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MISCELLANEOUS NOTES Pathni (1978),RitakumariandNair(1979)and Badolaetal. The detailed morphometric and meristic characters of (1982). Our observations on sexual dimorphism in Puntius bothmaleaswellasfemalefishwerestudied(Table 1),butno conchonius(Ham.-Buch.)isbasedon the study offiftymale striking differencewasseen.Thedifferencesare(i)malewith andfemalespecimenseach,collectedbetweenNovember2003 darkblackshadeon thedorsal, ventral andanalfins, absentin and January 2004. The fishes were segregated on the female(Fig. 1),(ii)Upperportionofthebodyshiningolivegreen mentioned sexual dimorphic characters, and dissected for and lower portion silvery in both sexes; but there is pinkish confirmation.Wegothundredpercentconfirmationandthen colourinmalesbetweenthesetwoportions,whichisnotvisible decidedtoreportitforanadditiontothescientificknowledge inthefemalespecimens,and(iii)thesnoutisbroaderonupper based on the study ofmorphometric characters. sideinthefemalecomparedtothemale(Fig.2). Badola, S.P., H.R. Singh & A.K. Dobriyal (1982): Note on sexual 198-210. dimorphism in Barilius bendelisis (Ham.). Indian J. Anim. Sci. Singh, H.R., S.P. Badola & A.K. Dobriyal (1987): Geographical 52(12): 1284-1286. distributional list of ichthyofauna of the Garhwal Himalaya Day, F. (1878): The Fishes of India: Being a Natural History ofthe with some new records. J. Bombay Nat. Hist. Soc. (84): FishesknowntoinhabittheseasandfreshwatersofIndia, Burma 126-132. andCeylon. William Dawson andSons Ltd. Pp. 778. Swarup,K.&A.Swarup(1975):SexualdimorphisminPseudeutropius Pathni,S.S.(1978):Anoteonsecondarysexualcharactersin Kumaun atherenoides (Bloch). Curr. Sci. 44 (16): 588. Mahseer Tor tor (Hamilton) and Torputitora (Ham.) in Uttar Talwar, PK. & A.G. Jhingran (1991): Inland fishes of India and Pradesh. Indian J. Anim. Sci. 48 (10): 773-775. adjacentcountries.Oxford&IBHPubl.Co.Pvt.Ltd.,NewDelhi. Ritakumari, S.D. & B.K. Nair (1979): Sexual dimorphism in the Pp. 250-295. Loaches Noemacheilus triangularis (Day) and Lepidocephahts Tilak,R.(1975):FurtherstudiesonthedimorphisminLepidocephahts thermalis (Cuv. & Val.). J. Anim. Morph. Physiol. 26(1-2): guntea (Hamilton). Newsl. Zool. Sttrv. India 1(4): 74-76. 21. SEXUAL DIMORPHISM IN FLATHEAD GREY MULLET MUGIL CEPHALUS (LINNAEUS)1 JencyPaul2-4, Honey Sebastian3, N.D. Inasu2-5andC.O. Joshi2-6 'Accepted May 2006 -Fisheries Research Laboratory, Post Graduate and Research Department of Zoology, Christ College, Irinjalakuda, 680 125, Kerala, India. Tost Graduate and Research Department of Zoology, Sacred Heart College, Thevara, Kochi, 682 013, Kerala, India. Email: [email protected] 4Email: [email protected] '’Email: [email protected] ‘’Email: [email protected] Introduction culture of fishes, hybridization experiments, hormonal sex Sexualdimorphismiswidespreadinnatureandcanbe control, identification of maturity stage, identification of influenced by sex specific natural selection resulting from hybrids, breeding season, induced breeding, seedling ecologicaldifferencesbetweenthesexes(ReimchenandNosil production technology and also in the observation of 2004). Differencesinthe selective pressuresexperiencedby courtship and mating, mate selection, andpreference. the sexes can ultimately result in the evolution of sexual The study on sexual dimorphism has been carriedout dimorphismofmorphologicaltraits(Andersson 1994).Many in avery few species offishes like Tetraodon travancoricus fishspeciesshowsexualdimorphism,aconditionwheremales (Inasu 1993),Puntiusfilamentosus(Thobias 1974),Priacanthus and females are different in colour and/or form, thus sexes hamrur(Tessy and Inasu 1998), and Ompokbimaculatus and canbedetectedexternally. Horabagrusbrachysoma(KurianandInasu 1997). Comparison of morphological features in males and Thepresentworkdealswiththesexualdimorphismof femalesofsimilarlengthgroupfacilitatetoworkoutthesexual the Flathead Grey Mullet M. cephalus belonging to Order dimorphism. Species that show difference in coloration Mugiliformes and Family Mugilidae. It is commonly called betweensexesaresaidtodisplaysexualdichromism(Martin ‘Kanambu’, ‘Alameen’or‘Thirutha’ inMalayalam,‘Madavai’ Moe2002). inTamil, and ‘Kathiparega’ inTelugu (Talwar and Jhingran Thestudyonsexualdimorphismisofgreatsignificance 1991).GreyMulletsaremostlymarine,distributedintemperate in taxonomy, bionomics, reproductive biology, monosex andtropical seas,estuariesandsomerivers,butspawninthe 226 J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007 MISCELLANEOUS NOTES Table1:Average bodyweightineach lengthgroupof Discussion maleandfemaleMugilcephalus(Linn.) In M. cephalus, mature male acquires a pinkish red Lengthgroup Totalnumberof Averageweight(gms) hue on the body particularly on the basal portion of 1st and Fishexamined 2nd dorsal fins, ventral fins and anal fin during the approach ofthebreeding season, butinfemalessuchcolorationis not (mm) Male Female Male Female noticed. The fine colour difference between the two sex 160-169 27 31 45.71 49.40 groups tend to fade once the breeding period is over. This 170-179 38 33 64.06 66.70 pattern oftemporary sexual dichromism is alsoobserved in 180-189 44 25 79.21 82.94 Tetraodon travancoricus (Joshi 2004), Horabagrus 190-199 30 41 82.5 87.00 200-209 - 24 - 100.20 brachysoma (Inasu 2004), Anabas testudineus (Roychan 210-219 - 27 - 108.70 2005),andBendelisischedra(PathaniandGaur 1989). Ithas a passive or active role in reproductive behaviour as the bright body colour attracts the opposite sex and helps in sea. This non-predatory fish feeds on zooplankton, completingthespawningact(MartinMoe2002andRoychan phytoplankton and detritus in the bottom mud. 2005).Variation in colourcan also be due toenvironmental, M. cephalusisoneofthecommonspeciesofmulletsin nutritional and ecological factors, such as competition, and theIndianregionwhichisabundantincatchesfromtheChilka predation. Theendocrineglandsalsoplay an importantrole lake(Orissa),MahanadiandGodavariestuaries, Pulicatlake inbreedingcoloration. (Tamil Nadu) and in the backwater lakes ofAstamudi and Femalesare heavierthanthemalesofthe samelength Vembanadu (Kerala). They withstand wide fluctuations in group. Forfacilitatingabettercomparisontheaveragebody salinityandsuitableforbrackishwaterpolyculturealongwith weight in each length group ofmale and female is given in shrimps,ChanosandpredatoryfishlikeLates(Thampy2002). Table 1.The largebodysizeoffemalefishcan beexplained Sea ranching ofM. cephalus has been done successfully in as the fecundity ofthe fish. Andersson (1994) reported that Hawaii(Grimes 1998)andalongtheGujaratcoast(Anon.2000). females tend to have larger gonads than males with large M. cephalus is reported as a potential fish for induced energy rich eggs, whereas males have much smallergonads maturationandbreedingtechnologieswithgreatsuccess(Rao thatproduce numerousrelatively inexpensive sperm. 2000). So the study on sexual dimorphism is of great This study has focused on the ultimate explanations significanceinthisfishasitisapreliminarysteptodistinguish ofthe observed sexual dimorphism inM. cephalus (Linn.), malesandfemales. yet it wouldbe interesting tofurtherexamine the proximate causes of these differences. Method ACKNOWLEDGEMENTS About 320 specimens (males 139 and females 181 of ) adult M. cephalus were collected in fresh condition from February to July 2005 from the estuarine region of We are grateful to Rev. Fr. Jose Chunkan (CMI), Kanakankadavu(Emakulumdistrict,Kerala).Theyweresorted Principal,ChristCollege,Irinjalakuda,forprovidingallfacilities intovariouslengthgroups.Thefinemorphologicaldifferences for the study. The co-author is also grateful to University between males and females ofthe same length group were GrantsCommissionforprovidingJuniorResearchFellowship studied and compared, and total weight of each fish was during the tenure of which the present work was carried recorded separately. out. REFERENCES Andersson, M. (1994): Sexualselection. Pub.by PrincetonUniversity (Gunther).Pp.25-29.In:Sexualdimorphismofsomeindigenous M Press. Braabury,J. andAndersson, (eds) 599pp. ornamentalfishes,Vol.I.MarineProductsExportDevelopment Anon. (2000): Biodiversity Conservation in West Bengal. Fishing Authority of India. chimes 21(1): 75-79 Jayaram, K.C. (1999): The Freshwater Fishes of the Indian region. Grimes,C.B. (1998): Marine Stockenhancement: Sound management Narendra PublishingHouse, Delhi. 395 pp. or techno-arrogance? Fisheries (Bethesda) 23(9): 18-23 Joshi,C.O. (2004): Systematics andBionomics oftetraodontidsalong Inasu, N.D. (1993): Sexual dimorphism of a fresh water puffer fish south west coast of India and inland'waters of Kerala. Ph.D. Tetraodon travancoricusHoraandNair,collectedfromTrichur Thesis, University ofCalicut, Kerala. district, central Kerala. J. Bombay Nat. Hist. Soc. 90: Kurian,Molly&N.D.Inasu(1997):Sexualdimorphismoftwoinland 523-524. edible catfishes Ompokbimaculatus (Bloch) andHorabagrus Inasu, N.D. (2004): Sexual dimorphism in Horabagrus brachysoma brachysoma (Gunther).J. Inlandfish. So.c. India29(2): 34-39. J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007 227 . MISCELLANEOUS NOTES MartinMoe,C.(2002):TheBreeder’sNet.Advancedaquarist’sonline Fishing chimes 24(12): 49-53. magazine. Pp. 216. Talwar, P.K. & A.G. Jhingran (1991): Inland Fishes of India and Pathani, S.S. & S.K. Gaur (1989): Secondary sexual dimorphism in Adjacent countries, Oxford & IBH Publishing Company, New Beriliusbendelisis(Ham.)andBeriliusvagra(Ham.).IndianJ. Delhi. 878 pp. Anim. Sci. 59(12): 1580-1581. Tessy Mandy, J. & N.D. Inasu (1998): Sexual dimorphism ofmarine Rao, G.R.M. (2000): Advances in Inland fisheries research In: (Eds: perch,Priacanthushamrur(Cuv. &Val.).J. BombayNat. Hist. Gopakumar, K., B.N. Singh & V.R. Chitrasni) Fifty years of Soc. 95(1): 132-134. fisheries research in India. Indian Council of Agricultural Thampy, D.M. (2002): Role of professionals in the development of Research, New Delhi, 124pp. inlandfisheriesinIndia.Pp.351-358.In:RiverineandReservoir Reimchen, T.E. & P. Nosil (2004): Variable predationregimes predict fishes ofIndia. SocietyofFisheriesTechnologists (India). MR the evolution of sexual dimorphism in a population of three Thoblas, (1974): Observations on the morphological variations spine stickleback. Evolution 58(6): 1274-1281. in Puntiusfilamentosus (Val.) Family Cyprinidae: with a Roychan,K.J.(2005):Secondarysexualcharactersinfreshwaterfishes. redescriptionofthe species. J. Inlandfish. Soc. India6: 45-50. 22. NEW RECORDS OF TWO EEL FISHES FROM GREAT NICOBAR ISLAND, BAY OF BENGAL 1 R. Rajaram2-4,M.Srinivasan2,S.AjmalKhan2,L. Kannan2-5,D.V. Rao3andKamalaDevi3 'Accepted September 10, 2004 -Centre ofAdvanced Study in Marine Biology, Annamalai University, Parangipettai 608 502, Tamil Nadu, India. ’Zoological Survey of India, Andaman and Nicobar Regional Station, Port Blair, India. 4Email: [email protected] ’Email: [email protected] Highlydiversifiedfishesoccurringinthecoastalwaters filamentous appendages; tube of anterior nostril with and coral reef areas of the Andaman and Nicobar Islands foliaceous appendages; dorsal and anal fins well developed, have been a source of continuous biodiversity research by origin of dorsal fin well before gill openings; pectoral fins various ichthyologists (Rao etal. 2000). During the present absent; dorsal, anal and caudal fins confluent. Body bluish study, detailed investigations on the fish samples collected black with yellow dorsal fin, anal fin black; both dorsal and from the coral reef areas around the Great Nicobar Island analfinswithwhitemargin. were made. Atotal of 176 species offin fishes belonging to Habitat: Foundinsandybeachareas. 106genera,71 familiesand 15orderswererecorded.Among Distribution:CentralandwesternPacifictoIslandsof these,twospeciesarenewdistributionalrecordstoAndaman IndianOcean. andNicobarIslands,BayofBengal.Thedescriptionsofthese two fishes belonging to families Muraenidae and Family:Moringuidae Moringuidae, classified underthe orderAnguilliformes, are 2. Black-tailedThrushEelMoringuabicolorKaup 1856 given here. MoringuabicolorKaup 1856,Cat.Apod.Fish.Pp. 107. Rataboura bicolor: Munro 1982. The Marine and SystematicAccount FreshwaterFishesofCeylon. Pp.63. Order: Anguilliformes Materialexamined:Onespecimen, 16.ii.2003,Kichad Family:Muraenidae Nullah,westcoastofGreatNicobarIsland,Reg.No.5168(B). 1. RibbonEelRhinomuraenaquaesitaGarman 1888 Description (mm): Total length 685; eye diameter 3; RhinomuraenaquaesitaGannan 1888. Bull.Essex.Inst. distance from snout to dorsal 630; depth of the body 14; Pp. 114. length of pectoral fin 6; caudal 5; dorsal 55; ventral 50; Rhinomuraenaquaesita: 1990.Randalletal.Fishesof 5 conical and short teeth arranged in single rows in jaws. theGreatBarrierReefandCoralSea.Pp.41 Body elongate, worm-like and cylindrical; posterior nostril Materialexamined:Onespecimen,204.2003,Lashman opens in apore in front ofeye; eyes small and covered with beach,eastcoastofGreatNicobarIsland,Reg. No. 5167(A). skin;lowerjawprojectingalittleinfrontofsnout;lateralline Description (mm): Total length 755, eye diameter 4, present; dorsal and anal fins small, confined to tail region; distance from snout to dorsal 30, body depth 15, caudal fin caudalregionformingapointwithwhichdorsalandanalfins length4, length ofdorsal fin 725, ventral 510. Body slender are confluent with caudal fin. Upper halfofbody brownish andelongated;cleftofmouthreachingfarbehindeye;triserial and lowerhalfpale yellow, caudal fin blackish with a white villiform teeth in both thejaws; tip ofjaws with barbel-like edge,otherfinslightyellow. 228 J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007