The superfamily EUNICEA is primarily characterized by the presence of a complex pharyngeal apparatus consisting of a pair of ventral mandibles and a varying number of paired dorsal maxillae. The highest number of maxillary pairs is five, which occurs in members of the ARABELLIDAE and LYSARETIDAE. The maxillary apparatus of the DORVILLEIDAE is here interpreted as composed of two or four maxillae with each maxilla separated into rows of denticles, rather than as two or four rows of numerous maxillae.
Maxillae I are often falcate and maxillae II, in most families, are larger and have more teeth than any other jaw-piece. The maxillae are supported posteriorly by paired maxillary carriers. A third median carrier is present in the ARABELLIDAE and LYSARETIDAE; an inferior paired carrier is present in certain DORVILLEIDAE.
The fully developed mandibles are similar in all members of the superfamily.
The parapodia are relatively simple in most species. Neuropodia are always well developed; the maximal development of notopodia is in the LYSARETIDAE, DORVILLEIDAE and ONUPHIDAE, where the notopodia are developed as long dorsal cirri with embedded acicula. EUNICIDAE, LUMBRINERIDAE and ARABELLIDAE have notopodial rudiments without embedded acicula.
Simple, capillary or limbate setae are present in all families in dorsal fascicles. They often have serrated or dentate cutting edges. Composite setae are present in all families except ARABELLIDAE, LYSARETIDAE and some LUMBRINERIDAE. The composite setae are typically falcate and may
have one to several teeth in addition to the falcate main fang. The distal end of each composite seta is covered with a long and pointed or short and blunt hood and the free margins are serrated or smooth. ONUPHIDAE, EUNICIDAE and LYSARETIDAE have enlarged, usually hooded, setae in subacicular positions, called subacicular hooks.
The families may be divided into three groups based on the structure of the pharyngeal apparatus. The first of these groups has paired, short maxillary carriers and at most five pairs of maxillae; this group includes ONUPHIDAE, EUNICIDAE, LUMBRINERIDAE and IPHITIMIDAE (new family). The second group has three prolonged maxillary carriers and at most five pairs of maxillae and includes ARABELLIDAE and LYSARETIDAE. The third group comprises the DORVILLEIDAE, which differs from the other families in that the maxillae are distally broken up in numerous separate denticles arranged
in rows. The maximal number of rows of maxillae is four. One or two pairs of short maxillary carriers are present.