Abstract
Black perch (Embiotoca jacksoni) are a common southern California fish that exhibits internal fertilization. During copulation, males transfer a spermatozeugmata to the female via an intromittent organ. Relatively little is known about the reproductive morphology of male black perch and the spermatozeugmata. The objective of our study was to describe the development of spermatocytes and the spermatozeugmata. We also used histology to examine the anal fin and describe the tissues of the intromittent organs. Black perch < 90 mm SL had testes that were composed of spermatocytes at all developmental stages. All stages of spermatocytes in addition to spermatozeugmata were present in males ³ 90 mm SL. On both sides of the anal fin at the anterior end, an intromittent organ was housed in a sheath composed of smooth muscle. Our research note is the first to document the formation of black perch spermatozeugmata within the testis. We also characterized the tissues of the intromittent organs and its muscular sheath which reside on an unmodified anal fin. The copulatory structures of embiotocid species have not been fully investigated, thus our work contributes to understanding the reproductive biology of surfperches.
