by CERF Hub scientist Robin Wilson, Museum Victoria

Determining patterns of diversity on Australia’s continental margin is the prime aim of the Biodiversity project within the Marine Biodiversity Hub, but that aim first requires us to describe that diversity.  Polychaetes (marine segmented worms) typically comprise 40% or more of species and of individuals in marine macrobenthic samples so they are a major component of benthic diversity. 

Their abundance and species richness means that polychaetes are well suited to providing data for bioregional studies and for historical biogeography, as well as for the surrogacy and prediction projects within the hub.  Processing of benthic samples from the most recent research cruises is thus underway in order to generate informative data sets from key polychaete families. 

Reviews of Australia’s polychaete fauna published during the past 10 years provide the taxonomic baseline for such studies, yet research cruises continue to make discoveries.  Exploration of previously poorly-sampled regions of Australia’s coastline has accelerated in recent years, with cruises to the Great Australian Bight and the Arafura Sea (supported by earlier projects of the then Department of Environment), and over most of the length of the Western Australian coast (CSIRO Voyages of Discovery – part of the hub’s data holdings).  Early results include the discovery of two families of polychaetes previously not known from Australia, and little-studied elsewhere: Hartmaniellidae and Fauveliopsidae.

Hartmaniellidae are jawed polychaetes, related to the much more common Eunicidae and Onuphidae (onuphids include the beachworms, well known to anglers on surf beaches).  The family Hartmaniellidae, however, is much less known and is only recorded from Japan, southeast Asia (Andaman Sea, Taiwan Strait, South China Sea), from Madagascar, and from the Gulf of Mexico. Only 3 species are known world wide, although 3 other records may represent undescribed species. We now have two Australian hartmaniellid specimens: one from the Arafura Sea thanks to a Geoscience Australia cruise where Buz Wilson from the Australian Museum led the biology program, and another from a South Australian Research and Development Institute voyage to the Great Australian Bight.  Some authors have suggested that the closest relatives of Hartmaniellidae are extinct polychaete families known from fossil jaws of Palaeozoic and Mesozoic ages, when they were probably more diverse and abundant.  Hartmaniellids have thus been given the title “living fossils” but this is no more so than for many other extant polychaete families, the majority of which have fossil histories or sister taxa dating to the Palaeozoic.  In each case where living hartmaniellids are known, only a single specimen or very few specimens were discovered despite extensive benthic surveys having been undertaken.  So it seems that, rather than being simply uncommonly collected, they may be rare in nature.  Their present distribution and diversity may ultimately have more to say about extinction than about speciation.  The Australian hartmaniellid specimens have not yet been studied in detail, so it is unknown if they represent undescribed species.

Fauveliopsidae are a family of short, vaguely grub-shaped polychaetes comprising about 20 species world-wide.  Most are deep sea species and most live in mollusc shells or in the tests of foraminifera, although one (just to be different) is a deep sea pelagic.  A Challenger station in Australian Antarctic territory collected one fauveliopsid but none were known from mainland Australia.  Recent sorting has discovered 4 specimens from 4 separate stations along the coast of Western Australia, at depths of 400-1400 m.  It would have been surprising if this cosmopolitan family had not eventually been found in Australian waters and their discovery in Australia in 2008 is a reflection of the scant collections of slope and deep sea benthos and the lack of deep sea capability of Australian research vessels.

The first step towards uncovering patterns in biodiversity is the ability to recognise the same species each time it is collected.  These recent discoveries among the polychaetes show that we are now becoming more capable in that goal, and for a more significant component of the marine fauna.

(Image shown:  First polychaete of the family Hartmaniellidae from Australian waters. This specimen is from the Arafura Sea and this ventral view shows the distinctive jawparts. Photo: Lucy Gibson, Museum Victoria.)