Contribution of Cytogenetics to the Debate on the Paraphyly ofPachycondylaspp. (Hymenoptera, Formicidae, Ponerinae)

Abstract

We present evidence of the paraphyly of the ant genusPachycondylaresulting from our cytogenetic studies on 29 populations in 18 species from Brazil and French Guyana. It is likely that karyotypes with a large number of chromosomes and comprising mostly small acrocentric chromosomes in species within thePachycondyla stricto sensugroup resulted from a succession of centric fission events. On the other hand, karyotypes with a small chromosome number comprising mostly metacentric chromosomes are also interpreted as little derived and tend to undergo centric fission. The karyotypes of the groupNeoponeraare more heterogeneous and probably undergo successive cycles of rearrangements tending to increase the chromosome number by centric fission. Theapicalisandverenaecomplexes form two probable sister groups that evolved independently due to centric fissions (verenae) and pericentric inversions (apicalis). Our results reveal the karyotype diversity in the genus and reinforce the hypothesis on the paraphyly ofPachycondyla.

Studies on the Karyotype of the AntPachycondyla harpax(Formicidae: Ponerinae: Ponerini) in Southern Bahia, Brazil

“…Mariano et al (2012) reported for the genus Pachycondyla a variation ranging from 2n = 12 [Pachycondyla unidentata Mayr 1862] to 2n = 104 [Pachycondyla striata (Smith 1858)]. These results strengthen the idea of paraphyly of the genus proposed by Schmidt (2013).…”

“…Such a pattern has been observed in other species of the same genus (Lucas et al 2002;Delabie et al 2008;Mariano et al 2012;Fernandes et al 2014) as in other genera such as Myrmecia (pilosula) (Imai et al 1994), all suggesting that a single morphospecies may correspond to 2 or more genetically isolated taxa . Additionally, morphological analyses of individuals of P. harpax collected in other locations, where cytogenetic analysis was not possible, revealed obvious differences, suggesting genetic divergence and possible karyotype variability.…”

“…A range of cytogenetic studies have been conducted in several insect orders (Hoshiba & Imai 1993;Van Wilgenburg et al 2006;Poggio et al 2007;Tavares et al 2010;Mariano et al 2012), providing information independent from morphological characters, commonly used for taxonomic studies, that may reveal differences and/or similarities between organisms with a priori indistinguishable characters (Sessions 1996). In the Formicidae, Lorite & Palomeque (2010) reported chromosomal variation in over 750 morphospecies of ants, rendering the family the highest in chromosomal variability amongst the insects.…”

A revision of the giant Amazonian ants of the genus Dinoponera (Hymenoptera, Formicidae)

“…Mariano et al (2008) interpreted the karyotype differences between populations as being due to a division of the species into allopatric populations during the Quaternary. Variability in the karyotype within a described species has been found in the Pachycondyla as well, and may represent cryp-tic species (Mariano et al 2012). Descriptions of the banding patterns on Dinoponera chromosomes are provided by Barros et al (2009) andde Aguiar et al (2011).…”

“…The evolutionary position of the genus within Ponerinae was resolved by Schmidt (2010). Based on the phylogenetic analysis of Schmidt (2010) and karyotype analysis by Mariano et al (2012), Dinoponera's closest living relatives are in the Pachycondyla species group consisting of P. crassinoda, P. harpax (Fabricius 1804), P. impressa, P. metanotalis Luederwaldt 1918, andP. striata Smith 1858.…”