Opilioacaridae
| Opilioacaridae | ||||||||||||
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Opilioacaridae |
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| Systematics | ||||||||||||
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| Scientific name of the order | ||||||||||||
| Opilioacarida | ||||||||||||
| With , 1902 | ||||||||||||
| Scientific name of the family | ||||||||||||
| Opilioacaridae | ||||||||||||
| With , 1902 |
The Opilioacaridae are a family of mites with a primeval physique, which are placed in their own order Opilioacarida (synonym: Notostigmata, Opilioacariformes). The family comprises six genera with about 20 known species.
features
They are soft-skinned mites about 1 to 2.5 mm long (without legs). On superficial examination, they resemble small harvestmen (Opiliones), which is also what the name refers to. When viewed from above (dorsal), the body is indistinctly divided into prosoma and opisthosoma , the prodorsum forms a plate that appears constricted. The segmentation of the opisthosoma is clearly recognizable by furrows in the body surface and by drawing. The opisthosoma consists of 12 segments (plus an anal tubercle, the segmental nature of which is ambiguous). The segmental nature, however, does not show in the cuticle , which is continuous and smooth and not divided into plates ( sclerite ). It is flexible, but very sturdy. On the side of the prosoma there are two pairs of eyes, and in the case of one genus (and one species known only in fossil form) three pairs of eyes, each forming a closely spaced group. The front part of the body, the gnathosoma , carries the mouthparts , has two long three-part chelicerae that end in real scissors (chela). The hips ( coxae ) of the feelers ( pedipalps ) form chewing mouthparts. On the side of the head there are very much enlarged and transformed, conspicuous bristles, which are referred to as rutellum. On the rest of the body there are numerous, sometimes spatulate, broadened bristles, the position and formation of which, as is usual with mites, are of high taxonomic value. The legs and buttons are elongated, the palps consist of six, the legs of seven segments. The first pair of legs is greatly elongated, it is not used for running, but serves as a sensory organ. At the top of the legs there are two claws and an adhesive pad.
When alive, the animals are clearly drawn in color, often with ringed legs, with green and blue tones being common, the basic color is more yellowish or brown. The color is only partially due to pigments in the cuticle; more important are pigment granules in the underlying tissue.
Female Opilioacaridae carry a short ovipositor (laying tube).
development
Opilioacarida develop with a total of five pre-imaginal stages. A prelarva hatches from the egg and transforms into a larva, both with six legs. The following stages, called proto-, deuto- and tritonymphs, have eight legs like the adults .
ecology
The animals have a relatively unspecialized diet, with only solid food being consumed. There is little evidence for a predator diet. A saprophage diet, especially of dead arthropods, seems to be particularly important . In addition, the animals take in a lot of pollen as food, at least at times .
Opilioacaridae can only be found very rarely and sporadically in their habitats. Most of the animals were found turning over stones, they are probably nocturnal and can be found walking around at night on the ground or in the vegetation. Opilioacaridae live exclusively in warm regions of the tropics and subtropics, mostly in quite dry (arid) habitats.
distribution
The animals are probably distributed worldwide in tropical and subtropical latitudes, whereby the range of the individual species can be quite small. Most of the species are known from the southern Mediterranean region, e.g. B. also from southern Italy. In America two genera are common, south to Argentina, north to the desert belt of the USA. Only one species has been described from Australia so far.
Systematics
The position of the Opilioacaridae in the system of arachnids has long been controversial. The animals have primarily anatomically primitive ( plesiomorphic ) features that are common in other subclasses of arachnids, but remain limited to this one group in the case of mites. Traditionally, they were placed as an independent lineage between the two large parent groups Acariformes (or Actinotrichida) and Parasitiformes (or Anactinotrichida). In the meantime, their inclusion in the Parasitiformes has established itself. They form the most basic branch in the system with all other Parasitiformes as a sister group.
Within the family Opilioacaridae, the following genera are distinguished:
- Opilioacarus (most species-rich genus, Eurasian)
- Neoacarus (in America), often considered a subgenus of Opilioacarus .
- Panchaetes
- Paracarus (only recent genus with six eyes)
- Adenacarus
- Caribeacarus
literature
- Jason A. Dunlop, Gerd Alberti: The affinities of mites and ticks: a review. In: Journal of Zoological Systematics and Evolutionary Research. Vol. 46, No. 1, 2007, pp. 1-18, doi : 10.1111 / j.1439-0469.2007.00429.x .
- Leendert van der Hammen: Studies on Opilioacarida (Arachnida). Volume 1: Description of Opilioacarus texanus (Chamberlin & Mulaik) and revised classification of the genera (= Zoologische Verhandelingen. Vol. 86, No. 1, ISSN 0024-1652 ). Brill, Leiden 1966.
- Manfred Moritz: subordination Opilioacarida. In: Alfred Kaestner (founder): Textbook of special zoology. Volume 1: Hans-Eckhard Gruner (Ed.): Invertebrates. Part 4: Hans-Eckhard-Gruner, Manfred Moritz, Wolfram Dunger: Arthropoda (without Insecta). 4th, completely revised and greatly expanded edition. Gustav Fischer, Stuttgart 1993, ISBN 3-334-60404-7 , p. 340 ff.
- Magdalene Vazquez, Hans Klompen: New species of New World Opilioacaridae (Acari: Parasitiformes) with the description of a new genus from the Caribbean region. In: Zootaxa . 2061, 2009, pp. 23-44.