Freshwater limpets

Latia manuherikia is the first fossil freshwater limpet to be found in New Zealand. It belongs to the family Latiidae, a group that provides strong evidence of a former land connection between New Zealand and South America.

Latia manuherikia is based on two specimens from approximately 20 million year old sediments deposited in an ancient lake near what is now Saint Bathans in Otago.  It was described as new to science by Te Papa’s Bruce Marshall.

The specimens were sorted from a large volume of sediment collected by Trevor Worthy (University of Adelaide), Te Papa’s Alan Tennyson, and other researchers.

Latia manuherikia is the first fossil record of Latia, a genus of freshwater limpets that are endemic to New Zealand, where it is represented by two living species, Latia neritoides and L. lateralis. The two living species are common in streams throughout the North Island, where they live attached to rocks. Latia species are unusual in being the only known luminescent freshwater molluscs in the world, the bright luminescence (a form of luciferin) being secreted by the animal when it is disturbed.

Latia species are of particular interest and importance because their closest relatives are freshwater snails of the family Chilinidae, which is endemic to South America, and unknown from anywhere else in the world. Since neither the adults nor their eggs or larvae can survive in the sea, the common ancestors of Latia and Chilinidae evidently date back more than 80 million years, when New Zealand began separating from the former continent of Gondwana, which broke up to form New Zealand, Antarctica, South America, Australia, New Caledonia, New Guinea, Africa, Madagascar and India.

Reference:
Marshall BA (2011) A new species of Latia Gray, 1850 (Gastropoda: Pulmonata: Hygrophila: Chilinoidea: Latiidae) from Miocene Palaeo-lake Manuherikia, southern New Zealand, and biogeographic implications. Molluscan Research 31: 47-52.   Online abstract.