Rev: 12/24/2021

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       Geomonhystera Andrassy, 1981
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Morphology and Anatomy:

Per Andrassy, 1981 definition of the genus, primarily terrestrial, often in moist soil environments or on moss in moist environments.


Cuticle smooth or very finely striated, with scattered somatic setae.
Body 0.5-1.2 mm.
Outer labial (6) and cephalic (4) setae well developed; lengths <60% of head diameter.
Ocelli absent.
Amphid foveae large, circular, 1-2 head widths from anterior.
Stoma funnel shaped, without teeth or denticles.
Defined by Andrássy as a terrestrial genus, so no aquatic forms with ocelli.
Esophagus cylindrical without terminal bulb.
Rectum muscular, usually >1 abd long.
Vulva at 75-85%, very close to anus, usually within 1-3 abd of anus.
Tail elongate conoid but not filiform, ventrally curved, terminating in a short, conoid spinneret.

    Ref: Andrassy (2005); Coomans and Eyualem-Abebe (2006).

Males rare in some species, spicules slender, ventrally arcuate, 1.5-2 x abd. Gubernaculum simple, without apophysis.
Median pre-cloacal papillae may be present.
Body size range for the species of this genus in the database - Click:
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Commonly found on tree bark associated with mosses and lichens, or in moist soil environments.

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Feed on bacteria and possibly substrate ingestion in which the substrate includes bacteria, protozoa, algae, etc. (Yeates et al., 1993).

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Biology and Ecology:

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Life Cycle:

For Ecophysiological Parameters for this genus, click 

Amphimictic or parthenogenetic.

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Ecosystem Functions and Services:

Free-living soil/terrestrial nematodes.

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Andr�ssy, I. 2005.  Free-living Nematodes of Hungary, Vol. I. Hungarian Natural History Museum, Budapest

Cid del Prado-Vera, I., Ferris, H., Subbotin, S.A. 2018. Six new and one known species of Geomonhystera (Nematoda, Monhysteridae) from moss, an epiphytic plant and soil in M�xico and Ecuador. Zootaxa 4471:76-110.


Coomans, A. and Eyualem-Abebe 2006.  Order Monhysterida. Pp 574-603 in Eyualem-Abebe, Traunspurger, W., Andrassy, I. (eds) Freshwater nematodes: ecology and taxonomy.


Yeates, et al. 1993. Feeding habits of soil nematodes. J. Nematology 25:315-331.


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Copyright © 1999 by Howard Ferris.
Revised: December 24, 2021.