ATTEMPTED HYBRIDIZATION OF THE GRASS SHRIMP PALAEMONETES (CARIDEA, PALAEMONIDAE) WITH AN EVALUATION OF TAXONOMIC CHARACTERS OF JUVENILES

Variation in morphological characters used to distinguish the 3 sympatric species of Palaemonetes (P. pugio, P. intermedius and P. vulgaris) is suggestive of natural hybridization. Interspecific crosses among the species and intraspecific crosses of allopatric populations of P. pugio were made to determine whether hybridization was feasible and to evaluate taxonomic characters of the juveniles. No interspecific matings produced larvae in the laboratory. Larvae from intraspecific matings of P. pugio and P. vulgaris were reared to 40 days of age. Larval survival rates, development time, and postlarval length of P. pugio and P. vulgaris were not different, but juveniles of P. pugio at 40 days after hatching were larger than those of P. vulgaris. At 40 days P. pugio had developed adult diagnostic features. P. vulgaris displayed sufficient variation in adult diagnostic features to resemble P. pugio in some cases. The intraspecific matings of P. pugio from widely separated populations were fertile, but there was some indication of reduced reproductive compatibility in crosses involving Virginia [USA] females and Florida males relative to intrapopulational controls.