Caridina Bruneiana, a New Species of Freshwater Shrimp (Decapoda, Caridea, Atyidae) from Negara Brunei Darussalam, Borneo
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Zoologica Scripta, Vol. 21, No. 1, pp. 49-55, 1992 0300-3256/92 $5.00 + .00 Printed in Great Britain Pergamon Press pic © 1992 The Norwegian Academy of Science and Letters Caridina bruneiana, a new species of freshwater shrimp (Decapoda, Caridea, Atyidae) from Negara Brunei Darussalam, Borneo SATISH C. CHOY Accepted 11 June 1991 Choy, S. C. 1992. Caridina bruneiana, a new species of freshwater shrimp (Decapoda. Caridea, Atyidae) from Negara Brunei Darussalam, Borneo.—Zool. Scr. 21: 49-55. A new species of the freshwater atyid shrimp, Caridina bruneiana from Negara Brunei Darussa- lam, Borneo is described. Caridina bruneiana is characterized by its moderately long and deep rostrum, pereiopod shape, spination and segmental ratios, the shape and spination of its posterior telsonie margin, egg size and the presence of an appendix interna on the endopod of the first male pleopod. The distribution of atyid shrimps in forested streams and their possible use as bio- indicators of stream water quality in tropical rainforests are briefly discussed. Satish C. Choy, Universiti Brunei Darussalam, Gadong 3186, BSB, Negara Brunei Darussalam. Introduction #3, same locality as female #2 (dissected); (BM 4/90) female #4, same locality as female #2 (dissectcd). Etymology. The specific epithet is given after Brunei. During a reconnaissance trip to the Bukit Patoi Forest Reserve, Belalong, Temburong District, Negara Brunei Description Darussalam, several specimens of a new atyid shrimp were collected at the confluence of the Belalong River and the Temburong River on 16 May 1990. The collection Body. Small, slender and subcylindrical. Holotype site is close to the Universiti Brunei Darussalam (UBD) ovigerous female, total length (TL) 23.6 mm, post-orbital Field Studies Centre and within the area of the 1991-1992 carapace length (CL) 4.6 mm, pre-orbital rostral length UBD/Royal Geographic Society (RGS) Brunei Rainfor- (RL) 3.6 mm, mean diameter of elliptical, non-eyed eggs est Project. The stream characteristics (under flooded 0.26 x 0.42 mm. Allotype adult male, TL 17.2 mm, CL conditions) were as follows: width 10-30 m, depth 0.5-2.5 3.4 mm, RL 2.7 mm, 1st, 3rd and 4th right pereiopods m, water velocity 3-150 cm s-1, pH 6.3, sandstone and regenerating, not of full size. Paratype female #1, TL gravel substratum. More specimens were subsequently 21.8 mm, CL 4.2 mm, ovigerous with eyed eggs 0.27 x collected from further downstream in the Temburong 0.45 mm. Paratype female #2, TL 22.3 mm, CL 4.5 mm, River near the Mini-Zoo at Batang Duri on 28 September ovigerous with non-eyed eggs 0.23 x 0.38 mm. Paratype 1990. Stream characteristics here were similar to those at female #3, TL 25.9 mm, CL 5.1 mm, ovigerous with eyed the confluence. Other fauna caught with Caridina were eggs 0.27 x 0.45 mm. Paratype female #4, TL 23.5 mm, the freshwater crab Parathelphusa valida Ng & Goh, the CL 4.7 mm. Dimensions of pereiopod segments and prawn Macrobrachium sp., and fishes Rasbora cephalo- ratios of some morphometric characters are given in taenia (Bleeker), R. taeniata Ahl, Nemachilus sp., and Tables I and II, respectively. Gastromyzon sp. Rostrum (Fig. 1A-C). Broad, length about 4.5 times The material studied is deposited in the British Museum (Natural breadth; of intermediate length, reaching, or just beyond, History), London (BMNH) and the Brunei Museum, Negara Brunei tip of antennular peduncle, either convex or straight; tip Darussalam (BM). unarmed; straight or directed slightly downwards; 24-28 dorsal rostral teeth, immovable, with 3-5 situated above- to behind-posterior orbital margin, setation between each Caridina bruneiana sp.n. (Figs 1-4, Tables I-II) pair of teeth; 3-5 ventral rostral teeth; a notch sometimes present and placed well in front of these; lateral carina dividing rostrum into 2 unequal parts and continuing Type material. Holotype (BMNH 1990:52) ovigerous female, from Negara Brunei Darussalam, on the upper reaches of Temburong River posteriorly to orbital margin. at Batang Duri (04°36'05"N, 115°06'45"E; altitude approx. 33Vi), 28 September 1990, coll. S. C. Choy. Allotype (BMNH 1990:51) adult male, same locality as holotype (dissected). Paratypes (BM 2/90) female Eyes (Fig. 1A, B). Small, on a short ocular peduncle; #1, same locality as holotype; (BM 3/90) female #2, from Negara cornea globular, well developed. Brunei Darussalam at the confluence of Belalong River and Temburong River (4°33'15"N, 115°09T5"E; altitude approx. 66 m), 16 May 1990, coll. Dr Kamariah Abbu Salim (dissected); (BMNH 1990:51) female Carapace (Fig. 1A-C). Smooth, glabrous; rostrum (RL) Zoologica Scripta 21 50 5. C. Choy Tabic I. Length (L) and width (W), in mm, of pereiopod segments of a primary and a secondary type specimen o/Caridina brunciana sp.n Dactyl us Propodus Carpus Mcrus Ischium L W L W L W L W L W Allotype male Pereiopod I 0.44 0.10 0.76 0.29 0.49 0.25 0.78 0.18 0.37 0.15 Pereiopod II 0.49 0.11 0.88 0.29 0.86 0.20 1.05 0.15 0.44 0.14 Pereiopod III* 0.15 0.09 0.76 0.11 0.49 0.15 0.98 0.20 0.49 0.20 Pereiopod IV 0.18 0.11 1.62 0.11 0.88 0.17 1.74 0.22 0.47 0.20 Pereiopod V 0.20 0.09 1.72 0.10 0.86 0.14 1.45 0.18 0.59 0.18 Paratype female #3 Pereiopod I 0.88 0.20 1.32 0.61 0.81 0.54 1.05 0.34 0.47 0.25 Pereiopod II 0.98 0.22 1.40 0.56 1.32 0.34 1.72 0.29 0.74 0.20 Pereiopod III 0.25 0.16 2.13 0.17 1.27 0.27 2.74 0.42 0.74 0.37 Pereiopod IV 0.22 0.15 2.38 0.17 1.25 0.27 2.50 0.40 0.71 0.32 Pereiopod V 0.32 0.16 2.70 0.17 1.18 0.25 1.94 0.29 0.83 0.28 * Small regenerating pereiopod. about 0.7-0.8 of carapace length (CL). Pterygostomian Antenna (Fig. IE). Scaphocerite reaching well beyond tip angle obtuse, slightly produced anteriorly. Antennal of antennular peduncle; outer margin straight or slightly spine pointed sharply and placed below lower orbital concave, without setae and ending in strong subapical angle, straight or slanting downwards dorsally and slightly tooth, tip of which lies just beyond tip of antennular concave ventrally. peduncle, both being overreached by the lamella which has plumose setae on inner and anterior margins. Anten- Antennule (Fig. ID). Peduncle 3-segmented; stylocerite nal peduncle about 0.5 length of scaphocerite and in line 0.75 length of basal segment; pointed anterolateral angle with or just before tip of basal antennular segment. of basal antennular segment acute reaching about 0.66 Flagella long and simple. length of second segment, which is about 0.66 length of basal antennular segment and about 1.5 times as long as Mandibles (Fig. 1G, H). Right mandible with 4-6 strong, third. First two segments with submarginal plumose setae sharp incisor teeth laterally; medially two groups of sim- (setal terminology after Pohle & Telford 1981); third ple setae, one group with 18-20 distinctly bent setae and segment fringed laterally and apically with same. Flagella other with 40-50 finer straight ones; molar process ridged. long and simple. Left mandible with 4-6 strong, sharp teeth separated by sharply ridged gap; 9 adjacent setae finely serrated, below which are about 15 simple setae adjacent to ridged molar process which has short brush-like setae. Table II. Caridina brunciana sp.n. Ratios (mean ± S.D., N = 5) of some morpho- Maxillula (Fig. II). Lower lacinia with broadly rounded metry characters selected from 30 that were calculated margin, bearing several rows of different types of setae (simple, denticulate and plumose); anteriorly long sub- r/CL 0.75 ± 0.03 marginal rows of denticulate and spatulate setae, lower t/CL 0.58 ± 0.04 a/CL 0.85 ± 0.17 ones more spinose, some setae placed proximally. Upper p3/CL 0.58 ±0.19 larcinia broadly elongate, inner edge straight with several p5/CL 0.54 ± 0.18 rows of strong spines as well as short, simple, denticulate hi 1/w 2.31 ± 0.22 h2 1/w 2.65 ± 0.21 and plumose setae. Simple and plumose setae on outer cl 1/w 1.92 ± 0.33 and lower inner margins. Palp truncate with long plumose c2 1/w 4.38 ± 0.32 setae near tip plus row of simple setae. ml 1/w 3.35 ± 0.64 m2 1/w 6.36 ±0.74 hl/cl 1.52 ± 0.09 Maxilla (Fig. 1 J). Upper and middle endite with marginal h2/c2 0.99 ± 0.07 simple and denticulate setae and submarginal plumose d3/p3 0.16 ± 0.02 d4/p4 0.12 ± 0.03 ones. Lower endite with simple setae; palp shorter than d5/p5 0.13 ± 0.01 cleft of upper endite, narrow and simple. Scaphognathite c3/p3 0.65 ± 0.05 with regular row of long plumose setae on distal margin c4/p4 0.53 ± 0.03 c5/p5 0.46 ± 0.03 with shorter simple ones continuing down proximal tri- m3/p3 1.29 ± 0.03 angular process which has many long simple setae, some m4/p4 1.06 ± 0.04 with prominent dilation near base.