EMBRYONIC-DEVELOPMENT OF THE TERRESTRIAL TURTLE TESTUDO-HERMANNI GMELIN, 1789

Testudo hermanni is a protected terrestrial turtle, the geographical distribution of which is discontinuous around the Mediterranean sea, and reduced to three relictual areas in France (Alberes, Maures, Corse). The knowledge of the embryonic stages is necessary for a determination of the sensitive stages to mortality in the stock farmings. The developmental stages described here deal with the most eastern subspecies T. hermanni boettgeri, whose individuals are kept in captivity at the station of observation and protection of the Maures turtle (S.O.P.T.O.M.) at Gonfaron (Var). Indeed, this turtle must not be reintroduced in France, where natural populations of T. hermanni hermanni are living. The embryos of T. hermanni boettgeri came from thirty three clutches. The eggs were incubated at 28-degrees-C in the SOPTOM laboratory. Twenty six stages are described between egg-laying and hatching. These stages are comparable to those described for the freshwater turtle, Chelydra serpentina (Yntema, 1968). Some minor peculiarties, detected at the last stages, concern the scale system for the tail and the limbs. The development of the terminal claw of the tail, which constitutes a morphological characteristic for the species, is described for the first time. The small axis of the egg generally coincids with the antero-posterior axis of the embryo. This tends to limit the length extension of the embryo, whereas the great axis of the egg allows a width extension of the embryo. Just before hatching, the carapace width is greater than its length. In spite of these peculiarities, the complete study of the embryonic development, carried out for the first time in a terrestrial form, confirms the great homogeneity of Chelonians. This homogeneity was already suggested by the comparison between the developmental stages of leatherback sea turtles and other aquatic turtles (Renous et al., 1989).