Polistes (Polistella) clandestinus 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 : 19-21

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

( Figs 61–74 )

Type material. HOLOTYPE: Ƥ ( IUNH, on long-term loan from the IEBR), labeled “ VIETNAM, Sa Pa NP office, Lao Cai, 1600 m, L.P.T. Nguyen, F. Saito & J. Kojima, 22.viii.2006 ”. PARATYPES: Vietnam: Lao Cai: 5 3, 3 Ƥ ( IEBR, IUNH, AMNH), same data as holotype; 3 3, 3 Ƥ ( IEBR, IUNH), alt. 1600 m, Sa Pa Town, 8.VII.2009, HP; 1 Ƥ, 2 3 ( IEBR), Xin Chai, Sa Pa, alt. 1350 m, 6.VII.2009, HP; 1 Ƥ ( IEBR), Hoang Lien NP, alt. 1660 m, 6.VII.2009, HP; 1 Ƥ ( IEBR), Cat Cat, Sa Pa, alt. 1450 m, 7.VII.2009, HP.

Diagnosis. This species can be distinguished from other known species of subgenus Polistella by the following combination of characters: scutellum entirely flat, in lateral view dorsal margin smoothly passing into either mesoscutum and metanotum; posterior face of propodeum with shallow median excavation about 0.3 × the maximum width of propodeum, in lateral view slope down in nearly straight line; metasomal sternum 2 in lateral view basally abruptly swollen ventrally, then ventral margin broadly rounded; male clypeus as wide as high.

Description. FEMALE. Body length 9–11 mm (holotype: about 9.5 mm); fore wing length 10–11.5 mm (holotype: about 10.5 mm).

Structure as in Polistes reliciniclypeus , but differing as follows: POD:OOD=1:2.1 ( Fig. 61 ); inner eye margins in frontal view about 1.1 × further apart from each other at vertex than at clypeus ( Fig. 62 ); anterior tentorial pit as far from eye margin as from antennal socket; clypeus in frontal view about 1.1 × as wide as high ( Fig. 62 ), in lateral view convex, smoothly curved anteriorly ( Fig. 63 ); antennal flagellomere 1 nearly 3 × as long as its apical width ( Fig. 64 ); scutellum entirely flat, in lateral view dorsal margin smoothly passing into either mesoscutum and metanotum ( Fig. 65 ); jugal lobe of hind wing rounded ( Fig. 66 ); posterior face of propodeum with shallow median excavation about 0.3 × maximum width of propodeum, in lateral view slope down in nearly straight line ( Fig. 65 ) (slightly convex in P. reliciniclypeus ; Fig. 31 ); metasomal sternum 2 in lateral view basally abruptly swollen ventrally in anterior half to two-third, then ventral margin broadly rounded ( Fig. 67 ).

Body surface sculpture as in P. reliciniclypeus , but dorsal half of clypeus covered with fine pale pubescence and ventral half with scattered deep large punctures, each baering sharply pointed golden bristle; mandible with scattered shallow punctures; frons and vertex to level of posterior ocelli with moderately close fine punctures; vertex behind posterior ocelli and gena with sparse fine punctures (punctures in ventral third of gena scaratted and deep), with space between punctures smooth; mesoscutum with dense fine punctures in addition to scattered deep flat-bottomed punctures; scutellum and metanotum with scattered moderately deep punctures; ventral metapleuron smooth, without punctures; propodeum with distinct transverse striae, and punctures between striae on lateral faces, interpuncture spaces weakly raised to interconnect striae.

Color. Black, with following parts yellow:clypeus except black basal and lateral margins, broad band along inner eye margin extending from bottom of frons to middle of eye emargination, line in dorsal part of gena along posterodorsal margin of eye, most ventral part of gena, narrow band along pronotal carina with branches running along posterodosal margin of pronotum, scutellum except for anterior margin, paired anterolateral spots on metanotum, scrobal spot on mesepisternum, paired lateral oval spot on posterior face of propodeum, propodeal valvula, narrow apical band on metasomal terga 1–5, entire visible part of tergum 4. Legs black, dorsal surface of femora and ventral surface of tibiae, all tarsus largely reddish brown. Wings semitransparent, pale brown; veins dark brown.

MALE. Body length 9.0–10.0 mm; fore wing length 9.0– 10.5 mm.

Structure as in female, but head in frontal view about 1.5 × as wide as high, eye strongly swollen laterally, inner eye margins about 1.4 × as further apart from each other at vertex as at clypeus ( Fig. 68 ); gena narrow, about 0.3 × as wide as eye in lateral view, with weakly raised blunt ridge running along posterior margin of eye; clypeus in frontal view about 1.2 × as wide as high ( Fig. 68 ), barely produced medioventrally, with apical margin very weakly and broadly rounded, in lateral view slightly convex dorsally, slightly bent backwards ventrally, and covered with dense short golden hairs; antennal scape short and thick, about 2.8 × as long as its maximum width; flagellum slender, flagellomere 1 as long as length of flagellomeres 2 and 3 combined, flagellomeres 2 and 3 each longer than wide; terminal flagellomere elongate, slightly curved, about 2 × as long as its basal width ( Fig. 69 ). Metasomal sternum 7 depressed medially ( Fig. 70 ), without tubercle ( Fig. 71 ).

Color. Similar to female, but with more abundant yellow markings as follows: clypeus entirely, mandible except for small black basal spot, ventral half of frons, narrow short band on gena along posterior margin of eye, antennal scape beneath, paired anterolateral spots on metanotum. Antennal flagellum reddish-brown to dark yellow beneath. Paired lateral yellow spots on propodeum much reduced in size.

Genitalia. Similar to that of Polistes reliciniclypeus sp. nov. except: the digitus distinctly swollen near base, narrowed in apical half ( Fig. 72 ); aedeagus with proxomoventral corner prominently produced proximally ( Figs 73, 74 ).

Nest. Although we were unable to collect the nest of this species, we saw frequent traffic of the wasps coming in and out through a small hole respectively of an electric meter and a window frame.

Remark. Among species of subgenus Polistella occurring in Vietnam, this species is most similar to Polistes dawnae , but it can be easily distinguished from the later by having the deeper median excavation of the propodeum, the metasomal tergum 1 with the anterodorsal corner between the anterior and dorsal faces more angulated, the second metasomal sternum in lateral view swollen ventrally in anterior half to two-third (one-third in P. dawnae ), the paired lateral yellow spots on propodeum small (large in P. dawnae ), and the male clypeus wider than high (as wide as high in P. dawnae ).

Etymology. The specific name, clandestinus , is a Latin adjective and refers to nesting of this species in a hidden place.

Figures

FIGURES 61 – 67. Polistes (Polistella) clandestinus sp. nov., Ƥ. 61. Ocelli, eye and posterior margin of vertex. 62 – 63. Head. 62. Frontal view. 63. Lateral view. 64. Right antenna. 65. Mesosoma, lateral view. 66. Jugal lobe of left hind wing. 67. Metasomal segments 1 and 2, lateral view. Scale 1 mm.

FIGURES 68 – 74. Polistes (Polistella) clandestinus sp. nov., 3. 68. Head, frontal view. 69. Left antenna. 70 – 71. Terminal sterna. 70. Ventral view. 71. Apical part, lateral view. 72. Inner aspect of paramere with digitus and volsella. 73 – 74. Aedeagus. 73. Ventral view. 74. Lateral view. Scale 1 mm.

FIGURES 27 – 33. Polistes (Polistella) reliciniclypeus sp. nov., Ƥ. 27 – 29. Head. 27. Frontal view. 28. Dorsal view. 29. Lateral view. 30. Left antenna. 31. Jugal lobe of left hind wing. 32. Mesosoma, lateral view. 33. Metasomal segments 1 and 2, lateral view. Scale 1 mm.