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Zootaxa 3974(2): 151-169 (2015)

Chinese

Uca (Xeruca), a new subgenus for the Taiwanese fiddler crab Uca formosensis Rathbun, 1921 (Crustacea: Decapoda: Ocypodidae), based on morphological and molecular evidence

Hsi-Te Shih

The fiddler crab Uca formosensis Rathbun, 1921 (Crustacea: Decapoda: Ocypodidae), restricted to the western part of Taiwan and the offshore Penghu (Pescadores) Islands in the Taiwan Strait, has been placed under the subgenus Uca (Gelasimus) Latreille, 1817 (= Uca (Thalassuca) Crane, 1975) based on only less than a dozen specimens, but later suggested under the subgenus Tubuca Bott, 1973 because the similarity of external morphology. A suite of characters of carapace, major cheliped, gastric mill, male first gonopod, and chela handedness, as well as the phylogenic relationships (mitochondrial 16S rDNA and cytochrome oxidase subunit I, and nuclear 28S rDNA), nevertheless support this species belongs to its own subgenus. A new subgenus Uca (Xeruca) subgen. nov. is herein established for U. formosensis.

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Key words: Xeruca, new subgenus, Uca formosensis, fiddler crab, Ocypodidae, taxonomy, Taiwan, 16S rDNA, cytochrome oxidase subunit I, 28S rDNA

FIGURE 1. Updated distributional records of Uca formosensis of Shih et al. (1999). Black squares (¢) (and gray area) and place names in boldface represent habitats with substantial number of individuals; empty squares (£) and place names in normal font represent habitats with none or few individuals, although the species was formerly recorded from these locations.

FIGURE 2. Uca formosensis. A, B, holotype (USNM 54472, CW 28.8 mm) recognized by Crane (1975); C, D, a paratype specimen (USNM 54472, CW 27.6 mm); E, F, from Haishangu, Hsinchu (NCHUZOOL 13849, CW 32.2 mm), showing the tuberculate swelling on carapace behind right dorsolateral margin (arrowed) (E) and left minor chela (F); G, from Cigu, Tainan (NCHUZOOL 13907, CW 31.8 mm) showing the left minor chela. E, F, G, scale = 5 mm.

FIGURE 3. Uca formosensis, from Haishangu, Hsinchu, Taiwan (NCHUZOOL 13673, CW 27.9 mm), A, dorsal view; B, frontal view showing the right major chela.

FIGURE 4. Carapaces of Uca formosensis and other species with similar morphology. A, U. formosensis (NCHUZOOL 13672, CW 29.6 mm, left-handed; modified from Shih et al. 1999); B, U. bellator (NCHUZOOL 13653, CW 18.7 mm, left-handed); C, U. seismella (USNM 137666, holotype, CW 13.0 mm, right-handed; modified from Crane 1975); D. U. polita (USNM 137667, holotype, CW 22.5 mm, right-handed; modified from Crane 1975); E, U. arcuata (NCHUZOOL 13660, CW 38.2 mm, left-handed); F, U. urvillei (NCHUZOOL 13661, CW 30.1 mm, left-handed); G, U. tetragonon (NCHUZOOL 13664, CW 18.3 mm, right-handed); H, U. jocelynae (NMNS 6177-001, holotype, CW 21.7 mm, right-handed).

FIGURE 5. Major chelipeds of Uca formosensis and other species with similar morphology. A, U. formosensis (NCHUZOOL 13672, CW 29.6 mm; modified from Shih et al. 1999); B, U. longidigitum (NCHUZOOL 13656, CW 16.7 mm); C, U. bellator (NCHUZOOL 13653, CW 18.7 mm); D, U. princeps (SMF 13164, CW 36.5 mm).

FIGURE 6. Uca formosensis, male right first gonopod (G1) (NCHUZOOL 13671, CW 33.0 mm). A, B, C, scale = 500 gm; D, E, scale = 1 mm.

FIGURE 7. Urocardiac ossicle of Uca formosensis. A, B, D, NCHUZOOL 13668 (CW 33.1 mm, ); C, NCHUZOOL 13669 (CW 14.2 mm, ); E, NCHUZOOL 13670 (CW 26.2 mm, ).

FIGURE 8. Urocardiac ossicles of Uca tangeri (A, NCHUZOOL 13655, CW 26.9 mm, ), U. stylifera (B, NCHUZOOL 13578, CW 21.9 mm, ), U. acuta (C, NCHUZOOL 13665, CW 19.0 mm, ), U. lactea (D, NCHUZOOL 13213, CW 15.4 mm, ), U. tetragonon (E, NCHUZOOL 13666, CW 17.0 mm, ), and U. vocans (F, NCHUZOOL 13667, CW 20.2 mm, ). A, B, E, F, scale = 10 mm; C, D, scale = 5 mm.

FIGURE 9. A Bayesian inference (BI) tree of Xeruca subgen. nov. and other related subgenera, based on the combined 16S rRNA, cytochrome oxidase subunit I genes (COI) and 28S rRNA. See Table 1 for details of the specimens. Probability values at the nodes represent support values for BI and maximum likelihood (ML).

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