Caridina rubella Fujino and Shokita, 1975

Cai, Y., 2006, Atyid shrimps (Crustacea: Decapoda: Caridea) of the Ryukyu Islands, southern Japan, with descriptions of two new species, Journal of Natural History 40 (38 - 40), pp. 2123-2172 : 2145-2148

Caridina rubella Fujino and Shokita, 1975

( Figures 6F–J , 7 and 8 )

Caridina rubella Fujino and Shokita, 1975, p 102 , fig. 6a–o [type locality: Izaga Cave, Morikaga Cave and a well near Hirara city of Miyako Island, Ryukyus, Japan]. Caridina rubella: Shokita and Nishijima 1976, p 71 ; Shokita 1979, p 203; 2003, p 250, figs. 18F, 19I; 2006d, p 61; Cai and Anker 2004, p 243; Fujita and Shokita 2005b, p 203.

Material examined

Holotype: female, cl 6.1 mm (dry), URB495 ; Izaga Cave , Miyako Island , Ryukyu Islands , Japan, coll. S. Shokita, 19 September 1964; paratype: 1 female, cl 5.4 mm (dry), URB496 , data same as holotype. Others: 1 male cl 4.8 mm, 7 females, cl 3.9–8.8 mm, URB Murikawa , Yamato-ga , Miyako Island, Ryukyu Islands, Japan, 23 October 1982.

Diagnosis

Rostrum straight or slightly upturned, reaching to end of second segment of antennular peduncle, or to end of scaphocerite. Rostrum with teeth throughout its dorsal margin, rostral formula 9–14+15–24/9–23. Antennal spine prominent, situated lower than suborbital angle; pterygostomian margin rounded; eyes strongly reduced. Preanal carina with spine. Telson with five pairs of dorsal spines, small posteromedial projection, lateral pair of spines longer than or as long as intermediate pairs of setae. Antennular peduncle 0.5–0.6 times as long as carapace. Stylocerite reaching to end of basal segment of antennular peduncle, or slightly beyond it. Scaphocerite 3.1 times as long as wide. First pereiopod with ischium much shorter than merus, carpus 1.0–1.5 times as long as chela, 4.2 times as long as high, chela 2.0–3.0 times as long as broad, finger distinctly longer than palm. Second pereiopod with ischium much shorter than merus, carpus 1.5– 2.0 times as long as chela, 8–12 times as long as high, chela 2.4–4.0 times as long as broad, fingers 1.5–2.0 times as long as palm. Third pereiopod with propodus not enlarged, its length 4.0–5.0 times as long as dactylus; dactylus ending in two claws, with two to four spines on flexor margin. Fifth pereiopod with propodus 5.0–6.5 times as long as dactylus, dactylus ending in one claw, with 13–17 spinules on flexor margin. Endopod of male first pleopod sub-triangular, no appendix interna. Uropodal diaeresis with 11–13 spinules.

Habitat

Subterranean water.

Remarks

The forms of the rostrum, the first two pereiopods and telson are much more variable than in the original description by Fujino and Shokita (1975). Holthuis (1978) described Caridina troglodytes , on the basis of four incomplete specimens from Danmin Cave near Konogusgus, New Ireland. Caridina troglodytes is very similar to C. rubella , most of its characters fall within the range of variation of C. rubella , except for the smaller number of ventral rostral teeth (2–8 vs. 9–23) and the fewer spinules on the dactylus of the fifth pereiopods (6 vs. 13–15). As the ventral rostral teeth are quite variable in both species and the supposed fifth pereiopod is unattached, and thus could be the fourth pereiopod instead, the identity of Holthuis’ species need more specimens for it to be ascertained. Shokita (1979) reported it from two more locations in southern Japan, one from subterranean water of Shiokawa River, Okinawa Island, Ryukyus, and the other from Suirendo Cave, Okinoerabu Island, Ryukyu Islands. Cai and Anker (2004) reported the occurrence of Caridina rubella from Palawan Island, the Philippines.

Distribution

Ryukyu Islands, Philippines.

Figures

Figure 6. Caridina laoagensis. A, third maxilliped; B, male first pleopod; C, endopod of male first pleopod; D, male second pleopod; E, appendix masculina and appendix interna of male second pleopod; Caridina rubella. F, cephalothorax and cephalic appendages, lateral view; G, first pereiopod; H, second pereiopod; I, third pereiopod; J, dactylus of third pereiopod. Scale: F51 mm; A, B, D, G–I50.5 mm; C, E, J50.2 mm (A–E, male, cl 3.5 mm, ZRC; F–J, female, cl 3.9 mm, URB).

Figure 7. Caridina rubella. A, cephalothorax and cephalic appendages, lateral view; B, first pereiopod; C, second pereiopod; D, third pereiopod; E, dactylus of third pereiopod; F, fifth pereiopod; G, dactylus of fifth pereiopod; H, scaphocerite; I, preanal carina. Scales: A, H50.5 mm; B–D, F51 mm; E, G50.2 mm; I51 mm (A–G, female, cl 5.5 mm, URB; H, I, female, cl 8.8 mm, URB).

Figure 8. Caridina rubella. A, cephalothorax and cephalic appendages, lateral view; B, diaeresis; C, telson; D, distal portion of telson; E, cephalothorax and cephalic appendages, lateral view; F, endopod of male first pleopod; G, appendix masculina and appendix interna of male second pleopod. Scales: A50.5 mm; B, D, F, G50.2 mm; C, E51 mm (A, B, female, cl 8.8 mm, URB; C, D, female, cl 5.5 mm, URB; E–G, male, cl 4.8 mm, URB).