High variability in chromosome number from a clade within the gourami family (Teleostei, Osphronemidae).

Identifying clades with extensive and conspicuous changes in diploid chromosome number (2n) is an important step in unraveling the evolutionary mechanisms underlying karyotype evolution. Here, we report low 2n in a monophyletic group of teleost fishes within the family Osphronemidae defined by their unique spiral egg structure (the "spiral egg" clade). We sampled seven of the nine known species within the spiral egg clade, reporting novel 2n for five species and confirming two others.