Cryptocercus
| Cryptocercus | ||||||||||||
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| Cryptocercidae | ||||||||||||
| Handlirsch , 1925 | ||||||||||||
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| Cryptocercus | ||||||||||||
| Scudder , 1862 |
Cryptocercus is a genus of cockroaches. It is monotypical by most authors; H. placed as the only genus in the family Cryptocercidae, which is thenassigned tothe superfamily Blattoidea . The epifamily Cryptocerciodae, which is also monotypical, is sometimes placed between these taxons . The genus has receivedgreat scientific attention, especially as a possible sister group and as a model organism for the evolution of termites . Several hundred scientific publications have appearedon Cryptocercus .
features
The species have an oval, closed body contour, highly arched and wingless in both sexes, they are reminiscent of woodlice or sapweed (Glomeridae) when viewed superficially . The color is black or black-brown, the nymphs are lighter (red-brown) in color and otherwise very similar to the adults . As is often the case with cockroaches, the head is slightly hanging under the pronotum and is hardly visible from above. The legs are relatively short but strong and have striking rows of thorns. The antennae are of moderate length and, when laid back, extend to about the middle of the body. The surface of the body is a bit shiny and has small thorns in certain places. The animals are between two and three centimeters long, depending on the species. The different species are morphologically extremely similar to one another and can only be distinguished by the fine structure of the genitals. Some forms have not been distinguished as "species" on the basis of morphology, but only on the basis of DNA sequences ( cryptic species ). The species status of these populations is contested by other researchers.
Way of life
Cryptocercus species live in partially decomposed branches and tree trunks (dead wood) lying on the ground in forests in the temperate climate zone (temperate). A wide range of tree species is colonized, both hardwood and coniferous wood. Wood is not only the habitat, but also the only basic nutritional basis of the animals. To do this, they eat chambers and extensive duct systems in the wood, often directly under the bark.
In all Cryptocercus species, a female, a male and their offspring live together in a gallery system. Occasionally a parent animal, usually the male, may be missing. The cohesion is broken with the sexual maturity of the young. The young adults, occasionally already the last larval stage, leave the gallery in search of mating partners and a new habitat. This form of coexistence, which does not lead to permanent socialization, is called "subsocial" in contrast to the "eusocial" insect states of hymenoptera and termites.
As with all cockroaches, the female of Cryptocercus lays her eggs in a covered structure, a so-called ootheca . It deposits this within the duct system. Each female lays two to four ooths, each containing around 30 to 40 eggs, during her lifetime. There is only one period of reproduction. The hatched nymphs seek the closeness of the parent animals with whom they form common aggregations. (Mutual body care english "grooming" ) and feeding ( Trophallaxis ) are common, the feeding does not mouth to mouth, but through feeding of separated wood fragments at the anus ( anus takes place). This behavior is seen as essential for the transmission of endosymbiotic bacteria and protozoa . For the most part, however, the nymphs feed independently of each other and of their parent animals on dead wood. Especially the older ones can start digging their own galleries. The younger nymph stages are said to be largely dependent on the parent animals for their nutrition. The development time of the nymphs is extraordinarily long. The animals need five years to reach sexual maturity, in exceptional cases up to seven years have been observed. The long development period is considered to be due to the low nutrient content of the food wood and the delay in development in the cold winter half year compared to their predominantly tropical relatives.
Endosymbionts
Like the so-called "lower termites" (all families with the exception of the Termitidae ), Cryptocercus is dependent on endosymbiotic eukaryotic protozoa, bacteria and archaebacteria in order to break down and digest the food wood. The symbiotic " flagellates " (unicellular organisms from the Parabasalia tribe and the order Oxymonadea in the Loukozoa tribe ) proved to be closely related to those in the rectum of termites. This is a strong indication of the close relationship between the two groups. This leads to the assumption that the special endosymbionts of the termites would already have been present in their ("presocial") ancestral species not yet living in states, which is often imagined to be very similar to Cryptocercus in their way of life. According to this theory, the transmission of the endosymbionts was an essential starting point for the evolution of social behavior. It is still controversial between different researchers whether this previously purely hypothetical parent species had pronounced brood care behavior. Approaches to such behavior can be seen in Crypotocercus . However, they are absent from a number of "lower" termites or at least not very pronounced.
distribution
The different Cryptocercus species colonize three spatially widely separated distribution areas: the east and west of North America and an area in East Asia : People's Republic of China and an adjacent area in Russia ( Ussuri region) and the Korean peninsula , some species mainly in mountain ranges. The Asian and American species presumably go back to a common starting population that was separated when the ancient continent Laurasia was split in the Miocene and Eocene .
Systematics
There is a scientific controversy about the position of the genus Cryptocercus . Most authors place the monotypic family Cryptocercidae for the genus, which is regarded as the sister group of the termites . This placement is supported by some morphological features, by DNA analyzes (molecular pedigrees) and by the relationship of the endosymbionts in the intestines of the animals. The renowned researcher Phillipe Grandcolas denies the independence of the Cryptocercidae. For him, the genus belongs to the Polyphagidae family, which today is mostly viewed as synonymous with the Corydiidae family . Grandcolas does not see Cryptocercus as being closely related to the termites and justifies this mainly with details in the structure of the genitals, some molecular studies support his point of view. He explains the matching endosymbiotic fauna with a later transfer of a termite species that occurs in the same habitat.
There are currently seven Asiatic and two North American species of the genus generally recognized. The species status of three further, genetically distinguishable, but morphologically extremely similar populations in eastern North America is viewed differently. A large part of the species was only described after 1990:
- Cryptocercus clevelandi Byers , 1997
- Cryptocercus darwini Burnside , Smith & Kambhampati , 1999
- Cryptocercus garciai Burnside , Smith & Kambhampati , 1999
- Cryptocercus hirtus Grandcolas & Bellés , 2005
- Cryptocercus kyebangensis Grandcolas , 2001
- Cryptocercus matilei Grandcolas , 2000
- Cryptocercus meridianus Grandcolas & Legendre , 2005
- Cryptocercus parvus Grandcolas & Park , 2005
- Cryptocercus primarius Bey-Bienko , 1938
- Cryptocercus punctulatus Scudder , 1862
- Cryptocercus relictus Bey-Bienko , 1935
- Cryptocercus wrighti Burnside , Smith & Kambhampati , 1999
swell
- Craig A. Burnside, Paul T. Smith, Srinivas Kambhampati (1999): Three New Species of the Wood Roach, Cryptocercus (Blattodea: Cryptocercidae), from the Eastern United States. Journal of the Kansas Entomological Society Vol. 72, No. 4: 361-378.
- Kiyoto Maekawa & Christine A. Nalepa (2011): Biogeography and Phylogeny of Wood-feeding Cockroaches in the Genus Cryptocercus. Insects 2: 354-368. doi : 10.3390 / insects2030354 (open access)
- Christine A. Nalepa (1984): Colony composition, protozoan transfer and some life history characteristics of the woodroach Cryptocercus punctulatus Scudder (Dictyoptera: Cryptocercidae). Behavioral Ecology and Sociobiology Volume 14, Number 4: 273-279. doi : 10.1007 / BF00299498 .
- Moriya Ohkuma, Satoko Noda, Yuichi Hongoh, Christine A. Nalepa, Tetsushi Inoue (2009): Inheritance and diversification of symbiotic trichonymphid flagellates from a common ancestor of termites and the cockroach Cryptocercus. Proceedings of the Royal Society London Series B 276: 239-245. doi : 10.1098 / rspb.2008.1094 .
- Yung Chul Park, Phillipe Grandcolas, Jae Chun Choe (2002): Colony composition, social behavior and some ecologica characteristics of the Korean wood-feeding cockroach Cryptocercus kyebangensis. Zoological science 19: 1133-1139.
- Roseli Pellens, Cyrille A. D'Haese, Xavier Bellés, Maria-Dolors Piulachs, Frédéric Legendre, Ward C. Wheeler, Philippe Grandcolas (2007): The evolutionary transition from subsocial to eusocial behavior in Dictyoptera: Phylogenetic evidence for modification of the “ shift-in-dependent-care ”hypothesis with a new subsocial cockroach. Molecular Phylogenetics and Evolution 43: 616-626. doi : 10.1016 / j.ympev.2006.12.017 .
- Beccaloni, GW: Blattodea Species File Online . Version 1.0 / 4.0. World Wide Web electronic publication. http://Blattodea.SpeciesFile.org (accessed January 10, 2012)
