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Nephtys longipes with everted pharynx

Nephtyids have a quadrangular prostomium that flattens anteriorly, terminating in a pair of antennae and a more ventrally located pair of simple palps. Nephtyids are often referred to in the literature as having two pairs of antennae; the present interpretation of the homology of palps and antennae follows Rouse & Fauchald (1997). The peristomium is reduced, and parapodia of anterior chaetigers surround the mouth. The first chaetigerous segment is smaller than the next and is usually anteriorly directed with prolonged dorsal and ventral cirri sometimes termed tentacular cirri. All subsequent segments are similar in form, and all parapodia are biramous; unlike most polychaetes, the body is distinctly squarish in cross section. Posterior segments taper gradually to the pygidum; the anus is terminal and has a single ventral cirrus. An eversible muscular pharynx is present, with a terminal ring of papillae and rows of subdistal papillae. Proximally the surface of the pharynx is bare or may carry verrucae, forming a granulate appearance. One pair of lateral jaws is present, and in Dentinephtys a pair of hard trepans with eight or nine whitish teeth is located internally on the everted pharynx. The biramous parapodia have dorsal and ventral aciculae throughout. Chaetae are capillaries and may be smooth, serrate, or barred; lyrate chaetae are also present in Aglaophamus, Inermonephtys and Micronephthys.

Identification tips

Recognising the family
Nephtyidae have compact bodies, somewhat rectangular in cross-section, and are live specimens exhibit a distinctive sinuous swimming/crawling movement. ...

Distinguishing species
The segment on which branchiae commence is an important character, as is the shape of the branchiae and the way in which they curl. The number and distribution of papillae on the pharynx is also very important, athough this may need to be dissected.


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