Ommatidae

Omma stanleyi

The Ommatidae are a species-poor family of beetles within the most primitive suborder of beetles, the Archostemata. The family occurs worldwide with six species in two subfamilies and genera before.

  • 4.1 subfamily Ommatinae
  • 4.2 subfamily Tetraphalerinae
  • 5.1 Notes and references
  • 5.2 Literature

Features

Beetle

The types of the two groups differ significantly from each other. The genus Omma be 6 to 27 mm long and 2-9 mm wide, of the genus Tetraphalerus reach a length from 10 to 16 millimeters, a width of 2 to 3.5 millimeters. In the former genus the body is flattened laterally rounded and has a brown to dark brown, almost black color. The body is covered with scales and scale-like hairs, which form white pattern in some species the head, thorax and wing covers. The entire body surface is covered with fine 30 to 100 microns in diameter measured tubercles. The mouthparts are directed forward, the head is slightly longer than wide. Dents for the sensor missing, the side -seated compound eyes are medium in size. The head tapers suddenly behind the eyes and thus has a neck. The antennae are laterally hinged to the head, before the eyes. You are elfgliedrig, thready and either the same length or shorter than the head and thorax together. Only in O. rutherfordi they reach behind the base of the pronotum. The thorax has no indentations for the legs. All corners of the pronotum are rounded, the widest point is located in the front half. The elytra bear 9-10 rows of typical for the subordination Archostemata longitudinal veins, which are interconnected by transverse veins so that there are windows in the interstices. The hind wings ( alae ) are well developed, as a rule, only in O. rutherfordi they are very short and do not have wings veins. The abdomen has five contiguous Ventrite.

The adults of the genus Tetraphalerus have slender, flattened body with parallel side edges. They are gray in color, sometimes with brown dot rows on the elytra. The Mikrotuberkel have a characteristic mushroom or umbrella shape with short, strong hair. The mouthparts are directed forward, the head is 1.5 to 1.7 times longer than wide. Grooves for the probe range from the sensor base below the eyes to the beginning of the neck. The eyes are laterally approximately in the middle of the head. The thread-like antennae are also elfgliedrig. In T. bruchi they are as long as the head, in T. wagneri as long as head and thorax together. The pronotum is widest in the middle, the front edge is narrower than the rear. All corners of the pronotum are rounded.

Larvae

The only known larva, which was probably belongs to the genus Omma found in Western Australia. She was 12 mm long and had an elongated and slightly flattened body. The head bears on each side four well-developed simple eyes ( ocelli ). He is pigmented weak with the exception of the mouthparts, behind the head, the body is pigmented pale yellowish. The mouthparts are directed forward. The antennae are four members. The including the well-developed Pretarsalklauen six-membered legs are short and far apart.

Occurrence

The family consists of two genera whose distribution is disjunct. The species of the genus Omma are in the east, southeast and southwest Australia spreads, whereas the genus Tetraphalerus occur in the southern half of South America. The species of the genus Omma colonize both densely forested coastal areas, and dry eucalyptus forests, west of the Great Dividing Range. The species of the genus Tetraphalerus live in open, dry bushland.

Way of life

Larvae of the genus Omma were found on dead wood and tree roots. Omma mastersii and Omma sagitta see a Ameisenwespenart and a similar Thanasimus species, is therefore suggested that these species form a Mimikryring ( Mullerian mimicry ). Because their habitat is assumed that develop the Tetraphalerus larvae in the roots or stems of shrubs. The adults seem to be nocturnal, which suggest frequent catches in light traps.

Taxonomy and systematics

The Ommatidae are delimited by the vertical cutting edges of the mandibles and by lying in deep indentations dorsal sensory hairs of the apical Palpomere of the other beetle families. The following species are known so far:

Subfamily Ommatinae

  • Omma mastersii
  • Omma stanleyi
  • Omma sagitta
  • Omma rutherfordi

Subfamily Tetraphalerinae

  • Tetraphalerus bruchi
  • Tetraphalerus wagneri

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