Cytogenetic data on the agro-predatory ant Megalomyrmex incisus Smith, 1947 and its host, Mycetophylax conformis (Mayr, 1884) (Hymenoptera, Formicidae)

Abstract

We provide the first karyotype description of the agro-predatory ant species Megalomyrmex incisus Smith, 1947 (Myrmicinae, Formicidae), and chromosome counts of its host Mycetophylax conformis (Mayr, 1884) (Myrmicinae, Formicidae) from geographically distinct populations. Colonies of both species were sampled from coastal areas of Ilhéus, Bahia, Brazil, and transferred to the laboratory. Metaphase spreads were prepared from the cerebral ganglia of defecated larvae. The slides were examined and pictures of the best metaphases were taken. The chromosome number for Megalomyrmex incisus was 2n=50 and n=25. The karyotype of this species consists of 20 metacentric and 5 submetacentric pairs. Thus, the karyotype formula of the diploid set was 2K=40M + 10SM and a fundamental number FN=100. The host species Mycetophylax conformis has 2n=30 and the karyotype consisting of 11 metacentric and 4 submetacentric pairs. The karyotype formula was 2K=22M + 8SM, and a fundamental number FN=60. Megalomyrmex incisus showed a slightly higher chromosome number, placed at the marginal range of the known distribution of haploid karyotypes of the Myrmicinae. The chromosome number and chromosomal morphology of Mycetophylax conformis corresponded to those of previously studied populations, suggesting its karyotype stability.

Intraspecific variation in the karyotype length and genome size of fungus-farming ants (genus Mycetophylax), with remarks on procedures for the estimation of genome size in the Formicidae by flow cytometry

“…morschi cytotypes ranged from 2n = 26 in the southern populations (RS and SC), to 2n = 28 in the Bahia population (BA), and 2n = 30 in the Rio de Janeiro (RJ) population ( Fig 3 ). These findings are consistent with those of previous studies (see [ 11 , 17 , 47 ]). No numerical or morphological variation was found among the M .…”

“…The diploid numbers of all M. conformis individuals analyzed here were 2n = 30, whereas the M. morschi cytotypes ranged from 2n = 26 in the southern populations (RS and SC), to 2n = 28 in the Bahia population (BA), and 2n = 30 in the Rio de Janeiro (RJ) population (Fig 3). These findings are consistent with those of previous studies (see [11,17,47]). No numerical or morphological variation was found among the M. conformis populations, whereas the number of chromosomes and karyotype did vary among the M. morschi population, as expected.…”

Assessing ploidy levels and karyotype structure of the fire ant Solenopsis saevissima Smith, 1855 (Hymenoptera, Formicidae, Myrmicinae)

“…The colony fractions of S. saevissima were taken directly to the laboratory, and while alive, the post-defecating larvae (without meconium; or pre-pupae) were isolated. As described by Imai et al (1988) and detailed by Cardoso et al (2017) , the cerebral ganglion of the larvae was removed and transferred to a container containing hypotonic colchicine solution (0.005% w/v colchicine in 1% sodium citrate solution) and incubated for 60 min in the dark. The time of incubation was adjusted considering the frequency of metaphases and standard condensation pattern (see Cristiano et al 2017 ).…”

Dynamic development of AT‐rich heterochromatin has followed diversification and genome expansion of psammophilous Mycetophylax (Formicidae: Attini: Attina)

“…Metaphase spreads were prepared from the cerebral ganglia of prepupae larvae, according to the protocol proposed by Imai et al (1988). The cerebral ganglion was dissected in colchicine–hypotonic solution (0.005% w/v colchicine in 1% sodium citrate solution) under a stereoscopic microscope, transferred to a new drop of colchicine–hypotonic solution and incubated in the dark for 1 h (Cardoso et al, 2017). The slides were evaluated using a phase contrast microscope.…”