Genetic Divergence and Phylogenetic Relationships in Grey Mullets (Teleostei: Mugilidae) Using Allozyme Data

Genetic divergence and phylogenetic relationships among five species of the Mugilidae family (Liza saliens, Liza aurata, Liza ramada, Chelon labrosus, and Mugil cephalus) were investigated, in the present study, on samples taken from Messolongi lagoon in Greece, using allozyme electrophoresis. Ten enzymic systems corresponding to 22 genetic loci were assayed, among which, four were found to be polymorphic in Liza saliens, Liza aurata, and Chelon labrosus, seven in Liza ramada, while only two were polymorphic in Mugil cephalus. Several loci showed different electrophoretic patterns among the species and thus, they can be useful in species taxonomy as diagnostic markers, as well as for further evolutionary studies. It must be underlined that among them the aGPD-2* locus proved to be species-specific, while the other ones can be also used in various combinations for the same purpose. The observed heterozygosity was found to range from 0.020 to 0.051. Allele frequencies of all loci were used to estimate Nei's (1972) genetic distance, which was found to range between 0.249 and 1.171 among the five species studied. UPGMA and NJ trees, obtained by genetic distance matrix methods, as well as, a tree based on the discrete character parsimony analysis were found to exhibit the same topology. Our result show that the three species of the genus Liza are clustered together, Chelon labrosus being closer to the previous clade, while Mugil cephalus being more distinct.     

Phenetic relationships of six species of mullets (<Emphasis Type="Italic">Mugilidae</Emphasis>) from the south Adriatic,as inferred from the study of the visceral and dermal skeleton

This study examines the interspecific variability and phenetic relationships in six southern Adriatic mullet species: Mugil cephalus (Linnaeus, 1758), Chelon labrosus (Risso, 1826), Liza aurata (Risso, 1810), Liza ramada (Risso, 1826), Liza saliens (Risso, 1810), and Oedalechilus labeo (Cuvier, 1829). Twenty-three morphometric characteristics of the visceral skeleton and the dermatocranium of mullets were analyzed. The major distinguishing characters were those of the jaws. M. cephalus was clearly separated from the other species; O. labeo differed to a somewhat smaller extent; and C. labrosus was the least distinguished species. The species of the genus Liza were phenetically most similar, while the other species of mullet differed significantly from them. The greatest distances were between M. cephalus and C. labrosus, as well as between M. cephalus and O. labeo. This text was submitted by the authors in English.     

Molecular Phylogeny of Grey Mullets (Teleostei: Mugilidae) in Greece: Evidence from Sequence Analysis of mtDNA Segments

Mitochondrial DNA sequence analysis has been used to explore genetic differentiation and phylogenetic relationships among five species of the Mugilidae family, Mugil cephalus, Chelon labrosus, Liza aurata, Liza ramada, and Liza saliens. DNA was isolated from samples originating from the Messolongi Lagoon in Greece. Three mtDNA segments (12s rRNA, 16s rRNA, and CO I) were PCR amplified and sequenced. Sequencing analysis revealed that the greatest genetic differentiation was observed between M. cephalus and all the other species studied, while C. labrosus and L. aurata were the closest taxa. Dendrograms obtained by the neighbor-joining method and Bayesian inference analysis exhibited the same topology. According to this topology, M. cephalus is the most distinct species and the remaining taxa are clustered together, with C. labrosus and L. aurata forming a single group. The latter result brings into question the monophyletic origin of the genus Liza.     

Genetic divergence and phylogenetic relationships in grey mullets (Teleostei: Mugilidae) based on PCR-RFLP analysis of mtDNA segments

The genetic differentiation and phylogenetic relationships among five species of the Mugilidae family (Mugil cephalus, Chelon labrosus, Liza aurata, Liza ramada, and Liza saliens) were investigated at the mtDNA level, on samples taken from Messolongi lagoon-Greece. RFLP analysis of three PCR-amplified mtDNA gene segments (12s rRNA, 16s rRNA, and CO I) was used. Ten, eight, and nine restriction enzymes were found to have at least one recognition site at 12s rRNA, 16s rRNA, and CO I genes, respectively. Several fragment patterns were revealed to be species-specific, and thus they could be useful in species taxonomy as diagnostic markers, as well as for further evolutionary studies. Seven different haplotypes were detected. The greatest amount of genetic differentiation was observed at the interspecific level, while little variation was revealed at the intraspecific level. The highest values of nucleotide sequence divergence were observed between M. cephalus and all the other species, while the lowest was found between C. labrosus and L. saliens. Dendrograms obtained by the three different methods (UPGMA, Neighbor-Joining, and Dollo parsimony), were found to exhibit in all cases the same topology. According to this, the most distinct species is M. cephalus, while the other species are clustered in two separate groups, the first one containing L. aurata and L. ramada, the other L. saliens and C. labrosus. This last clustering makes the monophyletic origin of the genus Liza questionable.     

Length–weight relationships for 22 fish species of the Mar Menor coastal lagoon (western Mediterranean Sea)

Length–weight relationships were estimated for 22 species of the Mar Menor coastal lagoon (south‐eastern Spain): Lipophrys dalmatinus, Salaria pavo, Callionymus pusillus, Aphanius iberus, Engraulis encrasicolus, Gobius cobitis, G. niger, G. paganellus, Pomatoschistus marmoratus, Symphodus cinereus, Chelon labrosus, Liza aurata, L. ramado, L. saliens, Mugil cephalus, Diplodus puntazzo, D. sargus sargus, Lithognathus mormyrus, Sarpa salpa, Sparus aurata, Hippocampus guttulatus and Syngnathus abaster. The captures were made in shallow areas of the lagoon during 2002–2004. Significant length–weight relationships were found for all species.     

Mitochondrial DNA divergence and phylogenetic relationships in mullets (Pisces: Mugilidae) of the Sea of Japan and the Sea of Azov revealed by PCR-RFLP-analysis

Three Mugilid species: Mugil cephalus (Linnaeus, 1758) and Liza haematocheila (Temminck et Schlegel, 1845; syn. Mugil soiuy, M. haematocheilus, L. soiuy, Chelon haematocheilus) from the Sea of Japan, as well as M. cephalus and Liza aurata (Risso, 1810) from the Sea of Azov were investigated on the basis of PCR-RFLP analysis of mitochondrial DNA (mtDNA) fragments, which included 12S/16S rRNA, and ND3/ND4L/ND4 genes. Among 61 individuals of three Mugilid species thirteen different haplotypes were detected. Eight and thirteen restriction endonucleases were found to be species-specific in 12S/16SrRNA and ND3/ND4L/ND4 respectively. This method may be useful for species identification. M. cephalus showed the largest genetic divergence while L. haematocheila and L. aurata were closely related and clustered together. The level of mtDNA differentiation between the two M. cephalus samples from the Sea of Japan and the Sea of Azov, i.e., nucleotide substitutions of approximately 3%, appeared to be relatively high.     

Morphological and morphometric changes of sagittae otoliths related to fish growth in three Mugilidae species

The aim of this study was to analyze morphologic and morphometric changes of sagittae otoliths throughout the growth of three mullets: Mugil liza, Mugil cephalus and Liza ramada. Fish were collected seasonally between October 2011 and April 2014, and three methods were used: regression analysis of traditional biometric characters; morphological analysis for group identification; and morphometrical analysis of shape indices among groups (circularity, rectangularity, aspect ratio and percentage occupied by the sulcus). In all species, dependence of standard length on otolith length and height were best described as power functions. Two morphological groups were identified for M. liza and M. cephalus, while three for L. ramada. Morphological changes were supported by morphometry differences only for the first two species. Smaller size specimens of M. liza had more rectangular otoliths with more percentage covered by the sulcus while bigger fish tended to have a more circular shape. For M. cephalus smaller size fish had a more elliptical shape. The observed changes may be reflecting life history changes, related to habitat or dietary shifting.     

Analysis of mitochondrial DNA: Taxonomic and phylogenetic relationships in two fish taxa (Pisces: Mugilidae and Cyprinidae)

To solve some systematic questions as well as to study genetic variability and evolutionary relationships in two groups of fish belonging to the Mugilid (Mugilidae) and Cyprinid (Cyprinidae) families, we have used restriction fragment length polymorphism analysis of mitochondrial DNA (mtDNA) fragments amplified in polymerase chain reaction. The analysis of three mtDNA fragments of 7220 bp total length of six Mugilid species has shown that Mediterranean Liza aurata, L. ramada, L. saliens, and Chelon labrosus form a common cluster, L. aurata and C. labrosus being the closest relatives, whereas L. haematocheilus (syn. C. haematocheilus) of the Sea of Japan forms a sister group to the Mediterranean cluster. It was found that Chelon and Liza genera are paraphyletic, and therefore their division into two genera is unnatural and they should be synonymized. According to priority, Liza species should be ascribed to Chelon genus. Mugil cephalus is the most distant compared to the rest of the species studied. The level of genetic divergence between allopatric samples of M. cephalus from the Sea of Japan and the Mediterranean Sea has proved to be very high—4.5% of nucleotide substitutions. The analysis of four mtDNA fragments of 9340 bp total length of six Cyprinid species has shown that L. waleckii is the most genetically distant. Pseudaspius leptocephalus is a sister group to Tribolodon species. All Tribolodon species form a common cluster with T. sachalinensis as a root. The remaining species form two branches, one of which includes T. nakamurai and T. brandtii, another one combines T. hakonensis and a new form of Tribolodon revealed that is close to T. hakonensis by its mtDNA (2.4% of nucleotide substitutions). This new form might be an independent species. Published in Russian in Biokhimiya, 2007, Vol. 72, No. 12, pp. 1651–1658.     

Spatial and temporal variations and assemblage structure of fish species in Beymelek Lagoon,Turkey

Spatial and temporal variations and assemblage structure of fish species were investigated in Beymelek Lagoon, on the south‐western Mediterranean coast of Turkey. A total of 3956 fish, mainly juveniles, from 24 species representing 11 families were sampled by gillnets and trammel nets from February 2006 to January 2007. Twelve of the species were marine straddlers, 11 were marine‐estuarine‐dependent and one was catadromous. Numerical contribution of marine‐estuarine‐dependent species to the total fish abundance was 86.2%, while marine straddlers contributed only 13.8%. Despite the higher number of species, the numerical abundance of marine straddlers was lower than the abundance of marine‐estuarine‐dependent species. The contribution of catadromous species by number was only 0.02%. The assemblage was taxonomically dominated by Sparidae (seven species, 51.3%), Mugilidae (five species, 36.0%), and Clupeidae (one species, 10.3%). Among sparids, Sparus aurata, Diplodus sargus and Lithognathus mormyrus contributed 38.0, 7.2 and 4.6% to the total catch, respectively. The most abundant mugilid species was Liza saliens with 25.2%, followed by Chelon labrosus 5.2%, and Liza aurata 4.0%. Contribution by the other mugilid species to total catch was quite low. The Clupeidae (10.3%) were represented by Sardinella maderensis with 9.1% of the total catch. While the upper reaches of Beymelek Lagoon were dominated by Sparus aurata and Liza saliens, dominant in the lower reaches were Sardinella maderensis, Sparus aurata, Diplodus sargus, Lithognathus mormyrus and Liza saliens. Sparids were generally caught from mid‐summer to mid‐winter while mugilids were caught throughout the year. Clupeids occurred mainly from autumn to spring.     

Saturnius minutus n. sp. and S. dimitrovi n. sp. (Digenea: Hemiuridae) from Mugil cephalus L. (Teleostei: Mugilidae), with a multivariate morphological analysis of the Mediterranean species of Saturnius Manter, 1969

Three species of the bunocotyline genus Saturnius Manter, 1969 are described from the stomach lining of mugilid fishes of the Mediterranean and Black Seas. Two of the species are new: S. minutus n. sp. occurs in Mugil cephalus off the Mediterranean coast of Spain; and S. dimitrovi n. sp., a parasite of M. cephalus off the Bulgarian Black Sea coast and the Spanish Mediterranean coast, was originally described as S. papernai by Dimitrov et al. (1998). In addition, S. papernai Overstreet, 1977 is redescribed from M. cephalus off the Spanish Mediterranean coast and from Liza aurata and L. saliens off the Bulgarian Black Sea coast. The three species are distinguished morphometrically using univariate and multivariate analyses. These results were verified using Linear Discriminant Analysis which correctly allocated all specimens to their species designations based on morphology (i.e. 100% successful classification rate) and assigned almost all specimens to the correct population (locality). The following variables were selected for optimal separation between samples: the length of the forebody, ventral sucker and posterior testis, the length and width of the posteriormost pseudosegment, and the width of the muscular flange at ventral sucker level.     

Critical thermal maxima of three species of Hawaiian estuarine fish: a comparative study*

Crticial thermal maxima (CTM) of three species of Hawaiian estuarine fishes were determined in relation to acclimation temperature and time of day. The species studied were Mugil cephalus L., Chelon engeli (Bleeker) and Kuhlia sandvicensis (Steindachner). Critical thermal maxima of all three species were significantly affected by acclimation temperature and time. In relation to acclimation temperature, Mugil cephalus and Chelon engeli have similar critical thermal maxima with Kuhlia sandvicensis having a critical thermal maxima about 1° C below that of the other two species studied. Mugil cephalus and Chelon engeli showed an increasing critical thermal maxima toward midday which decreased therafter. Critical thermal maximum of Kuhlia sandvicensis increased throughout the day.     

L'Intestin chez les Mugilidae (Poissons; Téléostéens) a différentes étapes de leur croissance I. Aspects morphologiques et histologiques

The intestine of Mugilidae (Pisces; Teleostei) at different growth stages. I. Morphological and histological aspects A morphological and histological study of the intestine of Mugilidae (Mugil cephalus, Liza aurata, Liza ramada and Liza saliens) has been carried out from the larval to the adult stages. The allometric relationship between length of intestine and standard length of fish are represented by regression lines correlated with species and kind of diet. S.E.M. observations on the intestinal mucosa surface show finger-like villi, as in Mammals. Histologically, the mucosa structure appears similar to that in others Teleosteans. The gobblet cells are scarce in the larval stages but very numerous in the juvenile stages; furthermore, they are more abundant in the posterior than the anterior part of the intestine (respectively 25 and 10%). Change in the feeding habits observed in young stages has no effect on the features of the intestine but notably increases its relative length.     

Phylogenetic relationships of mullets (Mugilidae) in China Seas based on partial sequences of two mitochondrial genes

Phylogenetic analyses of Mugilidae species from the China coast were carried out based on 16S and 12S rRNA mitochondrial gene sequences by maximum parsimony, maximum likelihood, Bayesian inference and neighbor joining analysis in the present study. The results suggested that Mugil cephalus is the most genetically divergent species among the Mugilidae. The four Liza species clustered together and formed a monophyletic group. The genera Osteomugil showed closer affiliation with Valamugil than with Ellochelon; these three genera then grouped together to form a monophyletic clade presenting as the sister group to Liza. Analyses of phylogenetic and genetic distance indicated that Southern and Northern lineages of Liza haematocheila may be two different species; likewise, strong genetic divergence existed between Southern and Northern M. cephalus lineages. In addition, our results supported the Southern origin of Chinese Mugilids, which is contrary to the hypothesis based on morphological characters.     

A key to the species of Mugilidae (Pisces) in the Northeastern Atlantic and Mediterranean, with explanatory notes

A key is given for identifying the eight species of Mugilidae of the Northeast Atlantic and Mediterranean. The use of Risso's names for four species is justified and explained and recognition is given to Tortonese's discovery that Mugil capurrii (Perugia) is a senior synonym of M. monodi Chabanaud. The relationship of Liza saliens to certain species of West and southern Africa is held to be additional support for the recognition of Protomugil Popov as a subgenus of Liza including these species. Chelon Röse, with type-species Mugil chelo Cuvier (= Chelon labrosus (Risso)), is recognized, following Jordan & Evermann (1917) and Schultz (1946), but its limits are differently conceived so as to include Crenimugil Schultz rather than Liza Jordan & Swain. The latter is held to comprise about 30 Old World species. The status of Chelon bispinosus (Bowdich) is discussed, with its bearing on possible population-differences in C. labrosus and the relationship of this species with C. crenilabis. The identity of Liza seheli (Forskål) is discussed and reasons are given for disagreeing with Wimpenny and others in applying this name to the species found at both ends of the Suez Canal zone. The latter is L. carinata (Ehrenberg in Cuvier & Valenciennes). Myxus maroccensis Mohr is believed to be a young Liza ramada.     

Molecular phylogeny of Mugilidae fishes revised

Systematics derived from morphological characters often does not correspond with the evolutionary processes underlying the divergence within a group of organisms. In the family Mugilidae (Teleostei) morphological similarities have resulted in inconsistencies between taxonomy and phylogeny among its species, and particularly for the genera Mugil, Liza and Chelon where both intrageneric and intergeneric phylogenetic clarifications are needed. To address these issues, the direct sequencing of the mitochondrial region that encodes Phenylalanine (69 bp), 12S rRNA (842 bp), cytochrome c oxidase subunit I (651 bp) and cytochrome b (702 bp) was carried out. The data reveal that Mugil platanus and Mugil liza represent a continuum of a single species, closely related to but distinct from Mugil cephalus which itself appears to comprise a grouping of multiple and closely related species. This species complex was genetically distinct from Mugil curema, which, based on three clearly diverged species identified in this study along the Atlantic coast of the Americas, requires extensive taxonomic revision throughout its world-wide distribution. Unlike the monophyly supported within Mugil, relationships within Liza are paraphyletic, and a taxonomic revision of the genera Liza, Chelon and Oedalechilus is needed.     

5S ribosomal RNA genes in six species of Mediterranean grey mullets: genomic organization and phylogenetic inference.

This paper describes a study of the 5S ribosomal RNA genes (5S rDNA) in a group of 6 species belonging to 4 genera of Mugilidae. In these 6 species, the relatively short 5S rDNA repeat units, generated by PCR and ranging in size from 219 to 257 bp, show a high level of intragenomic homogeneity of both coding and spacer regions (NTS-I). Phylogenetic reconstructions based on this data set highlight the greater phylogenetic and genetic diversity of Mugil cephalus and Oedalechilus labeo compared with the genera Liza and Chelon. Comparative sequence analysis revealed significant conservation of the short 5S rDNA repeat units across Chelon and Liza. Moreover, a second size class of 5S rDNA repeat units, ranging from roughly 800 to 1100 bp, was produced in the Liza and Chelon samples. Only short 5S rDNA repeat units were found in M. cephalus and O. labeo. The sequences of the long 5S rDNA repeat units, obtained in Chelon labrosus and Liza ramada, differ owing to the presence of 2 large insertion/deletions (indels) in the spacers (NTS-II) and show considerable sequence identity with NTS-I spacers. Interspecific sequence variation of NTS-II spacers, excluding the indels, is low. Southern-blot hybridization patterns suggest an intermixed arrangement of short and long repeat units within a single chromosome locus.     

Phylogenetic Analysis of Mediterranean Mugilids by Allozymes and 16S mt-rRNA Genes Investigation: Are the Mediterranean Species of Liza Monophyletic?

The family Mugilidae (Pisces, Mugiliformes) includes species which are present in all tropical and temperate regions. Six species, Chelon labrosus, Mugil cephalus, Liza aurata, L. ramada, L. saliens, Oedalechilus labeo, are commonly found in the Mediterranean. These species have been widely studied through morphological, biochemical, and molecular markers. However, their phylogenetic relationships, and therefore the assumed monophyly of Liza species, still remain unclear: To further investigate this topic, gene-enzyme systems and sequences of the partial 16S rRNA mitochondrial gene were analyzed in Italian samples of all six Mediterranean species. The phylogenetic reconstructions indicated M. cephalus as being the most divergent species and the existence of a main cluster including all the Mediterranean species of Liza and C. labrosus. The parametric bootstrap approach adopted to test alternative phylogenetic hypotheses indicated that the Mediterranean species of Liza do not form a monophyletic group exclusive of Chelon.     

Redescription of the fish parasite Nerocila japonica Schioedte & Meinert, 1881 (Crustacea: Isopoda: Cymothoidae), with comments on previous records of N. acuminata in Japanese waters

Nerocila japonica Schioedte & Meinert, 1881 is redescribed based on the holotype and specimens from various localities in Japanese waters. The following fishes are recorded as new hosts: Tribolodon hakonensis (Cyprinidae), Mugil cephalus, Liza affinis, Chelon haematocheilus (Mugilidae), Lateolabrax japonicus, L. latus (Lateolabracidae), Acanthopagrus latus, A. schlegelii schlegelii (Sparidae), Rhyncopelates oxyrhynchus (Terapontidae), Ditrema viride, D. temminckii temminckii (Embiotocidae), Chaenogobius gulosus, Acanthogobius flavimanus (Gobiidae), Pseudolabrus sp. (Labridae) and Aluterus monoceros (Monacanthidae). Specimens previously recorded as ‘Nerocila acuminata’ from Toyama Bay (the Sea of Japan) were examined, when available, and re-identified as N. japonica. As there has been no reliable record of N. acuminata Schioedte & Meinert, 1881 from off Japan, reports of this species in Japanese waters are considered to represent N. japonica.