Morphological characterization of testicular cells, spermatogenesis and formation of spermatophores in a fish ectoparasite Argulus bengalensis Ramakrishna, 1951 (Crustacea: Branchiura)

Male reproductive system of the fish ectoparasiteArgulus bengalensis(Crustacea: Branchiura)

“…The recent discovery of spermatophores in A. japonicus (Avenant‐Oldewage and Everts, ; Banerjee et al, ) and a deeper understanding of the structure and formation of this character in A. bengalensis (Banerjee et al, ) made the earlier descriptions (Avenant‐Oldewage and Swanepoel, ) of the male reproductive system for the genus obsolete. The issue thus demands a re‐evaluation of the earlier representation for a better understanding of the reproductive biology of the genus.…”

“…Each lobe comprises two separate enclaves or hubs. Banerjee et al () observed that the spermatogonial cells are kept within the outer enclave and the other differentiating cells of spermatogenic lineage are located at the inner enclave. Exile into a separate enclave helps the spermatogonial cells to maintain their stem cell property by concealing themselves from the signals leading into differential pathway (Banerjee et al, ).…”

“…Banerjee et al () observed that the spermatogonial cells are kept within the outer enclave and the other differentiating cells of spermatogenic lineage are located at the inner enclave. Exile into a separate enclave helps the spermatogonial cells to maintain their stem cell property by concealing themselves from the signals leading into differential pathway (Banerjee et al, ). This feature ultimately confers an advantage to their parasitic adaptability in terms of their endured fecundity throughout their reproductive phase (Guha et al, ) of life and hence, in the maintenance of their population size.…”

“…Concerning sperm transfer, Banerjee et al () reported as many as 20 spermatophores in the oviduct of a postmated female A. bengalensis . Martin (), Debaisieux (), and later Avenant‐Oldewage and Swanepoel () described that the spermathecae and thus spermathecal spines of the female are brought in direct contact with the male genital opening during copulation.…”

“…In Dolops , the male reproductive system was described (Fryer, ), in Argulus , the system is incompletely understood. Avenant‐Oldewage and Swanepoel () described the male reproductive structure in A. japonicus prior to the discovery of the spermatophore (Avenant‐Oldewage and Everts, ; Banerjee et al, ) of the genus. Furthermore, it was incomplete due to some misinterpretations about the male gamete structure and lack of information on their packaging which is now available (Banerjee et al, ); therefore, a redescription and in light of that an evaluation of the description of the system appeared necessary.…”