Three new species of Pseudothelphusa from Venezuela (Crustacea Brachyura Potamonidae)

During a study of the Potamonidae in the collections of the Museum of Biology of the Central University of Venezuela, Caracas, three undescribed species of Pseudothelphusa were found. One of these was discovered in material from the Venezuelan Guiana. While the other two probably came from the same area, the labels in the corresponding jars were only marked "Venezuela". The three species are closely related to each other as is suggested by the close similarity in the shape of the first pleopod of the male in each. The lateral teeth of the carapace are larger in these species than in the others described from northern Venezuela (Rodriguez, 1966). In the following descriptions the abbreviations cb. and cl. are used for "carapace breadth" and "carapace length", respectively. The material is deposited in the Museum of Biology of the Central University of Venezuela, Caracas, for which the abbreviation MB has been used, and in the Rijksmuseum van Natuurlijke Historie, Leiden. I am most grateful to the authorities of the Caracas institute for the privilege of studying these and other fresh-water crabs in their collections. I am greatly indebted to Mr. Andrés Eloy Esteves for the photographs that illustrate this paper. Pseudothelphusa orinoccensis new species (text-fig. 1, 2; pl. 1) The upper border of the front is well marked by a row of approximately 30 flat, square tubercles. In the type specimen this row is continuous, not interrupted in the middle by the median groove of the carapace, but in other specimens the ridge has a notch in the middle. Laterally the upper border joins abruptly the orbital margin. This upper border is straight in frontal