Subfamily Oncholaimellinae

Revised 03/09/24

Nematoda

Enoplea

Enoplia

Enoplida

Oncholaimina

Oncholaimoidea

Oncholaimidae

Oncholaimellinae De Coninck, 1965

Free-living marine nematodes. Several species reported from coastal mangrove swamps.

The Oncholimellinae is on of seven subfamilies of the Oncholaimidae (Adoncholaiminae, Krampiinae, Octonchinae, Oncholaimellinae, Oncholaiminae, Pelagonematinae and Pontonematinae), differentiated by features such as the number and length of teeth, the position of the largest tooth, the structure of the female reproductive system, and the presence and development of the Demanian system (Smol & Coomans, 2006; Smol et al., 2014).

The Oncholaimellinae has general characteristics of the family Oncholaimidae:

  • Free-living marine nematodes
  • Lips usually fused..
  • Large cylindrical buccal cavity, usually with 3 immovable teeth of unequal size  surounded in the posterior region by esophageal tissue
  • Esophageal glamds open through the teeth.
  • Amphidial fovea pocket-shaped, posterior to buccal cavity.
  • Esophagus muscular throughout length, esophageal gland openings just posterior to buccal cavity.
  • Males mainly diorchic, spicules varied in shape and size; gubernavulum present or absent.
  • Females didelphic amphidelphiuc or monodelphic prodelphic; ovaries reflexed.

Specific characteristsics of the subfamily Oncholaimellinae:

  • Right ventrosublateral tooth larger than the other teeth
  • Demanian system simple if present

The Demanian system is a set of canals, junctions and pores unique for some genera of Oncholaimidae. The system differs from simple (primitive) to more complex (advanced) in different genera and species.  The Demanian system  features in "traumatic insemination" in which the male uses spicules and secretions to puncture the cuticle of the posterior of the female to form a copulatory pore. Sperm are released into the pore. The sperm injected into the female move through terminal ducts and reach the main duct of the Demanian system. The sperm move forward in the main duct to the uterus through the uvette and ductus uterinus. Eggs are fetrilized in the uterus ( Coomans et al., 1988; Tchesunov, 2015).

 
Oncholaomidae - anterior 

Ref:  Neres, et al., 2014; Smol and Coomans, 2006; Smol, et al., 2014.

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References

Coomans, A., Verschuren, D., Vanderhaeghen, R. 1988. The demanian system, traumatic insemination and reproductive strategy in Oncholaimus oxyuris Ditlevsen (Nematoda, Oncholaimina). Zool Scr 17:15-23.

Neres, P.F., Da Silva, M.C., Miranda-Junior, G.V., Fonseca-Genevois, V., Esteves, A.M. 2014. Five new species of Oncholaimellus (Oncholaimidae: Nematoda) from north-east Brazil, with an emended diagnosis and an updated key to the genus . J. Marine Biol, Assoc. UK 94:703-727.

Smol N. and Coomans A. 2006. Order Enoplida. In Eyualem-Abebe Traunspurger W. and Andrassy I. (eds) Freshwater nematodes: ecology and taxonomy. Wallingford, UK: CABI Publishing, pp. 225–292.

Smol, N., Muthumbi, A., Sharma, J. 2014. Order Enoplida, 7.3. In Schmidt-Rhaesa, A. (ed) Handbook of Zoology. De Gruyter, Berlin

Tchesunov, A.V. 2015. Free-living nematode species (Nematoda) in hydrothermal sites of the North Mid-Atlantic Ridge. Helgoland Marine Research 69:343-384.

 

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