Lamellodiscus sanfilippoi n. sp. (Monogenea, Diplectanidae) parasite from the gills of Diplodus sargus (Teleostei, Sparidae) in Mediterranean Sea

Lamellodiscus sanfilippoi n. sp. takes place, among the other species of Lamellodiscus, in the "ergensi" sub-group (Amine et Euzet, 2005) characterized by the morphology of the dorsal lateral bars of the haptor. This sub-group comprises, in the Mediterranean, L. ergensi Euzet and Oliver, 1966, L. kechemirae Amine and Euzet, 2005, L. tomentosus Amine and Euzet, 2005, all parasite of Diplodus sargus, and L. baeri Oliver, 1974 parasite of Pagrus pagrus. L. sanfilippoi can be distinguished from the previous species by the morphology and size of the dorsal lateral bars. The new species is close to Lamellodiscus furcillatus Kritsky, Jiménez-Ruiz and Sey, 2000, a parasite of Diplodus noct in the Persian Gulf, but differs by the size of the haptoral sclerotised pieces and the morphology of the male copulatory apparatus. Lamellodiscus gussevi Sanfilippo (1978) et Lamellodiscus abbreviatus Sanfilippo (1978) are considered as nomina nuda.     

Genetic differentiation of Diplodus sargus (Pisces: Sparidae) populations in the south-west Mediterranean

Allozyme analysis of tissue samples of 1249 white sea bream Diplodus sargus from five localities of the south-west Mediterranean revealed a high degree of genetic polymorphism. The observed heterozygosity ranged from 0.4182 (Cape of Palos) to 0.3138 (Tabarca). Several populations were characterized by unique alleles. Examination of the spatial structure was performed using Nei's distances and F- statistics, and indicated genetic differences between groups. One group, which clustered Tabarca and Guardamar, could be explained by the small geographical distance between them. Mazarrón and Cape of Palos samples showed genetic divergence from other samples (Guardamar, Tabarca and Águilas) and this difference may be as a result of local current systems and larval dispersal.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 249–261.     

Biology of the annular seabream, Diplodus annularis (Sparidae), in coastal waters of the Canary Islands

The biology of the Canary Islands annular seabream Diplodus annularis (Linnaeus 1758) was studied from samples collected between January and December 1998. Fish ranged from 82 to 209 mm total length in size and from 8.7 to 137.1 g in weight. The mean length showed an increase with increasing water depth. Males showed a negative allometric growth and females isometric growth. The species was characterized by protandric hermaphroditism. The overall sex ratio was unbalanced in favour of males (1 : 0.79). The reproductive season extended from January to May, with a peak in spawning activity in March–April. Males reached maturity at a smaller length (103 mm, 1-year-old) than females (128 mm, 2-year-old). Fish aged 0–6 years were found. The von Bertalanffy growth parameters for all individuals were: L_∞=247.9 mm, k=0.268 years^–1, and t₀=–0.879 years.     

Characterization of eight microsatellite markers in the white sea bream, Diplodus sargus (Teleostei, Sparidae)

The white sea bream, Diplodus sargus (Teleostei, Sparidae), is a species with a high commercial importance in Mediterranean aquaculture. There is currently little information available about the genetic characteristics of cultured populations. In this survey, we have developed eight polymorphic microsatellites for the white sea bream using an enriched genome library protocol. All of them were polymorphic in the 67 individuals tested, 32 of which were wild specimens, and 35 were individuals from a captive F(1) broodstock. These markers can potentially be useful tools for use in population genetic studies.     

Reproductive characteristics of the benthic coastal fish Diplodus vulgaris (Teleostei: Sparidae) in the Canarian archipelago, northwest Africa

Diplodus vulgaris is characterized by a rudimentary hermaphroditism, with a low proportion of protandrous sex reversal. Male : female ratio is slightly unbalanced in favour of females (1 : 1.17), although no significant difference of the relation 1 : 1 was found. Both sexes have similar size distributions, with females predominating in larger sizes; a low proportion of intersexual individuals are distributed among the middle sizes. A protracted winter spawning season has been identified from November to March, with a peak in spawning activity in December–January. Size of maturity for males and females is attained in the second year of life.     

Microcotyle visa n. sp. (Monogenea: Microcotylidae), a gill parasite of Pagrus caeruleostictus (Valenciennes) (Teleostei: Sparidae) off the Algerian coast,Western Mediterranean

Parasite biodiversity of fish of the southern part of the Mediterranean sea is still incompletely explored. We describe here Microcotyle visa n. sp. from the gill filaments of the bluespotted seabream Pagrus caeruleostictus (Valenciennes) (Sparidae) collected off the Algerian coast. The identity of fish hosts was confirmed by barcoding. Microcotyle visa n. sp. is herein described and illustrated. Analysis of the cox1 gene of the monogeneans revealed minor intraspecific variation (1.4%), an order of magnitude lower than the distance between this species and other Microcotyle species (10–15 %). Microcotyle visa n. sp. is distinguished from Microcotyle erythrini van Beneden & Hesse, 1863, a congener infesting sparids, on the basis of morphological (size of clamps, number of testes) and molecular (cox1) differences. This is the fourth member of the genus known to parasitise a sparid host. A species of Paramicrocotyle sp. included in the molecular analysis was nested within a robust Microcotyle + Paramicrocotyle clade; in the absence of demonstrated molecular and morphological differences, we consider that Paramicrocotyle Caballero & Bravo-Hollis, 1972 is a junior synonym of Microcotyle van Beneden & Hesse, 1863 and transfer two species of Paramicrocotyle as Microcotyle danielcarrioni (Martinez & Barrantes, 1977) n. comb. and Microcotyle moyanoi (Villalba & Fernandes, 1986) n. comb.

     

Osmoregulation in juvenile Rhabdosargus holubi (Steindachner) (Teleostei: Sparidae)

Juvenile Rhabdosargus holubi (Steindachner), one of the commonest teleosts in south east African estuaries, are strong osmoregulators, showing little change in their internal osmotic concentration over an extremely wide salinity range. In 35‰ seawater the internal osmotic concentration is held at 370 mosmol/1. At a salinity of 1‰ the internal osmotic concentration falls to 216 mosmol/1 and at a salinity of 65‰ rises to 381 mosmol/1. When exposed to a new salinity the internal osmotic concentration does not change until after 10 h; this may be of considerable importance to fish living in areas subject to short term changes of salinity.     

Spatio-temporal movement patterns of Diplodus vulgaris (Actinopterygii, Sparidae) in a temperate marine reserve (Lampedusa, Mediterranean Sea)

The movements of a commercially important species, Diplodus vulgaris, were assessed in a marine-protected area to test whether their spatial and temporal activity patterns differ during and outside of their spawning season. Twelve adults were caught along the north-eastern coast of a small Mediterranean island, tagged with acoustic transmitters and released within or just outside the integral reserve. Fish detected, during both the seasons showed strong fidelity for the study area before and during the spawning season and their home range did not differ between seasons. Home ranges reached an asymptote between 12 and 174 days after release. Home range estimated by kernel utilization distributions ranged from 9,876 to 89,914 m², with core areas of 946 to 7,274 m². Temporal patterns frequently showed a dominant diel rhythm with most of detections occurring at daytime, independently of season. The variability in the movement patterns of D. vulgaris was lower between seasons (i.e., during and outside the spawning season) than at smaller temporal scale (i.e., between day and night) and was largely affected by inter-individual differences. Some conclusions arising from this and previous findings are useful to orient future studies on coastal fish movement and have direct implications for MPAs design.     

The occurrence of two xanthochromic fish,Epiniphelus marginatus (Serranidae) and Diplodus vulgaris (Sparidae) (Osteichthyes) in the eastern Mediterranean

Xanthism in fishes has a genetic basis that causes abnormal skin colouration of yellow to orange-gold. Xanthochromic specimens are rare in nature. We report two cases of adult xanthochromic specimens from the Mediterranean Sea: Epinephelus marginatus from Israel and Diplodus vulgaris from Greece and discuss the reason for the paucity of reports of xanthochromic fish from the Mediterranean.     

Description of Lamellodiscus confusus n. sp, (Monogenea: Diplectanidae), parasite of Sarpa salpa (Teleostei: Sparidae)

Lamellodiscus confusus n. sp., a diplectanid gill parasite of Sarpa salpa Linnaeus, 1758 (Sparidae) from the coast of Algeria, is described. This monogenean has been previously reported in Sarpa salpa, by various authors, under the name L. ignoratus. L. confusus n. sp. is included (among other Lamellodiscus of Mediterranean sparids) in the "ignoratus" sub-group (Amine & Euzet, 2005). L. confusus n. sp. can be distinguished from L. ignoratus by the shape and size of the haptoral ventral bar and the male copulatory organ. For comparison, illustrations of the ventral bar and the male copulatory organ of all Mediterranean species of the "ignoratus" sub-group are provided. The question of the host specificity of L. ignoratus is discussed.     

Lamellodiscus euzeti n. sp. (Monogenea:Diplectanidae), a parasite from Dentex canariensis and D. gibbosus (Teleostei:Sparidae) in the Atlantic Ocean and Mediterranean Sea

Lamellodiscus euzeti n. sp. (Monogenea:Diplectanidae) is described from the gills of two sparid fishes, Dentex canariensis (Steindachner) off Senegal and Ivory Coast and D. gibbosus (Rafinesque) off Senegal and Tunisia. The new species belongs to the "ignoratus" group, characterized by a lamellodisc with complete lamellae, a "lyre" shaped male copulatory organ type, and the "ignoratus" sensu stricto subgroup, characterized by a haptor with simple lateral dorsal bars. Lamellodiscus euzeti n. sp can be distinguished from all the congeneric species of the "ignoratus" subgroup by the presence of a prominent protuberance at the base of the curved part of the simple piece of the male copulatory organ (MCO), a large bulb at the base of the bifurcated piece of the MCO and the presence of 5-6 spines in the distal portion of the axial branch of the bifurcated piece of the MCO. Specificity and biogeography of Lamellodiscus species from sparid fishes are discussed.     

Reproductive biology of the annular seabream,Diplodus annularis (Linnaeus, 1758), in the Gulf of Gabes (Central Mediterranean)

Annular seabream, Diplodus annularis (Linnaeus, 1758), were caught off the coast of the Gulf of Gabes (Southern Tunisia, Central Mediterranean) between April 2008 and March 2010 by commercial catches. With a total 2066 specimens the fish ranged in size from 7.7 cm to 18.5 cm total length and from 7.5 g to 123.3 g in weight. Changes in biological parameters (weight, length, gonadosomatic index, hepatosomatic index and condition factor) were examined in order to provide information on the spawning period and reproductive cycle in the gulf. Overall sex ratio was 1 : 1.52 in favour of females. The reproductive season extends from March to June, with a spawning activity peak in May. Total length at sexual maturity was 10.5 ± 0.22 cm (males) and 10.6 ± 0.3 cm (females). The results of this study could help to establish a recommended minimum capture size.     

Mitochondrial phylogeny and biogeographic affinities of sea breams of the genus Diplodus (Sparidae)

Phylogenetic analyses, using 482 bp of the mitochondrial 16S rDNA and 461 bp of the control region of 16 Diplodus species and Oblada melanura, Pagellus bogaraveo and Pagellus acarne , all close relatives of Diplodus , identified the two representatives of Pagellus as the sister group of Diplodus. Oblada melanura was confirmed as the sister taxon of D. puntazzo , despite its different dental morphology and ecology. Within the genus Diplodus , three clades were identified, the first containing D. annularis and D. bellottii , the second D. vulgaris and D. prayensis , and the third comprising three subclades. These were formed by O. melanura clustering with D. puntazzo, D. fasciatus with D. cervinus , and by the Diplodus sargus sub-species assemblage which also included the West Atlantic taxa D. argenteus, D. bermudensis, D. holbrooki , and the Red Sea endemic D. noct. All members of the D. sargus assemblage were genetically closely related. Among them, D. sargus lineatus from the Cape Verde islands was resolved as most ancestral branch, pointing to the possibility that the diversification and spread of the D. sargus assemblage originated in this region. The hypothesis of stepwise speciation following colonization events within the D. sargus complex is fully supported by phylogenetic reconstruction.     

Cardicola aurata sp. n. (Digenea: Sanguinicolidae) from Mediterranean Sparus aurata L. (Teleostei: Sparidae) and its unexpected phylogenetic relationship with Paradeontacylix McIntosh, 1934

A new sanguinicolid trematode, Cardicola aurata sp. n., is described from gilthead seabream Sparus aurata L., from off the Spanish Mediterranean coast. The morphology of C. aurata sp. n. generally agrees with the diagnosis of the genus, however, in contrast to all other reported Cardicola spp. the male pore is located sub-medially at the posterior end of the body instead of sinistrally before the posterior end of the body. Based on a comparison of the morphology as well as partial 28S and ITS2 rDNA sequence data from the present species with that from closely related species, it was decided to emend the diagnosis of Cardicola rather than create a new genus, as the aberrant position of the male pore is likely to be an autapomorphy. The phylogenetic analyses revealed a close relationship between Cardicola and Paradeontacylix, two genera with considerable morphological differences; C. aurata sp. n. occupies a position intermediate to these genera. Thus, a morphological comparison of Cardicola, Paradeontacylix and Braya, a genus which is morphologically similar to Cardicola but clusters basal to the Cardicola/Paradeontacylix clade, was conducted. The results of this comparison showed that despite large differences with regard to body shape, the organisation of the internal organs is very similar in species of Cardicola and Paradeontacylix. The synopsis of morphological data and molecular phylogeny allows for interpretations regarding the importance of different morphological features for the phylogenetic inference of the Sanguinicolidae.     

Morphological and genetic characterization of the sharpsnout seabream populations (Diplodus puntazzo,Sparidae) along a boundary area between the two Mediterranean basins

In order to test the potential ecological role of the Siculo-Tunisian Strait as a geographic barrier, the morphological and genetic variation of eight Tunisian samples of the sharpsnout seabream, Diplodus puntazzo, were studied, based on 23 truss network elements and 13 polymorphic allozyme loci. Significant morphological differences were observed between studied samples, especially between lagoon ones. Although genetic data did not support the detected morphometric variation, F-statistics indices (F_IS and F_ST) revealed a significant departure from panmixia with heterozygote deficiencies and slight genetic differentiation between samples. Genetic results suggested the existence of moderate and local genetic heterogeneity that can be explained by the chaotic genetic patchiness hypothesis. Morphological and genetic results showed that the Siculo-Tunisian Strait does not seem to act as a barrier limiting the connectivity between the natural populations of D. puntazzo, at least at the scale of the Tunisian coast. Thus, the phenotypic variation identified in this study appears to be environmentally induced through the exploitation of different ecological niches and hydrodynamic constraints.     

The reproductive biology of Chrysoblephus laticeps and C. cristiceps (Teleostei: Sparidae)

A detailed histological study showed that in two protogynous sparids, Chrysoblephus laticeps (Cuvier) and C. cristiceps (Cuvier), gametogenesis follows a pattern typical of temperate sparids and marine teleosts in general. Fertilization is external and both species produce numerous small eggs which are pelagic. They have a restricted summer breeding season and gonadal recrudescence is well correlated with temperature and photoperiod. Behavioural observations showed that C. laticeps are pair-spawners, releasing their gametes well above the substratum after an elaborate courtship routine. The testes of these fishes are small in relation to those of other sparids and are thought to reflect basic differences in the mating systems of sex-changing and gonochoristic species.     

Field studies of the diet of Rhabdosargus holubi (Pisces: Teleostei: Sparidae)

Rhabdosargus holubi is a marine teleost endemic to south east Africa. The juveniles occur mainly in estuaries but the adults are largely confined to the sea. Stomach contents of over 2000 juvenile R. holubi were examined from fish captured in the open Kowie and Msikaba estuaries, and from the closed West Kleinemond and Kasouga estuaries. Juvenile R. holubi feed mainly on aquatic vegetation. The fish cannot, however, digest the vegetation eaten due to the absence of a cellulase or a method of breaking up the plant tissue. Therefore, the plant material is passed out in an undigested state. Epiphytic diatoms and sessile ectoprocts (Bryozoa) are, however, removed from the macrophytes or multicellular algae in the stomach, and are subject to digestion. Diatoms may form up to 50% of the dry weight of the plants consumed. A variety of animals was also eaten. Maximum total food consumption was estimated at 1·9% of body weight per day although this is probably an underestimate. Feeding only took place during daylight hours. The teeth of juvenile R. holubi are specialized for grazing aquatic plants and differ from those of adult R. holubi. Adults consume mainly bivalves and large crustaceans. It is suggested that the different food requirements of the adults and juveniles determine at what stage this species enters and leaves estuaries.     

Histopathology and cellular response in Enteromyxum leei (Myxozoa) infections of Diplodus puntazzo (Teleostei)

Enteromyxum leei is an intestinal parasite responsible for serious outbreaks in Mediterranean sharpsnout sea bream Diplodus puntazzo. E. leei infection was experimentally transmitted to healthy D. puntazzo (R) by cohabitation with infected donor fish. Haematological changes and histopathological damage were evaluated in relation to the course of infection. The prevalence of infection in R fish was 100% from day 10 post-exposure (p.e.) onwards, and the infection intensity and histopathological damage increased progressively. Different developmental stages were found in the infected intestines, including proliferative (stages 1–3) and sporogonic (stages 4 and 5) stages. Intestinal damage consisted of vacuolation, necrosis, detachment and sloughing of epithelium, and was correlated with the progression of the infection and with the development of the parasite. Sporogonic stages appeared from day 20 p.e. onwards. Initially, D. puntazzo seems to counteract the infection through the increase in leucocyte numbers, respiratory burst activity, haematopoietic activity and MMC. Two types of eosinophilic granular cells (EGC1 and EGC2) were detected in the intestinal epithelium and lamina propria. EGC1 numbers decreased with the progression of infection, whereas an increase in EGC2 occurred, mainly in the lamina propria. The involvement of the cellular immunity in the response of D. puntazzo to E. leei was demonstrated. The depletion of this response at a certain point of the infection could contribute to the high virulence of this myxozoan in this fish species.     

Phylogenetic relationships of the Sparidae (Teleostei: Percoidei) and implications for convergent trophic evolution

A phylogenetic analysis of the majority of sparid genera and representatives of the sparoid families Centracanthidae, Lethrinidae and Nemipteridae is presented using 87 predominately osteological characters. The Sparidae constitute a monophyletic grouping, with the inclusion of the centracanthid Spicara smaris , which nests deep within the ingroup. The phylogeny was then used to investigate agreement with the most recent molecular study, taxonomic stability of subfamilial classification and the evolution of feeding strategies. Results show that the incongruence between morphological and molecular data appears largely to be an artifact of errors in rooting. However, there appears to be real and substantial conflict between the molecular tree and the morphological data, which is not attributable to the different positions of the least congruent taxa. The data support the molecular hypothesis that none of the subfamilial classification, based on dentition and trophic specialization, is monophyletic, and should be rejected pending further taxonomic revision. The phylogeny supports multiple independent origins of trophic types and it is suggested that the evolutionary plasticity of the oral teeth of sparids has been fundamental to the adaptive radiation of this family compared to their closest allies. ©2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 76 , 269–301.