The "African" Shrimp Genus Potamalpheops in Australia, With the Description of P. Hanleyi, New Species (Decapoda: Alpheidae)

Abstract

Small shrimps collected from a mangrove creek in Darwin Harbor, Northern Territory, Australia, belong to a new species of alpheid shrimp, Potamalpheops hanleyi, which is described and illustrated. The genus Potamalpheops, not previously recorded from the Australian continent, is known from four species in West Africa, in brackish and fresh water, and a single species occurring in a cave in Mexico. The disjunct distribution on three continents suggests an ancient origin for the genus and an original Tethyan distribution. The genus Potamalpheops was first designated by Powell (1979) to include P. pylorus Powell from Nigeria, as well as two other species, originally described as species of Alpheopsis by Coutiere (1906) and Sollaud (1932), P. haugi from Gabon and P. monodi from the Cameroons and Senegal, respectively. The genus is also represented in Central America by a single troglobitic species, P. stygicola (Hobbs, 1973), from Oaxaca, Mexico, originally also placed in the genus Alpheopsis by Hobbs (1973) and subsequently transferred to the genus Potamalpheops by Hobbs (1983). The discovery of a further species on another continent, Australia, therefore represents a very considerable increase in the known distribution of the genus. The present lack of records between the known occurrences of species of Potamalpheops suggests that they represent relict populations derived from a former wider distribution, and an ancient origin in Tethyan seas.