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Maldanidae: Praxillella sp.

Maldanids usually have a fixed, maximum number of body segments. The head is formed from the prostomium, the peristomium and, sometimes, at least one achaetous segment. An eversible pharynx, with a simple axial or ventral buccal organ, is present; gular membrane is also present. Maldanids have paired nuchal slits and there is often a cephalic rim and cephalic keel. An anal plaque may also be present; it may have crenulations or cirri on the margin. Each small parapodium consists of a low, rounded notopodium, which has capillary chaetae of various kinds and a neuropodium, which forms a long torus with hooks in one or two rows. The hooks have a large main fang surmounted by a series of smaller teeth; a fringe, or ‘beard’, usually surrounds the basal teeth. The nephridial/coelomoduct system is restricted to a few anterior segments. Maldanids are tubicolous. The tubes usually have a membranous lining and are covered with mud, shell or sand, though some ‘tubes’ are as simple as consolidated burrows. The tubes often extend slightly above the sediment surface.

The above description is taken from Rouse (2000).

Identification tips

Recognising the family
This family is aptly known as the bamboo worms, as segments are elongate and the notopodia and neuropodia form distinct ridges at the segmental margins. Maldanids vary considerably in size, from a few mm to several cms in length. The structure of the anterior and posterior ends is variable. Some taxa have a well developed cephalic plate while in others this structure is poorly developed. The posterior end may have either a well developed anal plaque with crenulated margins or a final simple segment with either a dorsal or terminal anus. Prior to the pygidium a number of achaetous segments may be present. Some genera possess a variable number of segments.

Distinguishing species
Species are distinguished on the structure of the anterior and posterior ends, as well as the structure of the chaetae, anterior neurochaetae may differ in structure from subsequent ones. Because both anterior and posterior ends carry important characters, complete specimens are required for complete identification. Unfortunately, many specimens collected in benthic surveys are incomplete and therefore unidentifiable.


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