Research Article |
Corresponding author: Niklas Johansson ( chrysis32@yahoo.se ) Academic editor: Andreas Köhler
© 2016 Niklas Johansson, Cornelis van Achterberg.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Johansson N, Achterberg C van (2016) Revision of the Palaearctic Gasteruption assectator aggregate, with special reference to Sweden (Hymenoptera, Gasteruptiidae). ZooKeys 615: 73-94. https://doi.org/10.3897/zookeys.615.8857
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The Palaearctic species of the Gasteruption assectator aggregate (Hymenoptera, Gasteruptiidae) are revised and three species are recognised. Two species are re-instated: Gasteruption boreale (Thomson, 1883), stat. n. and G. nigritarse (Thomson, 1883), stat. n., and both are excluded from the synonymy with G. assectator (Linnaeus, 1758). The general distribution of both species is given for Europe and in detail for Sweden. A key to the valid Palaearctic species of the Gasteruption assectator aggregate is given; key characters and primary types are illustrated. Four new synonyms are listed: Foenus fumipennis Thomson, 1883, Trichofoenus breviterebrae Watanabe, 1934, and Gasteruption margotae Madl, 1987, are synonymized with Gasteruption boreale (Thomson, 1883) and Gasteruption brevicauda Kieffer, 1904, with G. undulatum (Abeille de Perrin, 1879).
Europe, Gasteruption boreale , Gasteruption nigritarse , key, new records, re-instated species, Sweden, synonyms
The predator inquiline wasp Gasteruption assectator (Linnaeus, 1758) (Hymenoptera, Gasteruptiidae) has been considered a very common species with wide intraspecific variation concerning both morphology and colouration (e.g. van
The first author studied specimens of the Gasteruption assectator aggregate deposited in the Evolutionsmuseet, Uppsala; The Swedish Malaise Trap Project (SMTP); the Biologiska Museet (
Ichneumon
assectator
Linnaeus, 1758: 566,
Foenus
assectator
;
Foenus
affectator
;
Gasteruption
assectator
;
Gasteruption
affectator
;
Ichneumon
annularis
Geoffroy in
High resolution photos of the lectotype female of G. assectator in the Linnaean collection coll. no 2652- “49 assectator” (Figs
Sweden (Skåne: Åhus, Blekinge; Halland: Breared; Småland: Repperda, Bäckebo, Hälleskog, Tvärskog, Robacken, Igersdela, Skillingaryd, Södra Vi, Korsberga; Gotland: Ardre, Stora Karlsö, Fårö, Mullvalds; Öland: Halltorp, Ekerum, Glömminge; Östergötland: Simonstorp, Borensberg)
Temples in dorsal view less parallel-sided and usually shorter than of G. boreale, head in dorsal view transverse, mostly distinctly wider than long. Occipital carina indistinct and not reflexed. Face mostly slightly narrower than that of G. boreale. Hypostomal bridge narrow, at most 0.5 times mandibular base (Fig.
G. assectator is the most widespread and common species of the assectator aggregate in Europe. Towards its northern distribution limits in northern Scandinavia it seems to be confined to coastal areas with more favorable climate than inland areas.
Gasteruption assectator occurs in a wide variety of habitats, varying from agricultural landscapes to deciduous forests and gardens. Most probably Hylaeus spp. are used as hosts.
Foenus
borealis
Thomson, 1883: 849;
Gasteruption
boreale
;
Foenus
fumipennis
Thomson, 1883: 848;
Trichofoenus
breviterebrae
Watanabe, 1934: 285;
Gasteruption
margotae
Madl, 1987c: 225–227,
In Thomsons collection in
The type series of Gasteruption fumipenne consists of the lectotype from Gotland. The size, habitus, antennae and smooth sculpture on the mesoscutum of the lectotype (Figs
The type series of G. margotae consists of the male holotype (Figs
The examined type series of G. breviterebrae (Fig.
Sweden (Småland: Bäckebo, Skillingaryd, Ränneslätt, Jönköping; Västergötland: Baskarp; Södermanland: Huddinge; Uppland: Rossholm; Dalarna: Leksand, Ludvika; Hälsingland: Hornslandet; Västerbotten: Vindeln, Hällnäs; Lycksele lappmark: Gällivare); Finland (Åland: Hammarland; Åbo: Harvaluoto).
Head in dorsal view almost parallel-sided behind eyes, elongate, about as wide as long (Figs
Female. Length of body 6–11 mm (fore wing 3.5–5.5 mm)
Head. Temples parallel-sided behind eyes in dorsal view. Occipital carina not raised. Frons and vertex with satin sheen. Malar space short, at most about 0.5 times mandibular base. Hypostomal bridge narrow, at most 0.5 times mandibular base. Eyes with dense white pubescence. Antenna short; sixth segment about 1.5 times longer than wide and subapical segment about 1.2 times longer than wide.
Mesosoma. Surface largely smooth with satin sheen, mesoscutal sculpture of almost equal intensity as on vertex. Antesternal carina narrow, non-lamelliform. Pronotal sides with very small pointed teeth antero-ventrally, but these are sometimes entirely absent. Upper half of mesopleuron mostly considerably weaker sculptured than its more rugose lower part.
Legs. Hind tibia stout as in G. assectator. Hind coxa often with weaker rugae apically than on basal half, dissolving amidst rugose background. Hind tibial spurs often brighter than hind tibia.
Metasoma. Ovipositor sheath entirely black or brown, 0.7–1.0 times as long as hind tibia, its apical half entirely with stout, black bristles angled backwards at about 45° (Fig.
Colour. Black. Mandible apically, hind tibial spurs and patches laterally on tergites 2–4 reddish brown. Patches rarely intercepted. Fore and middle tibiae mostly with indistinct yellow or ivory basal patch. Inner side of tibiae often orange. Basal ivory ring of hind tibia usually indistinct.
As Thomson’s name implies this species is most common in boreo-alpine areas. In northern Europe it is quite widespread and common at higher latitudes and high altitude sites in the southern part, but becoming scarcer towards the southern lowlands in Sweden. Specimens are examined from Austria, Bulgaria, Finland, Germany, Netherlands (den Dolder, de Bilt, Tilburg, Wageningen, Groesbeek, Rhenen, Velp, Maastricht, Drimmelen, Rotterdam, Voerendaal), Norway, Russia, Serbia and Sweden.
The species occur in (boreal) landscapes dominated by coniferous forests where it can be locally common. Many of the sites in Scandinavia are at high altitude. G. boreale is lacking from more open localities as well as in regions dominated by deciduous forests. It has been observed searching high stumps of Pinus trees and it also attends old wooden walls and artificial bee nests in gardens. Probably it is a kleptoparasitoid of Hylaeus spp.
Foenus
nigritarsis
Thomson, 1883: 849;
Gasteruption
nigritarse
;
Lectotype female (Figs
Sweden (Småland: Bäckebo; Skåne; Halland; Östergötland: Svensksund; Uppland: Grisslehamn, Svartsjö, Roslagsbro, Skansen; Öland: Borgehage, Himmelsberga).
Head dorsally more parallel-sided than in G. assectator, elongate and about as wide as long. Occipital carina indistinct and not reflexed. Mesoscutum superficially reticulate and (especially laterally) rugose, medio-posteriorly in front of scutellum more rugose-reticulate. Mesosoma laterally and face with long, thick golden pubescence. Hind tibia and basitarsus darker, often with the basal ring lacking or interrupted. Fore and middle tibiae often with large distinct ivory patch covering about one third of tibia. Metasoma mainly black with well-defined orange lateral patches on tergites 2–5 which might be partially reduced, especially in northern specimens. Ovipositor sheath entirely black or brown, 0.7–1.0 times as long as hind tibia and its apical half dorsally with stout, black bristles angled backwards at about 45°. The bristles are all conspicuously widened and bent apically, reminiscent of “velcro” (Fig.
Female. Length of body 8–11 mm (fore wing 4.0–5.5 mm)
Head. Temples parallel-sided behind eyes in dorsal view. Occipital carina not raised. Frons and vertex with satin sheen. Malar space short, at most about 0.5 times mandibular base. Hypostomal bridge at least 0.7 times width of mandibular base, medio-laterally often with distinct transverse striae. Face covered with dense golden pubescence.
Mesosoma. Surface vaguely reticulate and strongly shagreened. Antesternal carina narrow and non-lamelliform. Pronotal sides with very small pointed teeth antero-ventrally, but these are sometimes entirely absent.
Legs. Hind tibia rather stout as in G. assectator. Hind tibial spurs and hind tibia mostly similarly coloured.
Metasoma. Ovipositor sheath entirely black or brown, 0.7–1.0 times as long as hind tibia, its apical half dorsally with stout, black bristles angled backwards at about 45° and conspicuously widened and bent backwards apically.
Colour. Black. Mandible apically orange. Sometimes small patch on hind tibia baso-ventrally white or ivory. Northern specimens of both sexes often with entirely black hind tibia. Fore and middle tibiae often with large distinct ivory patch covering about one third of tibia. Fore, middle and hind tarsus black. Patches laterally on tergites 2–5 reddish brown. Last sternite apically often extensively orange. Colour of hind tibial spurs variable, mostly black or dark brown.
Gasteruption nigritarse is a rather rare locally but widespread species in Europe. Specimens examined from Austria, Germany, Czech Republic, Netherlands (Breda, Waalwijk, Putten (GE), Maastricht, Wageningen, Rhenen, Arnhem), Serbia, Sweden and Turkey.
The species primarily occur in small-scale agricultural landscapes where it is to be found especially on walls of log barns (Fig.
1 | Females (ovipositor present) | 2 |
– | Males (ovipositor absent) | 4 |
2 | Hypostomal bridge 0.7–0.8 times as wide as mandibular base and weakly striate medio-laterally (Figs |
G. nigritarse (Thomson, 1883), stat. rev. |
– | Hypostomal bridge narrow, at most 0.5 times as wide as mandibular base and without striation medio-laterally (Fig. |
3 |
3 | Mesoscutum and coxae more opaque, less rugose, smoother and with satin sheen (Figs |
G. boreale (Thomson, 1883), stat. rev. |
– | Mesoscutum and coxae more shiny and rugose, with a “fatty” gloss (Fig. |
G. assectator (Linnaeus, 1758) |
4 | Hypostomal bridge 0.7–0.8 times as wide as width of mandibular base and weakly striate medio-laterally (Figs |
G. nigritarse (Thomson, 1883), stat. rev. |
– | Hypostomal bridge narrow, at most 0.5 times width of mandibular base and without striation medio-laterally (Fig. |
5 |
5 | Mesoscutum and upper half of mesopleuron rather smooth with small puncture-like grooves and with satin sheen almost of the same intensity as vertex (Figs |
G. boreale ( |
– | Mesoscutum more roughly reticulate-coriaceus, especially near the sides of mesoscutum, visible even at lower magnifications (Fig. |
G. assectator (Linnaeus, 1758) |
We are grateful for the contributions of the following persons: Agnièle Touret-Alby (