EVOLUTION OF LARVAL DEVELOPMENTAL PATTERNS AND THE PROCESS OF FRESHWATERIZATION IN THE PRAWN GENUS MACROBRACHIUM BATE, 1868 (DECAPODA, PALAEMONIDAE)

The inland prawn genus Macrobrachium Bate, 1868, is supposed to have originated from marine ancestors sometime in the beginning of the Pleistocene and since then its members have invaded freshwaters to different degrees. As such, these prawns are found to occupy almost all types of aquatic bodies right from purely marine through estuarine, riverine to impounded waters. Consequently, they have evolved various types of developmental patterns. Based on information available on more than 40 species, three basic types of larval developmental patterns can abe recognized in this genus viz.. Prolonged or Normal Type (with 8 to 20 stages), Partially Abbreviated Type (with 2 or 3 stages) and Completely Abbreviated Type (with only 1 stage). However, there are several species showing transitional developmental patterns. Thus, the process of freshwaterization seems to be still continuing in the genus. Incidentally, the above knowledge can be applied in prawn culture as a basis for selection of a suitable candidate for forage species.