Insemination in Eight Species of Cheirodontine Fishes (Teleostei: Characidae: Cheirodontinae)

Reproductive morphology of Brittanichthys axelrodi (Teleostei: Characidae), a miniature inseminating fish from South America

“…The sperm of the inseminating stevardiine characids Corynopoma riisei, Diapoma speculiferum, Scopaeocharax rhinodus, and Tyttocharax tambopatensis and the inseminating glandulocaudine Mimagoniates barberi also have elongate nuclei with flat surfaces (Burns et al, 1998;Pecio et al, 2005). Though elongate the sperm nuclei of inseminating cheirodontine characids (e.g., Compsura gorgonae) are more rounded in transverse section (Burns et al, 1997). Of the 60þ species of Ostariophysi known to be inseminating, only six characid species (Attonitus irisae, Knodus sp., Kolpotocheirodon theloura, Planaltina britskii, Planaltina glandipedis, and Planaltina myersi) have sperm cells with spherical or slightly ovoid nuclei .…”

“…Insemination, whereby spermatozoa are introduced into the reproductive tract of a female, is, so far as known, rare among bony fishes in general, but is proving increasingly frequent among characids (Burns et al, 1995(Burns et al, , 1997(Burns et al, , 2000. We follow Meisner (2005) in recognizing a distinction between insemination and internal fertilization.…”

“…Thus, unless fertilized eggs are found in the ovary (thereby demonstrating fusion of egg and sperm, i.e., internal fertilization), the presence of spermatozoa in the reproductive tract of a female is termed insemination. When the presence of insemination is optimized onto a phylogeny of characid fishes (Burns et al, 1997;Malabarba and Weitzman, 2003;Weitzman et al, 2005), it appears to have multiple origins within an unnamed clade of species that synapomorphically lack supraorbital bones. Therefore, it is of great interest to recognize correlations among insemination and other morphological characters.…”

Comparative morphology of gill glands in externally fertilizing and inseminating species of cheirodontine fishes, with implications on the phylogeny of the family Characidae (Actinopterygii: Characiformes)

“…Species within Cheirodontini and the incertae sedis genera are all externally fertilizing, whereas those within Compsurini are all inseminating, as observed by the presence of spermatozoa in their ovaries (Burns et al, 1997;. The timing of fertilization in inseminating species, however, is unknown since no fertilized eggs have been observed in the ovaries (Burns et al, 1997(Burns et al, , 1998.…”

“…The timing of fertilization in inseminating species, however, is unknown since no fertilized eggs have been observed in the ovaries (Burns et al, 1997(Burns et al, , 1998. In addition to the Cheirodontinae, insemination has also been confirmed in all species within the subfamilies Glandulocaudinae and Stevardiinae (sensu Weitzman et al, 2005 and, and in several characid genera of uncertain affinities (Javonillo et al, 2009).…”