Luzarinae, Hebard, 1928

Timm, Vítor Falchi, Martins, Luciano De Pinho, Acosta, Riuler Corrêa, Szinwelski, Neucir, Pereira, Marcelo Ribeiro, Costa, Maria Kátia Matiotti Da & Zefa, Edison, 2021, Trends of karyotype evolution in the Neotropical long-legged crickets Phalangopsidae (Orthoptera, Grylloidea), Zootaxa 4938 (1), pp. 101-116 : 108

Luzarinae

Luzarinae includes 279 valid species and, although Zefa et al. (2010) reported this subfamily with the largest number of species chromosomally studied among the phalangopsids, the taxonomic reorganization presented by Cigliano et al. (2020) reduced this number from 21 to nine, four of them presented in this work. Up to now, the Luzarinae’s chromosome number ranges from 2n = 11 in I. puri and Strinatia brevipennis Chopard, 1970 to 2n = 17 in L. lata and Aracamby picinguabensis de Mello, 1992 ( de Mello 1992; Mesa et al. 1999).

The karyotype of L. lata is asymmetrical, with two small acrocentric pairs that have not been subjected to centric fusion. On the other hand, M. ornata and I. puri , as well as Strinatia teresopolis Mesa, 1999 and S. brevipennis ( Mesa et al. 1999) present symmetrical karyotypes, with all M/SM chromosomes, which show that their karyotype has reached the chromosomal derivation final stage by successive centric fusions. In M. ornata , the bivalent pair 4 has a CI close to the limit for acrocentric, showing that a pericentric inversion has occurred.

Luzaridella susurra presents an irregular karyotype with a marked size difference between the bivalent pairs 1 and 2 (large), in relation to pairs 3, 4 and 5 (small). Although pairs 1 and 2 are M/SMs, the CI of the pair 1 (close to acrocentric) indicates a pericentric inversion. On the other hand, the bivalent pair 3 is metacentric, being expected to be acrocentric like the bivalent pairs 4 and 5, suggesting that they have become metacentrics by a pericentric inversion. We consider this karyotype to be irregular because, despite the difference in size of pairs 1 and 2 in relation to the others, it is not possible to affirm that centric fusions are predominant in the chromosomal derivation process, but rather, pericentric inversions and fusions may be occurring concomitantly.

The chromosomal derivation in Aracamby (see de Mello 1992) included a reduction in the chromosome number by successive centric fusions, followed by pericentric inversions. In Aracamby mucuriensis de Mello, 1992 (2n = 13♁) there is only one pair of acrocentric, these being the smallest chromosomes of the complement. Aracamby balneatorius de Mello, 1992 (2n = 15♁) presents the acrocentric pairs 4 and 5, probably resulting from a pericentric inversion, as they present large size similar to the M/SM chromosome pairs 2, 3 and 6, and A. picinguabensis (2n = 17♁) has the largest amount of acrocentric chromosomes, with acrocentric pairs 3, 4 and 5 of similar size to the metacentric pair 2, suggesting that pericentric inversion occurred after the centric fusion process.