Torridincolidae
| Torridincolidae | ||||||||||||
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| Scientific name | ||||||||||||
| Torridincolidae | ||||||||||||
| Steffan , 1964 |
Torridincolidae is a family of beetles from the suborder Myxophaga . The animals feed on algae and blue-green algae and prefer to live on rocks that have been dampened by spray and covered with algae.
features
Beetle
The beetles have a body length of 1 to 2.7 millimeters. Their bodies are very dark or black in color, often with a metallic sheen. The convex body, also rounded on the sides, is relatively short and wide. However, there are also species (those of the subfamily Torridincolinae) with flattened bodies that have a distinct angle between the pronotum and the winged wing (Eltytren). The surface of the animals is either smooth or finely wrinkled. Some species have fine, upright hairs on the hair. The mouthparts on the strongly retracted head are directed forward (prognath). The distal part of the mouthparts is almost completely covered between the labrum and mentum . The labrum is exposed. The kidney-shaped compound eyes are large and protruding. The antennae are very short. They are nine segments , with the exception of the deleveinae , where they have 11 segments. The first two antennae ( scapus and pedicellus ) together form an urn-shaped structure. The segments of the antenna whip are slightly oblique and enlarge in diameter to the tip. The last link is thickened like a club. The pronotum is rounded at the side. The wings either have almost parallel lateral edges and clear grooves at the front or are rounded at the sides and have a smooth, fluffy surface (deleveinae). The hind wings are well developed and have an elongated, strongly receding anal field and a hem with a spiral surface structure along the entire edge. Only in Satonius kurosawai have the wings receded. The rails ( tibiae ) are long and slender, the tarsi are four-limbed, with the exception of the genus Delevea , in which they are five-limbed. The tarsi links closer to the body ( proximal ) are very short. Instead, the last two links in the tarsi are elongated. The claws are also relatively long. The abdomen has four or five visible sternites . The fourth is significantly shorter than the third and is completely covered in the genera Iapir and Claudiella . The ganglia of the first through eighth abdominal segments are all located in the thorax and are there contracted into a single mass. In some species, such as Iapir britskii , the males differ from the females ( sexual dimorphism ). Most species are identified at the species level using the genitals of the males.
larva
The larvae of all genera, with the exception of Incoltorrida , are known. The body of the larvae from the genus Delevea has almost parallel side edges and is almost cylindrical. The larvae of the genus Satonius are disc-shaped and strongly flattened. In some genera there are long hairs on the lateral edge of the tergites on the thorax, which are missing in Japir , Claudiella and Torridincola . The head is wider than it is long and has three or four ocelli on a conspicuous side elevation . The mouthparts are directed forward (prognath) or almost directed forward (subprognath). The back of the larvae is at least partially provided with scale-like structures with a sawn edge. The antennae have a short basal phalanx and an elongated distal segment. The area with the sensory cells is strongly regressed and flat, but is still clearly visible at the tip of the second segment. The semicircular thorax is about the same length as the abdomen and greatly enlarged. The first eight segments on the abdomen have long, pseudo-segmented tracheal gills that turn either laterally or laterally from the back (dorsolateral). The ninth sternite is well developed in the genus Selevea , otherwise regressed and triangular. The tenth segment is designed as a paired anal valve.
Doll
The so far known pupae are free (pupa libra), have no mandibles and can be recognized by a pair of tracheal gills, which are covered with a fine plastron mesh on each side of the first two abdomen gites. Pupation takes place within the last larval skin, from which only the tracheal gills protrude.
Occurrence and way of life
Both the larvae and the adults live completely aquatic and feed on algae or blue-green algae . The holotype and 16 paratypes of the first South American species of the family, Iapir britskii , were found when examining the stomach contents of a fish from the family of the true tetras (Characidae) that was caught in a stream in Rio de Janeiro (state) . Species of the genus Delevea live in temporary rivers, the species of the genus Satonius can be found in hygropetric habitats, such as on algae that grow on seeping water. The animals are generally found where water only wets stones a few millimeters, up to a maximum of two or three centimeters, such as in the spray zone of waterfalls or on fast-flowing mountain streams. Sometimes the adults can be found under tufts of vegetation or in detritus . As a rule, the beetles prefer very clean water, but Iapir britskii has also been found in a heavily polluted river near a small town in southern Brazil. In most species of Torridincolidae, the adults breathe through plastrons ; the larvae have elongated, segmented tracheal gills. The reproduction of beetles has only been little researched. We know that mating takes place in water, that the females only lay three to five eggs at a time and that the development from egg to imago in the species Ytu zeus takes a little less than four weeks. The adults do not swim, they only move around very slowly. In Central Africa, the beetles probably pollinate the flowers of Podostemaceaen , which grow on rocks in rapids or at waterfalls.
Taxonomy and systematics
The genus Delevea seems to be in a sister relationship to the other genera of the family, the genus Satonius is in such a relationship to the subfamily Torridincolinae. This means that the subfamily Deleveinae is paraphyletic . The group of the family without the genus Delevea is distinguished from the other beetle families by the special characteristics of the larvae. The monophyly of the subfamily Torridincolinae is supported by several autapomorphies , such as the broad dorsomedian keel on the head and the clear angle between pronotum and abdomen. The two genera Torridincola and Incoltorrida are related to the three Brazilian genera in a sister relationship.
So far, about 60 species in seven genera and two subfamilies are known:
- Deleveinae
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Torridincolinae
- Torridincola (southern and central Africa)
- Incoltorrida (Madagascar)
- Ytu (Southeast Brazil)
- Claudiella (Southeast Brazil)
- Iapir (Southeast Brazil)
supporting documents
Individual evidence
- ↑ a b c d e f Rolf G. Beutel, Richard AB Leschen: Handbuch der Zoologie - Coleoptera, Beetles, Volume 1: Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim) . 1st edition. de Gruyter , 2005, ISBN 3-11-017130-9 , p. 46 ff . (English).
- ↑ a b c d e Torridincolidae. Tree of Life webproject, accessed April 30, 2012 .
literature
- Rolf G. Beutel, Richard AB Leschen: Handbuch der Zoologie - Coleoptera, Beetles, Volume 1: Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim) . 1st edition. de Gruyter , 2005, ISBN 3-11-017130-9 (English).