Auanema melissense		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
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

Chromadorea

  Rhabditia

    Rhabditida

      Rhabditoidea

        Rhabditidae

Rhabditinae

Synonyms

Rhabditis melissensis Nigon, 1949

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Morphology and Anatomy:

• Cuticle with fine annulation. Lateral field inconspicuous, only weakly separated from the other part of body surface by lack of annules, ridges (alae) absent.
• Lip region not clearly offset from body contour, with six equal-sized sectors, two dorsal sectors, right lateral and subventral sectors and left lateral and subventral sectors form a triangular stomatal opening.
• Each lip with a setiform labial sensillum.
• Four setiform cephalic sensilla.
• Amphids oval-shaped pores at the level of the posterior end of cheilostom.
• Stoma cylindrical, about 7x longer than wide, with cheilostom, gymnostom and stegostom. Cheilostom and gymnostom simple cylinder; Pro- and meso-stegostom simple cylinder, comprising a little more than half of the stomatal tube (form pharyngeal sleeve); meta-stegostom slightly anisotopic and isomorphic with one small denticle on each sector.
•  Procorpus cylindrical; metacorpus a well-developed median bulb, isthmus slender, basal bulb rounded (not polygonal) with weak duplex haustrulum posterior to valves.
•  Cardia conspicuous.
• Nerve ring surrounding the posterior part of isthmus.
• Excretory pore conspicuous .Excretory tube extends anteriorly, and then reflexes to continue posterior. An excretory cell is located a little posterior to the excretory pore opening.
• Deirid at the same level as excretory pore.

Female and Hermaphrodite:

• Females and hermaphrodites morphologically indistinguishable.
• Vulva a hotizontal slit mid body; cuticle around the vulva lacks annulations.
• Didelphic, amphidelphis, gonads dorsally reflexed
• Germ cells arranged in two to three rows in distal half, well-developed oocytes arranged in a single row;
•  Oviduct connecting ovary (ovotestis) and spermatheca, formed by small rounded cells. Spermatheca and uterus with thick wall.
• Vagina perpendicular to body surface, with thick wall, constricted by sphincter muscle at the vagina-uterus junction.
•  Young females/hermaphrodites carry usually none or only one embryo in each uterus, older individuals, often more than 10 well-developed embryos are present in an expanded uterus.
• Two subventral and one dorsal rectal glands surrounding intestine-rectum junction and anterior part of rectum.
• Rectum as long or slightly longer than anal body diam.
• Anal opening a horizontal slit; posterior anal lip expands slightly in lateral view.
• Tail smoothly tapered to finely elongated conical tip but not filiform.

Males:

• Monorchic, testis on right of intestine;
• Two subventral and one dorsal cloacal (anal) glands visible at the level of anterior end of retracted spicules.
• Spicules with rounded manubrium, paired, forming a V shape in ventral view; smoothly arcuate in lateral view.
•  Gubernaculum short, narrow.
• The bursa is anteriorly open, supported by eight pairs of papillae (rays) arranged as follows <GP1, GP2, (GP3, CO), GP4, GP5d, GP6, (GP7d, GP8) phasmid>, where the distances between GP1-GP2, GP2-GP3 and GP6-GP7 are similar to each other, the distance between GP5d-GP6 is clearly larger and that between GP3-GP4 and GP4-GP5d is shorter; GP7d and GP8 are close to each other

Ref: Kanzaki et al., 2017; Tandonnet et al., 2022

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Distribution:

Auanema melissense was originally isolated from rotting starfruit on the Indian Ocean island of Reunion.

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Feeding:

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Biology and Ecology:

Auanema melissense is a species of entomopathogenic nematodes that appears to have a symbiotic association with bacteria of the family Enterbactericeae (Manjula et al., 2020).

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Life Cycle:

Auanema melissense reproduces by a rather unique form of parthenogenesis known as auto-pseaudogamy. In pseudogamy, the presence of  male sperm is necessary to activate development of oocytes but DNA is not transferred.  In most cases of pseudogamy, the sperm is obtained by copulation with other species. In auto-pseudogamy, females produce a small number of male offspring to satisfy their need for sperm (Launay et al., 2020).

Ecophysiological Parameters:

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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

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.

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