Archostemata
Tenomerga mucida from the family of Cupedidae
The subordination of Archostemata with only five families and currently 40 known species, a very small sub- order of the beetles ( Coleoptera).
Features
The medium sized beetles reach a body length of 5-26 mm and a width of two to nine millimeters. Exceptions to represent Micromalthus debilis and Crowsoniella relicta, which are much smaller and only about 1.5 millimeters wide. The coloration of the body goes from light gray to brown to black. The Notopleuralnaht on prothorax is visible, the cervical sclerites between the head and prothorax missing. All species except the two mentioned above are only partially sclerotized elytra. They are fully sclerotized only at the nine longitudinal veins and the front and rear end. The longitudinal wires are connected by numerous cross- veins. The space within these veins is thin and transparent. The body of the beetle is again in all species, with the exception of the two types mentioned above is covered with scales, which form colored patterns with some species. The eleven-membered antennae are thread-like ( filiform ) or beaded ( moniliform ). In some species they are only as long as the head, in others they reach nearly the length of the body. With the exception of the two types mentioned above is the Prementum a sclerite the labium, enlarged and has a center and a specialized Apodem muscles. The Prementum works in these species as a flap that closes the mouth opening and covers the maxillary and labial praise. The shape of the latter suggests that the beetles feed on pollen and plant juices. The mandibles are usually designed to be very strong and have sharp, vertically or horizontally aligned cutting surfaces.
When the larvae of Archostemata following autapomorphies occur: The head capsule of the larva has the back and abdominal side posteromediane dents, their mandibles carry three apical teeth, the Cardo of maxilla also has a side part, the wedge-shaped ligule on the labium is enlarged from the second instar larvae are formed on the abdomen end ampullae and the tenth abdominal segment is much reduced form. The adults are distinguished from the other groups of beetles by the shape of Prementums and a large, rounded dorso -lateral bump on Basalare, a sclerite on Episternum.
Occurrence
Representatives of this suborder are detected from South America ( Cupedidae, Ommatidae ), North America ( Cupedidae, Miromalthidae ), Europe ( Crowsoniellidae ), Asia ( Cupedidae, Jurodidae ) and Australia ( Cupedidae, Ommatidae ).
Fossil evidence
Fossil representatives of this group are detected from the Lopingium (Upper Permian). However, they are not closely related with the known from the Cisuralium (Lower Permian) genera, such as Tshekardocoleus. Groups such as Protocoleoptera, Permocupedidae, Rhombocoleidae and Triadocupedidae are among the most primitive members of the order of beetles, but all are already extinct at the beginning of the Triassic up to the latter; the Triadocupedidae survived until the beginning of the Jurassic. According to the latest findings, the Archostemata with the oldest beetles are not used because they participate in the main line of the entire beetle. However, all extant species of Archostemata represent a monophyletic group with many primitive characteristics dar.
The greatest diversity of species exhibited the Archostemata in the Mesozoic, where the Ommatidae in the Palearctic were very common and representative of the Cupedidae also lived in Europe. Several types of Cupedidae are detected in Baltic amber and fossils from deposits with an age between 49 million and two million years ago. During the ice ages the Cupedidae disappeared from Europe and then could not even establish.
Way of life
The way of life of most types of Archostemata is still unknown. All known species live on dead wood verpilztem. For them, less the type of wood, as the degree of decomposition seems to be important. At least from Micromalthus debilis and Tenomerga cinerea is known to develop both deciduous and coniferous to. The larvae have an elongate, parallel-sided body and the short legs of the six-membered rule. The mouthparts and digestive tract are typical for drilling in wood beetle larvae. Micromalthus debilis has a very unusual way of life for beetles. The species develops with four completely different from each other larval types, which also includes the unisexual reproduction by Paedogenese.
Taxonomy and systematics
In their description by Hermann Julius Kolbe 1908, the subordination originally included only the family Cupedidae, meanwhile her other four families are added, the position of the Jurodidae is still uncertain. The monophyly of the Archostemata is well founded on the basis of autapomorphies. The Cupedidae and Micromalthidae and the Crowsoniellidae and Ommatidae are Schwestertaxons. The Jurodidae be added to the group, because they have similar structures to the thorax. Against the classification, however, speaks the Flügeladerung and folding wings that speaks for classification under the Polyphaga. However till now no synapomorphy at the Jurodidae and a subset of the Polyphaga is found, the family is provisionally attributed to the Archostemata. The following families are included in the Archostemata:
- Ommatidae Sharp & Muir, 1912 (6 species)
- Crowsoniellidae Iablokoff - Khnzorian, 1983 ( 1 species )
- Micromalthidae Barber, 1913 ( 1 species )
- Cupedidae Laporte, 1836 (31 species)
- Jurodidae Ponomarenko, 1985 ( 1 species )