Stephanidae
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| Leach , 1815 |
The Stephanidae , sometimes also called crown wasps (from the Greek Stephanos (στέϕανος) for crown) are a family of hymenoptera . They are considered the most original group of the Waist Wasps (Apocrita) and as a sister group of all other Waist Wasps combined. With the Orussidae among the Symphyta they have some interesting similarities in way of life and body structure, which allow conclusions to be drawn about the evolutionary development of the waist wasps. The family has almost 350 species, three of which have been found in Europe and one in Germany.
features
They are mostly relatively large, parasitoid hymenoptera (" Legimmen ") with a number of special features in their physique that make them almost unmistakable. The always elongated and graceful body is mostly black in color, often with white and yellow drawing elements, but there are also dark brown or yellowish-straw-colored species. The rather large and almost round head can be moved in almost all directions. Two large complex eyes and three point eyes (ocelles) sit on it , the middle of which is usually surrounded by five thorn-like elevations. This structure reminded the descriptor of a crown (naming). The long and thread-like antennae have between 23 and 44 segments and are deflected at the upper edge of the clypeus , approximately at the level of the lower edge of the complex eyes. The basal flagellum limbs are much longer than the distal ones. The labrum and especially the mandibles are noticeably large and directed forward.
The structure of the pronotum is characteristic . This is broad at the back and elongated triangular towards the front into a "neck", at the tip of which the broader head rests. The "neck" region is always wrinkled and often has transverse ridges or keels, which are important for differentiating the species. The last pair of legs has noticeable peculiarities. The hind legs are strongly thickened and almost always have thorn-like teeth on the underside (three in S. serrator), the splint (tibia) is flattened at the base, thickened distally and with a slot-shaped pit on the outside. The modification serves as a carrier of a sensory organ, the subgenual organ, which occurs in many insects, but is particularly well developed in the Stephanidae. This subgenual organ serves as a vibration and shock sensor. The wing veins are quite diverse within the family and range from species with numerous veins and cells in the forewing to strongly reduced formations. As with all Apocrita , the first abdominal segment is fused as the propodeum with the metathorax , the propodeum of the Stephanidae has slit-shaped, modified stigmas . The second abdominal segment is drawn out into a noticeably long and thin stalk, at the tip of which the wider remaining abdomen ( metasoma ) is attached. The stem can be more than 20 times as long as it is wide. It sits on the middle section of the body ( mesosoma , ie thorax plus propodeum) above the rear hips, which means that the animals can resemble hunger wasps (Evaniidae); earlier they were often placed in their relatives. The females carry a long and slender ovipositor at the rear end of the abdomen, which protrudes just above the end of the abdomen when at rest. The ovipositor is at least body length, it can exceed the body length in some species several times. The largest species of the genus Megischus are around 75 millimeters long, including the ovipositor . The ovipositor, especially its tip, is specially hardened by the inclusion of zinc (not manganese , as with the real parasitic wasps) in order to enable drilling through wood. The stalk-shaped basal segment of the metasoma is stretched upwards during the act of lancing in order to be able to position the long ovens in the correct position on the surface.
Way of life
The larvae of the Stephanidae are parasitoids of insect larvae living in wood. In most of the known cases, their hosts are beetle larvae, especially jewel beetles and longhorn beetles . However, some species also show larvae of wood wasps . In the few species whose biology is somewhat better known (mostly from North America), the host specificity is low; a large number of hosts with a corresponding lifestyle are accepted for each species. The females look for suitable hosts by running around on the wooden surface. A suitable host is apparently recognized exclusively by the noises and vibrations of the wood that occur when the host larvae eat and that are perceived by the subgenual organs. The female drills its ovipositor at a suitable point through the wood to the host larva, which it covers with an egg. The hatching stephanid larva eats from the outside of the host larva (ectoparasitoid) within the feeding duct in the wood. In the last larval stage, the host larva is killed, pupation takes place deep in the wood without a shell or web. Only the hatching imago eats its way down a long passage from here to the surface of the wood; for this purpose, its mandibles have been redesigned and also hardened by the storage of heavy metals.
distribution
Most species in the family live in tropical and subtropical forests. The greatest biodiversity was found in tropical East Asia. Species are also known from dry to almost desert-like habitats, e.g. B. from Saudi Arabia and the United Emirates. The largest species, with a body length of a good 18 mm without ovules, live in Australia and New Caledonia. The family quickly becomes rarer towards the north. Three species live in Europe, two of them in the eastern Mediterranean. It reaches Central Europe with a single species, Stephanus serrator , which is also found in Germany and Austria. The species flies in summer (June to September) and is most likely to be found on dead wood, although stacked logs or fence posts are sufficient. It is seldom seen on flowers, it is unclear whether the imago consumes food at all. Observed females needed about an hour and a half to drill a hole in the wood.
Virtually all types of the family are considered very rare. Of most of the tropical species only a single specimen (the type specimen) has become known. There are indications that the rarity is at least partly due to the method, because the animals can only very rarely be caught using the standard detection methods for hymenoptera.
Systematics
The Stephanidae are characterized by numerous morphological peculiarities and are isolated within the hymenoptera so that they are the only family ( monotypically ) placed in their own superfamily Stephanoidea. The Stephanoidea are considered the most original line of development within the Waist Wasps. This positioning is mainly based on morphological findings and is only weakly supported by molecular family trees (which at least do not contradict it). The similarities in the way of life with the Orussidae , which are considered to be the closest relatives of the waist wasps among the "Symphyta", are striking. The families also agree in some morphological features, most notably in the eponymous "crown" of five thorns that surround the central ocellus on the vertex. If this family group can be confirmed, it would make the emergence of the waist wasps from ectoparasitoids of wood-dwelling beetle larvae highly probable. The morphology of the Stephanidae larvae has hardly been studied so far. In particular, it is unknown whether they, like all waist wasps, have a closed intestine up to the last larval stage.
The relationships within the family have not been finally clarified. A number of subfamilies are suggested, but other researchers dispute their justification. It is possible that some large genera such as Foenatopus are paraphyletic ("collective groups" for species that could not be accommodated elsewhere). A number of species described at the beginning of the 20th century were later synonymous. At the same time, many new species are still being described every year.
Aguiar (2004) provides an overview of the worldwide species population. Most of the Palearctic species were listed, described and illustrated by van Achterberg (2002).
Fossil record
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The oldest Stephanidae fossil comes from the Middle Cretaceous and was found as an inclusion in amber from New Jersey. Other fossil finds are also from Baltic amber .
Web links
Individual evidence
- ↑ Vilhelmsen, L., Turrisi, GF, Beutel, RG (2008): Distal leg morphology, subgenual organs and host detection in Stephanidae (Insecta, Hymenoptera). Journal of Natural History 42: pp. 1649-1663
- ↑ DLJ Quicke, P. Wyeth, JD Fawke, HH Basibuyuk, JFV Vincent (1998): Manganese and zinc in the ovipositors and mandibles of hymenopterous insects. Zoological Journal of the Linnean Society 124: pp. 387-396. doi : 10.1111 / j.1096-3642.1998.tb00583.x
- ↑ Alexandre P. Aguiar & John T. Jennings (2010): Order Hymenoptera, family Stephanidae. In: Arthropod fauna of the UAE, 3: pp. 299-305.
- ↑ Alexandre P. Aguiar & John T. Jennings (2005): First record of Stephanidae (Hymenoptera) from New Caledonia, with descriptions of four new species of Parastephanellus Enderlein. Zootaxa 1001: pp. 1-16.
- ↑ Jacek Hilszczanski (2011): New data on the occurrence of Stephanids (Hymenoptera, Stephanidae) in Turkey and Greece. Opole Scientific Society Nature Journal 44: pp. 192-196
- ↑ Alois Kofler (2008): The crown wasp, a very rare insect (Hymenoptera: Stephanus serrator). East Tyrolean Heimatblätter 7 (2/3)
- ↑ Ulrike Hausl-Hofstätter (2003): Stephanus serrator (F.) - a rare hymenoptera from Styria (Hymenoptera, Stephanidae). Joannea Zoologie 5: pp. 29-34
- ↑ Joachim Oehlke (1984): Contributions to the insect fauna of the GDR: Hymenoptera - Evanioidea, Stephanoidea, Trigonalyidea. Faunistic treatises (State Museum for Animal Science in Dresden) 11 (13): pp. 161–190.
- ↑ Ewald Jansen, Ulrich Bense, Klaus Schrameyer (1988): Stephanus serrator (Fabricius, 1798) in the Federal Republic of Germany (Hymenoptera, Stephanidae). Entomofauna 9 (22): pp. 421-425.
- ↑ L. Vilhelmsen (2001): Phylogeny and classification of the extant basal lineages of the Hymenoptera (Insecta). Zoological Journal of the Linnean Society 131 (4): pp. 393-442.
- ↑ Michael J. Sharkey, James M. Carpenter, Lars Vilhelmsen, John Heraty, Johan Liljeblad, Ashley PG Dowling, Susanne Schulmeister, Debra Murray, Andrew R. Deans, Fredrik Ronquist, Lars Krogmann, Ward C. Wheeler (2012): Phylogenetic relationships among superfamilies of Hymenoptera. Cladistics 28 (2012) 80-112. doi : 10.1111 / j.1096-0031.2011.00366.x
- ↑ Alexander P. Aguiar (2004): World catalog of the Stephanidae (Hymenoptera: Stephanoidea). Zootaxa 753.120 pp.
- ^ C. van Achterberg (2002): A revision of the Old World species of Megischus Brullé, Stephanus Jurine and Pseudomegischus gen. Nov., With a key to the genera of the family Stephanidae (Hymenoptera: Stephanoidea). Zoogische Verhandelingen Leiden 339: pp. 3–206.
- ↑ Michael S. Engel and David A. Grimaldi (2004): The First Mesozoic Stephanid Wasp (Hymenoptera: Stephanidae). Journal of Paleontology 78 (6): 1192-1197.
- ↑ Michael S. Engel & Jaime Ortega-Blanco (2008): The fossil crown wasp Electrostephanus petiolatus Brues in Baltic Amber (Hymenoptera, Stephanidae): designation of a neotype, revised classification, and a key to amber Stephanidae. ZooKeys 4: pp. 55-64. doi : 10.3897 / zookeys.4.49 .