WILLIAMS: CRABS OF THE GENUS CALLINECTES 



Figure 24. — Respective geographic distributions of Callinectes arcuatus Ordway, C. danae Smith, C. gladiator Benedict, and C. 

 similis Williams in the Atlantic and eastern Pacific oceans based on specimens studied and verified published records. 



indicate that a sample is not reasonably unified. 

 Throughout the genus great variation in mor- 

 phometry of the body makes keys for identification 

 involving proportions almost impossible to devise 

 unless qualified by exceptions. 



From a different viewpoint, Stephenson et al. 

 (1968) applied methods of numerical analysis to 

 44 species and putative subspecies of Portunus 

 (mainly from America, but certain Indo-Pacific 

 species for comparison), Callinectes, Arenaeus, 

 and Scylla, relying on presence or absence of 57 

 characters to build up a data matrix from which 

 character assessments could be made. The method 

 nicely demonstrates that Callinectes is a very 

 homogeneous group, but the internal relation- 

 ships implied do not correspond harmoniously 

 with classical interpretation. This is not a matter 

 of conflict, but simply one of judgment, the method 

 seeming to be limited by interpretation of charac- 



ter states, weighting being one serious problem 

 and choice of characters another. Were the 

 analysis run with different emphases, results 

 might reflect those to some extent. 



LARVAL DEVELOPMENT 



Among Callinectes species, larval development 

 of only C. sapidus and C. similis has been deter- 

 mined by hatching eggs and rearing in the 

 laboratory. Costlow, Rees, and Bookhout (1959) 

 and Costlow and Bookhout (1959) described seven 

 zoeal stages, atypically an eighth, and a megalopa 

 for C. sapidus. Larvae and megalopae of the two 

 species are apparently almost identical, the stages 

 being similar to those of other portunids (Costlow 

 and Bookhout, pers. commun.). Importantly, the 

 megalopae of Callinectes lack an internal carpal 

 spine on the chelipeds whereas megalopae of Por- 

 tunus have a well-developed spine on this member 



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