COMPARATIVE CHROMOSOME DATA ON TWENTY THREE SPECIES OF FAMILY COENAGRIONIDAE (ZYGOPTERA : ODONA.....

Karyological studies have been conducted on 23 species from seven genera in the Coenagrionidae family. These were collected during the pre-monsoon and post-monsoon seasons in states across North-West and North-East India. There are 21 male species and four female species among them. In males, 16 species have 2n=27 diploid chromosomes, while the remaining five have 2n=25. In females, all species have a diploid chromosomal number of 2n=28. The XO-XX type sex determination mechanism is found in all organisms. Agriocnemis obscura (9), Ceriagrion coromandelianum (d), Coenagrion dyeri (9), Pseudoagrion decorum (d), and Pseudoagrion rubriceps have all been found to have autosomal fragmentation (d&9). In gonial metaphase plates, the number of chromosomes ranges from 27 to 60. In the fragmentary stages, the sex element could not be distinguished. Chromosome behaviour and morphology during meiosis have been investigated and compared within families and genera.

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