Comparative morphology of the gonadal structure related to reproductive strategies in six species of neotropical catfishes (Teleostei: Siluriformes)

Abstract

We studied the relationship between the morphology of the reproductive system and the reproductive strategies of six neotropical catfishes using macroscopic and microscopic analyses. The reproductive system of the examined Siluriformes showed diversified characteristics, but permitted their being grouped according to three reproductive strategies: pelagic spawning, demersal spawning, and internally fertilizing. The pelagic spawners Pseudoplatystoma corruscans and Conorhynchos conirostris have testes that are characterized by filiform lobes, absence of testicular secretion, full-grown oocytes of small diameter, thin zona radiata, and cuboidal follicular cells. Pimelodus maculatus is morphologically distinct from the other two pelagic spawners catfishes due to the presence of testicular secretion. The demersal spawners Lophiosilurus alexandri and Rhinelepis aspera possess homogeneous testicular secretion, large mature oocytes, and columnar follicular cells. The most specialized reproductive system was observed in the internally fertilizing Trachelyopterus galeatus, which possesses a seminal vesicle accessory to the testes, spermatozoa with elongated nuclei that form spermatozeugmata, and a secretory ovarian lamellar epithelium that is associated with sperm storage. The reproductive system observed in Neotropical catfishes showed a relationship associated with the type of fertilization and the reproductive strategies of the six species studied.

Reproduction of Pimelodus maculatus(Siluriformes: Pimelodidae) in three section of Grande River basin, downstream Porto Colombia dam, south-eastern Brazil

“…The yellowish colour of the ovaries and the histological features of the follicular cells and zona pellucida of the vitellogenic oocytes are similar to what has been reported by Melo et al (2011). The funnel-shaped micropyle observed in P. maculatus in this study seems to be a common pattern for fish of the Pimelodidae family (Rizzo et al, 2002).…”

“…In this study, anastomosis of the seminiferous tubules, a characteristic of testes of the anastomotic tubular type as described by Parenti & Grier (2004), was observed. In the caudal portion of the spent testes of P. maculatus, globular acidophilic secretion was observed, as has also been observed by Melo et al (2011). Some studies showed that this secretion may be related to sperm maturation and nutrition and may play a crucial role in fertilisation (Mazzoldi et al, 2005;Chowdhury & Joy, 2007).…”

Seasonal changes in the gonadossomatic index, allometric condition factor and sex ratio of an auchenipterid catfish from eastern Amazonia

“…Burgess (1989) identified that the actual fertilization takes place only at the time of the egg deposition, without any males assistance, by using a storage of sperm (Melo et al, 2011), which the females could retain for up to four months (varying upon the species). Hence, the more accurate term ''internal insemination'' had been used recently instead ''internal fertilization'' (Burns et al, 2002;Mazzoldi et al, 2007;Parreira et al, 2009).…”

Annotated list and key to the stream fishes of Trinidad & Tobago

“…Native. Internal fertilisation (Downing Meisner et al 2000, Costa Melo et al 2011, eggs hidden but with no additional parental care (Bailly et al 2008). Carnivore.…”