SPERMATOPHORE TRANSFER AND SPERM STRUCTURE IN THE BRACHYURAN CRAB METOPOGRAPSUS MESSOR (DECAPODA: GRAPSIDAE)

Abstract

ABSTRACT In the brachyuran crab Metopograpsus messor mating occurs only among hard (intermolt) individuals. Our present light and electron microscopic studies reveal that the spermatophores received by the females during coitus are discernible within the spermathecae until 24 h postmating. The study demonstrates time-dependent dissolution of the spermatophores of M. messor within the spermathecal lumen. The spermatozoa of M. messor were subjected to electron microscopic analysis. In addition to decapod and brachyuran features, the spermatozoa of M. messor display characters typical of the heterotreme-thoracotreme assemblage crabs, such as acrosomal length : width ratio (1.2), and the concentric arrangement of the acrosomal zones around the perforatorium. While the onion lamellation of the outer acrosome zone represents a typical thoracotreme character, the occurrence of the accessory opercular ring is indicative of its affinity to the GrapsinaeSesarminae subfamilies within the Grapsidae.