A new genus of Anostomidae (Ostariophysi: Characiformes): Diversity, phylogeny and biogeography based on cytogenetic, molecular and morphological data

Differentiation and Evolution of the W Chromosome in the Fish Species of <b><i>Megaleporinus </i></b>(Characiformes, Anostomidae)

“…Parise-Maltempi et al [2013] obtained similar results using the WLm or WLe (i.e., WMm and WMe in the present study) sequences in L. friderici , L. striatus , L. lacustris , S. borelii , and S. isognathus , i.e., they found no chromosomes that shared these sequences. Ramirez et al [2017] proposed Megaleporinus based on morphological, cytogenetic, and molecular traits, which includes the majority of the species allocated previously to Leporinus , that have differentiated ZZ/ZW and Z 1 Z 1 Z 2 Z 2 /Z 1 W 1 Z 2 W 2 sex chromosomes [Galetti et al, 1984;Parise-Maltempi et al, 2007]. The findings of the present study nevertheless indicate that these species are closely related in terms of the evolution of differentiated sex chromosomes, irrespective of the genus ( Leporinus or Megaleporinus ) .…”

“…trifasciatus diversified early from the common ancestor in comparison with the other species of the genus. With the exception of M. muyscorum , all other species have a relatively recent common ancestor in comparison with M. trifasciatus [Ramirez et al, 2017]. In the present study, the differentiation of specific regions observed in the sex chromosomes of M. trifasciatus distinguished this species from the others analyzed using the same probes and technique.…”

“…However, differentiated sex chromosomes have an unusual distribution in fish. In some cases, the same system is found in all the species of a group, such as the ZZ/ZW system found in all the species of Triportheus [Artoni et al, 2001], and in the 10 species of Megaleporinus , which was created to distinguish the species with differentiated sex chromosomes from those with undifferentiated sex chromosomes [Ramirez et al, 2017]. In most other cases, however, the presence of differentiated sex chromosomes is sporadic.…”

“…The fish genus Leporinus was revised recently by Ramirez et al [2017], who allocated the species with differentiated sex chromosomes to a new genus, denominated Megaleporinus . This genus includes Megaleporinus obtusidens , M. reinhardti , M. macrocephalus , M. trifasciatus, and M. conirostris with sex chromosomes of the ZZ/ ZW type, and M. elongatus , which has a multiple system of sex chromosomes of the Z 1 Z 1 Z 2 Z 2 /Z 1 W 1 Z 2 W 2 type [Parise-Maltempi et al, 2007.…”

“…and Megaleporinus sp. Partially, this set of regulatory process would explain the different stages of chromosomal evolution of the ZW system observed in Leporinus sp2 (current L. geminis) [Ramirez et al, 2017] , L. elongatus (current M. elongatus) [Parise-Maltempi et al, 2007, and in M. trifasciatus .…”