as long as wide, F5– 9 wider than long, terminal flagellomere bullet-shaped, as long as its basal width ( Fig. 13 ). Mesosoma longer than wide in dorsal view ( Fig. 15 ). Pronotal carina strongly raised, reaching ventral corner of pronotum. Mesoscutum weakly convex, 1.1 times as long as wide between tegulae, with medial longitudinal smooth and shiny area running from apical margin to half length of the mesoscutum, with two depressed furrows running from apical margin to one-fourth length of the mesoscutum ( Fig. 15 ). Disc of scutellum slightly convex, in lateral view at the same level of mesoscutum ( Fig. 16 ). Metanotum weakly convex. Propodeum ( Fig. 17 ) with propodeal dorsum forming shelf like area behind metanotum, with horizontal area slightly shorter than the length of metanotum, concavity margined by a crest, posterior surface clearly separated from dorsal side by an upper sharp and well-developed carina, the carina produces to blunt tubercles behind metanotum and at lower lateral corner ( Fig. 17 ). Metasomal segment 1 ( Fig. 18 ) clearly narrower than segment 2, about 0.9 times as wide as the width of segment 2, truncate at base, anterior vertical surface convex, with dense coarse punctures, clearly separable from posterior horizontal part, with completed carina. T 1 in dorsal view about 1.58 times as wide as long; T2 almost as long as wide in dorsal view; S2 strongly depressed at base, in lateral view almost straight from base to half, then straight to apical margin ( Fig. 19 ); T1 and T2 with a narrow smooth band apically.

Vestiture. Body covered with medium silver hairs.

Sculpture. Clypeus with sparse punctures, each puncture bearing a very short bristle, border between punctures smooth, shining, and with micropunctures. Frons densely covered with very coarse punctures, border between punctures raised to form reticulations. Vertex with punctures similar to those on frons; gena with strong punctures, border between punctures smooth and much larger than those on vertex. Pronotum with punctures similar to those on vertex. Mesoscutum densely and coarsely covered with flat-bottom punctures, border between punctures raised to form reticulations; punctures on scutellum dense, smaller than those on mesoscutum, punctures on metanotum weaker than those on scutellum; scutellum with distinct median furrow. Mesepisternum with flat-bottomed punctures, punctures coarser than those on pronotum posterodorsally, small and sparse punctured and with a large smooth area anteroventrally; border between posterodorsal and anteroventral parts distinct, with epicnemial carina. Dorsal metapleuron with several strong striae, ventral metapleuron with sparse and shallow punctures, and several short striae. Propodeum with very coarse punctures and a smooth area on dorsal part, with dense and strong punctures, border between punctures sometimes weakly raised to form reticulation at lateral parts; posterior surface dull, rugose, with small shallow punctures at sides. T1 covered with strong punctures, border between punctures with minute punctures and sometimes larger than puncture diameter; punctures on T2 smaller and sparser than those on T1; T3 and T4 with weaker and smaller punctures; T5 and T6 with minute punctures. Tegula shiny, with sparse minute punctures.

Colour. Body almost black except two small orange- yellowish spots above between antennae. Wing strongly infuscated, veins dark brown.

Male. Unknown.

Distribution. North Vietnam.

Etymology. The specific epithet is taken from the Latin sparsus (= sparse), indicating the sparsely punctured clypeus of this species

Remarks. Pararrhynchium sparsum Nguyen & Ljubomirov , sp. nov. is close to P. tsunekii Tano & Yamane, 1983 in having the female clypeus with the flattened part well defined, with sparse fine punctures; scutellum with distinct median furrow; T1 with a distinct basal transverse carina; and the apical margin of T3 not lamellate. It can be differentiated from the later by the following characters: clypeus as long as wide (versus clypeus longer than wide in P. tsunekii ); propodeum with superior carinae apically forming a pair of blunt teeth behind metanotum (versus propodeum with superior carinae apically forming a pair of relatively sharp teeth behind metanotum in P. tsunekii ), and by the color pattern.

Pararrhynchium sparsum Nguyen & Ljubomirov , sp. nov. is also close to P. ornatum ( Smith, 1852) but can be differentiated from the later by the following characters: clypeus as long as wide (versus clypeus longer than wide in P. ornatum ); and apical margin of T3 not lamellate (versus apical margin of T3 lamellate, slightly bent upward in P. ornatum ).

Figures

FIGURES 18-20. Pararrhynchium sparsum Nguyen & Ljubomirov, sp. nov., holotype, female. 18. Metasoma, dorsal view. 19. Metasoma, lateral view. 20. Habitus. Scale bar: 1 mm.

FIGURES 13–17. Pararrhynchium sparsum Nguyen & Ljubomirov, sp. nov., holotype, female. 13. Head, frontal view. 14. Head, dorsal view. 15. Mesosoma, dorsal view. 16. Mesosoma, lateral view. 17. Propodeum, posterior view. Scale bar: 1 mm.