Cytogenetics studies in thirteen Brazilian species of Phaneropterinae (Orthoptera: Tettigonioidea: Tettigoniidae): main evolutive trends based on their karyological traits

the thirteen species of phaneropterinae here studied can be arranged in four different groups according to their basic karyological traits. all of them share the same kind of chromosomal sex determining mechanism with x0(male) and xx(female). the x chromosome differs among species and always appears heteropycnotic during prophase i, it is the largest in the set and segregates precociously during anaphase i. among the species, the karyotypes varies in fundamental number between 31 to 21. the meaning of these significant changes in the karyotypes in relation to the phylogeny within some large taxonomic group of species is discussed.