Indian Journal of Geo Marine Sciences Vol. 47 (02), February 2018, pp. 469-474 Karyomorophometry of two pony fishes, Secutor insidiator (Bloch, 1787) and Leiognathus equulus (Forsskal, 1775) (Leiognathidae) from the Odisha Coast, Bay of Bengal * Jaya Kishor Seth , Tapan Kumar Barik & Ramesh Chandra Choudhury P.G. Department of Zoology, Berhampur University, Berhampur-760007, Odisha, India * [E.mail: [email protected]] Received 25 January 2016 ; revised 17 November 2016 Somatic metaphase chromosomes of two marine fishes, Secutor insidiator and Leiognathus equulus of Leiognathidae, were obtained from the gill epithelial and kidney cells and their morphmetric analyses were done. S. insidiator showed 2n = 48 and NF = 48 with the chromosome formula, n = 24t. Whereas, L. equulus showed 2n = 48 and NF = 52 with the chromosome formula, n = 2 st + 22 t. [Key words: Secutor insidiator, Leiognathus equulus, Leiognathidae, Karyomorphometry] Introduction The number of marine and estuarine fish species such as its functional mechanism and the balance reported from Odisha is 607 belonging to 139 of the genetic complex. The possibilities of families and 27 order1-3. Of them, the family karyotype transformation are obviously limited. Leognathidae includes only 16 species. The Therefore, karyotypes can not adapt to the species of this family are commercially important boundless series of morphological and functional for their abundance, although they contribute variation realised by evolution6. However, of late, comparatively less amount of protein. These it has been felt that cyto-taxonomic approach with fishes are also used for the preparation of the knowledge on karyotypes could solve the fishmeal and other fish products. Moreover, they accumulated controversies brewed by morpho- belong to an important part of the food chain and taxonomy and typological studies in fishes, at food web of marine ecosystem. least in lower taxon levels. In comparison to other groups of animals, fishes Materials and Methods are less known chromosomally. Out of the 28,000 Live specimens were collected from the Bay of fish species known World over, only 12.2% of Bengal at Goplapur-on-Sea during the months of them are known karyotypically4-5. Moreover, such February to May, 2013. Identification of fishes information are centred on the fresh water forms was carried out based on the standard taxonomic while the marine species are chromosomally less keys7-8. The specimens were deposited in the attended. As karyotype is a definite and constant museum of the Animal Diversity Laboratory, character of each species, it has been considered Berhampur Univeristy, Odisha, India. (S. as the fundamental physical basis of evolution. It insidiaror registration number: is also endowed with the evolution of its own BUZOOLAD2013-24, L. equulus registration dictated by intrinsic conditions and requirements, number: BUZOOLAD2013-25). 470 INDIAN J. MAR. SCI., VOL. 47, NO. 02, FEBRUARY 2018 Mitotic metaphase spreads were obtained from gill epithelial and kidney cells by following the conventional colchicine- sodium citrate- aceto- methanol- flame drying- Giemsa technique reported earlier9. Absolute length of each chromosome in micra with standard deviation was measured and calculated from at least five camera lucida diagrams of mitotic metaphases from each species. Morphometric analyses like relative R c percentage length (L ) and centromeric index (I ) of the chromosomes were carried out and nomenclature of the chromosomes as per the standard format10. According to the decreasing length of the chromosomes, the karyotypes were prepared from the photomicrographs. Results In Secutor insidiator (Bloch, 1787), the diploid number, 2n = 48, was determined from 112 Fig.1-A - metaphases from 2 males and 21 metaphases from 1.Somatic metaphase of male Secutor insidiator (Bloch, 2 female specimens (Figure: 1-A). All the 1787) chromosomes in both the sexes were telocentrics 2. Karyotype of male 3. Somatic metaphase of female (t). Thus, the chromosome formula is n = 24 t and 4. Karyotype of female the number of fundamental arms in diploid complement (NF) = 48 in both sexes of S.insidiator. The chromosomes ranged between 2.97± 0.40 to 1.00± 0.19 micra in a total haploid genome length of 44.94 micra. The relative percentage lengths of the chromosomes vary from 6.66 to 2.22 (Table-1). Sex chromosome, if present, was not identifiable. In Leiognthus equulus (Forsskal, 1775), the diploid number, 2n=48, was determined from 25 Fig.1-B- metaphases from 2 female specimens (Figure: 1- 1.Somatic metaphase of female Leiognathus B). equulus(Forsskal,1775) 2. Karyotype of female Its diploid complement includes 2 pairs of sub- telocentrics (st) (nos.1 and 4) and 22 pairs of However, little attention has been paid to study telocentrics (t).The chromosomes range between the karyomorophology of the species of the 2.88 ± 0.46 to 1.18 ± 0.17 micra in haploid family Lieognathidae. Our present study deals genome length of 48.45 micra. However, the 5th with the karyomorphometric information of pair sometimes shows very short arms of variable another two species of the said family viz., length. Thus, the chromosome formula is n= 2 st Secutor insidiator (Bloch, 1787) and Leiognathus +22 t and the number of fundamental arms in the equulus (Forsskal,1775), which has been reported diploid complement (NF) = 52. The relative for the first time from the Odisha coast of the Bay percentage lengths of the chromosomes range of Bengal. The chromosomes of three species of from 5.94 to 2.44 (Table-2). the family Leiognathidae. viz., Photopectoralis bindus (Valenciennes, 1835), Nuchequula Discussion nuchalis (Temminck and Schlegel, 1845) and Gazza minuta (Bloch, 1795) have already been Karyotypic study on fish species provides 13 essential information on karyotypic variations. repoted ( Table:3). The possible mechanisms of such variations leading to speciation can be of use in solving many controversial problems of systematics11-12. SETH et al: KARYOMOROPHOMETRY OF TWO PONY FISHES 471 Table 1-Morphometric data of Secutor insidiator (Bloch, 1787) Chromosome Absolute length of the Relative Percentage Centromeric index Morphology number Chromosomes in micra length with S.D 1 2.97±0.40 6.60 0.00 t 2 2.66±0.33 5.92 0.00 t 3 2.47±0.32 5.50 0.00 t 4 2.33±0.36 5.19 0.00 t 5 2.25±0.36 5.01 0.00 t 6 2.16±0.32 4.82 0.00 t 7 2.12±0.34 4.71 0.00 t 8 2.06±0.35 4.59 0.00 t 9 2.02±0.32 4.49 0.00 t 10 1.97±0.28 4.38 0.00 t 11 1.91±0.30 4.25 0.00 t 12 1.85±0.29 4.13 0.00 t 13 1.82±0.28 4.05 0.00 t 14 1.76±0.26 3.92 0.00 t 15 1.73±0.26 3.85 0.00 t 16 1.69±0.27 3.76 0.00 t 17 1.65±0.26 3.66 0.00 t 18 1.59±0.26 3.54 0.00 t 19 1.53±0.24 3.40 0.00 t 20 1.47±0.24 3.27 0.00 t 21` 1.41±0.22 3.14 0.00 t 22 1.33±0.21 2.95 0.00 t 23 1.17±0.20 2.61 0.00 t 24 1.00±0.19 2.22 0.00 t 472 INDIAN J. MAR. SCI., VOL. 47, NO. 02, FEBRUARY 2018 Table 2-Morphometric data of Leiognathus equulus (Forsskal, 1775) Chromosome number Absolute length of the Relative Percentage Centromeric index Morphology Chromosomes in micra length with S.D 1 2.88±0.46 5.94 15.80 st 2 2.68±0.39 5.52 0.00 t 3 2.46±0.42 5.07 0.00 t 4 2.40±0.29 4.96 16.08 st 5 2.36±0.22 4.87 10.51 t 6 2.32±0.35 4.79 0.00 t 7 2.25±0.30 4.64 0.00 t 8 2.22±0.29 4.58 0.00 t 9 2.14±0.28 4.43 0.00 t 10 2.09±0.26 4.32 0.00 t 11 2.06±0.27 4.25 0.00 t 12 2.02±0.28 4.17 0.00 t 13 1.98±0.29 4.09 0.00 t 14 1.94±0.27 4.01 0.00 t 15 1.91±0.25 3.95 0.00 t 16 1.88±0.26 3.88 0.00 t 17 1.83±0.26 3.77 0.00 t 18 1.79±0.26 3.69 0.00 t 19 1.76±0.25 3.64 0.00 t 20 1.72±0.24 3.55 0.00 t 21` 1.65±0.24 3.40 0.00 t 22 1.56±0.16 3.22 0.00 t 23 1.46±0.16 3.01 0.00 t 24 1.18±0.17 2.44 0.00 t SETH et al: KARYOMOROPHOMETRY OF TWO PONY FISHES 473 Table 3-Summary of the chromosome features of the species available from the family Leiognathidae Species 2n NF Chromosome formula References P. bindus 40 40 n= 20 acrocentric/ telocentric Arkhipchuk, 1999 N. nuchalis 48 48 n = 24 acrocentric Arkhipchuk, 1999 G. minuta 48 48 n = 24 acrocentric Arkhipchuk, 1999 S. insidiator 48 48 n = 24 telocentric Present study L. equulus 48 52 n = 2 subtelocentric + 22 telocentric Present study The family Leiognathidae includes 9 genera viz. References Gazza, Leiognathus, Secutor, Photopectoralis, 1. Seth,J.K. and Sahoo,S., First record of Nuchequula, Eublekeria, Equulatis, Pempheris vanicolensis Cuvier,1881from Odisha coast, India.