PORT PHILLIP BAY


Ragworm 

Simplisetia amphidonta Hutchings & Turvey, 1982

View scientific description and taxonomy

Scientific Details

Family level description.
Nereididae are polychaetes with many uniform segments, without strongly differentiated body regions. The prostomium (head) has one pair of antennae, one pair of articulated palps, and two pairs of eyes. Four pairs of unjointed cirri emerge from the next segment behind the prostomium. Mouthparts comprise an eversible pharynx with one pair of terminal jaws, although these are usually only visible by dissection.

Species level technical description.
Prostomium with entire anterior margin. Maxillary ring of pharynx with conical paragnaths: Area I: about 11; II: 8; III: about 19; IV: 15-17. Oral ring paragnaths absent. Paragnaths red-brown and both conical and rod-like. Dorsal notopodial ligule not markedly elongate on posterior chaetigers. Not markedly broader on posterior chaetigers. Dorsal notopodial ligule not markedly reduced on posterior chaetigers. Prechaetal notopodial lobe present. Dorsal cirrus not terminally attached to dorsal notopodial ligule on posterior chaetigers. Dorsal cirrus length about 1 times ventral notopodial ligule at chaetiger 10-20. Neuropodial postchaetal lobe present, at least on some anterior chaetigers. Ventral neuropodial ligule on posterior chaetigers reduced, up to half length of acicular neuropodial ligule (absent posteriorly). Ventral cirri single. Notopodial homogomph spinigers present. Notopodial homogomph falcigers absent. Neuropodial dorsal fascicle fused falcigers present.

Taxonomy

Phylum:
Annelida
Class:
Polychaeta
Order:
Phyllodocida
Family:
Nereididae
Genus:
Simplisetia
Species:
amphidonta

General Description

In members of this genus there are robust, simple chaetae in which the articulation between shaft and blade is fused; these simple chaetae are usually dark enough to be seen under stereo microscope and are present in the middle buch of chaetae starting at about 12-15. Paragnaths are present, but only on the maxillary ring (closest to the jaws) of the eversible phayrnx. This species can be distinguished from the only other common member of the genus in southern Australia, Simplisetia aequisetis, by having 10 or fewer paragnaths on each of Areas II and III of the eversible pharynx, and these paragnaths are often a gold or brown colour (not dark). Simplisetia aequisetis occurs in estuarine conditions while Simplisetia amphidonta occurs in fully marine environments. Body up to about 3 cm long.

Habitat

Coastal bays, occasionally intertidal but normally at depths of 3-15 m.

Soft substrates

Distribution guide

South-eastern Australia.

Species Group

Worms Ragworms

Depth

Shallow (1-30 m)

Water Column

On or near sea floor

Max Size

3 cm

Commercial Species

No

Species Code

MoV 1094

Identify

Conservation Status

  • DSE Advisory List : Not listed
  • EPBC Act 1999 : Not listed
  • IUCN Red List : Not listed

Author

article author Wilson, R.

Robin Wilson is a Senior Curator of marine invertebrates at Museum Victoria.

citation

Cite this page as:
Wilson, R., 2011, Ragworm, Simplisetia amphidonta, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 21 Oct 2017, http://portphillipmarinelife.net.au:8098/species/7626

Text: creative commons cc by licence