Mymarommatidae
| Mymarommatidae | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name of the superfamily | ||||||||||||
| Mymarommatoidea | ||||||||||||
| Debauche , 1948 | ||||||||||||
| Scientific name of the family | ||||||||||||
| Mymarommatidae | ||||||||||||
| Debauche , 1948 |
The Mymarommatidae are a peculiar family of tiny hymenoptera , probably with a parasitoid way of life in insect eggs. Vilhelmsen and Krogmann called it "possibly the most enigmatic wasp taxon". The approximately 15 species described are distributed worldwide. About as many species have been found as fossils in amber.
description
Mymarommatidae are tiny wasps between 0.3 and 0.8 millimeters in length. They are unmistakable through a number of morphological peculiarities. The head capsule of the animals consists of two separate parts, which are separated by a membranous interruption behind the mandibles . The rear part forms a vertical plate, the front part with the eyes is hemispherical. Both parts can be pulled apart like an accordion or pushed into one another. However, the latter is possibly an artifact that only occurs on dead animals. The mandibles of the animals are toothed on the outside, they gape so far apart that they cannot be closed in life. The other mouthparts are rudimentary and have no function. It is believed that these structures are used by living animals to free themselves from the egg shell. Due to the inflated head, the mandibles would be pressed tightly onto the shell, which they could cut open. On the head there are also complex eyes made up of five to about 55 relatively large ommatidia , point eyes ( ocelles ) may be present or absent. The antennae are kneeled (kinked behind the long basal segment) and in the female they are clearly widened towards the tip (culled). They consist of nine to eleven segments in the female and twelve or thirteen segments in the male. At the middle section ( mesosoma ) the pronotum is shortened and not visible from above. The metanotum is also reduced in size. The lateral sections of the middle segment, the metanotum and the propodeum are fused into one compact structure. The fore wings are oval shaped and clearly stalked, they are covered by short hairs (microtricha). Apparently they have no veins . On closer inspection, however, reinforcements are visible in the stalk-shaped basal section, which, with a little imagination, can be homologated with the typical wing veins of the Chalcidoidea (wasps). The hind wings are rudimentary and tiny, they consist only of a narrow and short lobe, which has two bristles arranged like a pincer at the end. This means that they are firmly connected to the forewings of the living animal. It is noticeable that the membrane of the wings is not continuous, but rather has a clearly networked structure when viewed under the microscope, such a form of formation is unique within the hymenoptera. The legs have as with the Legimmen widespread, a two-part leg ring (trochanter), so a seemingly extra leg link the Trochantellus on. The spurs on the rails ( tibia ) are reduced to a single one on the anterior tibia. In the Mymarommatidae the free abdomen sits on the mesosoma with a small stalk ( petiolus ), which clearly consists of two segments. This type of formation is also unique among the (recent) hymenoptera. The rest of the free abdomen (or gaster ) is covered by large and smooth tergites and sternites , which overlap in a scale-like manner. It consists of six segments. The ovipositor of the female is hidden in the abdomen when at rest. When using the abdomen, the tip of the abdomen is presumably spread apart and the ovipositor rotated; it is then not inserted backwards but on the stomach side.
distribution
The family is spread around the world. Evidence is also available from isolated oceanic islands, including the Hawaiian Islands and various sub-Antarctic archipelagos. Only one species is known in Europe: Mymaromma anomala . The species was also found in Germany.
Way of life
The way of life of the Mymarommatidae is unknown. There are no observations in live animals or evidence of stages of development of any species. This may not be surprising given the size of the animals. However, all investigators suspect that they develop as parasitoids inside insect eggs. Some researchers are trying to suggest, in some kind of circumstantial evidence, that the most likely hosts are eggs of dust lice (Psocoptera). The wasps are found in the summer months, the long observation period suggests the existence of several generations. The density of finds, which was at least initially very rare, is certainly largely due to the methodology. The best evidence is obtained with yellow pan traps , after which a species has even been named ( Mymaromma ypt , from English yellow pan trap).
Systematics
The Mymarommatidae are managed in their own superfamily, the Mymarommatoidea, due to their numerous morphological peculiarities. The first researchers and discoverers suspected that the animals belong to the Mymaridae (dwarf wasps), another family of tiny hymenoptera, which parasitize insect eggs. This has not been confirmed. The superfamily belongs to a line of development of the hymenoptera, which mainly includes species with very small body size, the Proctotrupomorpha . These groups, also called “microhymenoptera”, are very species-rich, but extremely poorly researched. Sister group of the Mymarommatoidea are most likely the ore wasps (Chalcidoidea). This grouping was established on the basis of morphological characteristics, it is also supported by molecular studies.
The taxonomy of the Mymarommatidae was until the monograph by Gibson et al. confused. All recent species were sorted into the genus Palaeomymar , which was established on the basis of a fossil species.
Today the following genera are recognized:
- Mymaromma ,
- Mymaromella ,
- Zealoromma , 2 species from New Zealand
Fossil record
Fossil Mymarommatidae are relatively numerous, exclusively as inclusions (inclusions) in amber. There is evidence from almost all significant amber deposits. Many finds were published only after 2000. The family has existed at least since the Cretaceous . Some of the Cretaceous finds are assigned to an extinct second family (genus Galloromma , family Gallorommatidae). The position to the Serphitidae , another extinct family, is problematic . The Serphitidae were mostly considerably larger with rich wing veins, but they were the only other group to have a two-segment petiolus. While earlier investigators considered a connection to be very speculative and viewed this feature as a possible homoplasia , fossils have now been found that can be easily interpreted as possible transitional forms. It is possible that the Serphitidae are the parent group of the Mymarommatidae. If this is confirmed, the then common superfamily would have to be called Serphitoidea for reasons of priority.
supporting documents
Individual evidence
- ↑ Lars Vilhelmsen & Lars Krogmann (2006): Skeletal Anatomy of the Mesosoma of Palaeomymar anomalum (Blood & Kryger, 1922) (Hymenoptera: Mymarommatidae). Journal of hymenoptera research Vol. 15 (2): 290-306.
- ^ S. Vidal (2001): Chalcidoidea. In: Dathe, HH, Taeger, A. & Blank, SM (Ed.): Directory of the Hymenoptera of Germany (Entomofauna Germanica 4). Entomological News and Reports (Dresden), Supplement 7: 51-69.
- ^ Checklist of German Chalcidoidea
- ↑ Jonn T. Huber, Gary AP Gibson, Leah S. Bauer, Houping Liu, Michael Gates (2008): The Genus Mymaromella (Hymenoptera: Mymarommatidae) in North America, with a Key to Described Extant Species. Journal of Hymenoptera Research Vol. 17 (2): 175-194.
- ↑ SV Triapitsyn and VV Berezovskiy (2006): A new species of the genus Palaeomymar Meunier, 1901 (Hymenoptera: mymarommatidae) from the Russian far east, with notes on other species lpalaerarctic. Far Eastern Entomologist 159: 1-8.
- ^ Gary AP Gibson (1986): Evidence for monophyly and relationships of Chalcidoidea, Mymaridae and Mymarommatidae (Hymenoptera, Terebrantes). Canadian Entomologist 118: 205-240.
- ↑ James B. Munro, John M. Heraty, Roger A. Burks, David Hawks, Jason Mottern, Astrid Cruaud, Jean-Yves Rasplus, Petr Jansta (2011): A Molecular Phylogeny of the Chalcidoidea (Hymenoptera). PloS One 6 (11): e27023. doi : 10.1371 / journal.pone.0027023
- ↑ Jaime Ortega-Blanco, Xavier Delclòs, Enrique Peñalver, Michael S. Engel (2011): Serphitid wasps in Early Cretaceous amber from Spain (Hymenoptera: Serphitidae). Cretaceous Research 32: 143-154. doi : 10.1016 / j.cretres.2010.11.004
literature
- Gary AP Gibson, Jennifer Read, John T Huber (2007): Diversity, Classification and Higher Relationships of Mymarommatoidea (Hymenoptera). Journal of Hymenoptera Research 16: 51-146. download (PDF; 28.9 MB)