University Of Tasmania

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The Derwent River seastar: re-evaluation of a critically endangered marine invertebrate

journal contribution
posted on 2023-05-19, 21:23 authored by O'Hara, TD, Mah, CL, Hipsley, CA, Bribiesca-Contreras, G, Neville BarrettNeville Barrett

The Derwent River seastar, ‘Marginaster’ littoralis (Echinodermata: Asteroidea), has been assessed as critically endangered owing to its highly restricted range within one estuary in Tasmania, Australia. However, there have been concerns about the validity and status of the species. Here, we use non-invasive X-ray computed tomography to review the morphology of the holotype. This reveals the presence of internal ossicles to strengthen the disc margin, a character that requires the taxonomic transfer of this species to the family Asterinidae, genus Patiriella. The presence of relatively long marginal spinelets (0.7–0.9 mm) reliably distinguishes this species from the invasive congeneric Patiriella regularis (0.2–0.35 mm). These findings remove doubt about the validity of the species; the recorded habitat and restricted range of Patiriella littoralis are not exceptional for an asterinid seastar. The weight of evidence suggests that it is an endemic species, rather than a transient exotic introduced to Tasmania via shipping or food importation. Its known habitat has been severely impacted by urbanization, poor water quality and invasive species. Targeted surveys in 1993 and 2010 failed to find this species, and it is highly probable that the Derwent River seastar is now extinct; one of the few documented recent marine invertebrate extinctions.


Australian Research Council

Department of Environment, Water and Natural Resources

Department of Natural Resources and Environment Tasmania

Department of Parks and Wildlife (Western Australia)

Department of Primary Industries NSW

Parks Victoria

Smithsonian Institution


Publication title

Zoological Journal of the Linnean Society








Institute for Marine and Antarctic Studies


Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

Copyright 2018 The Linnean Society of London

Repository Status

  • Restricted

Socio-economic Objectives

Coastal or estuarine biodiversity; Assessment and management of terrestrial ecosystems