A North American Xanthoid Crab New to Britain

Abstract

INVESTIGATIONS of the fauna of artificially warmed docks in Swansea have revealed the presence of xanthoid crabs identified as Neopanope texana sayi (Smith). Specimens agree well with descriptions given by Rathbun¹ and Ryan², and they have been compared with material in the British Museum (Natural History). The previous known distribution of N. t. sayi was along the east coast of North America from Florida northwards to the Gulf of St. Lawrence^1,2 and the present record appears to be the first for the British Isles. There are shipping lines which operate between the east coast of North America and Swansea, and it is no doubt by this means that the crab has been accidentally transported. Wolff³ has previously suggested that the crabs Callinectes sapidus Rathbun and Rhithropanopeus harrisi Gould may have reached the coasts of Europe from North America in the ballast tanks of ships, and Neopanope has probably been carried to Britain in, the same manner. In North America N. t. sayi is reported especially from muddy places and on piles among algae². The habitat is similar in Swansea where specimens have been collected regularly among Ciona intestinalis (L.) and other fouling organisms⁴ on wooden piles, in a region where the floor of the dock is muddy. The occurrence of the crabs on dock piles and timbers would no doubt enable them or their larvæ to find their way into ships' condenser tubes and ballast tanks, in which they could then be transported to a new locality.