High content of constitutive heterochromatin in two species ofPseudonannolene(Diplopoda)

Abstract

-Due to the fact that a considerable amount of constitutive heterochromatin has been commonly found in millipedes, this paper presents the characterization of the chromosomal complement, through C-banding technique, of two species of millipedes belonging to the genus Pseudonannolene. The species Pseudonannolene tocaiensis shows 2n=20, with five chromosomal pairs almost completely heterochromatic and the remaining pairs with pericentromeric C+ blocks. P. silvestris shows 2n=16, with a large heterochromatic portion in the first two pairs of autosomes, which presented the long arms totally C+

Comparative cytogenetics in different populations of the cavernicolous diplopod Pseudonannolene strinatii (Diplopoda, Pseudonannolenidae)

“…Sumner (1990), however, affirms that chromosomic variants, such as variations in the heterocromatin, are kept in populations as a heteromorphism, not necessarily causing reduction of fertility and in this way not becoming reproductive barriers, and thus not leading to speciation. As expected, the nucleolus organizer regions are observed in pair 4 in all populations and correspond to heterochromatic portions (Campos & Fontanetti, 2004), as described by various authors for different groups animals, including others diplopods (Souza et al, 2005;Godoy et al, 2008). The silver impregnation revealed heteromorphisms for the size of the NOR in the chromosomes of the individuals of Jeremias and Areias de Cima Cave.…”

“…These present high amounts of the constitutive heterochromatin, about 65% of the diploid genoma of the species, a fact already observed in this and other species of other orders (Vitturi et al, 1997;Fontanetti et al 2002;Campos & Fontanetti, 2004;2005;Souza et al, 2005;Godoy et al, 2008). Pairs 5 and 6 of the individuals of the Laboratório Cave and pairs 4 and 5 of Jeremias Cave are heteromorphic based on C-banding.…”

A new species of Urostreptus (Diplopoda, Spirostreptidae): description and chromossome number

“…Acanthopetalum sicanum (Berlese, 1883) (Callipodida) presents about 60 and 56% of heterochromatin, respectively in males and females and Enologus oxypygum (Julida) about 67%, with this value being equal in males and females (VITTURI et al, 1997(VITTURI et al, , 2001). The Brazilian species Pseudonannolene tocaiensis Fontanetti, 1996, P. silvestris Schubart, 1944and P. strinatii Mauriès, 1974 also present a large amount of constitutive heterochromatin, representing in the later about 65% of the genome (CAMPOS & FONTANETTI, 2004;SOUZA et al, 2005).…”