Phalangopsinae

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 : 113

Phalangopsinae

After the Phalangopsidae’s taxonomic reorganization adopted by Cigliano et al. (2020), the subfamily presents now the greatest number of species cytogenetically studied, but all of them included in only two genera, Endecous and Eidmanacris .

The Endecous ’ species present a complex model of chromosomal derivation, with a group of species with 2n = 19, and most M/SM chromosomes in the karyotype ( Endecous (Endecous) chape Souza-Dias & de Mello, 2017 , E. onthophagus and Endecous (Endecous) itatibensis Rehn, 1918 ), and another composed of species with 2n = 21, with the majority of A/T chromosomes ( Endecous (Endecous) betariensis de Mello & Pellegatti-Franco, 1998 , Endecous (Endecous) alejomesai Zefa, 2010 and Endecous (Endecous) cavernicolus Costa Lima, 1940 ). In addition, Endecous (Pedroecous) troglobius Castro-Souza et al., 2020 and Endecous (Pedroecous) didymus Castro-Souza et al., 2020 also present 2n = 21♁, but with karyotypes bearing the majority of M/SM chromosomes. Endecous (Endecous) ubajarensis Zefa, 2014 presents a high reduction in the chromosome number (2n = 14♁) probably due to two successive X/autosomes centric fusion to form the sex-determining system X 1 X 2 0♁ ( Zefa et al. 2014).

The karyotype of E. onthophagus from Uruguay was classified by Zefa et al. (2010) according to CI proposed by Guerra (1986), and showed the pairs 4 and 5 acrocentrics. When reclassifying these homologous pairs according to Levan et al. (1964) we found the pair 4 is a submetacentric. In individuals from Pelotas/RS/ Brazil, pairs 4 and 5 are submetacentrics, showing that polymorphism occurs in pair 5 between individuals from both locations.

The irregular M/SM and A/T chromosomes distribution in Endecous species karyotypes, together with the variation in the FN shows that the chromosomal derivation in these species occurred with a predominance of pericentric inversions, and/or other type of rearrangements that occurs independently in each of these species.

The chromosomal derivation in E. meridionalis and E. bidentata points to a path in which the karyotypes reached the end of the chromosomal derivation by successive centric fusions, showed by the low number of chromosomes in the karyotypes, all of them M/SMs. However, a subsequent step to centric fusions was the occurrence of pericentric inversions adding to the karyotype of E. septentrionalis and E. alboannulata acrocentric chromosomes (pairs 5 and 6, and pair 2, respectively), which are approximately the same size as the other chromosomes of the karyotype. Eidmanacris corumbatai deserves special attention, as pericentric inversions gave the karyotype a greater number of acrocentric chromosomes, preserving the low chromosome number in the karyotype ( Mesa et al. 1998).