NIWA Guide to Polychaeta | Shore polychaetes | Shell polychaetes
Shell worm Dipolydora armata Spionidae (spionid)
Spionida (Annelida: Polychaeta)
Dipolydora  armata  (Langerhans, 1881).   Family Spionidae  
     Dipolydora armata colony on abalone shell
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Show available picture(s) for Dipolydora armata
 Identification tips:    Posterior notochaetal spines, few branchiae. 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 (colonial with interconnecting tubes). Recorded from living shells of New Zealand commercial shellfish: Haliotis iris, Perna canaliculus. Tube lining absent. Shell-boring shape random track single-width tube. Tube chimney present as glued debri/sand-grains.
 Nomenclature: Genus Dipolydora in Family Spionidae. Dipolydora armata. Described by Langerhans, published in 1880, as Polydora armata. Type locality: Madeira. Other synonyms: Polydora monilaris Ehlers, 1905
 Description:  Head region: Prostomium tip pronounced notch. Occipital antenna absent. Caruncle extends to mid chaetiger 2; separate mid-dorsal organ absent. Colouration: Dorsal pigmentation pattern absent, or present (may be present in juveniles); dark anterior dorsal pigmentation present (orange-brown prostomium noted in juveniles (on Bluff Haliotis, Sept 2002)). Palp banding absent. White mid-body or posterior dorsal pigmentation absent. Other colouration includes pygidium opaque white. Branchiae, chaetae, and pygidium: Branchiae adjoining parapodia 7 and following; near body end branchiae absent; end at 13. Anterior gut gizzard-like structure absent. Hooded hooks begin chaetiger 7; 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. Neurochaetal inferior chaetae below hooded hooks present. Chaetiger one notochaetae present; notopodial lobe present. Chaetae of chaetiger 5 'upper' (or 'posterior') row falcate with subterminal flange cowl-like, 'lower' (or 'anterior') row are 'companion' chaetae absent. Superior notochaetae of chaetiger 5 present. Posterior notochaetal spines present; mostly acicular. Pygidium with 4 distinct lobes, upper lobes smaller (a thick plug-like collar).
 Dimensions: Length 6 mm. Segment total 40.
 Reproduction: Larval nutrition nurse egg lecithotrophic. Architomic asexual division present. Reproductive period November - January (sexual), with probable asexual architomic population increase of immature individuals.
 Distribution:  World distribution includes New Zealand and elsewhere. Probably invasive or anthropochoric. Global distribution includes New Zealand mainland, Australia, within south east coast and Tasmanian zone, North America, Pacific coast (to Panamanian Isthmus), China, Taiwan, East China Sea region, Philippines, and South China Sea region, Mediterranean, Atlantic European coasts..
 Remarks:  Polydora armata probably has several further synonyms around the world. For example Polydora rogeri Martin, 1996 [fide Radashevsky & Nogueira 2003]
 Biology: Polydora armata can occur in colonies of spectacular densities. However, it is a very small surface borer and, while its presence may occasionally trigger shell-thickening, it is not normally shell-penetrative. Feeding group: Surface deposit/filter-feeding.
 Best References:   Biology: Radashevsky and Nogueira (2003) Life history, morphology and distribution of Dipolydora armata (Polychaeta: Spionidae).. Journal of the Marine Biological Association of the United Kingdom 83:375-384 Taxonomy: Read (1975) Systematics and biology of polydorid species (Polychaeta: Spionidae) from Wellington Harbour. Journal of the Royal Society of New Zealand 5:395-419.

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

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Data last edited 23/07/2004  (dd/mm/yy), and page last generated by G. Read, 25/07/2004  (dd/mm/yy)