NIWA Guide to Polychaeta | Shore polychaetes | Shell polychaetes
Shell worm Boccardia acus Spionidae (spionid)
Spionida (Annelida: Polychaeta)
Boccardia  acus  (Rainer, 1973).   Family Spionidae  
     Boccardia acus head and tail
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 Identification tips:    Acicular posterior notochaetal spines. Distinctive colour pattern(s) absent.
 Habitat: Estuarine, or intertidal marine, or inshore marine embayment, or marine shelf. Known from mollusc shell. In bivalves, or in gastropods. In self-created shell-borings, or in abandoned shell-borings, or in soft rock 'borings' (mudstone, shale, limestone). Recorded from living shells of New Zealand commercial shellfish: Atrina pectinata, Austrovenus stutchburyi, Crassostrea gigas, Haliotis iris, Ostrea chilensis, Pecten novaezelandiae, Perna canaliculus, Paphies spp. Occurrences in empty/dead shell also known. Tube lining present as central partition of sac-like boring. Shell-boring shape sac or pocket. Tube chimney present as glued debri/sand-grains.
 Nomenclature: Genus Boccardia in Family Spionidae. Boccardia acus. Described by Rainer, published in 1973, as Paraboccardia acus. Type locality: New Zealand, Papanui, Otago Peninsula. Other synonyms: none recorded
 Description:  Head region: Prostomium tip weakly notched. Occipital antenna absent. Caruncle extends to anterior chaetiger 3; separate mid-dorsal organ absent. Colouration: Eyes present, two pairs. Dorsal pigmentation pattern absent. Palp banding absent. White mid-body or posterior dorsal pigmentation absent. 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 present. Chaetiger one notochaetae present; notopodial lobe present. Chaetae of chaetiger 5 'upper' (or 'posterior') row falcate without ornamentation, 'lower' (or 'anterior') row are knob-tipped and bristle-topped with subterminal spur. Superior notochaetae of chaetiger 5 present. Posterior notochaetal spines present; mostly acicular (or includes weakly falcate tips). Pygidium flattened ventral half-disc.
 Dimensions: Length 40 mm. Width 0.8 mm. Segment total 120. Palps extend to about chaetiger 15. Usually a slim species.
 Reproduction: Active planktonic dispersal present. Larval nutrition mostly planktotrophic, with early larval release, or nurse egg lecithotrophic; poecilogony occurs. Paratomic budding absent or undetected. Reproductive period all year. Pelagic larva dorsal pigmentation as branched chromatophores, usually pairs.
 Distribution:  Occurs only in New Zealand. Not known to be invasive or anthropochoric. Global distribution includes New Zealand mainland..
 Remarks:  Boccardia acus is very similar to the free-living Boccardia syrtis, and neither species has distinctive colours, but B. acus posterior spines are straight or only slightly curved at the tips, rather than falcate (hooked).
 Biology: Boccardia acus is a slender species most often encountered boring on cockles. It creates sock-like (U-shaped) borings divided into 2 arms by a central partition of debris. Feeding group: Surface deposit/filter-feeding.
 Best References:   Biology: Read (2001) Shell-damaging worms; what and where are they?.. Aquaculture update 29:6-7 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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The information provided by this page and by the pages of the "more information" links is held in a structured form for rapid and frequent updating and improvement. Descriptive text is compiled from a number of database fields, some of which may occasionally be empty.
Data last edited 19/07/2004  (dd/mm/yy), and page last generated by G. Read, 25/07/2004  (dd/mm/yy)