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Fauveliopsidae
Description
The number
of segments varies from about 10 to more than 50, with
mature individuals of many species having a fixed number of
segments. The first and/or last few segments are often shorter
than the middle ones. The body surface is smooth and shiny, or minutely papillated
resulting in a rugose or dull appearance. Prostomium small, of variable shape (square, subglobular,
pyriform), which may be medially invaginated, and is usually
retracted between the first chaetiger; eyespots
are rarely present. A pair of large ciliated nuchal organs lie
dorso-laterally on the posterior prostomium. The
peristomium is a single annulus and includes ventrally a pair
of lateral lips (sometimes also a ventral lip) around the mouth.
Fauchald & Rouse (1997) interpreted these as palps, but other
studies suggest that palps are absent (Hartman 1978; Riser
1987). Rouse & Pleijel (2001) suggest that there is little
evidence to support this and larval studies are needed to
establish the true nature of the head. The pharynx is looped
dorso-ventrally from the mouth to the septum of chaetiger 2/3
(resembles a ventral buccal organ) and opens to a ventral
mouth; the gut is ciliated throughout its length and lacks a
sphincter.
Parapodia are biramous, with low papillate rami; the interramal
papillae vary in size and shape (conical, subspherical,
clavate) between species. Few simple chaetae are present in
each rami, including spines (which may be more or less
curved) and longer capillary chaetae. The thickness of both the spines and capillaries
typically varies slightly along the body, and intermediate
forms are sometimes present. Chaetal spines of the last
parapodium sometimes form a cage around the pygidium.
The pygidium is terminal and may be
surrounded by papillate anal cirri and/or may be retracted
within the last few segments.
The above description is based on Glasby (2000), which in turn is based on Fauchald & Rouse (1997).
Identification tips
Recognising the family
Fauveliopsids are small, grub-like worms which
are characterised by the presence of inter-ramal papillae in
each parapodium. Some members of the Flabelligeridae also have interramal papillae, but flabelligerids only have spines in neuropodia, whereas fauveliopsids have spines in both notopodia and neuropodia.
Distinguishing species
Two distinct morphs occur in the family. Some fauveliopsids are short-bodied,
cylindrical, indistinctly segmented, truncate at each end, and
preserved specimens are usually stiff and arched dorsally. The other body form in fauveliopsids is longer, inflated anteriorly and/or posteriorly and with more distinct segmentation.
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