Polistes (Polistella) brunus Nguyen & Carpenter, 2017

Nguyen, Lien Thi Phuong, Vu, Thuong Thi, Lee, John, X. Q. & Carpenter, James M., 2017, Taxonomic notes on the Polistes stigma group (Hymenoptera, Vespidae: Polistinae) from continental Southeast Asia, with descriptions of three new species and a key to species, Raffles Bulletin of Zoology 65, pp. 269-279 : 272-274

Polistes (Polistella) brunus Nguyen & Carpenter , new species

( Figs. 7–12 )

Material examined. HOLOTYPE: 1 female, pinned (deposited in the Institute of Ecology and Biological Resources, Hanoi). Original label: “ VIETNAM, Dak Lak, Ea Kar, Ea So, Ea So NP station 5, 12°55′24.3″N, 108°33′04″E, 95 m, Nest# VN-TN-2015-P-02, 15.IV.2015, L. T.P Nguyen, D.D Nguyen & M.P. Nguyen ”. PARATYPES: VIETNAM ( IEBR): Dak Lak : 7 females, 1 queen, same data as holotype ; 4 females, Station 5, Ea So natural reserve, Ea So, Ea Kar, 12°55′24.3″N, 108°33′04″E, 95 m, Nest # VN- TN-2015-P-03, 13 April 2015, coll. L. T. P Nguyen, D. D Nguyen & M.P. Nguyen ; 3 females, Yok Don NP station, Buon Don , 12°52′19.1″N, 107°48′25.9″E, ca 190 m, 9 June 2013, coll. L. T. P. Nguyen ; 2 females, Buon Don, 28 April 2008, coll. H. T. Ngo; Gia Lai: 2 females, Ia Pal, Chu Se, 13°39′46.2″N, 108°08′04″E, ca 370 m, 25 July 2012, coll. L. T. P. Nguyen; Quang Tri: (1 female, A Ngo, Dak Rong, 150–200 m, 31 May 2006; 1 female, Ta Rut, Dak Rong, 300 m, 2 May 2006) Insect Systematic Department collectors.

Diagnosis. This species can be distinguished from congeners by the following combination of characters: Gena in lateral view about 0.8 times as wide as eye; length of lateral margin of clypeus lying along inner eye margin slightly shorter than diameter of antennal socket and about as long as the length of malar space; flagellomere I 2.8 times as long as its maximum width; body coarsely punctate, mainly brown.

Female. Body length 10.1–13.7 mm (holotype: 11.9 mm); fore wing length 9.2–13.4 mm (holotype: 11.3 mm).

Head in frontal view about 1.1 times as wide as high ( Fig. 7 ); in dorsal view weakly swollen laterally behind eyes, then narrowed posteriorly, with posterior margin shallowly and broadly emarginate. Vertex slightly raised in area within ocelli, slightly declivous behind posterior ocelli towards occipital carina; with two small foveae just behind posterior ocelli ( Fig. 8 ); POD: OOD = about 1: 1.5; POD about 2.1 times Od ( Fig. 8 ). Gena, in lateral view about 0.8 times as wide as eye ( Fig. 10 ); occipital carina fine, evanescent on ventral third of gena. Inner eye margins weakly convergent ventrally, in frontal view about as far apart from each other at clypeus as at vertex. Antennal sockets closer to inner eye margin than to each other; the distance from anterior tentorial pit to antennal socket as far as to inner eye margin; interantennal space weakly raised. Clypeus in frontal view slightly wider than high, produced ventrally into blunt angle ( Fig. 7 ); in lateral view strongly swollen anteriorly; length of lateral margin of clypeus lying along inner eye margin slightly shorter than diameter of antennal socket and about as long as the length of malar space. Antenna: scape 2.8 times as long as its maximum width; flagellomere I 2.8 times as long as its maximum width, about 1.3 times as long as the length of flagellomeres II and III combined; flagellomere II and III longer than wide; flagellomere IV–IX wider than long, terminal flagellomere bullet-shaped, about 1.2 times as long as its basal width.

Pronotal carina sharply raised, produced dorsally into thin lamella in dorsal part, slightly sinuate backward on lateral side, nearly reaching ventral corner of pronotum. Mesoscutum strongly convex, as long as wide between tegulae; anterior margin broadly rounded. Scutellum convex, slightly concave medially. Metanotum weakly convex, with strongly depressed anterior margin. Propodeum short ( Fig. 9 ); posterior face widely (about half the maximum width of propodeum) and shallowly excavated medially, more or less smoothly passing into lateral faces; propodeal orifice elongate, about 1.8 times as long as wide (measured at widest part), somewhat narrowed in dorsal half. Wings hyaline, jugal lobe of hind wing large and pointed.

Metasomal tergum I short, about 0.9 times as long as its apical width, in lateral view abruptly swollen dorsally just behind basal slit for reception of propodeal suspensory ligament; corner between anterior and dorsal faces rounded. Sternum II in lateral view swollen ventrally in smoothly curved line to apical margin.

Clypeus with scattered large punctures, each bearing sharply pointed golden bristle; tomentum on clypeus covering approximately dorsal half of clypeus. Mandible with scattered medium deep punctures. Frons covered with shallow punctures. Vertex and gena with sparse small and shallow punctures; area around ocelli almost smooth, with several shallow punctures close to median ocellus; ventral third of gena with scattered coarse punctures. Pronotum with dense, coarse flat-bottomed punctures ( Fig. 10 ). Mesoscutum with dense, medium, shallow punctures. Punctures on scutellum denser and coarser than those on mesoscutum. Punctures on metanotum sparser and shallower than those on scutellum. Mesepisternum with dense, coarse, well-defined punctures in posterodorsal part (punctures in dorsal margin similar to those on pronotum), scattered punctures in anteroventral part; border between posterodorsal and anteroventral parts indistinct. Dorsal metapleuron with several short and weak striae; ventral metapleuron with sparse shallow punctures. Propodeum with strong transverse striae ( Fig. 9 ), striae weaker laterally. Metasomal segments with minute punctures in addition to scattered small punctures (stronger and larger on sterna); sternum V−VI covered with long hairs.

Colour. Dark brown; following parts yellow to orange-yellow: apical margin of clypeus, spot at base of mandible, band along inner eye margin extending from bottom of frons to middle of eye emargination; valvula; apical band of tergum I extending laterally toward its base, a medial band on tergum IV; thin longitudinal stripe on hind coxae; middle and hind tarsi; following parts black: propodeum posteriorly, abdomen except yellow parts, all legs except tarsi.

Male. Unknown.

Nest. Nest#VN-TN-2015-P-02 ( Fig. 12 ) was collected together with eight females. The nest was attached to a woody crossbeam of a house, at about 2 m above the ground, and has 56 cells, with four pupae. Nest#VN-TN-2015-P-03 was collected with five adult female wasps. The nest was attached to a ceiling of a store, about 1.3 m above the ground, and has 58 cells, with six pupae. The structural and morphological characters are as follows: Comb tough, pliable “paper”-like in texture, more or less uniformly gray in cell wall, subcircular (about 23 × 20 mm for Nest#VN-TN-2015-P-02 and about 26 × 23 mm for Nest#VN-TN-2015-P-03) in view from side of cell opening, expanded concentrically from the single petiole, with surface corresponding to cell bottom slightly convex. The two nests have the single petiole central; in Nest#VN-TN-2015-P-02 it is 3.2 mm long and 1.0 × 0.9 mm thick, and in Nest#VN-TN-2015-P-03 it is 4.8 mm long and 1.3 × 0.9 mm thick at the mid-length of petiole, with a thin central core of plant fibers, enlarged strictly with adult oral secretion, dark brown and lustrous, secretion coat expanded on comb back around the petiole and on substrate in a thin film about 2 × 2.5 mm. Cells are generally arranged in regular rows, hexagonal at open end when surrounded by other cells, with free margins rounded; for Nest#VN-TN- 2015-P-02 each cell expanded towards open end, 4.7 mm (range 4.2–5.7 mm; n=10) wide at open end, 11.7 (range 10–13.3 mm; n=10) mm deep in full grown cells, cell wall about 0.08 mm thick, for Nest#VN-TN-2015-P-03 each cell expanded towards open end, 4.5 mm (range 4.0– 5.6 mm; n=10) wide at open end, 14.5 mm (range 10.8–16 mm; n=10) deep in full grown cells, cell wall about 0.09 mm thick. Cocoon caps white, produced beyond rim of cell by 1–4 mm, slightly domed.

Distribution. Known only from localities in Vietnam listed above.

Etymology. The specific name, brunus , is a Latin adjective, referring to the brown body colour.

Figures

Figs. 7–12. Polistes brunus, new species, female. 7, Head, frontal view; 8, Vertex, dorsal view; 9, Propodeum, dorsal view; 10, Head & thorax, lateral view; 11, Habitus. Scale bar = 1 mm. 12, Nest.