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The prostomium is truncated and the peristomium reduced lips. A pair of lateral antennae and a median antenna usually present. The ventral palps are fused the ventral side of the first segment; they taper and have articulations. Nuchal organs have not been observed. The arrangement of the longitudinal muscles has not been recorded. Segmentation of the body is distinct. The first segment curves around the prostomium and bears welldeveloped parapodia, the neuropodia of which are fused to lower side of the head; chaetae are present in some taxa and two pairs of tentacular cirri may be present. In other segments, the neuropodia are better developed than notopodia, but both have a well-developed ramus. The dorsal cirri alternate with elytra in segments in Pholoides; Pholoe, however, lacks cirriform dorsal cirri and elytra are present on every second segment anteriorly and on all posterior segments. Ventral cirri and pair of pygidial cirri are present. Branchiae and epidermal papillae are lacking and lateral organs and dorsal cirrus organs have not been observed. The buccal organ is an axial, muscular, eversible pharynx, bearing terminal papillae anteriorly and two pairs of dorso-ventrally arranged jaws. gular membrane is lacking; the gut is a straight tube. In juvenile Pholoe minuta, nephridia reported to be metanephridia without any mesodermal involvement; the condition of mature individuals is unknown. Aciculae are present. Compound falcigerous chaetae are present and have single ligaments (soft tissue connects the shaft to blade in compound chaetae); they resemble those present certain sigalionids (for example, Sthenelanella). Other chaetae are variously ornamented capillaries. Epidermal papillae similar to those present in the aphroditids may be present.

The above definition is taken from Hutchings (2000), which in turn is based on that of Fauchald Rouse (1997).

Identification tips

Recognising the family
Pholoids are small scale worms in which the dorsal surface may be covered with scattered tubercles and the ventral surface may bear papillae. Members of the genus Pholoides have concentric rings on each elytron, such rings are absent on other members of the family.

Pholoids are most likely to be confused with one of the other families that also have dorsal rows of scales. The quick guide to scale worms should help separate these 6 families.

Distinguishing species
Genera definitions in this family are currently being debated, and it has been suggested that the only valid genus in the family is Pholoides and the correct family name is Pholoididae and the genus Pholoe should be placed within the Sigalionidae.


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