title: Comparative cytogenetics of three species of Dichotomius (Coleoptera, Scarabaeidae).
abstract: Meiotic and mitotic chromosomes of Dichotomius nisus, D. semisquamosus and D. sericeus were analyzed after conventional staining, C-banding and silver nitrate staining. In addition, Dichotomius nisus and D. semisquamosus chromosomes were also analyzed after fluorescent in situ hybridization (FISH) with an rDNA probe. The species analyzed had an asymmetrical karyotype with 2n = 18 and meta-submetacentric chromosomes. The sex determination mechanism was of the Xy(p) type in D. nisus and D. semisquamosus and of the Xy (r) type in D. sericeus. C-banding revealed the presence of pericentromeric blocks of constitutive heterochromatin (CH) in all the chromosomes of the three species. After silver staining, the nucleolar organizer regions (NORs) were located in autosomes of D. semisquamosus and D. sericeus and in the sexual bivalent of D. nisus. FISH with an rDNA probe confirmed NORs location in D. semisquamosus and in D. nisus. Our results suggest that chromosome inversions and fusions occurred during the evolution of the group.
authors.affiliation: Centro de Ciências Biológicas, Departamento de Genética, Universidade Federal de Pernambuco, Recife, PE Brazil.
authors.forename: Guilherme Messias
authors.initials: GM
authors.lastname: da Silva
authors.forename: Edgar Guimarães
authors.initials: EG
authors.lastname: Bione
authors.forename: Diogo Cavalcanti
authors.initials: DC
authors.lastname: Cabral-de-Mello
authors.forename: Rita de Cássia
authors.initials: Rde C
authors.lastname: de Moura
authors.forename: Zilá Luz Paulino
authors.initials: ZL
authors.lastname: Simões
authors.forename: Maria José
authors.initials: MJ
authors.lastname: de Souza