ON THE FRESHWATER PALAEMONID PRAWNS FROM THE FIJI ISLANDS (, )

BY

SATISH C. CHOY School of Natural Resources, The University of the South Pacific P.O. Box 1168, Suva, Fiji Islands

INTRODUCTION

So far no comprehensive study has been made of the freshwater palaemonid prawns from the Fiji Islands. Only a few have previously been recorded or described by different workers at different times. The first freshwater to be collected from the Fiji Islands was concinnus Dana (recorded by Dana, 1852, as Palaemon concinnus and Palaemon exilimanus; the two being synonyms) during the U.S. Exploring Ex- pedition, 1838-42. Macrobrachium lar, the most common of the Indo-Pacific species of the sub-genus Macrobrachium, has been repeatedly reported by various authors (such as Hess, 1865, and De Man, 1887, both as Palaemon ruber; Semper, 1868, and Miers, 1876, both as Palaemon ornatus; Bate, 1888, as Bithynis lar; Borradaile, 1898, as Palaemon lar). Ortmann (1891) reported Macrobrachium latimanus and M. lepidactyloides as Palaemon latimanus and P. hir- timanus, respectively. During the present century only a few records have been added to the above. Adamson (1935) recorded the presence of Palaemon latimanus ( = Macrobrachium latimanus) in Fiji while Laird (1956) mentioned Palaemon concinnus in relation to mosquito ecology. Holthuis (1950) reviewed and updated the taxonomic status of the palaemonid prawns including those from Fiji. The record of Macrobrachium intermedium (Stimpson) (recorded as Palaemon (Leander) in- termedium by Miers, 1884) from Fiji was considered as doubtful by Holthuis (1952) who also reported that Macrobrachium hirtimanus reported by Ortmann (1891) and himself (1950) actually belonged in Macrobrachium lepidactyloides. A report on the biological studies conducted in the area around the Monasavu hydro-electric dam in Central Viti Levu (Institute of Natural Resources, 1977) included a photograph of M. lar and another of M. lepidactyloides (the latter be- ing recorded as Astacus sp.). Both these species were collected from below the Monasavu Falls. A later study (Institute of Natural Resources, 1979) reported on a Macrobrachium species collected from below the Vuwa Falls 270

(Wainisavulevu Creek, Central Viti Levu). This species was identified as Macrobrachium lepidactyloides and is included in this paper. An environmental progress report on the Namosi Copper project (Namosi Joint Venture, 1979) also incorporated a photograph of several species of prawns identified only by their local names (except for M. lar). The present paper deals with material of eleven species belonging to two genera which were collected from several localities in Fiji during 1979 and 1980. Localities once described are not repeated. Full synonymies for most species are to be found in Holthuis (1950). The material examined is deposited in the collection of Rijksmuseum van Natuurlijke Historie, Leiden (RMNH) and The University of the South Pacific (USP), Fiji Islands. I wish to record my gratitude to Professor L. B. Holthuis for confirmation of the species identified and for helpful suggestions and comments on the manuscript. This work was jointly funded by the Institute of Natural Resources and the Institute of Marine Resources of The University of the South Pacific.

Macrobrachium australe (Gu6rin, 1838) Palaemondispar - Miers, 1879: 493; 1880: 383. Macrobrachiumaustrale - Holthuis, 1950: 125, figs. 27-30. Material examined. - Bureta River, near Lovoni village, Ovalau (17°41'10"S 178°47' 30 "E), alt. 35 m ; width of stream 3 to 10 m, depth 0.1 to 1.5 m, flow 0.2 to 0.6 ms-1, bot- tom gravel interspersed with black basalt boulders, overhanging bank vegetation; 20 July 1980; 4 specimens (1 a, RMNH Cat. No. 35409). Kuludrusi Creek, off Buca Bay road about 22 km past Savusavu, Vanua Levu (16°45'15"S 179°27' 25 "E), 80 m; width of stream 2 to 8 m, depth 0.2 to 0.6 m, flow 0.1 to 0.5 ms-1, bottom gravel interspersed with basalt boulders; 16 July 1980; 12 specimens (8, RMNH Cat. No. 35412). Saivou Creek, above a roadside waterfall on the transinsular highway, Vanua Levu ( 16°37' 10 "S 179° 10' 0 "E),300 m; width of stream 0.2 to 1. 5 m, depth 0.1 to 0.5 m, flow 0.2 to 0.5 ms-1, bottom soapstone interspersed with basalt gravel, flows through abandoned Colocasia esculenta(Linn.) Schott and Piper methysticumForst. plantation; 29 October 1980; 3 specimens (1 juv., RMNH Cat. No. 35414). Tacilevu Creek, Vanua Levu (16°46'45"S 173°37'15"E), 5 m, width of stream 3 to 8 m, depth 0.2 to 1.2 m, flow 0.1 to 0.3 ms-1, bottom basalt gravel interspersed with boulders, overhanging vegetation; 30 October 1980; 2 specimens (1 juv., RMNH). Savura Creek, below first waterfall upstream of bridge, Viti Levu (18°05'0"S 178°26'50"E), 40 m, width of stream 3 to 7 m, depth 0.5 to 1.5 m, flow 0.2 to 0.5 ms-1, bottom gravel in- terspersed with basalt boulders; 26 October 1980; 4 specimens (2 juv., RMNH Cat. No. 35413).

Remarks. - Although most specimens are juveniles they can be easily to this The rostral teeth formula is This is assigned species. 2)304123-4 . species widely distributed throughout the Indo-Pacific region ranging from Madagascar and the Seychelles to Samoa and the Marquesas Islands in Polynesia (Holthuis, 1950; 1978). This is the first record from Fiji.