Polistes helveticus
| Polistes helveticus | ||||||||||||
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Polistes helveticus from Belgium on their nest |
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| Scientific name | ||||||||||||
| Polistes helveticus | ||||||||||||
| Neumeyer , 2014 |
Polistes helveticus is a hymenoptera from the family of the wasps (Vespidae) in the subfamily of the field wasps (Polistinae). The species was onlysplit offfrom the petite field wasp ( Polistes bischoffi )in 2014after differences had been recognized and examinations of body features and mitochondrial DNA confirmed that it was an independent species. The new description of this species led to the fact that most of the specimens designatedas Polistes bischoffi , especially in Central Europe, correctlyconcern Polistes helveticus . It was found that around 450 specimens were incorrectly labeled in Switzerland and that only fewer than 10 genuine Polistes bischoffi specimens could be found in collectionsuntil the new species was first described. In southern Europe this is the other way around. The specific epithet helveticus means “Swiss” and refers to Switzerland, wherethe oldest known specimen, a female, was discovered in1882 in Bätterkinden ( Canton Bern ).
features
It is a small species, dark in color compared to the other Polistes species, in which the second limb ( pedicellus ) and the flagellum of the antennae are black on the upper side in both sexes. This distinguishes the species from the Zierlichen Feldwesp ( Polistes bischoffi ), from which it was not distinguished as an independent species for a long time.
The females can be identified by their diminished or absent epicnemial suture on the thorax , the black hypopygium , the equally colored rear hips, the black mesoscutum , which only rarely has a pair of fine yellow spots, and the usually black propodeum on the side, which is rare on each side each has a yellow stain. The males can be identified by their cheeks, which are narrowed directly behind the compound eyes when viewed from above, and the yellow epicnemium and mesosternum. Polistes helveticus and P. bischoffi are the only two European Polistes species that often lack the epicnemial suture in females. Since these two species are easily distinguishable due to their different colors (especially the antennae), confusion with other Polistes species is hardly possible. Only in rare cases in which the epicnemial suture is well developed in females of P. helveticus can they be confused with females of the mountain wasp ( Polistes biglumis ). In this case, however, the two species can be easily distinguished by the ratio of the length of the lower face to the lateral distance between the ocelles.
female
Females have a body length of 9.7 to 14.1 millimeters and a fore wing length of 8.5 to 11.2 millimeters. The front plate ( clypeus ) is yellow with a black border and has a large black spot in the center, which is either isolated or more often as a transverse band reaches the side edges of the front plate. The face has an almost triangular yellow spot on the inside of the compound eyes , adjacent to them. There is a small elongated yellow spot on the upper part of the cheeks. The front bears a pair of horizontally running yellow stripes that seldom merge into one another.
On the mesosoma , the surface texture changes from coarse on the mesepisternum to smooth on the epicnemium, often evenly. The pronotum has a pair of longitudinal stripes on the rear edge that do not reach the transverse stripe on the collar of the pronotum. The scutellum and the metanotum each have a pair of yellow horizontal stripes. The propodeum usually has a pair of crescent-shaped spots on its back. On the mesopleuron there is a noticeable yellow spot on the otherwise largely black pronotum side. The propodeum is yellow on the sides. The tegulae are yellow in front and behind and have a rather transparent area in between. The legs are yellow and orange; they are black only on the hips ( coxes ), the thigh ring ( trochanter ) and large parts of the thighs ( femora ). In particular, the entire base of the legs is black.
On the metasoma , each tergum has a continuous yellow band at the rear, which is however slightly notched in black. There are also two yellow spots on the second tergum; only rarely are there two small yellow spots on the first tergum. On the second and third sternum , the yellow band on the posterior margin is usually, if often only very slightly, interrupted. On the third to fifth sternum the bandage is clearly interrupted and only developed as yellow spots on the side.
male
Males are 9.6 to 12.4 millimeters long and have a forewing length of 8.9 to 9.9 millimeters. With them, the mandibles, the area from their base to the underside of the compound eyes, the forehead plate, the face and the lower part of the frons are colored yellow. There is an elongated yellow spot on the upper part of the cheek. The upper part of the frons, the crown and the back of the head are black. On the lower, yellow part of the fron, at the anterior edge of the torulus, there is a small, dark area that is usually isolated but rarely reaches the anterior part of the top of the fron. The front plate is rounded apically and has almost no groove on the side.
On the mesosoma, the pronotum is yellow and has a horizontal stripe along the collar that occasionally extends down to the acute angle of the pronotum. The legs are yellow and orange, only the top of the hips, thigh rings and thighs are black. The black coloring occasionally extends to the lower thighs, the yellow coloring occasionally extends to the upper side of the hips of the front and middle legs. The rest of the mesosoma is colored the same as in the females.
On the metasoma, the yellow band at the back of the second tergum extends laterally to the base, but is partially interrupted. The other terga are colored like the females. Most specimens have two yellow spots on the second sternum. The back of the third to fifth sternum has a continuous yellow band; it is interrupted on the sixth sternum and absent on the hypopygium .
distribution and habitat
In comparison to Polistes bischoffi, Polistes helveticus is the species occurring in the north. Its distribution extends from eastern France and northern Italy via Switzerland, southern Germany, Liechtenstein and Austria to the Czech Republic and Slovakia. Of the two species, only a syntopic occurrence, i.e. colonization of the same habitats, is known from Switzerland . Sympatric , i.e. in the same geographical area, they also occur in Austria. Apart from that, the "new" distribution of Polistes bischoffi according to current knowledge only includes southern Europe to western Asia.
The species is widespread in Switzerland and usually inhabits moist habitats such as floodplains, swamps, moors and pits with gravel and sand. They have been detected from 200 meters above sea level in France to 980 meters above sea level in Muggio ( Canton Ticino , Switzerland).
Way of life
The nests are usually created on reeds, alders, willows and other plants below a height of 40 centimeters on vertical trunks with a diameter of two to three centimeters. The documented flight time for females ranges from the beginning of April in Switzerland to the end of November for Germany, but the main flight time is in July and August. Males were found in Germany on July 21 at the earliest; the latest find is from October 1st in Switzerland.
Individual evidence
- ↑ a b c d e f g h i j k Rainer Neumeyer, Hannes Baur, Gaston-Denis Guex, Christophe Praz: A new species of the paper wasp genus Polistes (Hymenoptera, Vespidae, Polistinae) in Europe revealed by morphometrics and molecular analyzes . ZooKeys 400, April 11, 2014, pp. 67-118, doi : 10.3897 / zookeys.400.6611 , accessed December 19, 2016.
