Rev 07/02/2023
Chromadorea Rhabditia
Rhabditida
Rhabditoidea
Rhabditidae
Type species of the genus: Auanema rhodense Kanzaki, Kiontke, Tanaka, Hirooka, Schwarz, Muller-Reichert, Chaudhuri, Pires-daSilva, 2017
The generic epithet áua is derived from 'hair' in Tupi, an indigenous language from South America (Kanzaki et al., 2017).
In establishing the genus, Kanzaki et al., 2017. included three species previously described as genus Rhabditis:
A. reciprocum (Sudhaus, 1974)
A. seurati (Maupas, 1916)
A. viguieri (Maupas, 1900)
.
General Characteristics:
Median bulb well developed, round to square.
Female:
Dauer juveniles
Ref: Kanzaki et al., 2017; Sudhaus, 2023
Males:
Generally rare
Much smaller than females and hermaphrodites
Bursa on male tail open, peloderan or leptoderan with more or less distinctly bilobed posterior margin;
8 pairs of genital papillae one or two precloacal, the 5th and 7th attached to the dorsal surface of the fan; the 6th is separate, the 7th and 8th close together.
Spicules separate and dagger-shaped; gubernaculum half as long as spicules
Phasmids papilliform, posterior to genital papillae
Describesd from various bacteriophilic environments: A. freiburgense from a dung pile in an animal enclosusre in Germany; A. melissense from a rotting starfruit, and A. rhodense from soil baioted with blood-engorged deer ticks (Sudhaus, 2023).
Bacteria
Nematodes of the genus Auanema are interesting models for studying sex determination mechanisms because they exhibit trioecy; their populations consist of three sexual morphs (males, females, and hermaphrodites) and produce skewed sex ratios (Tandonnet et al., 2022)
The co-existence of males, females and hermaphrodites, a rare mating system known as trioecy, has been considered as an evolutionarily transient state. In nematodes, androdioecy (males/hermaphrodites) as found in Caenorhabditis elegans, is thought to have evolved from dioecy (males/females) through a trioecious intermediate.
Thus, trioecious species are good models to understand the steps and requirements for the evolution of new mating systems (Kanzaki ewt al., 2017).
Auanema spp. exhibit trioecy: that is the co-existence of males, females and hermaphrodites. The life cycle is short and progeny many similar to other rhabditid nematodes, for example Caenorhabditis.
Kanzaki, K., Kiontke, K., Tanaka, R., Hirooka, Y., Schwarz, A., Muller-Reichert, T., Chaudhuri, J., Pires-daSilva, A. 2017. Description of two three-gendered nematode species in the new genus Auanema (Rhabditina) that are models for reproductive mode evolution. Nature Scientific Reports 7:11135
Sudhaus, W. 2023. An update of the catalogue of paraphyletic Rhabditidae (Nematoda) after eleven years. Soil Organisms 95: 95-116
Tandonnet, S., Haq, M., Turner, A., Grana, T., Paganopoulou, P., Adams, S., Dhawan, S., Kanzaki, N., Felix, M-A., Pires-daSilva, A. 2022. De novo Genome Assembly of Auanema melissensis, a Trioecious Free-Living Nematode. J. Nematology 54: | DOI: 10.2478/jofnem-2022-0059