Ten species of the decapod crustacean genus Callianassa have been collected in south Florida. Of that number, Callianassa branneri (Rathbun) and C. acanthochirus (Stimpson) had been reported previously from the area, but C. marginata Rathbun, C. latispina
Dawson, C. longiventris A. Milne-Edwards, C. rathbunae Schmitt, and C. guassutinga Rodrigues had not. In addition, three new species, C. trilobata,C. fragilis, and C. quadracuta, were discovered and reported earlier (Biffar, 1970). All species are
described and illustrated. The accounts include complete synonymies, numerous new records for both south Florida and other areas of the western Atlantic, color notes, remarks on the ecology of the species, and a discussion of the intraspecific variation and interspecific affinities. The
literature dealing with all western Atlantic species has been reviewed, and measurements and terminology used in the descriptions have been defined. Two keys have been provided to make possible identification of most western Atlantic species of Callianassa. The first key is based solely
on large chelipeds, and the second utilizes characteristics from the remainder of the animal. These keys include 19 species. Insufficient information exists to permit inclusion of C. occidentalis Bate and C. grandimana Gibbes in either key, but the latter species is discussed
in detail. Callianassa siguanensis (Boone) is synonymized with C. branneri.
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