Revised
01/30/26
Free-living marine nematodes.
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As of 2020, the family Xennellidae
comprises two genera, Xennella Cobb,
1920 and Porocoma Cobb, 1920.
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Nematodes have a cephalic capsule
and an annulated cuticle with longitudinal
ridges ; but similar to most Trefusiina
in having outer labial and cephalic
setae in separate circles and pocket-shaped
amphideal fovea, as well as lacking metanemes (Lorenzen 1981)..
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Cuticle annulated except in X. cephalata
Cobb, 1920 where it is apparently smooth; longitudinal ridges on
cuticle usually present.
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Amphideal fovea pocket-shaped, horseshoe-shaped
or circular.
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Anterior sensilla arranged in a 6 +
6 + 4 pattern; long, setose outer labial and cephalic
sensilla of similar length.
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Tapering cephalic capsule present (Xennella)
or absent (Porocoma); when present, cephalic capsule offset from
rest of body by constriction, cuticular
discontinuity and/or thickened cuticle.
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Buccal cavity minute,
tubular, without teeth.
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Female reproductive system monodelphic (Xennella)
or didelphic (Porocoma).
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Male reproductive system monorchic (at least in
Xennella suecica Allgén, 1935); spicules short, arcuate;
gubernaculum present or absent, precloacal supplements present or absent.
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Type genus Xennella Cobb, 1920..
Andrassy, I. 2009. Free-living Nematodes of Hungary
(Nematoda Errantia) Vol. 111. Humgarian Natural History Museum, Budapest.
508p.
Golden, A.M. and D.G. Murphy, 1967. Encholaimoidea (Nematoda: Dorylaimida), a
new superfamily representing dorylaimid specimens with cephalic setae. Proc.
Helmith Soc Washington. 34:94-98