NIWA Guide to Polychaeta | Shore polychaetes | Shell polychaetes
Shell worm Boccardia knoxi Spionidae (spionid)
Spionida (Annelida: Polychaeta)
Boccardia  knoxi  (Rainer, 1973).   Family Spionidae  
     Boccardia knoxi dorsal anterior
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 Identification tips:    Tube lining and projecting tube is a clear secretion. Distinctive colour pattern(s) absent.
 Habitat: Intertidal marine, or inshore marine embayment. Known from mollusc shell. In bivalves, or in gastropods. In self-created shell-borings, or under/in coralline/sponge/calcareous crust (other than on shell), or in serpulid tube walls. Recorded from living shells of New Zealand commercial shellfish: Atrina pectinata, Haliotis iris, Ostrea chilensis, Perna canaliculus. Tube lining constructed of clear secretion. Shell-boring shape random track single-width tube. Tube chimney present as secretion.
 Nomenclature: Genus Boccardia in Family Spionidae. Boccardia knoxi. Described by Rainer, published in 1973, as Paraboccardia knoxi. Type locality: New Zealand, Otago Harbour. Other synonyms: none recorded
 Description:  Head region: Prostomium tip bifurcation absent, or weakly notched. Occipital antenna absent. Caruncle extends to anterior chaetiger 4; separate mid-dorsal organ absent. Colouration: Eyes present, one pair. Dorsal pigmentation pattern absent. Palp banding absent. White mid-body or posterior dorsal pigmentation absent. Other colouration includes weak white pigmentation on pygidium, traces of dusky brown pigment intersegmentally in ventral midbody, and light-reflecting surface granules on posterior dorsal surface. Branchiae, chaetae, and pygidium: Branchiae adjoining parapodia 2-4, then 6 and following; longest branchiae on chaetiger 10 or later; near body end branchiae absent. Anterior gut gizzard-like structure absent. Hooded hooks begin chaetiger 8; bifid, hook shaft constriction (manubrium) absent, anterior hooded hook main fang more or less oriented at right angles to the shaft with wide angle to apical tooth. Alternating capillaries adjacent hooded hooks absent; neurochaetal inferior chaetae below hooded hooks absent. Chaetiger one notochaetae present; notopodial lobe present. Chaetae of chaetiger 5 'upper' (or 'posterior') row falcate without ornamentation, 'lower' (or 'anterior') row are cupped (sub-terminal complete flange), with central point (flange incomplete). Superior notochaetae of chaetiger 5 absent. Inferior neurochaetae of chaetiger 5 present. Posterior notochaetal spines absent. Pygidium pad shaped. Pygidium small, not extending wider than last chaetigers.
 Dimensions: Length 25 mm. Width 0.5 mm. Segment total 100. Palps extend to about chaetiger 25. Short plump with noticeably narrow head.
 Reproduction: Active planktonic dispersal present. Larval nutrition mostly planktotrophic, with early larval release, or nurse egg lecithotrophic; poecilogony occurs. Reproductive period all year.
 Distribution:  World distribution includes New Zealand and elsewhere. Not known to be invasive or anthropochoric. Global distribution includes New Zealand mainland, Australia, within south east coast and Tasmanian zone..
 Remarks:  B. knoxi has been implicated as a blister-inducing species in abalone and Pacific oysters. Further verification of this is required as in each case where this was reported the blister-inducing species P. hoplura was present.
 Biology: Borings are long and 'single track' parallel to shell surface, never penetrating shell interiors. B. knoxi is protected inside its parchment-like tube lining when external shell layers flake away due to dense borings. Feeding group: Surface deposit/filter-feeding.
 Best References:   Biology: Read (1975) Systematics and biology of polydorid species (Polychaeta: Spionidae) from Wellington Harbour.. Journal of the Royal Society of New Zealand 5:395-419 Taxonomy: Rainer (1973) Polydora and related genera (Polychaeta: Spionidae) from Otago waters. Journal of the Royal Society of New Zealand 3:545-564.

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 Genus diagnosis More pictures Further references (biology, etc) Family Spionidae

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Data last edited 19/07/2004  (dd/mm/yy), and page last generated by G. Read, 25/07/2004  (dd/mm/yy)