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Nephtyidae
Description
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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.
Description | Identification
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