Gonadal morphology of the weedy seadragon, Phyllopteryx taeniolatus (Lacépède): characterisation of ovarian and testicular maturation

Abstract

Because little is known about the reproductive biology of the weedy seadragon, Phyllopteryx taeniolatus, we sought to characterise for the first time the morphology and histology of the gonads of female and male weedy seadragons. Each seadragon ovary consisted of a pair of cylindrical tubes with a total of four tubes per female with follicles arranged with less mature oocytes originating from the germinal ridge and progressively more advanced oocytes occurring in a spiral fashion around the periphery of less-developed oocytes. Seadragon testes had a system of interconnecting seminiferous tubules with spermatocyte development occurring within the tubule. Spermatocytes were observed along the testis wall and appeared to emerge into the lumen where further development of spermatocytes occurred. This study represents the first examination of the gonadal structures of the weedy seadragon, a species currently classified by the International Union for Conservation of Nature (IUCN) as ‘Near Threatened’. The descriptions of morphological development of the gonads may be useful in the histological identification of the stages of gametogenesis and reproductive status of other syngnathids. In addition, this information may also provide useful information in elucidating the phylogeny of this family of fishes.