Escuela de Ciencias Aplicadas del Mar, Universidad de Oriente, Isla de Margarita,VenezuelaSummaryMolecular phylogenetic studies are very scarce for the Mugil-idae family; the present analysis using DNA sequences of themitochondrial 16S rRNA and cytochrome b genes is the firststudy involving Brazilian mugilids. The results corroborate themonophyly of Mugil and are elucidative for the taxonomy ofBrazilian mugilids. Mugil curema is clearly divided into twogenetically distinct taxa, M. curema type I being closer relatedto Mugil hospes and the true M. curema (type II) groupingsignificantly with M. incilis. The results also suggest that Mugilliza and Mugil platanus should be treated as a single species oreven populations of Mugil cephalus.IntroductionMugilids are coastal marine, brackish water and freshwaterfishes, distributed worldwide in tropical and temperate seas,migrating offshore to spawn. Mullets are very importantcommercial species and are highly exploited throughout theirdistribution (Cervigo´n, 1993; Cervigo´n et al., 1993). They arepopularly known in Brazil as tainha, parati, curima˜, cai´ca andpratiqueira (Menezes, 1983; Menezes and Figueiredo, 1985).The most recent taxonomic revision (Thomson, 1997) recog-nizes 14 genera and 64 valid species, Mugil being the only oneoccurring in the Atlantic coastal waters of Brazil. The numberof mugilid species reported for the northern coast of SouthAmerica, including the entire Brazilian coast, varies between 7and 8 (Cervigo´n et al., 1993; Thomson, 1997; Menezes et al.,2003). The discrepancies are related to Mugil hospes,M. cephalus, M. platanus and the suppressed name ofM. gaimardianus.Accurate species identification is the first step in eachsuccessful conservation and fisheries management program(Ludwig, 2006). Identification of mugilid species is problem-atic, especially in juvenile stages, because of their highlyconserved external morphology and the paucity of usefultaxonomic characters (Menezes, 1983; Menezes and Figuei-redo, 1985; Cervigo´n, 1993; Thomson, 1997) and homo-geneous karyological structure. The majority of species showsa diploid number of 48 chromosomes (Cataudella et al., 1974;Delgado et al., 1992; Jorda˜o et al., 1992; Crosetti et al., 1993;Rossi et al., 1996, 1997; Nirchio et al., 2001, 2003), except forM. curema which has a diploid number of 24 or 28 (Le GrandeandFitzsimons,1976;Nirchio et al.,2003,2005),andM.incilispresenting 2n = 28 (Galetti et al., 2000).Because of the economic importance of this fish family it isessential to improve the current identification keys and takeadvantage of the powerful molecular markers now available.Mitochondrial DNA has been widely used in fish taxonomybut only a few Mediterranean mugilid taxa have so far beensubjected to molecular phylogenetic analysis. Caldara et al.(1996) used the mitochondrial cytochrome b and 12S rRNAgenes to evaluate the phylogenetic relationships among Chelon,Oedalechilus, Liza and Mugil. According to these authors,based on DNA sequences the arrangement produced was verydifferent from the current taxonomy based on morphology.Nuclear data of allozymes and mitochondrial 16S rDNAsequences (Rossi et al., 2004) suggest that the Mediterraneanspecies of Liza do not form a monophyletic group, inagreement with the previous results of Caldara et al. (1996).The present phylogenetic analysis based on the 16S rRNAand cytochrome b mitochondrial genes is the first for Brazilianmugilids (Western Atlantic), and includes previously studiedMediterranean taxa (Mugil, Chelon and Oedalechilus). Thephylogenetic trees depicted from both genes are congruent andsurprisingly reveal two possible species morphologically iden-tified as Mugil curema, but clearly distinguished by the DNAanalyses. Molecular data also suggest that Mugil liza andMugil platanus should be treated as a single species or possiblypopulations of Mugil cephalus.Materials and methods
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Mar 9, 2017
V E L Da Silva + 3
Open Access
