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Alciopidae
Description
The anterior margin of the
prostomium carries a pair of antennae and a more ventral pair
of palps. A median antenna is located between
the eyes. Nuchal organs are present; they are ciliated and
located posterior to the eyes. The peristomium is reduced. The
pharynx is muscular and eversible, and bears at least one pair
of papillae or grasping fleshy lateral horns placed distally;
jaws are absent. The first segment is incomplete dorsally, and
has one pair of tentacular cirri; the next two segments have
two to four pairs of tentacular cirri. Biramous
parapodia with leaf-like dorsal cirri, which may be reduced on
anterior-most segments, commence on segment 4. Chaetae are
simple or compound, and aciculae are present.
The pygidium has one pair of cirri or a single pygidial cirrus.
The above description is based on Wilson (2000), which in turn is based on Fauchald & Rouse (1997).
Identification tips
Recognising the family
The Alciopidae have fragile, thin, trasparent bodies and large complex spherical eyes with an internal lens. These eyes are unique within the polychaetes and will distinguish alciopids from related families. Being pelagic, alciopids are not encountered in benthic samples.
Distinguishing species
The structure and form of the parapodia and chaetae provide
all the characters necessary to attain a generic identification; a
single well-preserved parapodium is sufficient. Species characters ... RW to finish ...
Description | Identification
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