OCCURRENCE OF PALAEMONETES VARIANS (LEACH, 1814) (DECAPODA, PALAEMONIDAE) IN A BRACKISH POND IN ALGERIA

Abstract

In May 1983, many specimens of palaemonids belonging to the species Palae monetes varions (Leach, 1814) were found in one of many ponds in the marshy area near Oran, west of Algiers. This species has a wide geographical distribution and lives under different and even extreme climatic and environmental conditions. It is common in fresh and brackish ponds and estuaries of northern Europe (Bour don, 1965; Do Chi et al., 1978; Fincham, 1979; Smaldon, 1979; Antonopoulou, 1987; Antonopoulou & Emson, 1992; Smaldon, 1993) and Tunisia (Heldt, 1953) and has been the subject of various studies. The ease with which it can be raised has enabled complete study of its larval stages (Boas, 1889; Sollaud, 1923; Fincham, 1979). Despite this, P. varions has rarely been found along the western Mediterranean coasts of France (Gourret, 1897; No?l, 1992; Bardin, 1994) and has only recently been reported at the mouth of the Rh?ne river (i.e., the Camargue) (Rosecchi et al., 1998). The reason for these few reports from Mediterranean Europe and Africa may be due to confusion of P. varions with other species of the same genus, such as P. zariquieyi Sollaud, 1939 in Spain, P. antennarius (H. Milne Edwards, 1837) in Italy and P. mesogenitor Sollaud, 1912 in Tunisia, or with species of the genus Palaemon (cf. Rosecchi et al., 1998). Therefore, it seems worthwhile reporting this recent finding in Algeria, if only to add to our knowledge of the distribution of this small shrimp. The specimens were captured with a common net at a depth of a few centimetres along the shores of the brackish Lake Gharabas, on the road from Oued Tlelat to Arzew (fig. 1) and they are characterized by one post-orbital tooth and 4 (rarely 3 or 5) pre-orbital teeth on the superior rostral margin, as well as by a pair of plumose setae between the apical spines of the telson (fig. 2).