Revised 05/04/24
Chromadorina
Chromadoroidea
Selachinematidae Cobb, 1915
Two subfamilies: Choniolaiminae Schuurmans-Stekhoven & Adam, 1931 and Selachinematinae Cobb, 1915
A family of marine nematodes.
Choniolaiminae: Buccal cavity spacious, divided into two compartments, anterior portion broad, posterior narrow; reinforced by cuticularised rhabdions in both portions. Mandibles absent.
Selachinematinae: Buccal cavity spacious, divided into two compartments, with posterior rhabdions modified into protrusible denticulate mandibles
Marine nematodes, considered voracius predators.of, among others, smaller nematodes.
Most often reported from relatively coarse sediments in shallow water environments but also occur in deep-sea habitats.
Usually a stout cylindrical body, anteriorly truncate.
Cuticle punctated with or without lateral differentiation.
Head sensillae may be jointed.
Buccal cavity spacious, divided into two compartments, Complex buccal armament of rhabdions, denticles, or heavy mandibles, for capture of nematode prey.
Multispiral amphids.
Pharynx with or without posterior bulb, anterior bulb sometimes present
Percentages of selachinematids and other predator taxa in nematode assemblages are usually low in mud and silty sediments., more abundant in sandy sediments with higher species diversity and prey density.
12 genera as of 2016.
Halichoanolaimus the most common, diverse and widely distributed; Cheironchus less common but widely distributed.
Females: didelphic-amphidelphic, ovaries reflexed
Males: Usually two outstretched testes, either on same or different sides of the intestine; pre-cloacal supplements usually present, usually cup-shaped, sometimes setose, papilliform, rarely tubular.
Ref: Leduc, 2013; Leduc and Zhao, 2016; Tchesunovet al., 2020.
Bongers, T. De Nematoden van Nederland.
Goodey, T and J.B. Goodey, 1963. Soil and Freshwater Nematodes. Methuen. London
Leduc, D. 2013. Two new genera and five new species of Selachinematidae (Nematoda, Chromadorida) from the continental slope of New Zealand. European Journal of Taxonomy 63: 1-32.
Leduc, D., Zhao, Z.Q. 2016. Molecular characterisation of five nematode species (Chromadorida, Selachinematidae) from shelf and upper slope sediments off New Zealand, with description of three new species. Zootaxa 4132:59-76.
Neira, C., Decraemer, W. 2009. Desmotersia levinae, a new genus and new species of free-living nematode from bathyal oxygen minimum zone sediments off Callao, Peru, with discussion on the classification of the genus Richtersia (Chromadorida: Selachinematidae. Organisms, Diversity and Evo;ution 9, 1:e1-1.e15
Tchesunov, A., Jeong, R. Lee W. 2020. Two New Marine Free-Living Nematodes from Jeju Island Together with a Review of the Genus Gammanema Cobb 1920 (Nematoda, Chromadorida, Selachinematidae). Diversity 2020, 12, 19; doi:10.3390/d12010019.
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