Xeruca Shih, 2015

Zhang, Ying-Chen & Shih, Hsi-Te, 2022, Fig. 3 in Historical Biogeography of the Group (Anura, Leptodactylidae): Identification of Ancestral Areas and Events that Modeled their Distribution., Zoological Studies 61 (71), pp. 1-29 : 24

Xeruca Shih, 2015 Xeruca formosensis (Rathbun, 1921) ( Fig. 16 , Table 3)

Material examined: zoea I (from ñ 15.0 mm, NCHUZOOL 16789, Siansi, Changhua, coll. Y.-C. Zhang et al., 12 Aug. 2018); zoea I (from ñ 26.4 mm, NCHUZOOL 16790, Yangang River estuary, Hsinchu, coll. Y.-C. Zhang et al., 18 Sep. 2020).

Size: 0.35 ± 0.011 mm, rdl. 0.52 ± 0.016 mm, dsl. 0.08 ± 0.004 mm, rsl. 0.10 ± 0.004 mm.

Carapace ( Fig. 16A ): Lateral spines lacking, dorsal spine curved, relatively short, rostral spine straight, dorsal spine and rostral spine with pointed termination. Eyes round and sessile.

Antennule ( Fig. 16B ): Uniramous, endopod absent. Exopod smooth, unarticled, with 2 aesthetascs and 2 simple setae terminally.

Antenna ( Fig. 16C ): Protopod basal region smooth, distal end acuminate, bearing 2 rows of spines. Exopod short, with 2 terminal simple setae, setae exceeding tip of protopod. Endopod absent.

Maxillule ( Fig. 16D ): Epipod seta absent; coxal endite with 4 plumodenticulate setae and 1 plumose seta; basial endite with 4 plumodenticulate setae and 1 plumose seta; endopod 2-articled, proximal article without setae, 4 sparsely plumose in distal article; exopod seta absent.

Maxilla ( Fig. 16E ): Coxal endite bilobed with 3+3 plumose setae; basial endite bilobed with 5+4 plumose setae; endopod bilobed with 1+2 terminal sparsely plumose; scaphognathite with 4 densely plumose setae and a long acuminate posterior process with microtrichias.

First maxilliped ( Fig. 16F ): Basis with 2+2+3+2 sparsely plumose setae; endopod 5-articled with 2, 2, 1, 2, 5 plumose setae; exopod 2-articled with 4 terminal long plumose setae.

Second maxilliped ( Fig. 16 G): Basis with 1+1+1+1 sparsely plumose setae; endopod 3-articled with 0, 0, 5 plumose setae; exopod 2-articled with 4 terminal long plumose setae.

Pleon ( Fig. 16H ): With 5 pleonites, second pleonite with a pair of relatively acute dorsolateral spines pointing anterodorsally; third pleonite with a pair of relatively obtuse dorsolateral spines pointing posterodorsally; fourth pleonite wider than other pleonites. Pleopods absent.

Telson ( Fig. 16H ): Telson bifurcated, inner margin with 6 (3+3) serrate spines.

A key to zoeal stage I of the 15 species of fiddler crabs from Taiwan

(* The cw of parental females are shown in Table 2)

1. Carapace with dorsal and rostral spines very reduced .................. ................................................................................. 2 ( Gelasimus )

- Carapace with dorsal and rostral spines well-developed ........... 3

2. Antennal exopod with 1 terminal simple seta ............................... ............................................. G. borealis , G. jocelynae , G. vocans

- Antennal exopod with 2 terminal simple setae ...... G. tetragonon

3. Antennal only with protopod, without exopod ........................... 4

- Antenna with protopod and exopod ........................................... 5

4. Carapace with dorsal spine longer (dsl/rdl> 0.18) ....................... .............................................................................. Austruca lactea

- Carapace with dorsal spine shorter (dsl/rdl <0.17) ...................... ....................................... Paraleptuca ( P. crassipes , P. splendida )

5. Antennal exopod with 1 terminal simple seta ............................ 6

- Antennal exopod with 2 terminal simple setae .......................... 7

6. Carapace with dorsal spine longer (dsl/rdl> 0.18), size larger (cl.> 0.4 mm)* ...................................................... Austruca perplexa

- Carapace with dorsal spine shorter (dsl/rdl <0.17), size smaller (cl. <0.4 mm)* .............................................................................. .......................... Tubuca arcuata , T. coarctata , T. paradussumieri

7. Antenna with terminal simple setae longer than protopod ............ ........................................................................ Xeruca formosensis

- Antenna with terminal simple setae shorter than protopod ........ 8

8. Carapace with dorsal spine longer (dsl/rdl> 0.18) ....................... ..................................................................... Austruca triangularis

- Carapace with dorsal spine shorter (dsl/rdl <0.17) ................... 9

9. Size larger (cl.> 0.4 mm)* ............................. Tubuca dussumieri

- Size smaller (cl. <0.4 mm)* ................................... Tubuca acuta

Figures

Fig. 16. Xeruca formosensis, zoea I. A, carapace; B, antennule; C, antenna; D, maxillule; E, maxilla; F, first maxilliped; G, second maxilliped; H, pleon and telson.