Xeruca Shih, 2015

Shih, Hsi-Te, Ng, Peter K. L., Davie, Peter J. F., Schubart, Christoph D., Türkay, Michael, Naderloo, Reza, Jones, Diana & Liu, Min-Yun, 2016, Systematics of the family Ocypodidae Rafinesque, 1815 (Crustacea: Brachyura), based on phylogenetic relationships, with a reorganization of subfamily rankings and a review of the taxonomic status of Uca Leach, 1814, sensu lato and its subgenera, Raffles Bulletin of Zoology 64, pp. 139-175 : 159

Xeruca Shih, 2015 , status nov.

( Fig. 12B )

Xeruca Shih, 2015: 154 . Type species: Uca formosensis Rathbun, 1921 , by original designation. Gender feminine.

Diagnosis. Large-sized species (carapace width about 30 mm in adults); dorsal carapace surface without posterolateral striae; front narrow; cornea round; eyestalks slender; adult male major cheliped very large; right- or left-handed, deep fingers (with straight cutting margins>1/2 length of fingers), pollex without ventral carina, outer surface of major manus with moderate-szied to large tubercles, carpus with anterodorsal area flattened to facilitate chela flexion, setae on merus of minor cheliped long, thin; male pleonites free; pleonal locking mechanism absent; no setae on lateral margins of posterior stem region of urocardiac ossicles in gastric mill. Taiwan endemic.

Species included:

Xeruca formosensis ( Rathbun, 1921) .

Remarks. Although Rathbun described this large endemic Taiwanese species in Rathbun (1921), it was not well known until the work of Shih et al. (1999). Crane (1975) placed it with U. tetragonon and the U. vocans species-complex, in Thalassuca (= Gelasimus ), although she had examined only a few specimens. Shih et al. (1999) suggested that it was closely related to Tubuca , but cautioned that more study was needed to confirm its status. Shih (2015) recently established a separate taxon Xeruca for this species based on morphological (see Rosenberg, 2001) and molecular evidence. The present work ( Fig. 2 ) and Shih (2015) show Xeruca to be basal to the main Tubuca clade which confirms earlier relationship speculation ( Crane, 1975; Shih et al., 1999; Rosenberg, 2001). The monotypic Xeruca is confined to Taiwan Island and the adjacent Penghu Islands, and thus has the smallest distribution of any genus in the Ocypodidae ( Fig. 4 ).

Figures

Fig. 12. Photographs of some species of the genera Tubuca, Xeruca and Ucides. A, T. urvillei (Ranong, Thailand); B, X. formosensis (Taiwan); C, D, U. cordatus (Brazil).

Fig. 2. A Bayesian inference (BI) tree of the family Ocypodidae and outgroups, based on the combined 28S, 16S and COI markers. The solid circle at the node means it is strongly supported by both BI (≥ 90) and ML (≥ 70); and the open circle means only one method is strongly supported. Name of species or genus quoted means it is suggested as a synonym in this study.

Fig. 4. The distribution of 11 genera of fiddler crabs, mainly based on Crane (1975) and the website (http://www.fiddlercrab.info/index. html; Rosenberg, 2014).