Caridina okinawa, Cai, 2006

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 : 2154-2156

Caridina okinawa , new species

( Figure 12 )

Material examined

Holotype: female, cl 6.5 mm, USNM-123426, Ingue Cave at Yomitan Village, Okinawa Island, Ryukyu Islands, Japan, coll. D. W. Rhodes, 3 March 1967.

Description

Rostrum ( Figure 12A ) short, straight, reaching near end of second segment of antennular peduncle; dorsal margin with 12 teeth, three of them on carapace, ventral margin with five very small teeth; inferior orbital angle of carapace fused with antennal spine, sharp and long; pterygostomial angle rectangular. Sixth abdominal somite 0.50 times as long as carapace, 1.6 times as long as fifth somite, slightly shorter than telson. Telson terminating in median projection; five pairs of dorsal spinules, one pair of dorsolateral spines near distal end, four pairs of spines on distal margin, lateral pair shortest, sublateral pair longest; preanal carina high, with a small spine. Scaphocerite 2.8 times as long as wide.

Eyestalk short, eye with an undeveloped cornea. Antennular peduncle stout, 0.5 times as long as carapace; stylocerite reaching slightly beyond end of basal segment of antennular peduncle.

Third maxilliped reaching to end of third segment of antennular peduncle, with ultimate segment shorter than penultimate segment. Epipods on first four pereiopods. First pereiopod ( Figure 12C ) stout, reaching to middle of second segment of antennular peduncle, ischium much shorter than merus, merus 2.0 times as long as broad, as long as carpus; carpus excavated anteriorly, shorter than chela, 1.2 times as long as high; chela 1.9 times as long as broad; fingers 0.6 times as long as palm. Second pereiopod ( Figure 12D ) reaching end of second segment of antennular peduncle, ischium much shorter than merus, merus slightly longer than carpus, 5.4 times as long as broad; carpus 1.3 times as long as chela, 5.0 times as long as high; chela 2.4 times as long as broad; fingers 1.3 times as long as palm. Third pereiopod ( Figure 12E, F ) reaching end of third segment of antennular peduncle, propodus normal shape, distinctly shorter than merus, 9.0 times as long as broad, 4.5 times as long as dactylus; dactylus ending in two strong claws; 2.6 times as long as wide (spines included), with five accessory spines on flexor margin. Fifth pereiopod ( Figure 12G, H ) reaching to end of basal segment of antennular peduncle, propodus distinctly longer than merus, 11 times as long as broad, 4.7 times as long as dactylus; dactylus 2.6 times as long as wide, ending in two large claws, with 26 spinules on its flexor margin. Uropodal diaeresis with 17 spinules.

Habitat

The specimen was collected from subterranean water.

Etymology

The new species is named after the type locality, Okinawa Island, Ryukyus , used as a noun in apposition .

Remarks

With respect to the rostral formula, and the long stylocerite, Caridina okinawa , new species, is very different from all the epigean Caridina species from the Ryukyus. It is however, most similar to C. cantonensis Yu, 1938 (cf. Cai and Ng 1999) from southern China. It could be distinguished by the shorter stylocerite (reaches to the end of basal segment of antennular peduncle vs. distinctly beyond); the less developed eyes (vs. well developed in C. cantonensis ); the shorter finger of the first pereiopod (0.6 times as long as palm vs. as long as palm).

Distribution

Known only from the type locality, Okinawa Island, Ryukyu Islands .

Figures

Figure 12. Caridina okinawa. A, cephalothorax and cephalic appendages, lateral view; B, preanal carina; C, first pereiopod; D, second pereiopod; E, third pereiopod; F, dactylus of third pereiopod; G, fifth pereiopod; H, dactylus of fifth pereiopod. Scales: A, B51 mm; C, D, E, G50.5 mm; F, H50.2 mm (female, cl 6.5 mm, holotype, USNM- 123426).