Variation in male reproductive system characters in Corydoradinae (Loricarioidei: Callichthyidae) reflects the occurrence of different lineages in this subfamily

Abstract

Callichthyidae comprises a well-corroborated monophyletic group divided into two subfamilies: Corydoradinae and Callichthyinae. A recent proposal, based on molecular data, suggests that Corydoradinae is composed by nine monophyletic lineages, possibly genera. The species pertaining to those lineages have extensive modification in the size of genome, including diploid, tetraploid and octoploid species. Considering the occurrence of these monophyletic lineages and that the variations in DNA content may imply in significant alterations on the structure of spermatozoa, this study analyzed the morphology of the male reproductive system and the morphometry of the head of the spermatozoa of representatives of the nine lineages of Corydoradinae, seeking for particular characteristics of each lineage. Morphological data revealed a high intra-lineage variation, larger than that observed among species of different lineages. In contrast, morphometric data obtained for eight out of the nine lineages, revealed large congruency with the hypothesis that Corydoradinae is composed by different lineages. These results demonstrate that there is a correlation among variations in DNA content and the size of the spermatozoon head, thus providing additional subsides for the definition of the Corydoradinae lineages.Keywords: Monophyly, Morphometry, Spermatozoa, Variations in DNA.A família Callichthyidae compreende um grupo monofilético bem corroborado, dividida em duas subfamílias: Corydoradinae e Callichthyinae. Uma proposta recente, baseada em dados moleculares, sugeriu que a subfamília Corydoradinae é composta por nove linhagens, possivelmente gêneros. As espécies pertencentes a cada uma destas linhagens possuem extensivas modificações no tamanho do genoma, incluindo espécies diplóides, tetraplóides e octaplóides. Considerando a ocorrência dessas diferentes linhagens e que as extremas variações em conteúdo de DNA podem implicar em alterações significativas na estrutura dos espermatozoides, o presente estudo analisou a morfologia do sistema reprodutor masculino e a morfometria da cabeça dos espermatozoides de representantes das nove linhagens de Corydoradinae, procurando características particulares em cada uma. Os dados morfológicos revelaram a ocorrência de grande variação dentro das linhagens, maior que aquela observada entre espécies de diferentes linhagens. Diferentemente, os dados morfométricos obtidos para oito das nove linhagens revelaram grande congruência com a atual proposta para Corydoradinae. Estes resultados demonstram que há correlação entre as variações em conteúdo de DNA e o tamanho da cabeça dos espermatozoides, fornecendo, assim, subsídio adicional para a definição das nove linhagens de Corydoradinae.

Comparative Morphological Studies on Testes and Seminal Vesicles of African Catfish (Clarias gariepinus) and Nile Tilapia (Tilapia nilotica)

“…They reported that the bilateral testes of Nile fish were suspended from the dorsal portion of the body cavity, ventral to the kidneys. The location and portion of the seminal vesicles observed in this present study were similar to the report of Mazzoldi et al (2007) and Spadella et al (2017) in Callichthyidae family with the secretory activity occurring in the caudal portion with or without the seminal vesicles. Also in the families of Heteroneustidae, Clariidae and Auchenipteridae seminal vesicles occur in the caudal region of the reproductive system, as reported by Meisner et al (2000).…”

Redescription of Corydoras undulatus Regan, 1912 (Siluriformes: Callichthyidae), with comments on the identity of Corydoras latus Pearson, 1924

“…Males specimens exhibit a genital papillae with a tubular shape as most species of Corydoradinae and most species of lineage 6 [22]. Males are generally smaller than females with a darker color pattern tending to form clear longitudinal irregular lines on the laterals of the body vs .…”