Longosomatidae

Identification guide

The description of the single genus of Longosomatidae, Heterospio, is that of the family, and follows Borowski (1995).

Heterospio
The prostomium is subtriangular and carries eversible nuchal organs. The peristomium is reduced and bears a pair of grooved palps. The thoracic region of 7 to 9 (usually 9) chaetigers has segments with low postchaetal lobes; dorsal and ventral cirri are absent. Post-thoracic chaetigers are markedly elongate. Segmental divisions are poorly delimited. Up to eight pairs of filament-like dorsal branchiae are present on thoracic chaetigers from chaetiger 2. The posterior end consists of several short inflated segments carrying falcate spines, pygidial cirri are absent. Aciculae are absent; chaetae occur in dense fascicles of capillaries, including thickened aristate and subuluncini-like capillaries, and spines.

Borowski (1995) tabulates and compares the 6 known species of Heterospio, as well as several undescribed forms.

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