Family ENCHYTRAEIDAE d'Udekem, 1855

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Family ENCHYTRAEIDAE d'Udekem, 1855

Compiler and date details

Adrian M. Pinder

Enchytraeidae D'Udekem, J. 1855. Nouvelle classification des Annelides setigeres abranches. Bulletin de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique 22: 533-555.
Type genus:
Enchytraeus Henle, 1837.

Introduction

Enchytraeids are generally small pale coloured worms with simple-pointed chaetae often arranged ventro-laterally and laterally, rather than ventro- and dorso-laterally. They inhabit a wide range of habitats, from marine sediments, to stream and lake beds (including salt lakes in Australia) and are common members of terrestrial soil communities. There are over 450 species in 28 genera worldwide. The Australian fauna (39 species in eight genera) is smaller than expected for such a large and diverse land mass with an extensive coastal area. However, the Australian fauna is very poorly studied, other than the marine enchytraeids of some regions (south-western Australia and Darwin). Freshwater and terrestrial habitats have been particularly neglected.

The first report of enchytraeids from Australia was by Michaelsen (1907), who noted four species from south-western Australia, including two new: Grania principissae from intertidal sediments and Marionina normani from a freshwater brook. Later, Benham (1905, 1922) and Stephenson (1932) published accounts of four species from the Macquarie Islands, found in peat bogs and along the shoreline. No further work was undertaken on Australian enchytraeids until Springett (1971) described three species of terrestrial Distochopus from south-western Australia, and Jamieson (1977) described a subspecies of Grania macrochaeta from the Great Barrier Reef. More recently, some work has been done on marine enchytraeids from Albany and Rottnest Island in Western Australia (Coates 1990; Coates & Stacey 1993), Darwin (Coates & Stacey 1997; Healy & Coates 1997) and Tasmania (Rota & Erseus 2000).

Of the eight genera known to occur in Australia, six (Enchytraeus, Grania, Randidrilus, Stephensoniella, Lumbricillus and Marionina) are recorded from the marine intertidal or shallow subtidal, with one species of Marionina also reported from freshwater and Lumbricillus also known from brackish water. Cognettia occurs in peat bogs and Distichopus in terrestrial habitats with some incursions into the supralittoral habitats of beaches.

There is presently no widely accepted subfamilial classification for the Enchytraeidae. Cernosvitov (1937) proposed a such a classification, but it has been largely ignored. Coates (1989) provided a phylogenetic analysis of many genera that could serve as the preliminary basis for assessing the subfamilial classification proposed by Cernosovitov or for suggesting a new scheme.

Enchytraeids feed on microorganisms, bacteria, fungi, microalgae and protists (Didden 1993). They are important, as are other clitellates, in the breakdown of organic materials and nutrient cycling in a variety of habitats. In acidic soils and on some organically enriched beaches, or even those covered during oil spills, these worms can be among the most abundant macrofauna involved in bioturbation of sediments.