Secernentea was a class of nematodes in the Classical Phylogeny System (Chitwood, 1958) and is no longer in use.[1][2] This morphological-based classification system has been replaced by the Modern Phylogeny system, where taxonomy assignment is based on small subunit ribosomal DNA (SSU rDNA).[3][4]

Scientific classification
Kingdom: Animalia
Phylum: Nematoda
Class: Secernentea

Diplogasteria (disputed)
Rhabditia (paraphyletic?)
Tylenchia (disputed)
and see text

Characteristics of Secernentea are:

  • Amphid apertures are pore/slit-like
  • Derids are present in some; located near nerve ring
  • Phasmids are present; posterior
  • Excretory system is tubular
  • Cuticle is striated in two to four layers; lateral field is present
  • Three esophageal glands; esophageal structure varies
  • Males generally have one testis
  • Caudal alae are common
  • Sensory papillae are cephalic only; may be caudal papillae in males
  • Mostly terrestrial
  • Rarely found in fresh or marine water


Subclasses and orders of Secernentea are:[5]

Some families traditionally considered to be Rhabditida seem to be closer to the Tylenchida. If the Tylenchia are to be maintained as separate, they probably will be included therein.


  1. "WoRMS - World Register of Marine Species - Secernentea". Retrieved May 24, 2018.
  2. Olsen, Oliver Wilford (1986). "Animal Parasites: Their Life Cycles and Ecology". Courier Corporation. doi:10.1086/408868. Cite journal requires |journal= (help)
  3. De Ley, P., and M. Blaxter. 2004. "A New System for Nematoda: Combining Morphological Characters with Molecular Trees, and Translating Clades into Ranks and Taxa." Nematology Monographs and Perspectives 2. Brill, Netherlands: 633–53.
  4. De Ley, P., Wilfrida Decraemer, and A. Eyualem. 2006 "Introduction: Summary of Present Knowledge and Research Addressing the Ecology and Taxonomy of Freshwater Nematodes." CABI.
  5. Tree of Life Web Project (ToL) (2002): Nematoda. Version of January 1, 2002. Retrieved November 2, 2008.
  6. Nickle, W.R. (ed.), (1991). Manual of Agricultural Nematology. New York, NY: Marcel Decker.

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