Terrestricythere, Schornikov, 1969

Horne, David J., Smith, Robin J., Whittaker, John E. & Murray, John W., 2004, The first British record and a new species of the superfamily Terrestricytheroidea (Crustacea, Ostracoda): morphology, ontogeny, lifestyle and phylogeny, Zoological Journal of the Linnean Society 142 (2), pp. 253-288 : 285-287

BIOGEOGRAPHY OF TERRESTRICYTHERE

Living populations (represented by large numbers of individuals) of Terrestricythere species have only been found in two parts of the world: the coastal regions of the NW Pacific (Kuril Islands and near Vladivostok) ( Schornikov, 1969, 1980) and the coast of southern England (as described herein). As discussed above, we do not consider the record of two specimens from a lake in France ( Scharf & Keyser, 1991) to be adequate evidence of a viable living population.

Podocopida Cytheroidea Ishizaki, 1968 1913 )

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Cypridoidea Eucypris virens (Jurine, 1820),1870 )

Furcal rami of A-6 instars Not drawn to scale

sp.

This presents us with an interesting problem: do the English populations represent a hitherto unrecognized component of the native British fauna, or an invasion of an alien species? The fact that Terrestricythere has never previously been reported in the British Isles (in spite of more than a century and a half of collecting on British coasts by many ostracod specialists) could be explained by its unusual habitat, which is likely to have been ignored by those seeking ostracods, but it could also be an indication that it has been introduced to the area relatively recently. The northwest Pacific region is home to two known Terrestricythere species and, as little ostracod research has been done in that area, it could harbour more, perhaps being the centre of distribution of this genus. Its ability to survive in merely damp conditions for weeks or months would clearly be advantageous to transport by migrating birds (as has been proposed for cypridoidean ostracods with resting eggs; see, e.g. Horne & Smith, 2004), which, as we have already noted, would help to explain the isolated records in France and at Porlock.

Transport by human activity is another possibility, and we speculate that the transfer of amphibious mil-

A-7 Pore Systems

Terrestricythere Loxoconcha Uncinocythere occidentalis elisabethae sp. nov. uranouchiensis Ishizaki, 1968 (Kozlof f & Whitman, 1954) Terrestricytheroidea (Loxoconchidae) ( Entocytheridae ) Cytheroidea Cytheroidea itary vehicles and/or aircraft between the north-west Pacific and north-west Europe during World War II might have provided opportunities for introducing the ostracod to Britain. Whether T. elisabethae is a rare British endemic or a potentially damaging invader, it deserves greater attention than it has hitherto received.