White desert beetle
| White desert beetle | ||||||||||||
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| Scientific name | ||||||||||||
| Onymacris plana | ||||||||||||
| Peringuey , 1886 |
The white desert beetle ( Onymacris plana ) is a species of the black beetle family .
features
The beetle is relatively large with a body length of around 22 millimeters. It is black in color with a smooth, shiny pronotum and roughly wrinkled (rugose) elytra . The body surface can be colored white to varying degrees by a wax coating, with all transitions occurring. It could be shown that the extent of the white coloring correlates with the place where it was found: while animals from the fog-influenced, relatively cool coastal areas are almost always black, animals from the interior are predominantly white. Although direct studies are still pending, it is generally known from insects that the wax ( lipid ) shell of the cuticle is the essential protection against water evaporation.
The beetle is short-oval with very elongated legs. The body shape shows a distinctive sexual dimorphism . The males have laterally strongly widened elytra flattened at the top, these were also decisive for the species name. It was shown that the larger the beetle, the more pronounced the broadening. These males were more successful in competition than females. The males take considerable risks when looking for mating partners and are more likely to be preyed on by predators than the females.
Ecology and way of life
The beetles only inhabit pure sandy deserts in the Namib . Thanks to their long legs, the animals can run very quickly and bury themselves in the sand so that the heat doesn't get too bad for them. The beetles are tied to dune areas. However, they do not live on the vegetation-free sand, but rather prefer the island-like, small patches of vegetation that are interspersed here. There are essentially two species: the grass Stipagrostis sabulicola and the Naras ( Acanthosicyos horrida ) belonging to the cucurbit family . The beetles need the plants both as a food source and as sun protection in the midday, which they spend buried in their shade. They mainly feed on dead plant biomass (litter), but have a particular preference for Naras flowers. The larvae live below the surface and also feed on parts of plants.
Although the beetles, like all related species, are unable to fly, they can continually cover long distances. By recapturing marked animals, distances of 20 kilometers can be detected in a short time. Despite the lack of flight ability, they are therefore capable of further spreading ( migration ). However, they essentially stick to sandy areas and avoid other surfaces.
Taxonomy
It has recently been shown that the genus Onymacris is paraphyletic to related genera . Onymacris plana belongs to a clade of species with a partially white body surface (which is sometimes considerably more pronounced in related species), which is more closely related to the genus Physadesmia than to the purely black Onymacris species.
swell
- Hubert Roer (1975): On the way of life of the Namib desert beetle Onymacris plana Peringuey (Col., Tenebrionidae, Adesmiini) with special consideration of its migration behavior. Bonn Zoological Contributions 26 (1-3): 239-256.
Individual evidence
- ↑ Elizabeth McClain, Mary K. Seely, Neil F. Hadley, Vivian Gray (1985): Wax Blooms in Tenebrionid Beetles of the Namib Desert: Correlations with Environment. Ecology Vol. 66, No. 1: 112-118.
- ↑ Margit M. Enders, Holger Schüle, Joh R. Henschel (1998): Sexual Dimorphism, Fighting Success and Mating Tactics of Male Onymacris plana Péringuey (Coleoptera: Tenebrionidae) in the Namib Desert. Ethology Volume 104, Issue 12: 1003-1019. doi : 10.1111 / j.1439-0310.1998.tb00049.x
- ↑ Polis, Gary A., Joseph D. Barnes, Mary K. Seely, Joh R. Henschel, and Margit M. Enders. 1998. Predation as a major cost of reproduction in Namib desert Tenebrionid beetles. Ecology 79: 2560-2566.
- ↑ Portrait at ecoport
- ↑ Trip Lamb & Jason E. Bond (2013): A multilocus perspective on phylogenetic relationships in the Namib darkling beetle genus Onymacris (Tenebrionidae). Molecular Phylogenetics and Evolution Volume 66, Issue 3: 757-765. doi : 10.1016 / j.ympev.2012.10.026