The first cytogenetic characterization of the poisonous black widow spider Latrodectus gr. curacaviensis from Brazil, with chromosomal review of the family Theridiidae (Arachnida, Araneae)

Chromosomes of Theridiidae spiders (Entelegynae): interspecific karyotype diversity in Argyrodes and diploid number intraspecific variability in Nesticodes rufipes

“…The chromosomal characteristics observed in A. elevatus were extremely discrepant from those described for 30 species of Theridiidae previously studied, including five representatives of the genus Argyrodes (see Araujo et al , 2010). Thus, this is the first record of the karyotype formula 2n(male) = 21 = 20+X with biarmed chromosomes for a theridiid spider.…”

“…It appears thus that the main trend of chromosome evolution within Araneoidea was the reduction of the diploid number with the conservation of the sex chromosome system. In Theridiidae, diploid numbers higher than 2n(male) = 22, such as the 2n(male) = 24 observed in one species of Argyrodes , Chrysso , and in some individuals of Parasteatoda tepidariorum (Montgomery, 1907; Kageyama and Seto, 1979; Datta and Chatterjee, 1983), 2n(female) = 28 and 2n(female) = 26 found in species of Latrodectus , as well as diploid numbers lower than 2n(male) = 22, such as 2n(female) = 16 and 2n(female) = 18 also reported in Latrodectus (Araujo et al , 2010) and the 2n(male) = 21 of A. elevatus , probably correspond to a derived condition originated from the 2n(male) = 22.…”

“…The karyotype 2n(male) = 22+X 1 X 2 with acro/telocentric chromosomes is highly conserved among the Araneoidea spiders, considering that, with the exception of Theridiidae, it was observed in approximately 80% of the species belonging to five different families (Araujo D, PhD Thesis, Instituto de Biociências de Rio Claro, UNESP, São Paulo, 2007). Nevertheless, among the theridiids, the karyotype with 2n(male) = 20+X 1 X 2 , and acro/telocentric chromosomes is the most widespread and was already observed in species of all subfamilies already investigated (Araujo et al , 2010). It appears thus that the main trend of chromosome evolution within Araneoidea was the reduction of the diploid number with the conservation of the sex chromosome system.…”

“…Among eight other theridiids, the 2n(male) = 22+X 1 X 2 was observed in Argyrodes gazingensis , Chrysso scintillans , and Parasteatoda tepidariorum , and chromosome numbers ranging from 2n(female) = 16 to 2n(female) = 28 were reported for five species of Latrodectus . The chromosome morphology was only described for three of these eight species, which exhibited acro/telocentric chromosomes (reviewed in Araujo et al , 2010). …”

Chromosomal similarities between Nephilidae and Tetragnathidae indicate unique evolutionary traits among Araneoidea

“…Those regions were not described on sex chromosomes in any of the 14 species of Araneidae, Linyphiidae, Nesticidae and Theridiidae that were cytogenetically analyzed with similar procedures to that employed here (Matsumoto 1977;Tugmon et al 1990;Gunnarsson & Andersson 1992;Araujo et al 2010Araujo et al , 2011Stávale et al 2010;Zhao et al 2010). The importance of sharing secondary constrictions on sex chromosomes is still more relevant when we notice that these regions are also related to NORs, as revealed by silver impregnation in the species analyzed here and in the tetragnathid spiders examined by Král et al (2011).…”