Comparative cytogenetics among populations of two Bothriurus species (Scorpiones, Bothriuridae)

<i>Bothriurus</i> Peters, 1861 is one of the most diverse genera within the family Bothriuridae. However, to date, only five species have been analyzed using a cytogenetic approach. In this study, for the first time, two populations of <i>Bothriurus asper</i> Pocock, 1893 and nine populations of <i>Bothriurus rochai</i> Mello-Leitão, 1932, two species from northeastern Brazil, were analyzed with respect to diploid number, chromosomal behavior during meiosis, and the localization of heterochromatin and nucleolus organizer regions (NORs). For <i>B. asper</i>, a diploid number of 2n = 30 was recorded in geographically distant populations, whereas <i>B. rochai</i> exhibited intraspecific variation in diploid number (2n = 16 and 2n = 18), representing the lowest diploid numbers ever reported for the family Bothriuridae. Despite the variability in diploid number, the number and localization of NORs remained stable among the populations of <i>B. rochai</i>. When comparing heterochromatin patterns between the two species, larger blocks of constitutive heterochromatin were observed in <i>B. asper</i> than in <i>B. rochai</i>. Variation in the amount of heterochromatin among populations of <i>B. rochai</i> was also observed; in this case, the population with the lowest amount of heterochromatin also exhibited the greatest variation in post-pachytene cell configurations. This is the first study to cytogenetically analyze multiple populations of species within the genus <i>Bothriurus</i>, and it significantly expands the karyotypic information available for scorpions with monocentric chromosomes.