Family Cyatholaimidae

Revised 06/05/25

Nematoda

Chromadorea

Chromadoria

Chromadorida

Chromadorina

Chromadoroidea

Cyatholaimidae Filipjev, 1918  (also sometimes attributed to Micoletsky, 1922)

• cuticle with transverse rows of punctations; lateral punctations may be larger, irregular or arranged in longitudinal rows.
• inner labial sensilla usually setiform; six outer labial sensilla and four cephalic sensilla jointed in a single circle of ten setae
• stoma shallow, with large dorsal tooth and two small subventral teeth
• Cheilostome supported by 12 cutucular folds (rugae)
• amphids multispiral
• esophago-intestinal valve prominent, usually without terminal bulb
• female didelphicamphidelphic with anterior and posterior antidromously reflexed gonads always on different sides of the intestine
• male dinorchic, testes  on opposite sides of the intestine, rarely monorchic; with precloacal supplements present or absent.
• free-living, primarily marine nematodes often reported from coastal waters but some species from brackish and freshwater

Cyatholaimidae: anterior features. Drawings from Cunha, 2023

Five subfamilies, generally differentiated by arrangement of anterior sensilla, armament of the stoma, form of the cuticular ornamentation, presence or absence of pre-cloacal supplements and general morphology:

Cyatholaiminae Filipjev, 1918

Nyctonematinae Bussau, 1993

Paracanthonchinae Deconinck, 1965

Pomponematinae Gerlach & Riemann, 1973

Xenocyatholaiminae Gerlach & Riemann, 1973

As concluded by Cunha (2023) most genera in the family Cyatholaimidae genera lack sufficient information about synapomorphic characters. The family is possibly non-monophyletic. The definition of genus and species, and even of the subfamilies, are based on combinations of multiple characters that are not informative from a phylogenetic standpoint.

 References:

Bongers, T. De Nematoden van Nederland.

Cunha, B.R. 2023. Diversity of Free-living Marine nematodes: Taxonomy and Syatematic of Family Cyatholaimidae. PhD Thesis, University of Campinas, Brazil

Datta, T.K., Miljutin, D.M., Chakraborty, S.M. Mohapatra, A. 2016. Cyathoshiva amaleshi gen. n. sp. n. (Nematoda: Cyatholaimidae) from the coast of India. Zootaxa 4126:577-586.

Goodey, T and J.B. Goodey, 1963. Soil and Freshwater Nematodes. Methuen. London

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