Embryological Comparison of Lepomis macrochirus X macrochirus and Lepomis macrochirus X gibbosus

James Robert Heckman, Elizabethtown College


The bluegill, Lepomis macrochirus Rafinesque, and the pumpkinseed, Lepomis gibbosus (Linnaeus), were crossed by an artificial fertilization technique. This resulted in two types of offspring; that is, Lepomis macrochirus X macrochirus and Lepomis macrochirus X gibbosus. A comparative study was made: (1) to determine the incubation time, (2) to determine the per cent hatched, (3) to compare standard length of the early larva, and (4) to compare heart development. The results were: (1) the hybrid cross, under the specific circumstances of the experiment, had a 3.1 hour faster mean incubation time than the pure cross, (2) the hybrid cross gave the higher per cent hatched, 63.4% (625) as compared to 51.7% (834) for the pure cross, (3) no significant standard length difference was found, and (4) heart differentiation began with a tubular heart and ended with the development of a series of four chambers. No morphological difference in heart development was observed. There were, however, differences in heart positioning and maturation. © 1969 Taylor & Francis Group, LLC.