prostomium


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prostomium

(prō-stō′mē-əm)
n. pl. prosto·mia (-mē-ə)
The anterior portion of the head of an annelid worm, situated in front of the mouth.

pro·sto′mi·al (-əl) adj.

prostomium

that part of the head of some annelids and molluscs which lies in front of the mouth.
References in periodicals archive ?
websteri showed variation in palp pigmentation pattern, the shape of the anterior edge of the prostomium, the shape of the major spines on chaetiger 5, and shape of the pygidium (Table III).
Diagnosis: The prostomium is split anteriorly and the notopodial ligules are well developed anteriorly but reduced in posterior segments.
Other authors (Ewing, 1984; Read, 2000) have suggested that the first segment posterior to the prostomium, or peristomium, is dorsally subdivided, and includes two segments, a position that we agree with, due to the fact that in C.
Body straight and white, resembling a boon of flax, segments extended; anteclitellar portion tapering; prostomium conical, sharp, often ending with a small knob (Fig.
antennata Savigny, 1822, the antennae are more markedly moniliform, the prostomium is more prominent and the peristomium does not cover the eyes.
Morphologically, it is characterized by a blunt prostomium forming a hood over its mouth.
The operculum (Figure 1a) is a thick muscular plate which forms the anterodorsal surface of the (fused) prostomium and peristomium.
A pair of transparent palps is located terminally and nearly ventrally on the prostomium about 0.
The specimens of this family have elongated bodies, with a rounded prostomium carrying two small palps located near the mouth.
Naineris bicornis is the most similar species, and the only differences are the bifid prostomium, the distinct fimbriation of branchiae and a slightly larger number of thoracic chaetigers, about 50, of which 10 form the transition region (Hartman 1951, Taylor 1984).