| Abstract |
The sexual endopodite constitutes a secondary sexual character very
significant for sex identification in Atyaephyra desmaresti (Millet, 1931). The
study of the relative growth of this character was based on the analysis of
allometry which describes the relative growth of the morphometric characters
compared to a reference variable (the overall length of the animal). Compari-
son of the average size of sexual endopodite on 600 shrimps (300 males and
300 females) from three tunisian damms (Sidi Salem, Lebna and Sidi Saâd),
reveals the existence of a sexual dimorphism very accentuated at the level of
the populations of Sidi Salem and Lebna. Both for males and females, the
highest average size of the sexual endopodite was observed in the specimens
from Lebna damm, and the lowest in those from Sidi Salem damm. A sexual
dimorphism is also noted concerning the growth of this sexual organ related
to the overall length. Indeed, allometry was positive in females from the three
populations, whereas in males, it was negative in the population from Sidi
Salem and isometric in populations from Lebna and Sidi Saâd. The compari-
son of the regression lines of relative growth of the sexual endopodite among
the three populations studied showed differences of slope or position for the
two sexes, indicating the influence of mesologic parameters on the growth of
this secondary sexual character. During the three phases of the reproductive
cycle of Atyaephyra desmaresti, the relative growth of the sexual endopodite
in females showed a positive allometry in general, seldom isometric; in males,
growth was more variable, with an allometry constantly negative in the post
reproductive period in the three reservoirs. |
