Chromosome Survey of Some Australian Tettigoniids (Orthoptera-Tettigonioidea): Two Species with Neo-XY Sex-Determining Mechanism

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

“…The reduction in the number of chromosome arms by the integration of autosomal chromatin in the Phaneropterinae was already observed by Ferreira (1969) in Tinzeda albosignata Brunner von Watternwyl, an Australian species with 2n♂ = 25 acrocentric chromosomes and by Mesa & Ferreira (1977) in Dichopetala brevihastata Morse collected in USA, with 2n♂ = 23 acrocentric chromosomes. Both species have in common a very large pair of chromosomes comprising nearly half of the whole autosomal chromatin, with a high number of chiasmata, well out of the normal if compared with other chromosomes in Tettigoniidae.…”

“…The karyotype 2n♂ = 31 was observed in 48 of 86 species studied and half of them show only acrocentric chromosomes with a NF = 31, collected in several localities around the world except in Australia, Japan (Ohmachi 1935), Brazil (Ferreira 1969(Ferreira , 1976(Ferreira , 1977Ferreira et al 1976), Canada (Beaudry 1973), Italia (Messina et al 1975 This kind of karyotype was considered by Ferreira (1977) as the ancestral for the majority of Phaneropterinae, and those different from the basic one derived by mean of different kind of rearrangements. The 2n♂=21 karyotype with all the chromosomes acrocentric, seems to be another branch of ancestry but not too recent since it was found in Australia and South America thought an independent origin can not be put aside.…”

“…The variability in chromosome number and morphology found among the Phaneropterinae is by far larger than in the remaining subfamilies, their extremes going from 2n♂ = 33 to 2n♂ = 16 (Pearson 1929, Dave 1965, Ferreira 1969, Cisneros-Barrios et al 1990. Between those extremes, species with 2n♂ = 32, 31,30,29,28,27,25,23,21,20,19, and 17 chromosomes were studied.…”

“…The literature shows that species of Phaneropterinae present a large chromosomal morphological and numerical variability, and their extreme limits in number of chromosomes (Ferreira 1969). The majority of its species are 2n♂ = 31 with all the chromosomes acrocentric or a derived number, originated mainly by tandem fusions, robertsonian changes and pericentric inversions.…”

“…The sex determining mechanism is X0♂ -XX♀ in the majority of species. Only six species are neoXY♂ -neoXX♀ and one of the X 1 X 2 Y♂ -X 1 X 1 X 2 X 2 ♀ type (Dave 1965;White et al 1967;Ferreira 1969Ferreira , 1976Alicata et al 1974).…”