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Taxonomic information across the Internet

Spionidae

This questionnaire deals with describing specimens of the family Spionidae Grube 1850. Spionids are common members of soft-sediment communities and are particularly species rich. For example, they account for 12.8% of all polychaetes collected off the west coast of Phuket Island in Thailand (Hylleberg & Nateewathana, 1984. Proceedings of the First International Polychaete Conference. Linnean Society of New South Wales).

What does a spionid look like?

Pygospio elegans - a spionid worm

Spionids are elongated worms. The body regions are not rigidly distinct but can be differentiated by changes in the shape of the parapodia and types of setae. They use two long palps to carry food to the mouth, (sometimes called tentacles) which arise on the peristomium. Unfortunately, the palps have a tendency to drop off when the animal is fixed. The prostomium is variable in shape between genera and species, so it is a good taxonomic character. Branchiae or gills are found in most genera and their distribution is also a taxonomic character. Again branchiae break off when the animal is fixed unless care is taken to relax the specimen first. Parapodia are biramous, possessing a dorsal notopodium and ventral neuropodium. Setal types include simple capillaries, thickened sabre setae and hooks (which may be hooded).

What other families could be confused with the Spionids?

Heterospionidae. Superficially, specimens of this family may resemble spionids. They have a similar shape of body and long feeding palps arising from the peristomial region. There are distinct differences: the anterior part of the body possesses long filiform branchiae or gills which are more like those found on cirratulids, the setae of posterior segments form nearly complete rings around the segment, most of the setae are simple capillaries. (See Heterospionidae in the Family Browser)

Trochochetidae. This family possesses species with distinct body regions and there are three processes projecting from the prostomial region. The neuropodia of the first setiger (the first segment bearing setae) are long and project forwards forming an open mesh around the head. (See Trochochaetidae in the Family Browser)

Chaetopteridae. Apart from the very distinctive Chaetopterus variopedatus, other species can superficially resemble spionids. They can be distinguished by the lack of neuropodial (ventral) setae, by the presence of enlarge setae on setiger 4, distinctly lobed posterior notopodial lobes and a distinctive enlarged mouth region, and the presence of neuropodial uncini. (See Chaetopteridae in the Family Browser)

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