PROTANDRIC HERMAPHRODITISM IN A MOLE CRAB, EMERITA ASIATICA (DECAPODA: ANOMURA)

¹ Department of Zoology, University of Madras, Madras-600 005, India

Protandric hermaphroditism in a mole crab, Emerita asiatica, is described. Neotenous males occur at 3.5 mm carapace length (CL) and above, whereas females acquire sexual maturity at 19 mm CL. The neotenous males, as they continue to grow, gradually lose male functions and reverse sex around 19 mm CL. The disappearance of genital papillae is the first visible sign of sex reversal; spermatogonial activity in testes ceases but hyperactivity of the mesodermic cells ensues. In the CL range of 19-22 mm, the male's gonad comprises inactive testicular and active ovarian portions; the median ovarian limb beyond the fused posterior extremity of the testes lacks testicular elements; and the vas deferens is intact but a pair of functional oviducts is formed. These intersexuals possess three pairs of pleopods. A few have eggs, and thus constitute secondary females in the population. Androgenic glands, active in the neotenous males, show signs of degeneration in the larger males, and disappear in the intersexuals. The mesodermic cells of the gonad undergo important functional changes during sex reversal. Sex-changers with incomplete transformation of testis into ovary and imperfectly differentiated oviducts are also reported.