Distribution and conservation status of two endemic Tasmanian crustaceans, Allanaspides hickmani and Allanaspides helonomus (Syncarida: anaspididae)

Abstract

Extant representatives of the ancient crustacean family Anaspididae (Syncarida) are restricted to the island state of Tasmania, Australia. The most recently described species, Allanaspides helonomus Swain, Wilson, Hickman & Ong, 1970 and A. hickmani Swain, Wilson & Ong, 1971, were described from buttongrass moorland in southwestern Tasmania. Large areas of their habitat were subsequently inundated for hydroelectric power generation. We surveyed the extant distributions of A. hickmani and A. helonomus, assessed potential threats to the species, and reviewed their conservation status against state, national and international criteria. A. hickmani is restricted to a single catchment and occurs in a very small number (<10) of highly fragmented subpopulations on the margins of two hydroelectric impoundments. A. helonomus has a substantially larger range and Area of Occupancy spanning three separate catchments, and is now known to also occur in the Lake Pedder hydro-electric impoundment. Both species are listed as vulnerable on the IUCN Red List. This listing appears warranted for A. hickmani based on its restricted Area of Occupancy and the small number of extant subpopulations. However, A. helonomus no longer appears to fulfil the IUCN criterion for vulnerable. Neither species appears to be eligible for listing as vulnerable under the Australian Environment Protection and Biodiversity Conservation Act 1999 and the Tasmanian Threatened Species Protection Act 1995. The current listing of A. hickmani as rare under the Tasmanian Threatened Species Protection Act 1995 appears warranted as extant subpopulations may be at risk of extinction. The level of risk for A. helonomus is considerably lower than is the case for A. hickmani, and A. helonomus may not be eligible for listing as rare. The potential impacts of climate change on buttongrass moorland may present the most serious long-term threat to the two Allanaspides species.