A new species of Endecous Saussure, 1878 (Orthoptera, Gryllidae) from northeast Brazil with the first X1X20 chromosomal sex system in Gryllidae

Abstract

In this paper we describe a new species of Luzarinae cricket collected from the cave "Gruta de Ubajara, municipality of Ubajara, State of Ceará, Brazil, highlighting phallic sclerites morphology and chromosome complement as diagnostic characters. We presented meiotic and mitotic characterization in order to define the karyotype with 2n = 12 + X1X2♂/12 + X1X1X2X2♀. This represents the first record of X1X20 chromosomal sex system in Gryllidae.

Repetitive DNA chromosomal organization in the cricket Cycloptiloides americanus: a case of the unusual X1X20 sex chromosome system in Orthoptera

“…The submetacentric X 2 that was described by Mesa et al (2002) corresponds to autosomal pair 4, which occurs invariably in two copies in both sexes and is easily recognized in some cells due to the occurrence of less-condensed chromatin in the middle of the long arm. The X 1 X 2 0♂/X 1 X 1 X 2 X 2 ♀ sex-determining system that has been described in the cricket C. americanus is a rare case of this type that has been observed in Orthoptera, but it is apparently common in some other invertebrates, such as spiders (White 1973;Maddison and Leduc-Robert 2013;Forman et al 2013;Zefa et al 2014) and some species of Heteroptera (Ueshima 1979;Kusnetzova 1988); Homoptera (Morgan 1915;White 1940) and Nematoda (Walton 1924;White 1940), and it is uncommon in eukaryotes as a whole. Concerning the origin of this system, in spiders, for example, the X 1 X 2 0 sex-determining system is considered a plesiomorphic feature, and various hypotheses for its origin have been raised, including the duplication of the original X chromosome, centric fragmentation, fission and the translocation of an X segment to a centric fragment of a supernumerary chromosome, among others (reviewed by Araujo et al 2012).…”

“…M. Palacios-Gimenez · D. C. Cabral-de-Mello (*) Departamento de Biologia, Instituto de Biociências/IB, UNESP-Univ Estadual Paulista, Rio Claro, São Paulo CEP 13506-900, Brazil e-mail: mellodc@rc.unesp.br system have been observed, with the occurrence of some distinct derived sex-systems, in most cases neo-XY♂/XX♀ and neo-X 1 X 2 Y♂/X 1 X 1 X 2 X 2 ♀ and even X 1 X 2 0♂/X 1 X 1 X 2 X 2 ♀ in the cricket species Cycloptiloides americanus and Endecous ubajarensis (Mesa and de Mesa 1967;White 1969White , 1973Hewitt 1979;Mesa et al 1982Mesa et al , 2002Castillo et al 2010;Palacios-Gimenez et al 2013;Zefa et al 2014). The Robertsonian (Rb) and tandem fusions, dissociations and inversions involving autosomes and sex chromosomes seem to be major evolutionary causes in the emergence of neosex chromosomes in this group (White 1973;Hewitt 1979;Bidau and Martí 2001;Mesa et al 2002;Castillo et al 2010).…”

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

“…The chromatin bridge in anaphase II of O. valensis occurs in other species of Orthoptera, usually related to chromosome breaks and rearrangements ( Figure 2f ) ( Warchałowska-Śliwa et al, 2005 ; Zefa et al, 2014a ). Chromatin bridges are chromatin segments positioned parallel to the segregating chromosomes during anaphase II ( Fenech et al, 2011 , Bizard and Hickson, 2018 ).…”

“…This differential heteropycnosis occurs through the earlier condensation of chromosome X in the initial phases of cell division ( Bidau and Martí, 2010 ). X/autosome rearrangements may give rise to derived sex systems, from the original X0♂/XX♀ to Neo-XY♂/XX♀, X 1 X 2 Y♂-X 1 X 1 X 2 X 2 ♀, and X 1 X 2 0♂-X 1 X 1 X 2 X 2 ♀ ( White, 1957 ; Saez, 1963 ; Mesa et al , 2002 ; Zefa et al, 2014b ; Palacios-Gimenez and Cabral-de-Mello, 2015 ).…”

Ethology of the cricket Endecous (Endecous) chape Souza-Dias & de Mello, 2017 (Orthoptera: Grylloidea: Phalangopsidae) I: Agonistic and reproductive behavior

“…Within the Phalangopsidae, Endecous is an exclusively Neotropical genus, and is one of the most diverse genera of Luzarinae. The genus includes three subgenera and 18 species, all of which inhabit leaf litter associated with rock gullies, burrows, caves, and any natural cavities , Zefa et al 2014, Bolfarini and Bichuette 2015, Souza-Dias et al 2017). These crickets are generalists, have cavicolous and straminicolous populations, and, so far, three troglobitic species have been recognized (Souza-Dias et al 2017).…”