Earthworms (Annelida : Oligochaeta) of Vanua Tu (New Hebrides Islands).

Abstract

Twenty-one species of earthworms, one including two subspecies, are recorded from Vanua Tu (New Hebrides). They comprise 18 species of the 'Pheretima' group of genera, including Amynthas (five spp.), Metapheretima (eight spp.), Polypheretima (one sp.), Pheretima (two spp.) and Pithemera (two spp., one with two subspecies), and three common pantropical species, Dichogaster bolaui, Ocnerodrilus occidentalis and Pontoscolex corethrurus. Seven new species are described. The systematics of the earthworms of Vanua Tu are reviewed, and species in the 'Pheretima' group are classified according to the revisions of Sims and Easton (1972) and Easton (1979). A key is provided for identification of all species. Vanua Tu earthworms show little evidence of niche separation or local speciation and it is concluded that most, if not all, the species have been introduced to the archipelago by pre-European and European man. Relationships between Vanua Tu earthworms and those of other Pacific islands are discussed, and it is shown that a large proportion of the species belong to a widely distributed 'Pacific basin' group. The affinities of this group are with south-east Asian and Indo-Malayan forms, and they are considered to be a group analogous to the small group of European lumbricid species that have been spread by man through much of the temperate regions of the earth.