“…The chromosomal number ranges from 2n = 52 to 62, including B chromosomes and different SCSs ( Blanco et al, 2012 , 2017 ; Deon et al, 2020 ; Sassi et al, 2020 ; Sassi et al, 2021 ). In phylogenetic reconstructions, three distinct clades were proposed for the genus, thus reinforcing the extensive diversification experienced by the lineage; also, it is grouping the species according to their South American distribution: (I) from the Guyana shield rivers; (II) from the northern Brazilian rivers; and (III) from the Brazilian south/southeast rivers ( Londoño-Burbano and Reis, 2021 ). Three SCSs were detected so far: (1) the X 1 X 1 X 2 X 2 /X 1 X 2 Y system, present in H. punctata , H. duriventris, and H. villasboas , and (2) a proto/neo-XX/XY system in H. rondoni , both belonging to clade II, and (3) the XX/XY 1 Y 2 system in H. carvalhoi, H. intermontana, and Harttia sp.1, species which belong to clade III ( Centofante et al, 2006 ; Blanco et al, 2017 ; Sassi et al, 2020 ; Sassi et al, 2021 ; Deon et al, submitted ).…”