Auanema

 

Contents

 

Rev 07/02/2023

  Classification Biology and Ecology
Morphology and Anatomy Life Cycle
Return to Auanema Menu Ecosystem Functions and Services
Distribution Management
Return to Rhabditidae Menu Feeding  References
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Classification:

Chromadorea
  Rhabditia

    Rhabditida

      Rhabditoidea

        Rhabditidae

 

        Auanema Kanzaki, Kiontke, Tanaka, Hirooka, Schwarz, Muller-Reichert, Chaudhuri, Pires-daSilva, 2017

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)

 

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Morphology and Anatomy:

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General Characteristics:

  • Stoma opening triangular, each sector of glottoid apparatus with 1 denticle
  • Stoma long, stegostom comprises about half of stoma (pharyngeal sleeve present), ornamentation of metastegostom indistinct;
  • Median bulb well developed, round to square.

  • Trioecious, 3 sexes may be present: males, females and hermaphrodites.
  • dauer juveniles exhibit tube-wavibng behavior

Female:

  • Tail conical

 Dauer juveniles

  • Develop into females
  • Exhibit waving bahavior, presumably to enhance a phoretic contact.

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

Body size range for the species of this genus in the database - Click:
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Distribution:

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).

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Feeding:

      Bacteria

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Biology and Ecology:

  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).

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Life Cycle:

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.

For Ecophysiological Parameters for this genus, click 
 
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Ecosystem Functions and Services:

 

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Management:

 

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References:

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

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Copyright 1999 by Howard Ferris.
Revised: July 02, 2023.