Karyomorphological Variations in the Chromosome Complement of Orthetrum Taeniolatum of Family Libellulidae (Odonata: Anisoptera)

Karyomorphological Variations in the Chromosome Complement of Orthetrum taeniolatum of Family Libellulidae (Odonata: Anisoptera)

Gurinder Kaur Walia*, Harbhajan Kaur and Jaspreet Kaur

Department of Zoology and Environmental Sciences, Punjabi University, Patiala-147002, Punjab, India

Received November 21, 2012; accepted November 6, 2014

Summary Orthetrum taeniolatum, collected from the Patnitop area of Jammu and Kashmir, has been cytogenetically studied. The species possesses diploid chromosome number 2n=21m with X0 type sex determining mechanism. During the course of meiosis, two autosomal bivalents are distinctly large as compared to the remaining autosomal bivalents. The X chromosome also shows the phenomenon of precocious segregation. The reduction in chromosome number from the type number (2n=25m) is due to the fusion of two autosomal pairs, which is very common in case of holokinetic chromosomes. This type of karyomorphological variations in the species has been observed for the ﬁrst time.

Key words Orthetrum, Chromosome complement, Autosomal fusion, Precocious segregation.

The modal number of the family Libellulidae is 2n=25 (22A+2m+X0). The family is characterized by the presence of a pair of micro-chromosomes. Libellulids possess holocentric chromosomes and have post-reductional division of sex chromosomes. Autosomal fusions and autosomal fragmentations have been considered to be the key mechanism of the karyotypic evolution in Odonata (Kiauta 1969b). Earlier cytogenetic data on genus Orthetrum pertains to only 22 species. Out of these, 10 species have been reported from India. The majority of the species show diploid chromosome number 2n=25m (Oguma 1917, 1930, 1942, Oksala 1939, Kichijo 1942, Omura 1955, 1957, Dasgupta 1957, Kiauta 1969a, b, 1972, 1975, Kiauta and Ochssee 1979, Tyagi 1978, Handa and Batra 1980, Thomas and Prasad 1981, 1986, Handa et al. 1984, Walia and Sandhu 2002a). Variations in the chromosome number from the modal number due to fragmentations and fusions of the chromosomes in the Orthetrum genus have also been reported. Among these are n=12–14 in Orthetrum coerulescens and n=12 in Orthetrum brachiale (Kiauta 1969b); n=14 in Orthetrum Julia falsum (Boyes et al. 1980) and 2n=23 (without m-chromosomes) in Orthetrum iuzonicum, Orthetrum japonicum internum (Walia and Sandhu 2002b). During the present study, the chromosomal complement and behaviour of chromosomes during meiosis in Orthetrum taeniolatum have been studied. Karyomorphological variations due to fusion of two autosomal pairs have been observed, which result in the decrease of chromosome number from 2n=25m to 2n=21m. Earlier, 2n=25m has been reported in the same species (Kiauta 1972, 1975, Kiauta and Kiauta 1976, Tyagi 1978, Kiauta and Kiauta 1982, Handa and Batra 1980, Handa et al. 1984, Thomas and Prasad 1986, Walia and Sandhu 2002a). They have collected the specimens from different localities than the present locality. Cytogenetical data pertaining to the genus Orthetrum has also been tabulated and compared.

* Corresponding author, e-mail: [email protected] DOI: 10.1508/cytologia.80.95 96 G. K. Walia et al. Cytologia 80(1)

Materials and methods

Male specimens of Orthetrum taeniolatum were collected from water bodies of the Patnitop area of Jammu and Kashmir. Live male specimens were dissected in 0.67% saline to take out the gonads. The gonads were ﬁxed in Carnoy’s ﬁxative (3 : 1:: absolute alcohol : glacial acetic acid) and slides were prepared by the air-drying technique. Slides were stained in carbol fuchsin by following the technique suggested by Carr and Walker (1961) and well-spread mitotic and meiotic plates were microphotographed.

Results

The spermatogonial prometaphase plate possesses long thread-like uncondensed chromosomes which cannot be differentiated individually (Fig. 1A). In the diplotene stage, 11 elements are visible; out of these, 10 are autosomal bivalents and one is an X chromosome. Eight autosomal bivalents including m-bivalent are showing single chiasma per bivalent, while two large autosomal bivalents are having two interstitial and two terminal chiasmata (Fig. 1B). Similarly, during

Fig. 1. A) Spermatogonial prometaphase. B) Diplotene stage: n=11 (9AA+1mm+X0), two large autosomal bivalents (shown with arrow head). C, D) Diakinesis: large autosomal bivalents (shown with arrow head). E) Metaphase I: two large autosomal bivalents (shown with arrow head). F) Prophase-II: all the chromosomes show ε-shape structure. Bar=0.01 mm. 2015 Karyomorphological Variations in Orthetrum taeniolatum 97

Table 1. Cytogenetical data pertaining to genus Orthetrum of family Libellulidae.

Chromosome S. No. Taxa References complement

1. Orthetrum abbotti (Calvert) 2n=25 (22A+2m+X0) Boyes et al. 1980. 2. Ortherum albistylum (Selys) 2n=25 (22A+2m+X0) Oguma 1917, 1930, 1942, Kichijo 1942, Omura 1955. 3. Orthetrum azureum (Rambur) 2n=25 (22A+2m+X0) Kiauta 1969b. 4. Orthetrum brachiale (Palisot de 2n=21 (20A+X0), Kiauta 1969b, Kiauta and Ochssee 1979. Beauvois) 2n=25 (22A+2m+X0) 5. Orthetrum cancellatum (Linnaeus) 2n=25 (22A+2m+X0) Oksala 1939, Dasgupta 1957, Kiauta 1969a. 6. Orthetrum chrysostigma (Burmeister) 2n=25 (22A+2m+X0) Kiauta and Ochssee 1979, Boyes et al. 1980. 7. Orthetrum coerulescens (Fabricius) 2n=21 (20A+ X0) Kiauta 1969b. 8. Orthetrum glaucum (Brauer) 2n=25 (22A+2m+X0) Dasgupta 1957, Handa and Batra 1980, Handa et al. 1984, Tyagi 1978, Walia and Sandhu 2002a. 9. Orthetrum guineese (Ris) 2n=25 (22A+2m+X0) Kiauta and Ochssee 1979. 10. Orthetrum iuzonicum (Brauer) 2n=23 (22A+X0) Walia and Sandhu 2002b. 11. Orthetrum japonicum (Uhler) 2n=25 (22A+2m+X0) Oguma 1917, 1930, Kichijo 1942, Omura 1957. 12. Orthetrum japonicum internum 2n=25 (22A+2m+X0), Oguma 1917, 1933, Kichijo 1942, Omura 1955, (Mclachlan) 2n=23 (22A+X0) Kiauta and Kiauta 1976, Walia and Sandhu 2002b. 13. Orthetrum julia falsum (Longfeild) 2n=25 (22A+2m+X0) Boyes et al. 1980. 14. Orthetrum luzonicum (Brauer) 2n=25 (22A+2m+X0) Kiauta and Kiauta 1982, Thomas and Prasad 1981. 15. Orthetrum monardi (Schmidt) 2n=25 (22A+2m+X0) Kiauta and Ochssee 1979. 16. Orthetrum pruinosum neglectum 2n=25 (22A+2m+X0) Dasgupta 1957, Kiauta 1969a, b, Tyagi 1978, (Rambur) Kiauta and Kiauta 1982, Walia and Sandhu 2002a. 17. Orthetrum sabina (Drury) 2n=25 (22A+2m+X0) Asana and Makino 1935, Makino 1935, Kichijo 1942, Ray Chaudhury and Dasgupta 1949, Bagga 1961, Kiauta 1975, Tyagi 1978, Kiauta and Kiauta 1982, Thomas and Prasad 1981. 18. Orthetrum sabina sabina (Drury) 2n=25 (22A+2m+X0) Walia and Sandhu 2002a. 19. Orthetrum taeniolatum (Schneider) 2n=25 (22A+2m+X0) Kiauta 1972, 1975, Tyagi 1978, Handa and Batra 1980, Handa et al. 1984, Thomas and Prasad 1986, Walia and Sandhu 2002a. 20. Orthetrum testaceum (Burmeister) 2n=25 (22A+2m+X0) Kiauta and Kiauta 1982. 21. Orthetrum triangulare melania (Selys) 2n=25 (22A+2m+X0) Omura 1955. 22. Orthetrum triangulare triangulare 2n=25 (22A+2m+X0) Kiauta 1969a, b, Tyagi 1978, Handa and Batra (Selys) 1980, Walia and Sandhu 2002a.

diakinesis 11 elements are present and two large autosomal bivalents are clearly distinguishable. The X chromosome shows precocious segregation (Fig. 1C, 1D). At metaphase I, two large autosomal bivalents are clearly distinct and the X chromosome is completely divided (Fig. 1E). In prophase-II, all the chromosomes acquire ε-shape structures, which are the characteristic of odonate chromosomes. The X and m-chromosomes cannot be differentiated during this stage (Fig. 1F). Cytogenetical data pertaining to genus Orthetrum has been enumerated in Table 1.

Discussion

So far, cytological data is available on 22 species of genus Orthetrum (Oguma 1917, 1930, 1942, Asana and Makino 1935, Makino 1935, Oksala 1939, Kichijo 1942, Ray Chaudhuri and Dasgupta 1949, Omura 1955, 1957, Dasgupta 1957, Bagga 1961, Kiauta 1969a, b, 1972, 1975, Kiauta and Kiauta 1976, Kiauta and Ochssee 1979, Tyagi 1978, Boyes et al. 1980, Handa and Batra 1980, Kiauta and Kiauta 1982, Handa et al. 1984, Thomas and Prasad 1986, Walia and Sandhu 2002a, d). The majority of the species show diploid chromosome number 2n=25m, which 98 G. K. Walia et al. Cytologia 80(1) is the modal number of the family Libellulidae. Few exceptions due to fragmentations and fusions of the chromosomes have also been reported in the genus. In Orthetrum coerulescens, the chromosome number varies from n=12–14 (Kiauta 1969b). The number decreases due to fusion, which results in large autosomal bivalents or absence of m-chromosomes, and an increase in chromosome number is due to the fragmentation of chromosomes. Similarly, autosomal fusion decreases the chromosome number from n=13 to 11 in Orthetrum brachiale (Kiauta 1969b). Boyes et al. (1980) discussed the increase in chromosome number n=14 and the precocious segregation of the X chromosome in Orthetrum Julia falsum. The absence of m-chromosomes has also been noticed in Orthetrum iuzonicum and Orthetrum japonicum internum, which reduced the chromosome number from 2n=25 to 23 (Walia and Sandhu 2002b). In the present study, Orthetrum taeniolatum possesses 2n=21m with X0 type sex determining mechanism. During the course of meiosis (diplotene to metaphase-I), two autosomal bivalents are distinctly large due to the fusion of the two largest autosomal pairs of the complement. Large autosomal bivalents also show three to four chiasmata, while the remaining autosomal bivalents possess single chiasma, which is the characteristic of the odonate chromosomes. The X chromosome also shows the phenomenon of precocious segregation. Earlier data pertaining to the same species shows the chromosome number 2n=25m (Kiauta 1972, 1975, Tyagi 1978, Handa and Batra 1980, Handa et al. 1984, Thomas and Prasad 1986, Walia and Sandhu 2002a). They have collected the specimens from entirely different localities than that of the present locality (Patnitop, Jammu and Kashmir). Variations in the chromosome complement could be due to the geographical adaptations, or it might be that the species is under the process of karyotypic evolution and possesses unstable complement. This type of karyomorphological variations in the species has been reported for the ﬁrst time.

References

Asana, J. J. and Makino, S. 1935. A comparative study of the chromosomes in the Indian dragonflies. J. Fac. Sci., Hokkaido Imperial University, Ser. VI 4: 67–86. Bagga, S. 1961. Cytology and cytochemistry of gametogenesis of Indian dragonflies. Ph.D. Thesis, Delhi University, Delhi. Boyes, J. W., Van Brink, J. M. and Kiauta, B. 1980. Sixteen dragonfly karyotypes from the republic of South Africa and Swaziland, with evidence on the possible hybrid nature of Orthetrum Julia falsum Longfeild (Anisoptera: Libellulidae). Odonatologica 9: 131–145. Carr, D. H. and Walker, J. E. 1961. Carbol-fuchsin as a stain for human chromosomes. Stain Technol. 30: 233–236. Dasgupta, J. 1957. Cytological studies of some Indian dragonflies. II: A study of the chromosomes during meiosis in thirty species of Indian Odonata (Insecta). Proc. Zool. Soc. Calcutta 10: 1–65. Handa, S. M. and Batra, H. N. 1980. Cytology of ten species of dragonflies (Anisoptera: Odonata). In: Proceedings of the 67th Indian Science Congress, Part III, Calcutta. p. 103. Handa, S. M., Mittal, O. P. and Batra, H. N. 1984. Chromosomes in ten species of dragonflies (Anisoptera: Odonata). Research Bulletin of the Panjab University. Science 35: 65–75. Kiauta, B. 1969a. Sex chromosomes and sex determining mechanisms in odonata, with review of the cytological conditions in the family Gomphidae, and references to the karyotypic evolution in the order. Genetica 40: 127–157. Kiauta, B. 1969b. Autosomal fragmentations and fusions in Odonata and their evolutionary implications. Genetica 40: 158–180. Kiauta, B. 1972. Notes on new and little known dragonfly karyotypes. II. Male germ cell chromosomes of four East Mediterranean species, Lestes barbarus (Fabricius), Calopteryx splendens amasina Barteney (Zygoptera: Lestidae, Calopterygidae), Caliaeschna microstigma (Schneider) and Orthetrum taeniolatum (Schneider) (Anisoptera: Aeschnidae, Libellulidae). Genen Phaenen 15: 95–98. Kiauta, B. 1975. Cytotaxonomy of Dragonflies, with Special Reference to the Nepalese Fauna. Nepal Research Centre, Kathmandu. Kiauta, B. and Kiauta, M. 1982. The chromosome numbers of sixteen dragonfly species from the Arun Valley, Eastern Nepal. Notul. Odonatol. 9: 143–146. Kiauta, B. and Kiauta, M. A. J. E. 1976. The chromosomes of some dragonflies from the Langtang valley, Central 2015 Karyomorphological Variations in Orthetrum taeniolatum 99

Nepal. Odonatologica 5: 347–354. Kiauta, B. and Ochssee, B. V. 1979. Some dragonfly karyotypes from the Voltiac Republic (Haute Volta), West Africa. Odonatologica 8: 47–54. Kichijo, H. 1942. Insect chromosomes. III. Order of dragonflies, Pt. 1. Nagasakai Medical Journal 20: 1084–1092. (In Japanese) Makino, S. 1935. A comparative study of the chromosomes in the Indian dragonflies. Jpn. J. Genet. 11: 234–235. Oguma, K. 1917. Entomology and cytology. In: Nagano, K. (ed.). A Collection of Essays for Mr. Yasushi Nawa, Written in Commemoration of His Sixtieth Birthday, October 8, 1917. Gifu. pp. 105–114. Oguma, K. 1930. A comparative study of the spermatocyte chromosome in allied species of the dragonfly. J. Fac. Sci., Hokkaido Imperial University, Ser. IV 1: 1–32. Oguma, K. 1942. Observationes de formis compositionibusque chromosomatum et dispositionibus eorum in tempore divisionis atque propositio aliquorum novorum terminorum. Jpn. J. Genet. 18: 205–216. Oksala, T. 1939. Uber tetraploidie der binde-und fettgewabe bei den odonaten. Hereditas 25: 132–144. Omura, T. 1955. A comparative study of the spermatogenesis in the Japanese dragonflies I: Family Libellulidae. Biol. J. Okayama Univ. 2: 95–135. Omura, T. 1957. A comparative study of the spermatogenesis in the Japanese dragonflies. II. Families Aeschnidae, Gomphidae and Calopterygidae. Biol. J. Okayama Univ. 3: 1–86. Ray Chaudhuri, S. P. and Dasgupta, J. 1949. Cytological studies on the Indian dragonflies I. Structure and behaviour of chromosomes in six species of dragonflies (Odonata). Proc. Zool. Soc., Bengal 2: 81–93. Thomas, K. I. and Prasad, R. 1981. The chromosomes of five Indian dragonflies (Odonata). Perspectives in Cytology and Genetics 3: 629–632. Thomas, K. I. and Prasad, R. 1986. A study of the germinal chromosomes and C-band patterns in four Indian dragonflies (Odonata). Perspectives in Cytology and Genetics 5: 125–131. Tyagi, B. K. 1978. Studies on the chromosomes of Odonata of Dun Valley (Dehradun, India). Ph.D. thesis, University of Garhwal, Srinagar. Walia, G. K. and Sandhu, R. 2002a. Chromosomal data on seven species of genus Orthetrum (Libellulidae: Anisoptera: Odonata). Bionature 22: 7–12. Walia, G. K. and Sandhu, R. 2002b. Reduction in chromosome number in five libellulid species. Fraseria 7: 13–16.