Abstract
In this contribution a new species of the land crab genus Gecarcinus Leach, 1814, from the Neotropical Pacific coast of South America is described and illustrated. In addition to its unique body color, Gecarcinus nobilii sp. n. is distinguished from congeners by a distinctly wider carapace front and differences in the shape of the infraorbital margin. The new species is not isolated from Gecarcinus populations from the Pacific coast of Central America by an insurmountable geographic barrier. Considering the closure of the Panamanian Isthmus as a calibration point for morphological divergence between the trans-isthmian mainland populations of Gecarcinus, the virtual lack of morphological differentiation (other than color) between them and the distinctness of G. nobilii sp. n. suggests that G. nobilii sp. n. evolved from a common ancestor before the Isthmus closed.
Highlights
Land crabs of the genera Gecarcinus Leach, 1814, Johngarthia Türkay, 1970, and Gecarcoidea H
The authors observed a remarkable variability in color and even color changes in single individuals, leaving open the possibility that Pacific G. lateralis might approach the range of variability observed in Atlantic G. lateralis
While the color of examined G. lateralis from the Atlantic coast (n= 362) varied within the range described by Martinez and Bliss (1989), the color of individuals of Pacific G. lateralis examined in this study (n= 316) showed little variation (Fig. 8G, H) and did not approach the range of variability found in G. lateralis from the Atlantic coast of Central America (Table 2) and Bermuda and Bimini Islands
Summary
The description of a new species of the Neotropical land crab genus Gecarcinus Leach, 1814 (Crustacea, Decapoda, Brachyura, Gecarcinidae).
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