Polistes (Polistella) gilvus Nguyen, Kojima & Saito

Nguyen, Lien Thi Phuong, Kojima, Jun-Ichi & Saito, Fuki, 2011, Polistes (Polistella) wasps (Hymenoptera: Vespidae: Polistinae) from mountainous areas of northern Vietnam, with description of five new species, Zootaxa 3060, pp. 1-30 : 17-19

Polistes (Polistella) gilvus Nguyen, Kojima & Saito , sp. nov.

( Figs 54–60 , 88 )

Type material. HOLOTYPE: Ƥ ( IUNH, on long-term loan from the IEBR), labeled “ VIETNAM, Co Ma, Thuan Chau, Son La, 1600 m, Nest #: 2008-SL-P-1, L.P.T. Nguyen, H.P. Pham, 07.vi.2008 ”. PARATYPES: Vietnam: Son La: 8 Ƥ ( IEBR, IUNH, AMNH), same data as holotype; Lao Cai: 1 Ƥ ( IEBR), Sa Pa, alt. 1500–2000 m, 17– 18.V.2003, ISD-c; 1 Ƥ ( NSM), Mt. Phan Xi Pang, alt. 1750–1950 m, Hoang Lien Son Mts., 2–5.X.1995, M. Tomokuni.

Diagnosis. This species can be distinguished from other known species of subgenus Polistella by the following combination of characters: female clypeus weakly convex, in lateral view anterior margin smoothly passing into supraclypeal area; propodeum with strongly and sharply raised transverse striae; border between posterior and lateral faces of propodeum marked by blunt angulation; metasomal sternum 2 in lateral view square in outline, with corner between anterior and ventral faces bluntly angled.

Description. FEMALE. Body length 8.5–9.5 mm (holotype: about 8.5 mm); fore wing length 9–10 mm (holotype: about 9 mm).

Structure similar to that of Polistes lepcha , but different as follows: POD:OOD=1:1.9; POD about 1.6 × Od ( Fig. 54 ); clypeus in frontal view about 1.1 × as wide as long ( Fig. 55 ), in lateral view weakly convex ( Fig. 56 ); antennal flagellomere 1 slightly greater than 2.5 × as long as its maximum width ( Fig. 57 ); scutellum convex ( Fig. 58 ); jugal lobe of hind wing rounded ( Fig. 59 ); metasomal sternum 2 in lateral view square in outline, with corner between anterior and ventral faces bluntly angled ( Fig. 60 ).

Body surface sculpture as in P. lepcha , but propodeal striae weaker.

Color. As in P. l e pc h a except paired small lateral spots on metanotum present.

MALE. Unknown.

Nest. A nest (Nest#: 2008-SL-P-1) collected in Thuan Chau, Son La was examined ( Table 1 ); one of its resident females is designated as the holotype of this species.

The nest had only two pupae as immatures, and was attached to a thin branch of a shurub about 1.5 m above the ground. The nest characters are as follows: Petiole single, terminal, 3.5 mm long, 2 × 2.5 mm thick, with thin core of plant fibers, enlarged strictly with adult salivary secretion, black and lustrous; salivary coating extended onto substrate and largely onto back of comb. Comb rather tough, pliable in texture, uniformly grayish brown, fan shape in ventral view, ventral surface convex, dorsal surface deeply concave. Cells arranged in regular rows and round at open end, but partly irregularly arranged, where some cells are pentagonal; each cell gradually expanded towards open end, 2.5 mm (range 2.3–3.0 mm; n=10) wide at bottom and 4.1 mm (range 3.9–4.6 mm; n=10) wide at open end, 12.6 mm (range 11.2–13.4 mm; n=10) deep; cell wall about 0.02 mm thick. Cocoon caps slightly domed beyond rim of cell, pale yellow.

Remark. Among species of subgenus Polistella occurring in Vietnam, this species is most similar to Polistes lepcha , but can be easily distinguished from the latter by having the clypeus in lateral view less swollen and smoothly passing into the supraclypeal area ( Fig. 56 ) (in P. lepcha , slightly concave in the supraclypeal area; Fig.

16), propodeal striae weaker, the border between posterior and lateral faces of the propodeum less sharp, and the second metasomal sturnum in lateral view with the anteroventral corner angled, not produced anteriorly ( Fig. 60 ) (in P. lepcha sharply angled, slightly produced anteriorly, Fig. 20). The nest cocoon caps are also different in color, namely pale yellow in this species while pale green in P. l e p c h a.

Etymology. The specific name, gilvus , is a Latin adjective and refers to the pale-yellow cocoon caps. Distribution. Known only from northern Vietnam.

Figures

FIGURES 54 – 60. Polistes (Polistella) gilvus sp. nov., Ƥ. 54. Ocelli, eye and posterior margin of vertex. 55 – 56. Head. 55. Frontal view. 56. Lateral view. 57. Right antenna. 58. Mesosoma, lateral view. 59. Jugal lobe of left hind wing. 60. Metasomal segments 1 and 2, lateral view. Scale 1 mm.

FIGURES 85 – 88. Nests of Polistes species of subgenus Polistella occurring in northern Vietnam. 85. P. dawnae (Nest # 2009 - DB-P- 01). The thick and thin arrows indicate the position of the primary petiole and the subsidiary petioles, respectively. 86. P. l e p c h a (Nest # VN-P- 2006 - 3). 87. P. reliciniclypeus sp. nov. (Nest # VN-P- 2006 - 13). 88. P. gilvus sp. nov. (Nest # 2008 - SL-P- 1).