New species of tree cricket Oecanthus Serville, 1831 (Orthoptera: Gryllidae: Oecanthinae) from Reserva Natural Vale, Espírito Santo, Brazil, with chromosome complement

Abstract

A new species of the genus Oecanthus Serville, 1831 from Reserva Natural Vale, state of Espírito Santo, Brazil is described. The new species differs from other of this genus in characteristics of the pseudepiphallus main lobe, endophallic sclerites, posterior median lobe of the metanotal gland and black spots on the femora and tibiae. The chromosome number is 2n=16+XY♂=18 and 2n=16+XX♀=18, and this complement present one pair of autosomes less than the other five cytological studied species.

Study of four Neotropical species of tree crickets Oecanthus Serville, 1831 (Orthoptera, Gryllidae) using cytogenetic and molecular markers

“…The large chromosomes in O. pictus differed from other karyotypes, with one metacentric, one submetacentric, and one acrocentric pair ( Figure 5 and Table 4 ). Our results for O. valensis were congruent with those of Milach et al (2016 ) ( Table 4 ). B chromosomes were observed in only two species of the genus; in O. valensis they were small and larger than chromosome Y ( Figure 1b ), and in O. pellucens were small and similar in size to chromosome Y ( Hewitt, 1979 ; Milach et al , 2016 ).…”

“…We found that O. pallidus had the smallest diploid number, 2n = 18, as previously reported for O. valensis and Oecanthus sp., and O. pictus had the highest chromosome number in the genus, with 2n = 21. The other species did not show wide chromosome variability, with diploid numbers ranging from 2n = 19 to 20 ( Johnson, 1931 ; Makino, 1932 ; Ohmachi, 1927 , 1935 ; Kitada, 1949 ; Hewitt, 1979 ; Aswanianarayana and Ashwath, 2005 ; Milach et al, 2016 ). The sex-chromosome system was as previously described for the other species of the genus (X0 and XY) ( Johnson, 1931 ; Makino, 1932 ; Ohmachi, 1927 , 1935; Kitada, 1949; Hewitt, 1979 ; Aswanianarayana and Ashwath, 2005 ; Milach et al , 2016 ).…”

“…Oecanthus Serville, 1831 is the largest genus, with 74 described species and a worldwide distribution ( Walker, 1962 ; Cigliano et al, 2021 ). Described karyotypes of oecanthine crickets show variations in the chromosome number, morphology, and sex-chromosome system, although the chromosome sets of only eight species have been studied so far ( Johnson, 1931 ; Makino, 1932 ; Ohmachi, 1935 ; Kitada, 1949 ; Hewitt, 1979 ; Milach et al, 2016 ; Zefa et al, 2018 ). One of these is Neoxabea brevipes Rehn, 1913, with 2n = 24 autosomes + two sex chromosomes (XY or X 1 X 2 0) ( Zefa et al , 2018 ); the other seven species belong to the genus Oecanthus ( Johnson, 1931 ; Makino, 1932 ; Ohmachi, 1935; Kitada, 1949; Hewitt, 1979 ; Milach et al , 2016 ).…”

“…Described karyotypes of oecanthine crickets show variations in the chromosome number, morphology, and sex-chromosome system, although the chromosome sets of only eight species have been studied so far ( Johnson, 1931 ; Makino, 1932 ; Ohmachi, 1935 ; Kitada, 1949 ; Hewitt, 1979 ; Milach et al, 2016 ; Zefa et al, 2018 ). One of these is Neoxabea brevipes Rehn, 1913, with 2n = 24 autosomes + two sex chromosomes (XY or X 1 X 2 0) ( Zefa et al , 2018 ); the other seven species belong to the genus Oecanthus ( Johnson, 1931 ; Makino, 1932 ; Ohmachi, 1935; Kitada, 1949; Hewitt, 1979 ; Milach et al , 2016 ). Neoxabea brevipes and O. valensis Milach and Zefa, 2016 inhabit the Neotropical bioregion; O. nigricornis Walker, 1869 and O. quadripunctatus Beutenmüller, 1894 the Nearctic; O. longicauda Matsumura, 1904 and O. pellucens (Scopoli, 1763) the Paleoarctic; and O. indicus Saussure, 1878 and Oecanthus sp.…”

“…The first group comprises large chromosomes, consisting of two or three autosome pairs and the X chromosome. The second comprises small (dot-like) chromosomes, including five, six, or seven autosome pairs and the Y chromosome, when the sex-chromosome system is XY ( Johnson, 1931 ; Makino, 1932 ; Ohmachi, 1927 , 1935 ; Kitada, 1949 ; Hewitt, 1979 ; Aswanianarayana and Ashwath, 2005 ; Milach et al, 2016 ).…”