Markiana nigripinnis (Perugia, 1891) as a putative member of the subfamily Stevardiinae (Characiformes: Characidae): spermatic evidence

Abstract

The genus Markiana was until recently recognized as incertae sedis in the family Characidae, even though alternative placements for this genus have been advanced since its original description. More recently, it was hypothesized that Markiana nigripinnis is part of a clade informally named the Astyanax clade, indicating the putative close relationship of Markiana with the genus Astyanax. Examination of sperm ultrastructure of representatives of Astyanax and M. nigripinnis shows no evidence for this hypothesized close relationship. Rather, the spermatozoa of M. nigripinnis share characters found in spermatozoa of the non-inseminating members of the subfamily Stevardiinae, such as an angle of nuclear rotation equal to 85º resulting in a lateral position of the double nuclear fossa and flagellum. As with the non-inseminating Stevardiinae, sperm nuclei are also slightly elongate toward the flagellum, the proximal centriole is partially inside the nuclear fossa and anterior and oblique to the distal centriole, and the midpiece is short and strongly asymmetric. Additionally, M. nigripinnis shares with the other members of the Stevardiinae the presence of only four teeth in the inner row of the premaxillary and a short triangular ectopterygoid, which is never more than twice the length of the palatine.O gênero Markiana até recentemente foi reconhecido como incertae sedis na família Characidae, apesar da localização alternativa para este gênero desde sua descrição original. Mais recentemente, surgiu a hipótese de que Markiana nigripinnis faz parte de um clado chamado informalmente de "Astyanax clade", indicando a suposta relação de Markiana com o gênero Astyanax. A análise da ultraestrutura dos espermatozoides de representantes do gênero Astyanax e M. nigripinnis não mostra nenhuma evidência de estreita relação. Pelo contrário, os espermatozóides de M. nigripinnis compartilham o padrão encontrado nos espermatozoides dos membros não-inseminadores da subfamília Stevardiinae, tais como, um ângulo de rotação nuclear igual a 85º resultando em uma posição de lateral da fossa dupla nuclear e do flagelo. Assim como nos Stevardiinae não inseminadores, os núcleos dos espermatozoides também são ligeiramente alongados em direção ao flagelo, o centríolo proximal é anterior e oblíquo em relação ao centríolo distal e parcialmente inserido na fossa nuclear, e a peça intermediária é curta e fortemente assimétrica. Além disso, M. nigripinnis compartilha com os outros membros da Stevardiinae a presença de apenas quatro dentes na série interna da pré-maxila e um osso ectopterigoide curto e triangular, que nunca ultrapassa o dobro do comprimento do osso palatino.

Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling

“…The inclusion of M. nigripinnis within clade A is a novel hypothesis. Although this species has ii+9 dorsal-fin rays, the plesiomorphic condition according Malabarba and Weitzman [19], other morphological characteristics including spermatozoa ultrastructure which is very similar to those of the non-inseminating members of clade 55, the presence of only four teeth in the inner premaxillary tooth row, and a short triangular ectopterygoid which is never more than twice the length of the palatine [79] corroborate the hypothesis that M. nigripinnis belongs to clade 55. Mirande [22,23] did not find Markiana to be a member of clade A, but did propose a sister group relationship between M. nigripinnis and Bryconamericus scleroparius .…”

Molecular phylogeny of the subfamily Stevardiinae Gill, 1858 (Characiformes: Characidae): classification and the evolution of reproductive traits

“…Composition of the tribes Diapomini, Glandulocaudini, Hysteronotini, Landonini, Phenacobryconini, Stevardiini, and Xenurobryconini follows [ 13 , 19 , 36 ]. Genera originally included in Stevardiinae [ 6 ] or subsequently by other authors indicated by superscripts matching the reference number [ 8 , 19 – 21 , 31 , 36 , 66 – 68 ]; Genera in bold were included in this study…”

Gross anatomy and histology of the alimentary system of Characidae (Teleostei: Ostariophysi: Characiformes) and potential phylogenetic information

“…Oliveira et al, 2011 ), it is included in the Stevardiinae. Interestingly, Baicere-Silva et al (2011) found, from data of sperm and spermatogenesis, similarities between Markiana and the Stevardiinae, supporting the molecular approach and supporting the idea that additional morphological information is needed.…”