CHROMOSOMAL DATA ON SEVEN SPECIES OF GENUS ORTHETRUM (LIBELLULIDAE ANISOPTERA ODONATA)
G. K. WALIA *
Department of Zoology, Punjabi University. Patiala – 147 002.
R. SANDHU *
Department of Zoology, Punjabi University. Patiala – 147 002.
*Author to whom correspondence should be addressed.
Abstract
Cytogenetical analysis on seven species of genus orthetrum belonging to family Libellulidae from North and North-east Indian states have been carried out. Among these, Onthetrum glaucum, Orthetrum pruinosum neglectum, Orthetrum sabina sabina, Orthetrum taeniolatum and Orthetrum triangulare triangulare possess diploid numbers 25 m, that is typical libellulid number. The remaining two species, Orthetrum iuzonicum and Orthetrum japonicum internum show variation from this number in having 2n=23, without m chromosomes. All the species possess XO-XX type sex determining mechanism. Variation in chromosome number, total chromosome length (TCL), m : X & longest autosome : X ratios have been studied for the first time in this genus.