Cytogenetics studies in Brazilian species of Pseudophyllinae (Orthoptera: Tettigoniidae): 2n(♂)=35 and fn=35 the probable basic and ancestral karyotype of the family tettigoniidae

Abstract

-The karyotypes of fi ve species of Brazilian Pseudophyllinae belonging to four tribes were here studied. The data available in the literature altogether with those obtained with species in here studied allowed us to infer that 2n(♂)=35 is the highest chromosome number found in the family Tettigoniidae and that it is present in species belonging to Pseudophyllinae, Zaprochilinae and in one species of Tettigoniinae. In spite of that all fi ve species exhibit secondary karyotypes arisen surely by a mechanism of chromosomal rearrangement of centric fusion, tandem fusion and centric inversion types from those with 2n(♂)=35 and FN=35, they share some common traits. The X chromosome is submetacentric (FN=36), heteropicnotic during the fi rst prophase, the largest of the set but its size is rather variable among the species and the sex chromosomal mechanism is of the XO( ♂ ), XX( ♀ ) type. The chromosomal rearrangements involved in the karyotype evolution of the Pseudophyllinae and its relationship with those of the family Tettigoniidae are discussed and we propose that the basic and the ancestral karyotype of the Tettigoniidae is formed by 2n(♂)=35, FN=35 and not by 2n(♂)=31, FN= 31, as usually accepted.

Contrasting the Chromosomal Organization of Repetitive DNAs in Two Gryllidae Crickets with Highly Divergent Karyotypes

“…The Orthoptera order comprises more than 25,700 species, which form the most diverse group of polyneopteran insects [ 1 , 2 , 3 ]. Variability in the dipoid number has been documented in distinct lineages, which range in the most highly studied groups from 2n(♂) = 15 to 2n(♂) = 35 in katydids Tettigoniidae [ 4 , 5 , 6 ], from 2n(♂) = 8 to 2n(♂) = 23 in Acrididae grasshoppers [ 7 , 8 , 9 ] and from 2n(♂) = 7 to 2n(♂) = 29 in Gryllidae crickets [ 9 , 10 , 11 , 12 , 13 ], although the modal number of chromosomes has been documented, such as 2n(♂) = 23 in grasshoppers and 2n = 21 in Gryllidae crickets [ 8 , 9 ]. This extreme karyotypic divergence has been attributed to multiple major chromosomal restructuring events, such as centric fusions, tandem fusions, reciprocal translocations, dissociations and inversions involving autosomes and sex chromosomes [ 8 , 9 ].…”