Polistes

Kojima, Jun-Ichi, Saito, Fuki & Nguyen, Lien Thi Phuong, 2011, On the species-group taxa of Taiwanese social wasps (Hymenoptera: Vespidae) described and / or treated by J. Sonan, Zootaxa 2920, pp. 42-64 : 57-58

Key to currently valid Polistes species occurring in Taiwan

A total of 13 nominal species of the genus Polistes are recognized in the Taiwanese fauna. All of them but P. huisunensis Kuo, 1987 were recognized by Sonan. As noted above (see Polistes mandarinus var. eboshinus ) and also by Starr (1992), there seem to be a few more Polistes species (described and/or undescribed) occurring in Taiwan. The following key is primarily based on that of Starr (1992), and we added characters that would make the key to work only for valid species currently recorded from Taiwan. In other words, those that are not keyed out with this key would be new to Taiwan and/or undescribed species.

1. Pronotal fovea present. Clypeus not or barely produced above the anterior tentorial pit............................... 2

- Pronotal fovea absent. Clypeus dorsally produced far above the anterior tentorial pit. Dorsal mesepisternal groove and epicnemial carina absent. (Subgenus Polistella Ashmead)........................................................... 6

2. Punctures on mesepisternum fine, clathrate. Pronotal carina shortened, not lamellate below fovea. Prestigma of fore wing short, less than 0.5 × length of pterostigma (measured along ventral part), with straight tip. Dorsal mesepisternal groove and epicnemial carina present. Male clypeus weakly and broadly rounded apically, flattened medioventrally, with low ridges on both lateral margins of median flat area.......................................... P. (Polistes) chinensis (Fabricius)

- Punctures on mesepisternun coarse, larger than their interstices. Pronotal carina lamellate ventrad to fovea. Prestigma of fore wing distinctly more than half as long as length of pterostigma, with slightly recurved tip. (Subgenus Gyrostoma Kirby )... 3

3. Either dorsal mesepisternal groove or epicnemial carina absent. Body more or less uniformly reddish brown to dark brown, without yellow markings.............................................................................. 4

- Dorsal mesepisternal groove and epicnemial carina both present. Ground color of body black with abundant yellow markings. Male terminal sternum with paired apical apophyses......................................................... 5

4. Dorsal mesepisternal groove present; epicnemial carina absent. Gena not extremely developed; in profile of head, posterior margin of gena more or less smoothly and evenly curved, female gena about 1.3 times and male gena about 1.1 times as wide as eye. Malar space not very long, in female about 0.3 as long as antennal scape. Not extraordinarily large species; body length

(head + mesosoma + first two metasomal segments) usually less than 21 mm, fore wing length less than 22 mm ................................................................................. P. (Gyrostoma) tenebricosus Lepeletier - Dorsal mesepisternal groove absent, epicnemial carina present. Gena extremely developed, especially in male; in profile of head, female gena distinctly swollen posteriorly near level of eye top and about 1.4 times as wide as eye, and male gena about 3.5 times as wide as eye. Malar space long, in female about 0.4 of length of antennal scape. Extraordinarily large species; body length (head + mesosoma + first two metasomal segments) usually more than 23 mm, fore wing length more than 26 mm ................................................................................ P. (Gyrostoma) gigas (Kirby)

5. Anterolateral corner of propodeum hardly produced laterally. Female occipital carina evanescent ventrally, not reaching base of mandible. Male clypeus touching eyes. Male terminal antennal flagellomere slightly curved, not flattened. Male terminal sternal apophyses short and broad (see Starr, 1992: fig. 39a)................... P. (Gyrostoma) jokahamae Radoszkowski

- Anterolateral corner of propodeum rather strongly angled, produced laterally. Female occipital carina complete, reaching base of mandible. Male terminal antennal flagellomere spatulate. Male terminal sternal apophyses long and narrow (see Starr, 1992: fig. 39b)................................................................... P. (Gyrostoma) rothneyi Cameron

6. Second metasomal sternum evenly and weakly rounded, in lateral view gradually and weakly swollen toward its posterior margin, with ventral margin evenly and weakly curved ( Fig. 1 ).................................................... 7

- Second metasomal sternum more or less truncate basally, in lateral view ventral margin strongly swollen ventrally in anterior part, then becoming more or less parallel to ventral margin of second tergum ( Figs. 2–5 )............................ 10

7. Pronotum with strong transverse striae, without distinct punctures; dorsal and lateral face separated by distinct angle running back toward tegula. Body almost entirely reddish brown............................. P. (Polistella) strigosus Bequaert

- Pronotum covered with dense punctures, without distinct striae; dorsal surface smoothly curved down to lateral surface. Body more bright colored, with yellow markings................................................................. 8

8. Small species, body length (head + mesosoma + first two metasomal segments) less than 11 mm, fore wing length less than 12 mm. Fore wing with distinct dark spot anterodistally, occuying distal two-thirds of marginal cell and anterior parts of second and third submarginal cells. First metasomal tergum in lateral view not thick, lower than long; anterior truncation behind basal slit for reception of propodeal suspensory ligament indistinct......................... P. (Polistella) stigma (Fabricius)

- Medium-sized species, body length (head + mesosoma + first two metasomal segments) more than 13 mm, fore wing length more than 14 mm. Fore wing without distinct dark spot. First metasomal tergum in lateral view thick, about as high as long; anterior truncation behind basal slit for reception of propodeal suspensory ligament distinct ( Fig. 1 )................... 9

9. Female clypeus just below tentorial pits barely swollen anteriorly, with lateral margins in frontal view weakly convex (see Saito et al. 2007: fig. 2A,B), thus in lateral view passing into supraclypeal area smoothly or with very slight convexity (see Saito et al. 2007: fig. 2H). Male clypeus with suture for dorsolateral margin barely visible. Male terminal flagellomere proportionally shorter, about 2.8 times as long as its basal width (see Saito et al. 2007: fig. 2I). Furrow between metanotum and propodeum deep (see Saito et al. 2007: fig. 2K)................................... P. (Polistella) formosanus Sonan

- Female clypeus just below tentorial pits weakly swollen anteriorly, with lateral margins in frontal view convex (see Saito et al. 2007: fig. 2A,B), thus in lateral view with more or less distinct convexity in supraclypeal area. Male clypeus with suture for dorsolateral margin visible. Male terminal flagellomere proportionally longer, about 3.4 times as long as its basal width (see Saito et al. 2007: fig. 2J). Furrow between metanotum and propodeum shakkow (see Saito et al. 2007: fig. 2L) P. (Polistella) japonicus de Saussure

10. Female clypeus slightly higher (distance from bottom of dorsal emargination to apex) than wide (distance between upper points where clypeus touches eyes) ( Fig. 6 ). Female (often male) frons, vertex and mesoscutum substantially red- to reddishbrown-marked. Female mandible yellow. Second metasomal sternum in lateral view with ventral margin broadly rounded in anterior one-third to half of the segment ( Fig. 2 ). Female clypeus yellow. Propodeum with paired wide yellow bands...................................................................................... P. (Polistella) shirakii Sonan

- Female clypeus slightly wider than or as wide as high ( Figs 7–9 ). Frons, vertex and mesoscutum entirely black. Female mandible orange to reddish brown............................................................................ 11

11. Propodeum with paired wide yellow bands. Pronotum behind pronotal carina red with narrow yelow borders in front and behind. Female clypeus yellow to yellowish orange, with narrow dark band on each side. Second metasomal sternum in lateral view strongly swollen ventrally in anterior one-fifth to one-fourth of the segment ( Fig. 3 ).. P. (Polistella) takasagonus Sonan

- Propodeum except valvulae entirely black or with at most paired very short, slight yellow stripes. Pronotum behind pronotal carina not yellow marked. Female clypeus reddish brown..................................................... 12

12. Medium-sized, robust wasp; fore wing length 10–14 mm. Metanotum in lateral view at its front edge projecting up, not in continuous line with scutellum. Median excavation of propodeum shallow, but more or less defined laterally, wide, anteriorly wider than or as wide as posterior width of disk of metanotum. First metasomal tergum robust ( Fig. 4 ), slightly longer (distance in lateral view from posterior margin of basal slit for reception of propodeal suspensory ligament to the posterodosal end) than high (in lateral view hight at the posterior margin), about 1.2 times as wide (maximum width in dorsal view) as long; in lateral view basal truncation distinct. Second metasomal sternum in lateral view strongly swollen ventrally in anterior one-third of the segment, then ventral margin angulate ( Fig. 4 ). Male terminal flagellomere very long, about 3 times as long as its basal width (see Starr 1992: fig. 40j). Female gena mainly red, with continuous red band next to eye. Female cypeus relatively densely punctured ( Fig. 8 ), covered with short appressed tomentum in dorsal third to half. Male clypeus about as long as wide.................................................................................. P. (Polistella) huisunensis Kuo

- Small, medium-robust wasp; fore wing length 8–10 mm. Metanotum in lateral view at its front edge in continuous line with scutellum. Median excavation of propodeum shallow, ill-defined laterally, narrow, narrower than posterior width of disk of metanotum ( Fig. 10 ). First metasomal tergum not so robust ( Fig. 5 ), about 1.1 times longer than high, about 1.1 times as wide as long; in lateral view basal truncation not so distinct. Second metasomal sternum in lateral view swollen ventrally in about

Figures

FIGURES 1 – 10. Characters of Taiwanese Polistes species, Ƥ. 1. P. formosanus. 2, 6. P. s h ir a k i i. 3, 7. P. takasagonus. 4, 8. P. huisunensis. 5, 9 – 10. P. eboshinus. 1 – 5. First and second metasomal segments, lateral view. 6 – 9. Clypeus. 6. Indicating width (w) and height (h) of clypeus measured. 8 – 9. Showing punctures on right half. 10. Metanotum and propodeum, posterolateral view. Scale 2 mm for 1 – 5, 10; 1 mm for 6 – 9.