Caridina malayensis, Cai & Ng & Choy, 2007

Cai, Yixiong, Ng, Peter K. L. & Choy, Satish, 2007, Freshwater Shrimps Of The Family Atyidae (Crustacea: Decapoda: Caridea) From Peninsular Malaysia And Singapore, Raffles Bulletin of Zoology 55 (2), pp. 277-309 : 305-307

Caridina malayensis , new species

( Fig. 17 )

Material examined. – Holotype: ovigerous female, c1 3.1 mm, with eggs 0.9 × 0.55 mm, ZRC 2007.0453 , stream at Nee Soon Swamp, Singapore, coll. Y. Cai, 8 Sep.1998.

Paratypes: 16 males, cl 2.1–2.4 mm, 30 ovigerous females, cl 2.8–3.6 mm, 23 female, cl 2.3–3.2 mm, ZRC 2007.0454 , data same as holotype .

Others: Peninsular Malaysia: 1 female, cl 3.7 mm, 1 ovigerous female, cl 3.8 mm, eggs 1.0x 0.6 mm, ZRC 2007.0455 , Kg. Jasa Sapakap , collected from blackwater, 1°31'30.5"N 103°27'47.7"E, coll. H. H. Tan, 15 Aug.1995 ; 2 females, cl 3.2–3.6 mm, 1 ovigerous female, cl 3.4 mm, 2007.0456, about 50 m after 63 km to Tg. Pinang, 1°05'55.3"N 104°22'45.4"E, from brown water, pH 5.2, coll. H. H. Tan, 29 Jun.1995 ; 4 males, cl 2.4–2.6 mm, 2 females, cl 2.8 mm, 1 ovigerous female, cl 3.2 mm, ZRC 2007.0457 , northern Selangor, peat swamp forest, small stream, along Sungai Besar to Tg. Malim road, blackwater, coll. P. K. L. Ng, 2 Jun.1992 ; 1 female, cl 3.0 mm, 1 ovigerous female, cl 3.5 mm, ZRC 2007.0458 , northern Selangor peat swamp forest, coll. P. K.L. Ng, 27 Apr.1995 . Singapore: 1 male, ZRC 2007.0459 , Nee Soon , swamp forest, coll. K. Yong & K. L. Yeo, 30 Mar.1990 ; 1 male, cl 2.3 mm, 2 females, cl 3.0– 3.2 mm, 1 ovigerous female, cl 3.0 mm, eggs 0.85 × 0.55 mm, ZRC. 2007.0460, Nee Soon , outside camp gate, coll. D. Yeo et al., 15 Dec.1994 ; 2 males, cl 2.3–2.4 mm, 3 females, cl 3.1–3.2 mm, 15 ovigerous females, cl 3.3–3.8 mm, 3 juv., ZRC 2007 . 0461, edge of Nee Soon , swamp forest, flowing water, coll. P. K. L. Ng, 15 Jan. 195 ; 4 males, cl 2.2–2.4 mm, 2 females, cl 2.5–3.2 mm, 11 ovigerous females, cl 3.1–3.5 mm, ZRC 2007.0462 , Lorong Banir, 29 Dec.1994 ; 1 female, cl 3.5 mm, ZRC 1995.506 , Nee Soon, swamp forest, Singapore , coll. P. K. L. Ng, Jun.1990 .

Description. – Rostrum ( Figs. 17A, B ) short, straight, reaching slightly beyond end of basal segment of antennular peduncle, or near middle of second segment, not beyond this segment, rostral formula 3–5+7–11/0–4, ventral teeth small or indistinct. Inferior orbital angle acute, fused well with antennal spines; pterygostomian margin broadly rounded.

Sixth abdominal somite 1.4 times as long as high, 0.6 times of carapace, 1.6 times as long as fifth somite, as long as telson. Telson ( Fig. 17C ) 2.6 times as long as wide, distal margin rounded, not terminating in a projection, with 3 pairs of dorsal spinules and a pair of dorsolateral spinules; distal end with 3 or 4 pairs of spines, lateral pair longer than intermediate pairs. Preanal carina ( Fig. 17Q ) triangular, pointed, without spine.

Eyes well developed, anterior end reaching to 0.7 times length of basal segment of antennular peduncle. Antennular peduncle ( Fig. 17D ) 0.7 times as long as carapace; basal segment of antennular peduncle longer than combined length of second and third segments, anterolateral angle reaching to 0.4 times length of the second segment, second segment distinctly longer than third segment. Stylocerite reaching to 0.8 times length of basal segment of antennular peduncle. Scaphocerite ( Fig. 17E ) 3.3 times as long as wide.

Incisor process of mandible ( Fig. 17F ) ending in a row of small teeth, molar process truncated. Lower lacinia of maxillula broadly rounded, elliptical, upper lacinia elongated, with a number of distinct teeth on inner margin, palp slender. Upper endites of maxilla ( Fig. 17G ) subdivided, palp short, scaphognathite tapering posteriorly with numerous long, curved setae at posterior end. Palp of first maxilliped ( Fig. 17H ) ending in a finger-like projection. Second maxilliped ( Fig. 17I ) typical, arthrobranch well developed. Third maxilliped ( Fig. 17J ) reaching to end of second segment of antennular peduncle, with ultimate segment slightly longer than or as long as penultimate segment.

Epipods well developed on first pereiopod, absent in last 4. First pereiopod ( Fig. 17K ) reaching to anterior end of eye; merus 2.4 times as long as broad, distinctly shorter than carpus; carpus excavated anteriorly, shorter than chela, 2.6 times as long as high; chela 2.5 times as long as broad; fingers 1.8 times as long as palm. Second pereiopod ( Fig. 12L ) reaching to end of second segment of antennular peduncle; merus distinctly shorter than carpus, 4.9 times as long as broad; carpus 1.3 times as long as chela, 6.4 times as long as high; chela 3.3 times as long as broad; fingers 1.6 times as long as palm. Third pereiopod ( Figs. 17M, N ) reaching to end of antennular peduncle, propodus 12.5 times as long as broad, 4.0 times as long as dactylus; dactylus 3.4 times as long as wide (spines included), terminating in a claw, with 4 or 5 accessory spines on flexor margin. Fifth pereiopod ( Figs. 17O, P ) reaching to end of second segment of antennular peduncle, propodus 14 times as long as broad, 2.8 times as long as dactylus; dactylus slender, 4.7 times as long as wide (spinules included), terminating in one claw, with 42–45 spinules on flexor margin.

Endopod of male first pleopod subtriangular, 2.6 times as long as wide, reaching to 0.3 times length of exopod, no appendix interna. Appendix masculina of male second pleopod reaching to half length of endopod.

Uropodal diaeresis ( Fig. 17 R ) with 14–21 movable spinules.

Ovigerous females with eggs sized 0.90–0.96 × 0.55–0.60 mm.

Habitat. – Acid-water forest rivers, streams or black water in peat swamps.

Etymology. – The species is named after its currently known distribution, the Malay Peninsula.

Remarks. – With regard to the form of the rostrum and pereiopods, C. malayensis most closely resembles C. bakoensis Ng, 1995 . It can readily be distinguished from C. bakoensis by the absence of an appendix interna on the endopod of the male first pleopod. In addition, the rostrum of C. bakoensis is proportionately shorter in majority, reaching only to or slightly beyond the distal end of basal segment of antennular peduncle, while that of C. malayensis normally reaches to or beyond the middle of the second segment of the antennular peduncle; the eggs of C. malayensis are relatively smaller (0.90–0.96 × 0.55–0.60 vs.1.0–1.1 0.6–0.63 mm); and the anterolateral angle of the basal segment of the antennular peduncle reaches to 0.4 times the length of the second segment (vs. 0.25 times in C. bakoensis ).

Distribution. – Peninsular Malaysia and Singapore (present study).

Figures

Fig. 17. Caridina malayensis, new species: A, B, cephalothorax and cephalic appendages; C, distal portion of telson; D, antennular peduncle; E, scaphocerite; F, mandible; G, maxilla; H, first maxilliped; I, second maxilliped; J, third maxilliped; K, first pereiopod; L, second pereiopod; M, third pereiopod; N, dactylus of third pereiopod; O, fifth pereiopod; P, dactylus of fifth pereiopod; Q, preanal carina; R, diaeresis. Scale bars: A, B, D, E = 1 mm; C, N, P, R = 0.2 mm; F–M, O, Q = 0.5 mm. (A, ovigerous female, cl 3.1 mm, holotype, Nee Soon, Singapore, ZRC; B–R, male, cl 2.9 mm, Nee Soon, Singapore, ZRC).

Fig. 12. Caridina excavatoides: A, cephalothorax and cephalic appendages; B, first pereiopod; C, second pereiopod; D, third pereiopod; E, dactylus of fifth pereiopod; F, fifth pereiopod; G, dactylus of fifth pereiopod; H, male first pleopod; I, male second pleopod. Scale bars: A = 1 mm; B–D, F = 0.5 mm; E, G = 0.1 mm, H, I = 0.2 mm. (A–C, H, I, male, cl 2.6 mm; D–G, ovigerous female, cl 2.8 mm; all material from Sungai Besar, Kuantan, Peninsular Malaysia, ZRC).