Reproductive biology of Pseudotocinclus tietensis (Siluriformes: Loricariidae: Hypoptopomatinae), a threatened fish species

Reproductive cycle Gonads Pseudotocinclus tietensis Fecundity Cascudo.

Authors

  • Jandyr A. Rodrigues-Filho Foundation Institute of Fisheries of the State of Rio de Janeiro
  • Renato M. Honji Instituto de Biociíªncias, Universidade de Sào Paulo, Rua do Matào, Trav. 14, 321, 05508-090, Brasil.
  • Paulo H. Mello Instituto de Biociíªncias, Universidade de Sào Paulo, Rua do Matào, Trav. 14, 321, 05508-090, Brasil.
  • Maria I. Borella Instituto de Ciíªncias Biomédicas, Universidade de Sào Paulo Av. Prof. Lineu Prestes, 1524, Sào Paulo 05508-900, Brasil.
  • Alexandre W.S. Hilsdorf Universidade de Mogi das Cruzes. Av. Dr. Cí¢ndido Xavier de Almeida e Souza, 08701-970, Brasil.
  • Renata G. Moreira Universidade de Mogi das Cruzes. Av. Dr. Cí¢ndido Xavier de Almeida e Souza, 08701-970, Brasil.
June 30, 2017

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Pseudotocinclus tietensis is endemic to the Upper Tietíª River basin and classified as vulnerable. The reproductive biology of this species is still unknown, therefore, we investigated its reproductive strategy and gonad development during its annual reproductive cycle. The fish were collected throughout one year, and histology of the gonads, fecundity and oocyte diameter was conducted. Three phases of gonad maturation were found in males and females (immature, developing, and spawning capable), and the development stages of the gametes were identified within each stage. In the testes, four stages of gamete development were distinguished: spermatogonia, spermatocytes, spermatids and spermatozoa. During spermiation, the spermatozoa were released into the tubular lumen and then continued through the efferent ducts. In the ovaries, five stages of gamete development were identified: chromatin nuclear, perinucleolar, yolk vesicle formation, vitellogenic and ripe. The minimum diameter of ovulating oocytes was 297 µm, and the absolute fecundity was 64 to 306 oocytes. Males with spermatozoa in the lobular lumen and females with vitellogenic and ripe oocytes were found throughout the year. Pseudotocinclus tietensis has asynchronous ovarian development and gametes with fertilization capacity can be eliminated throughout the annual cycle.