Fiddler crabs (genus Uca) with broad-fronts (BF) belong to a group of small-sized species with complex behaviors and have been suggested to be more “advanced” compared to the narrow-fronted species groups. Three Indo-West Pacific subgenera, Austruca Bott, 1973, Cranuca Beinlich & von Hagen, 2006, and Paraleptuca Bott, 1973, are reappraised using two mitochondrial (16S rRNA and cytochrome oxidase I) and one nuclear (28S rRNA) markers. The phylogenetic analyses show that the three clades agree relatively well with the three subgenera as currently defined. Our study confirms that the Indo-West Pacific BF species that had been placed with the American Celuca sensu Crane, 1975, are genetically unsupported, and should be classified in Austruca, together with U. sindensis (Alcock, 1900) (currently in Paraleptuca). Austruca now contains 11 species. Cranuca, a subgenus established with only U. inversa (Hoffmann, 1874), is supported by its monophyly and its significant distance from other subgenera. In addition, Paraleptuca (= Amphiuca Crane, 1975) is restricted for U. chlorophthalmus (H. Milne Edwards, 1837), U. crassipes (White, 1847) and U. splendida (Stimpson, 1858). The two American BF subgenera, Minuca Bott, 1954 and Leptuca Bott, 1973, form a mixed clade and further studies will be needed to clarify their validity.

Key words: Uca, Austruca, Cranuca, Paraleptuca, fiddler crab, 16S rRNA, cytochrome oxidase I, 28S rRNA.

Figure 1. A Bayesian inference (BI) tree of species of the Indo-West Pacific (IWP broad-fronted (BF) fiddler crabs (subgenera Austruca, Paraleptuca and Cranuca) and the comparative taxa (the American Minuca and Leptuca, the eastern Atlantic Afruca, and IWP narrow-fronted Tubuca, Australuca and Gelasimus), based on the combined 16S rRNA, cytochrome oxidase subunit I genes (COI) and 28S rRNA. Probability values at the nodes represent confidence values for BI and maximum likelihood (ML). The doted lined block means the Uca lactea complex. For the clade of “Minuca & Leptuca”, the species names with gray block belong to the subgenus Minuca, and the remaining species belong to the subgenus Leptuca.