P.G. Department of Zoology, Berhampur University, Berhampur , Odisha, India. [E.mail:

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1 Indian Journal of Geo Marine Sciences Vol. 47 (02), February 2018, pp 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 , Odisha, India * [E.mail: jkseth52@gmail.com] 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 reported from Odisha is 607 belonging to 139 families and 27 order 1-3. Of them, the family Leognathidae includes only 16 species. The species of this family are commercially important for their abundance, although they contribute comparatively less amount of protein. These fishes are also used for the preparation of fishmeal and other fish products. Moreover, they belong to an important part of the food chain and food web of marine ecosystem. In comparison to other groups of animals, fishes are less known chromosomally. Out of the 28,000 fish species known World over, only 12.2% of them are known karyotypically 4-5. Moreover, such information are centred on the fresh water forms while the marine species are chromosomally less attended. As karyotype is a definite and constant character of each species, it has been considered as the fundamental physical basis of evolution. It is also endowed with the evolution of its own dictated by intrinsic conditions and requirements, such as its functional mechanism and the balance of the genetic complex. The possibilities of karyotype transformation are obviously limited. Therefore, karyotypes can not adapt to the boundless series of morphological and functional variation realised by evolution 6. However, of late, it has been felt that cyto-taxonomic approach with the knowledge on karyotypes could solve the accumulated controversies brewed by morphotaxonomy and typological studies in fishes, at least in lower taxon levels. Materials and Methods Live specimens were collected from the Bay of Bengal at Goplapur-on-Sea during the months of February to May, Identification of fishes was carried out based on the standard taxonomic keys 7-8. The specimens were deposited in the museum of the Animal Diversity Laboratory, Berhampur Univeristy, Odisha, India. (S. insidiaror registration number: BUZOOLAD , L. equulus registration number: BUZOOLAD ).

2 470 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- acetomethanol- flame drying- Giemsa technique reported earlier 9. 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 percentage length (L R ) and centromeric index (I c ) of the chromosomes were carried out and nomenclature of the chromosomes as per the standard format 10. 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 metaphases from 2 males and 21 metaphases from 2 female specimens (Figure: 1-A). All the chromosomes in both the sexes were telocentrics (t). Thus, the chromosome formula is n = 24 t and 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 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 metaphases from 2 female specimens (Figure: 1- B). Its diploid complement includes 2 pairs of subtelocentrics (st) (nos.1 and 4) and 22 pairs of telocentrics (t).the chromosomes range between 2.88 ± 0.46 to 1.18 ± 0.17 micra in haploid genome length of micra. However, the 5 th pair sometimes shows very short arms of variable length. Thus, the chromosome formula is n= 2 st +22 t and the number of fundamental arms in the diploid complement (NF) = 52. The relative percentage lengths of the chromosomes range from 5.94 to 2.44 (Table-2). Discussion Karyotypic study on fish species provides essential information on karyotypic variations. The possible mechanisms of such variations leading to speciation can be of use in solving many controversial problems of systematics Fig.1-A - 1.Somatic metaphase of male Secutor insidiator (Bloch, 1787) 2. Karyotype of male 3. Somatic metaphase of female 4. Karyotype of female Fig.1-B- 1.Somatic metaphase of female Leiognathus equulus(forsskal,1775) 2. Karyotype of female However, little attention has been paid to study the karyomorophology of the species of the family Lieognathidae. Our present study deals with the karyomorphometric information of another two species of the said family viz., Secutor insidiator (Bloch, 1787) and Leiognathus equulus (Forsskal,1775), which has been reported for the first time from the Odisha coast of the Bay of Bengal. The chromosomes of three species of the family Leiognathidae. viz., Photopectoralis bindus (Valenciennes, 1835), Nuchequula nuchalis (Temminck and Schlegel, 1845) and Gazza minuta (Bloch, 1795) have already been repoted 13 ( Table:3).

3 SETH et al: KARYOMOROPHOMETRY OF TWO PONY FISHES 471 Table 1-Morphometric data of Secutor insidiator (Bloch, 1787) Chromosome number Absolute length of the Chromosomes in micra with S.D Relative Percentage length Centromeric index Morphology ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t 21` 1.41± t ± t ± t ± t

4 472 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 Chromosomes in micra with S.D Relative Percentage length Centromeric index Morphology ± st ± t ± t ± st ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t ± t 21` 1.65± t ± t ± t ± t

5 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 n= 20 acrocentric/ telocentric Arkhipchuk, 1999 N. nuchalis n = 24 acrocentric Arkhipchuk, 1999 G. minuta n = 24 acrocentric Arkhipchuk, 1999 S. insidiator n = 24 telocentric Present study L. equulus n = 2 subtelocentric + 22 telocentric Present study The family Leiognathidae includes 9 genera viz. Gazza, Leiognathus, Secutor, Photopectoralis, Nuchequula, Eublekeria, Equulatis, Aurigequula and Karalla.Their phylogentic analysis by using 16s mitochondrial r-rna gene revealed that they were monophyletic 14. The results of the present study on S. insidiator are in complete agreement with the earlier reports of Arkhipchuk on N. Nuchalis and G. minuta 13. However, in L. equuluus, although it bears the same chromosome number (2n = 48), differ from that of S. Insidiator, G. minuta and N.nuchalis in the NF, which has been increased from 48 to 52. This increase in NF keeping the 2n constant might have resulted due to pericentric inversions on 2 pairs of chromosomes (Chromosome number 1 and 4, Table-2) during the course of speciation. This indicates that in Leiognathidae, karyotypic conservation has prevailed with minor variations in the karyotype during the process of speciation. However, the species P. bindus has shown drastic variations in its karyotype with 2n = 40 and NF = 40. Accordingly, Seah et al. 14 also indicated its separate lineage from the rest species of the family. Acknowledgement Authors are thankful to the Head, P. G. Department of Zoology, Berhampur University for providing laboratory facilities. References 1. Seth,J.K. and Sahoo,S., First record of Pempheris vanicolensis Cuvier,1881from Odisha coast, India. International journal of advanced life Science. Vol-6(3) (2013) Seth, J.K. and Sahoo, S., First record of Diagramma pictum (Thunberg, 1792) from the Odisha coast, Indian Journal of Geo-Marine Science; 43(6) (June, 2014) Barman,R.P., Mishra, S.S., Kar, S., Mukharjee, P. and Saren, S.C., Marine and estuarine fish fauna of Orissa. Rec. Zool. Surv. India, occ., 260 (2007) Nelson J. S., Fishes of the World, 4th edn. New York: John Wiley and Sons, Inc. (2006) Arai,R., Fish karyotypes. A check list. Springer Japan. (2011) pp Benazzi,M., Cytotaxonomy and evolution: General Remarks. In: Chiarelli, A. B. and Capanna, E. (Eds.), Cytotaxonomy and Vertebrate Evolution. Academic Press, London and New York. (1973) pp Talwar, P. K. and Kacker, R. K., The commercial sea fishes of India. (Handbook, Zoological Survey of India),4 (1984) Fischer, W and Bianchi, G., (eds). FAO Species Identification sheets for Fishery purpose, Western Indian Ocean; (Fishing area 51), (Prepared and printed with the support of the Danish International Development Agency (DANIDA). Rome, Food and Agricultural Organization of the United Nations) vols 1-6 (1984): pag. var. 9. Choudhury,R.C., Prasad, R and Das, C. C., Chromosomes of six species of marine fishes. Caryologia. 32 (I). (1979) Levan,A., Fredga, K., and Sandberg, A.A., Nomenclatute for centromeric position on chromosomes. Hereditas 52(1964)

6 474 INDIAN J. MAR. SCI., VOL. 47, NO. 02, FEBRUARY Choudhury,R.C., Chromosomes of Scorpion fish, Gymnapistus Niger (Cuvier) (Scorpaenidae: Scorpaeniformes). Advances in Biosciences.Vol.11(II) (1992) Choudhury,R.C., Prasad, R and Das, C. C., Chromosomes of four Indian marine Catfishes (Bagridae, Ariidae: Siluriformes) with a hetromorphic pair in male Mystus gulio. Caryologia. 46 (2-3) (1993) Arkhipchuk,V.V., Chromosome database. Database of Dr.Victor Arkhipchuk.(1999) Seah,Y.G., Gires, U., Mohamad, C.A.R., Arsad, A.B. and Ghaffar, M.A., Phylogeny and morphological delineation of Leiognathidae in the water peninsular of Malaysia. Costal Marine Science 35(1) (2012)