Analysis of the karyotype structure in Ricolla quadrispinosa (Linneus, 1767): inferences about the chromosomal evolution of the tribes of Harpactorinae (Heteroptera, Reduviidae)

Abstract

The subfamily Harpactorinae is composed of six tribes. Phylogenetic studies bring together some of Harpactorinae tribes, but by and large the data on evolutionary relationships of the subfamily are scarce. Chromosome studies are of great importance for understanding the systematics of different groups of insects. For Harpactorinae, these studies are restricted to some subfamilies and involved only conventional chromosome analysis. This work analyzed cytogenetically Ricolla quadrispinosa (Linneus, 1767). The chromosome number was determined as 2n = 24 + X1X2Y in males. In metaphase II the autosomal chromosomes were organized in a ring with the pseudo-trivalent of sex chromosomes in its center. After C-banding followed by staining with DAPI, AT-rich blocks in autosomes were observed and the negatively heteropycnotic sex chromosomes. The data obtained, together with existing data for other species of the group, indicated that different chromosomal rearrangements are involved in the evolution of the species. In addition, a proposal of karyotype evolution for the subfamily, based on existing phylogenetic studies for the group is presented.

New evidence for the presence of the telomere motif (TTAGG) n in the family Reduviidae and its absence in the families Nabidae and Miridae (Hemiptera, Cimicomorpha)

“…Both species were found to have 28 chromosomes at spermatogonial metaphases (Figs 1, 5), and 12 autosomal bivalents and 4 univalent sex chromosomes at spermatocyte metaphases I (MI) (Figs 3,6a,b). Such a chromosomal complement has been reported for all so far studied species of the genus Rhynocoris Hahn, 1834 and also for half the studied species of the tribe Harpactorini (see for review: Tiepo et al 2016). The autosomes of spermatogonial metaphases and in turn both bivalents (MI) and univalent autosomes (MII) in meiosis are of a more or less similar size.…”

“…could have originated through the fission processes of the original X chromosome of an ancestor with a simple system XY. Although we studied no females and have thus no direct confirmation of such interpretation of sex chromosome system in these two species, it is likely, as it represents the prevalent pattern reported for their close relatives (Tiepo et al 2016). Three X chromosomes are of similar size and the smallest chromosomes of the complement.…”

“…As with other reduviid species (see e.g. Poggio 2007, Tiepo et al 2016, at MII the autosomes are arranged to form a ring, with sex chromosomes being positioned inside the ring as a pseudo-tetravalent without having a visible connection between them (Figs 4, 7).…”

A new species of the genus Rhaphidosoma Amyot et Serville, 1843 (Heteroptera, Reduviidae), with data on its chromosome complement

“…Previous original papers and revisions reported the chromosome complements of approximately 80 species (3% of the described ones) in about 40 genera (10% of the recognised ones) of Harpactorinae (Kpordugbe 1979;Ueshima 1979;Poggio et al 2007;Kaur et al 2012;Kaur and Kaur 2013;Bardella et al 2014;Souza et al 2014;Tiepo 2016;Grozeva et al 2019). The vast majority of the studied species belong to the most species-rich tribe Harpactorini; however, several species have also been studied in the tribes Apiomerini (six species, two genera), Rhaphidosomatini (two species, two genera), and Dicrotelini (one species).…”

“…Despite the holokinetic nature of chromosomes, which is believed to facilitate karyotype evolution through chromosomal fusions and fissions (fragmentations), most harpactorine species have a diploid autosomal number of 24 (24A) as was concluded earlier by Poggio et al (2007) based on an almost three times smaller data set. Species with a different number of autosomes (numbers 26, 22, 20, 18, 12, and 10 are presently known) are very rare, the second most common number, 22, being found mainly in the tribe Apiomerini (see Tiepo 2016). Another characteristic feature of harpactorines is multiple sex chromosome systems, with the number of X-chromosomes varying from one to five in different species (XY, X 1 X 2 Y, X 1 X 2 X 3 Y, X 1 X 2 X 3 X 4 Y, X 1 X 2 X 3 X 4 X 5 Y), while the system X 1 X 2 X 3 Y clearly predominates in the subfamily.…”