Subfamily Pontonematinae

Revised 06/16/26

Phylum Nematoda

Class Enoplea

Subclass Enoplia

Order Enoplida

Suborder Oncholaimina

Superfamily Oncholaimoidea

Family Omcholaimidae

Pontonematinae  Gerlach & Riemann, 1934

Free-living marine nematodes.

The Pontonematinae  is one 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 Pontonematinae  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 Pontonematinae:

  • Cuticle smooth.
  • Buccal cavity about twice as long as wide. Both ventrosublateral teeth equal in length and larger than the dorsal tooth.
  • Females didelphic-amphidelphic. Demanian system absent.
  • Males wit spicules strongly curved; gubernaculum with distal wings.
  • Males have one or several supplements.
  • Marine.

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).

 

Ref:  Mordukhovich et al., 2015; 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.

Gerlach, S.A. and Riemann, F. 1974. The Bremerhaven checklist of aquatic nematodes. A catalogue of Nematoda, Adenophorea including the Dorylaimida. Supplement 4, Part 2. Veröffentlichungen des Instituts fur Meeresforschung in Bremerhaven, pp. 405-736.

Mordukhovich, V., Atopkin, D., Fadeeva, N., Yagodina, V., Zograf, H. 2015. Admirandus multicavus and Adoncholaimus ussuriensis sp. n. (Nematoda: Enoplida: Oncholaimidae) from the Sea of Japan. Nematology 17:1229-1224

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.

Shimada, D. and Kajihara, H. 2014. Two new species of free-living marine nematodes of Adoncholaimus Filipjev, 1918 (Oncholaimida: Oncholaimidae: Adoncholaiminae) from Hokkaido, northern Japan, with a key to species and discussion of the genus. Nematology 16: 437-451

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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