Caridina palawanensis, Shokita, 2006

Shokita, Yixiong Cai Shigemitsu, 2006, Report On A Collection Of Freshwater Shrimps (Crustacea: Decapoda: Caridea) From The Philippines, With Descriptions Of Four New Species, Raffles Bulletin of Zoology 54 (2), pp. 245-270 : 256-259

Caridina palawanensis , new species

( Figs. 5 , 6A, B )

Material examined. – Holotype: 1 ovig. female, cl 4.1 mm, NSMT, Panitian River , upper stream, ca 30 km from river mouth, Palawan Island, Philippines, 6 Aug.1985.

Paratypes: 2 males, cl 2.6-2.9 mm, 2 ovig. females, cl 3.8-4.1 mm, ZRC , 3 males, cl 2.2-2.8 mm, 2 ovig. females, cl 4.1-4.2 mm, 2 females, cl 2.6-2.8 mm, UR, data same as holotype .

Description. – Rostrum straight (5A), reaching to or beyond end of antennualr peduncle, or slight beyond end of scaphocerite, armed dorsally with 21 to 29 teeth throughout the dorsal margin, including 2 to 3 posterior to postorbital margin; armed ventrally with 5 to 10 teeth on anterior half; antennal spine distinctly lower than sub-orbital angle. Pterygostomian angle sub-rectangular.

Third abdominal somite with moderately convex dorsal profile. Sixth abdominal somite 0.6 times as long as carapace, 1.8 times as long as fifth somite, slightly longer than telson. Telson ( Fig. 5B, C ) 3.4 times as long as wide, terminating in a small projection, with four pairs of dorsal spinules and one pair of dorsolateral spinules; lateral pair of distal spines slightly longer than intermediate pairs. Preanal carina small, lacking spine ( Fig. 5K ).

Eyes well developed, small, anterior end reaching to 0.7 length of basal segment of antennular peduncle. Antennular peduncle 0.7 times as long as carapace; basal segment of antennular peduncle longer than sum of second and third segment length; second segment distinctly longer than third segment. Stylocerite reaching to 0.7 length of basal segment of antennular peduncle. Scaphocerite ( Fig. 5D ) 3.7 times as long as wide.

Mouthparts similar to that of Caridina cebuensis , new species. Palp of first maxilliped broadly triangular, ending in a fingerlike projection. Second maxilliped typical of the genus. Third maxilliped reaching beyond end of second segment of antennular peduncle, with ultimate segment longer than penultimate segment.

Epipods on first four pereiopods. First pereiopod ( Fig. 5E ) reaching to anterior margin of the eye stalk; ischium shorter than merus; merus 2.7 times as long as broad, slightly shorter than carpus; carpus excavated anteriorly, shorter than chela, 1.8 times as long as high; chela 2.0 times as long as broad; fingers distinctly longer than palm. Second pereiopod ( Fig. 5F ) reaching beyond second segment of antennular peduncle; ischium shorter than merus; merus shorter than carpus, 5.3 times as long as broad; carpus 1.3 times as long as chela, 5.5 times as long as high; chela 2.6 times as long as broad; fingers 1.6 times as long as palm. Third pereiopod ( Fig. 5G, H ) reaching to end of antennular peduncle, propodus distinctly shorter than merus, 13 times as long as broad, 4.2 times as long as dactylus; dactylus 3.0 times as long as wide (spines included), with 6 accessory spines on its flexor margin. Fifth pereiopod ( Fig. 5I, J ) reaching to end of second segment of antennular peduncle, propodus 14 times as long as broad, 3.0- 3.6 times as long as dactylus; dactylus 3.7 times as long as broad, with 49 spinules on its flexor margin.

Endopod of male first pleopod ( Fig. 6B ) triangular, one fourth length of exopod, no appendix interna. Appendix masculina of male second pleopod ( Fig. 6A ) half of endopod length, with appendix interna reaching half of appendix masculina length.

Uropodal diaeresis ( Fig. 5L ) with 17 movable teeth.

Ovigerous females with egg sized 0.78-0.82x 0.40-0.45 mm in diameter.

Habitat. – Caridina palawanensis , new species, was collected from Panitian River, upper stream, ca 30 km from river mouth, Palawan Island.

Etymology. – The new species is named after its type locality – Palawan Island, Philippines.

Remarks. – With respect to the rostrum, the egg size, the pereiopods, Caridina palawanensis , new species, is most similar to C. williamsi Cai & Ng, 2000 . It could be distinguished from C. williamsi by the endopod of the male first pleopod, which has no appendix interna (vs. has a distinct appendix interna at the distal end of the endopod in C. williamsi ), the telson which terminates in a small projection (vs. no such projection in the latter), and the shorter antennular peduncle (0.7 times as long as carapace vs. 0.85-1.0 times in C. williamsi ).

Distribution. – Philippines.

Figures

Fig. 5. Caridina palawanensis, new species, ovig. females, cl 4.1 mm, paratype, ZRC, Panitian River, upper stream, ca 30 km from river mouth, Palawan Island Philippines:A, cephalothorax and cephalic appendages, lateral view; B, telson;C, distal portion of telson;D, scaphocerite; E, first pereiopod; F, second pereiopod; G, third pereiopod; H, dactylus of third pereiopod; I, fifth pereiopod; J, dactylus of fifth pereiopod; K, preanal carina; L, uropodal diaeresis. Scale bars: A, B, D = 1 mm; E-G, I, K = 0.5 mm; C = 0.2 mm; H, J = 0.1 mm.

Fig. 6. Caridina palawanensis, new species, male, cl 2.8 mm, ZRC, Panitian River, upper stream, ca 30 km from river mouth, Palawan Island, Philippines: A, male second pleopod; B, male first pleopod. Caridina sumatrensis, male, cl 3.2 mm, ZRC, Santacruz River, Palawan Island, Philippines: C, cephalothorax and cephalic appendages, lateral view; D, first pereiopod; E, second pereiopod; F, third pereiopod; G, preanal carina. Potamalpheops miyai, male, cl 3.0 mm, ZRC, Surigao mangrove, Mindanao Island, Philippines:H, cephalothorax and cephalic appendages, lateral view; I, second pereiopod; J, propodus and dactylus of third pereiopod; K, fifth pereiopod; L, uropodal diaeresis. Scale bars: A, B = 0.2 mm, C, H = 1 mm, D-G, I-L = 0.5 mm.