Tardigrades from Australian Marine Caves. With a Redescription of Actinarctus neretinus (Arthrotardigrada)

Abstract

Several marine caves in Australia have been investigated for meiofauna using a freshwater technique to shock large sediment samples. Several species of nematodes, gastrotrichs, crustaceans, polychaetes and aplacophorans were found, and one new species of kinorhynch has been described. In addition, two new species of loriciferans from marine caves in New South Wales, Australia, are under description. This paper is the second in a series describing the unique meiofauna in submarine caves and inland anchialine caves of Australia. The paper deals with the tardigrade fauna of two caves, Jim's Cave and Fish Rock Cave, both located off the coast of New South Wales. The sediment consists of carbonate sediments (shell-hash to shell-gravel) mixed with organic detritus. The abundance of tardigrades is very low in the two caves, but the species diversity is very high. The following arthrotardigrade genera have already been found: Actinarctus, Batillipes, Dipodarctus, Halechiniscus, Raiarctus, Styraconyx, Tanarctus, Tholoarctus, and Wingstrandarctus. The cave fauna of tardigrades seems not to be related to the well-investigated high energy beach fauna of tardigrades along the East Coast of Australia. Most surprising is the discovery of the species Actinarctus neretinus known from the Italian cave, Grotta Cattedrale, supporting the theory that marine caves serve as refuges for an old Tethyan fauna.