A review on intraspecific karyomorphological variations of m chromosomes in family Libellulidae (Anisoptera: Odonata)

Background Family Libellulidae is one of the largest families of suborder Anisoptera (Odonata) including 1035 species of 144 genera throughout the world. Libellulids are distributed all around the globe, while some are cosmopolitan and some are endemic. Cytogenetic data pertains to 258 libellulid species and chromosome number varies from 2n = 6-47. Majority of the species possess 2n (male) = 25, which is the modal number of the family. The m chromosomes are considered as the fragments of autosomes and are present in 78% of studied libellulid species. Main body Presently, 29 libellulid species have been catalogued based on various research articles related to cytogenetic studies regarding intraspecific chromosomal variations especially due to the m chromosomes within the same or different geographical populations of the species. Conclusions Odonata possess holokinetic chromosomes and m chromosomes are the fragments of autosome. The break can occur at any time, at any place, which is responsible for variations in the size of m chromosomes. These variations also depend on the geographical distribution of the species which persists over generations by the action of natural selection and also play role in speciation.