Micromalthus debilis
| Micromalthus debilis | ||||||||||||
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Micromalthus debilis, ♀ |
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Micromalthidae | ||||||||||||
| Barber , 1913 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Micromalthus | ||||||||||||
| Le Conte , 1878 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Micromalthus debilis | ||||||||||||
| Le Conte , 1878 |
Micromalthus debilis is the only described species ofthe Micromalthidae beetle family. The beetle is found in North and South America, but has also spread to Africa, Asia and Europe.
features
The beetles become 1.5 to 2.5 millimeters long and have a somewhat elongated body. The pronotum is narrower than the head, both parts become increasingly wider towards the front. The compound eyes protrude clearly from the side. The body is dark brown, almost black, the legs and the short antennae are a little lighter in color. The animals have only a slightly sclerotized body.
Occurrence
The beetle's original homeland is likely the eastern United States . The first specimens were described by LeConte of Detroit in 1878 , where they were found in rotted wood. However, since 1938, the animal was also found in South Africa , Hong Kong , Cuba , Brazil , Hawaii and British Columbia , presumably through human displacement . Reports from New Mexico and Florida followed in 1991. In the same year Europe was reached with the discovery point Gibraltar .
Way of life
The larvae live in damp dead wood , especially oak and chestnut .
Life cycle
The life cycle of the beetle was first described by Herbert Spencer Barber in 1913 . It appeared so unusual that experts initially did not believe the results. However, further investigations, in particular by John William Sutton Pringle in 1938, could largely confirm Barber's discovery. The life cycle looks like this:
From fertilized eggs hatch first, highly mobile, so-called Triungulinus larvae, which in turn develop into legless larvae and basically become females. They can either develop into a fully grown diploid female beetle via a pupal stage , or they can become sexually mature in the larval stage after a last molt. The offspring arise through so-called pedogenesis without fertilization, unisexual reproduction ( parthenogenesis ), which, however, is brought forward to a stage of juvenile development. This results in three variants. The paedogenetische female is viviparous ( viviparous ) and produces Triungulinus larvae that develop into one of the two female molds ( Thelytokie ) that paedogenetische female lays a single unfertilized egg from which at the end of a haploid , adult, male Beetle develops ( arrhenotocia ), this male has only short legs as a larva and eats its mother ( matriphagia ), or the pedogenetic female lays several unfertilized eggs which can develop into males as well as females ( amphitocia ). Only adult female beetles mate with males and only lay fertilized eggs.
literature
- DA Pollock, BB Normark: The life cycle of Micromalthus debilisLeConte (1878) (Coleoptera: Archostemata: Micromalthidae): historical review and evolutionary perspective. In: Journal of Zoological Systematics and Evolutionary Research. 40, 2002, p. 105, doi : 10.1046 / j.1439-0469.2002.00183.x .
Web links
- Micromalthus debilis in Fauna Europaea