Polistes (Polistella) tenebris Nguyen & Lee, 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 : 276-278

Polistes (Polistella) tenebris Nguyen & Lee , new species

( Figs. 22−30 )

Material examined. HOLOTYPE: female, pinned (deposited in the Lee Kong Chian Natural History Museum ( LKCNHM), National University of Singapore ( NUS), Singapore. Original label: “ JXQL#0056 , SINGAPORE, Tampines Street 41, 1°21′32.2″N, 103°56′41.9″E, 19 m, Nest #Singapore- 2012-P-01, 6. VI.2012, John L. ” . PARATYPE: ( NUS, tentatively in IEBR on long-term loan from NUS): 4 females, 8 males, same data as holotype ; 1 female, Mandai Road , 14 June 2014, coll. J.X.Q Lee ; 2 females, 1 male, Sungei Buloh , Wetland Reserve, Nest #Singapore-2013-P-02, 5 November 2013, coll. John L ; SINGAPORE ( NUS): 1 female, Nee Soon , coordinates unknown, 5 September 2012, coll. Z.W.W. Soh ; 1 female, Kent Ridge , National University of Singapore, School of Design and Environment, 1°17′51.4″N, 103°46′13.8″E, 14 July 2015, coll. M.S. Chua ; 1 female, Holland Woods , 1°19′58.1″N, 103°46′52.3″E, 1 October 2014 , collector unknown; 1 female, Orchard Central , 1°18′00.0″N, 103°50′27.6″E, 30 April 2015, coll. C. Roscoe , NUS.

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 as long as diameter of antennal socket and slightly shorter than the length of malar space; flagellomere I slightly greater than 3 times as long as its maximum width; body with dense and coarse punctures; body nearly entirely black; wings transparent except dark spots at apical margins of fore wings.

Female. Body length 10−11 mm (holotype: 10.6 mm); fore wing length 9.8−10.8 mm (holotype: 10.4 mm).

Structure as in Polistes communalis , new species and P. brunus , new species, but differing as follows: POD: OOD = about 1: 1.3; POD about 2 times Od. Gena in lateral view about 0.8 times as wide as eye ( Fig. 24 ). Inner eye margins, in frontal view 1.1 times further apart from each other at vertex than at clypeus. Clypeus in frontal view as wide as high ( Fig. 22 ), length of lateral margin of clypeus lying along inner eye margin as long as diameter of antennal socket and slightly shorter than the length of the malar space. Antenna: scape 2.9 times as long as its maximum width; flagellomere I slightly greater than 3 times as long as its maximum width; terminal flagellomere as long as its basal width.

Body punctures denser and coarser than in P. communalis , new species. Dorsal metapleuron with short and thin striae.

Colour. Black; following parts orange-yellow: apical margin of clypeus, a narrow band along inner eye margin extending from bottom of frons to middle of eye emargination; a short narrow band on gena along eye margin, lower part of gena close to eye and clypeus, a narrow band at basal margin of metanotum; two longitudinal narrow stripes on posterior face of propodeum; valvula; apical band of tergum I (extending laterally toward its base) and tergum IV; thin longitudinal stripe on hind coxae; following parts dark brown: mandible, tergum VI and hind femora.

Male. Body length 9.0 mm– 10 mm; fore wing length 8.8 mm– 9.8 mm.

Similar to female, but differing from the latter as follows: head about 1.2 times as wide as high in frontal view ( Fig. 26 ); inner eye margins 1.3 times as long from each other at vertex as at clypeus; gena in lateral view about 0.4 times as wide as eye; clypeus ( Fig. 26 ) in frontal view 1.1 times as high as wide, only slightly produced ventrally, evenly and slightly convex apically, in lateral view weakly convex in dorsal part. Antenna more slender than in female; scape short, about 2.5 times as long as its maximum width; flagellomere I longer than length of flagellomeres II and III combined; terminal flagellomere elongate, slightly curved, about 2 times as long as its basal width. Metasomal sternum VII depressed medially, without tubercle.

Body surface sculpture as in female, but clypeus with scattered medium punctures, densely covered with short silver hairs together with long golden bristles, and with a faint longitudinal ridge medially.

Colour and marking pattern similar to female, but clypeus and mandible entirely black.

Male genitalia. Lamina volsellaris desclerotised and fused with cuspis. Digitus in inner aspect of paramere ( Fig. 27 ) about 3.3 times as long as wide (measured at widest part), distinctly swollen near base, gradually narrowed apically to mid-length, then slightly swollen towards the rounded apex. Aedeagus ( Figs. 28, 29 ): penis valves about 0.6 times as long as basal apodeme, in ventral view narrowest near mid-length, weakly swollen proximally from mid-length then distinctly produced laterally near proximal margin, in lateral view slightly thickened in proximal one fourth and with dorsal margin weakly sinuate, with proximoventral corner produced into obtuse angle ( Fig. 29 ); ventral margins of penis valves finely serrate along entire length.

Nest. The first nest ( Fig. 30 ) was a mature one found on 4 June 2012 built in a tree of Melaleuca bracteata (var. “Revolution Gold”) at a height of approximately 2.2 m. It was subsequently collected on 6 June 2012, with eight wasps. Some of the cells were accidentally crushed during the collection, so the total number of cells was estimated to be between 125 and 140. Approximately 60 cells had produced adults at least once; 42 cells contained pupae; the rest contained eggs or larvae. Nest description as follows: Comb roughly oval (approximately 51 × 39 mm) in view from side of cell opening, colour ranging from light graybrown to medium reddish-brown, paper-like in texture, being made mainly of plant fibers and oral secretions from the adult wasps. The nest was joined directly to the tree by a single petiole positioned slightly excentrically; The petiole was broken and lost during the collection process, but was approximately 3 mm long. Cells were built away from the petiole and sloping downwards in the center but curving upwards again from cells being built higher up and at an angle facing outwards diagonally from the inner cells, roof dark and shiny due to secretions from adult wasps, cells generally arranged in roughly regular rows, hexagonal at open end when surrounded by other cells, free margins generally rounded, weakly expanded towards open end, 3.9 mm (range 3.7−4.3 mm; n=10) wide at open end, and 15.5 mm (range 15−17 mm; n=10) deep in cells containing pupae or having produced adults, not including cocoon caps; Cocoon caps white, slightly domed, produced beyond rim of cell by 1–3 mm.

The second nest was a young one found on 5 November 2013 built on the underside of a leaf of Dillenia suffruticosa , at a height of approximately 2.5 m, and was collected on the same day. Three adult wasps were found on the nest, one of which was clearly the foundress. Five cells had produced adults, out of which four had larvae inside and one with an egg. However, after approximately 45 minutes of observation prior to collecting the nest, no other adults returned. The nest consisted of 21 completed cells and 12 incomplete ones. Among the complete cells, 11 contained pupae, eight contained larvae and two contained eggs. The 12 incomplete cells were occupied by eggs or small larvae. Nest description as follows: Comb roughly spherical, approximately 30 × 30mm, paper-like in texture, being made mainly of plant fibers and oral secretions from the adult wasps. Colour light gray-brown. The nest was joined to the underside of the leaf by a single petiole positioned centrally. Again, the petiole was broken and lost during the collection process, but was approximately 3 mm long. The roof is dark and shiny due to a covering of secretions from adult wasps, though not as much as the first nest; Cells are generally arranged in roughly regular rows, hexagonal at open end when surrounded by other cells, free margins generally rounded, weakly expanded towards open end, 3.8 mm (range 3.7−4.1 mm; n=5) wide at open end, and 15.3 mm (range 15−17 mm; n=5) deep in cells containing larvae or pupae or having produced adult, not including cocoon caps; Cocoon caps white, slightly domed, produced beyond rim of cell by 1−2.7 mm.

Distribution. Known only from localities in Singapore listed above.

Etymology. The specific name, tenebris , is a Latin adjective, referring to the black body of the species.

Figures

Figs. 22–30. Polistes tenebris, new species. 22–25, female. 22, Head, frontal view; 23, Propodeum, dorsal view; 24, Head & thorax, lateral view; 25, Habitus. 26–29, male. 26, Head, frontal view; 27–29, Genitalia. 27, Inner aspect of paramere with digitus and volsella; 28, 29, Aedeagus (28, Ventral view; 29, Lateral view). Scale bar = 1 mm. 30, Nest.