Lecithochirium Musculus Research Articles

Metazoan Parasites of Common Sole (Solea Solea) and Scaldfish (Arnoglossus Laterna) (Pleuronectiformes) from Sinop Coast of Black Sea.

SummaryThe metazoan parasites were investigated of two flatfish the common sole, Solea solea (n:140) and the scaldfish, Arnoglossus laterna (n: 22) in the Sinop coast of Black Sea from June 2015 to June 2017. A total of 15 metazoan parasite species belonging to Digenea (6), Cestoda (3), Acanthocephala (1), Nematoda (4) and Isopoda (1) taxonomic groups were identified. Solea solea was found to be infected by Condylocotyla pilodora, Proctoeces maculatus, Opecoelidae gen. sp., Metadena sp., Stephanostomum sp., Progrillotia sp., Capillaria gracilis, Cucullanus campanae, Solearhynchus rhytidotes and Nerocila orbignyi. Arnoglossus laterna was found to be infected by Lecithochirium musculus and Grillotia erinaceus. Scolex pleuronectis, Hysterothylacium aduncum and Dichelyne minutus were determined in both flatfish. Infection prevalence and mean intensity values were recorded for each parasite species. Infection values for each parasite species in relation to season and fish size were also determined and compared as comparatively. This study is the first one assessing the metazoan parasites both of S. solea and A. laterna collected from the Turkish coast of Black Sea. While Condylocotyle pilodora and Capillaria gracilis are new parasite records for S. solea, Grillotia erinecaus is new parasite record for A. laterna. Moreover, this paper is the first report on occurrence of Opecoelidae gen. sp., Metadena and Stephanostomum genera in S. solea.

Temporal and spatial changes in the composition and structure of helminth component communities in European eels Anguilla anguilla in an Adriatic coastal lagoon and some freshwaters in Italy

The composition and diversity of the helminth component communities in eels Anguilla anguilla were determined in three separate localities in Italy: an Adriatic coastal lagoon, Comacchio and two freshwater localities, the River Po and the Lake Piediluco. Data from Comacchio lagoon were analysed over 15 years to determine whether community composition and diversity changed significantly overtime. The community was species rich (nine species, all marine except Proteocephalus macrocephalus) and was dominated by a suite of digeneans: Deropristis inflata, Helicometra fasciata, Lecithochirium musculus and Bucephalus anguillae. The community showed little change in composition over the period, but the relative abundance and dominance of the species did alter. By contrast, the component communities in the freshwater localities were species poor and the dominant species were freshwater acanthocephalans, Pomphorhyncus laevis in River Po and Acanthocephalus rhinensis in Lake Piediluco. The helminth community of Lake Piediluco with five species was richer than that of the River Po with only three species, but was poorer than that of Comacchio lagoons. Similarity indices between samples from Comacchio were high; between the lagoon and the freshwater localities and between the two freshwater localities, similarity indices were very low. Helminth component community structure in coastal lagoons was comparable across Europe. The helminth community in the River Po was similar to those in the River Tiber and other European rivers whilst that in Lake Piediluco was similar to that in other European lakes. Levels of the pathogenic Anguillicoloides crassus in swim bladders were consistently lower in prevalence and abundance in the coastal lagoons than in freshwater localities. This suggests that this parasite may have little impact on migrating eels if they are indeed primarily of marine origin and so it may be of little importance in the recent decline of eel populations throughout Europe.

Redescriptions of two frequently recorded but poorly known hemiurid digeneans, Lecithochirium musculus (Looss, 1907) (Lecithochiriinae) and Ectenurus lepidus Looss, 1907 (Dinurinae), based on material from the western Mediterranean

Two frequently reported but poorly known hemiurid digeneans, Lecithochirium musculus (Looss, 1907) (Lecithochiriinae), from the stomach of Trachinus draco and Citharus linguatula, and Ectenurus lepidus Looss, 1907 (Dinurinae), from the stomach of Spicara maena, are redescribed based on material from off the Barcelona coast of the western Mediterranean. The two species are commented upon, and Lecithochirium israelense Fischthal, 1980 is considered a synonym of L. musculus. Records of the two species in the Mediterranean Basin and North East Atlantic region are summarised.

Topography and ultrastructure of the tegument of Lecithochirium musculus (digenea: Hemiuridae), a parasite of the European eel Anguilla anguilla (osteichthyes: Anguillidae)

The tegumental ultrastructure of the stomach fluke Lecithochirium musculus was studied using scanning and transmission electron microscopy. The surface of the tegument was smooth and covered by transverse cytoplasmic ridges. Cobblestone-like units of the tegument were observed on the ventral surface. Invagination and evagination of the ecsoma induced variations in the tegumental surface. The ultrastructural study revealed that the tegument of L. musculus had a typical syncytial organization with a distal cytoplasm lying over a basal matrix and cytons. Two types of intra-tegumental sensory structures were observed. Type 1 sensory receptor was a domed-like fusiform structure consisting of a smooth elevation of the tegument. Four receptors of this type were observed on the anterior dorsal surface of the fluke. Three nerve bulbs filled with electron-lucent material and mitochondria composed this receptor. Hemispherical electron-dense collars were observed at the top of the nerve bulbs. Striated rootlets laid just beneath the hemispherical electron-dense collars. Type 2 sensory receptor presented two morphological variations, i.e., a bulb-like monolobed structure, and a bulb-like bilobed structure observed at two different degrees of evagination. For both variations, the nerve bulb enclosed mitochondria, electron-lucent material, and a conical electron-dense collar from which extended a striated rootlet. Numerous sensory receptors of this type were observed around the ventral sucker.

Helminth Parasites From the Stomach of Conger Eel, Conger conger, From Madeira Island, Atlantic Ocean

Geographic variations in the diversity and prevalence of helminth parasites of fish can provide important clues as to the relatedness of fish populations. In the present work, the stomachs of 64 conger eels, Conger conger, collected during 1999 and 2000, were examined for the presence of parasites. Four fish were infected with L3 stages of the nematode Anisakis simplex s.l. (Anisakidae), 1 with the nematode Cristitectus congeri (Cystidicolidae), 1 with the acanthocephalan Rhadinorhynchus pristis, 17 with postlarvae of Sphyriocephalus tergestinus (Eucestoda: Trypanorhyncha), and 55 with Lecithochirium spp. (Digenea: Hemiuridae). The hemiurids were the most abundant parasites, with a total of 385 individuals recovered. Strong aggregated distributions were found for both the digeneans, Lecithochirium musculus and Lecithochirium fusiforme, with variance-to-mean ratios (s2/x) and index of discrepancy (D) 13.98 and 0.672 (for L. musculus) and 8.08 and 0.90 for L. fusiforme, respectively. Intensity of L. musculus, L. fusiforme, and S. tergestinus showed significant relationships with depth of capture. Differences in number of species and prevalence were found between Madeira and the Atlantic coasts of the Iberian Peninsula.

Parasitological diversity of the common goby,Pomatoschistus microps(Krøyer, 1838), in estuarine systems along the Portuguese coast

Summary Parasitological diversity of the common goby Pomatoschistus microps along the Portuguese coast was studied based on samples collected using beam trawls in five coastal estuaries (Ria de Aveiro, Tagus, Sado, Mira and Guadiana estuaries) between May and July 2006. The classes Digenea, Cestoda, Nematoda and phylum Mastigophora were found, with Digenea Cryptocotyle sp. and Lecithochirium musculus being the most abundant taxa. Prevalence and mean abundance of Cryptocotyle sp. were highest in Ria de Aveiro (74%) and Mira estuary (28.05), respectively, whereas L. musculus values of both indices were highest in Sado estuary (prevalence = 64%; mean abundance = 11.77). Values varied along the Portuguese coast; the discriminant analysis based on the number of parasites showed some overlap between estuaries, although successfully separating the Sado and Mira estuaries. Overall, variations in estuaries were explained by different environmental pressures, leading to differences on host abundance and life-history of the parasites. Feeding behaviour and habitat selection therefore play a crucial role in shaping the biology, ecology and parasite assemblages of the common goby along the Portuguese coast.

Genetic variability of natural populations of trematodes of the genus Lecithochirium parasites of eels.

Allozyme variation within and among populations of 3 species of the genus Lecithochirium (Trematoda: Hemiuridae) was studied by starch gel electrophoresis. In total, 19 loci were analysed in 7 populations. The level of genetic variability was relatively high in all populations. The percentage of polymorphic loci (0.95 criterion) observed per population varied from 21.0% to 55.5%, and expected heterozygosity levels varied from 0.082 to 0.197. All populations showed significant heterozygote deficiencies. In Lecithochirium fusiforme most of the deviations from Hardy-Weinberg proportions were within the populations and this species showed moderate population structuring (F(IS)=0.486, F(ST)=0.142, Nm= 1.51) and accordingly low intraspecific genetic distances (D=0.003 to 0.027). A significant lack of heterozygotes for several polymorphic loci was revealed in Lecithochirium rufoviride and Lecithochirium musculus. The most probable cause of the population genetic subdivision in L. rufoviride is the presence of at least 1 cryptic species in the populations studied. Although the lowest percentage of fixed genetic differences was that between L. fusiforme and L. musculus, two different algorithms for the construction of evolutionary trees on a matrix of genetic distances confirmed that L. fusiforme and L. rufoviride are phenetically the most closely related species.

Seasonal Occurrence and Diversity of Hemiuridae (Trematoda: Digenea) in Conger Eels (Conger conger) from Spain

Between the spring of 1999 and the spring of 2002, 196 conger eels, Conger conger, were collected from the Ría de Arousa, Galicia, Spain, and examined for hemiurid flukes. Five trematode species belonging to the family Hemiuridae were found: Hemiurus communis, Lecithochirium fusiforme, Lecithochirium rufoviride, Lecithochirium furcolabiatum, and Lecithochirium musculus. The 2 most common species were L. fusiforme and L. rufoviride, each with a prevalence of more than 80%. Furthermore, both species occurred simultaneously in 145 conger eels (74%). In contrast to the population of L. rufoviride, the mean intensity and abundance of L. fusiforme revealed a clear seasonal pattern, with peak values coinciding with each of the 3 winters studied. However, the prevalence of L. fusiforme did not increase significantly during winter. These differences may be related to an aggregated distribution of the parasite. The results show that infrapopulations of this species fluctuate greatly in the host with time and suggest that this parasite matures relatively quickly but does not survive for much longer than 3 mo in conger eels.

On the presence of Lecithochirium musculus (Digenea: Hemiuridae) in Conger conger.

Lecithochirium musculus (Looss, 1907) is a hemiurid trematode common in Anguilla anguilla (Linnaeus, 1758) in the Mediterranean and Black Seas and the north-east Atlantic Ocean. This worm is also a parasite of a wide range of fish predators of gobiids. However, the presence of this fluke in species of the genus Conger (Cuvier, in Oken, 1817 ) is uncertain. Although there are reports of immature specimens identified as L. musculus in Conger myriaster and Conger japonicus from Japan (Yamaguti S. 1934: Jpn. J. Zool. 5: 249– 541; Ichihara A. 1974: Proc. Third Int. Congress Parasitol. 3: 1614–1615), these records require confirmation because there are several morphologically similar species with which they may be confused (Gibson D.I., Bray R.A. 1986: Bull. Brit. Mus. Nat. Hist. Zool. 51: 83–89). These authors confirm that L. musculus has not been identified accurately as a parasite of species of the genus Conger, therefore the few recordings of this worm in conger eels may actually correspond to other species. Although L. musculus has been reported as a parasite of C. conger (Artedi, in Linnaeus, 1758) in the Mediterranean Sea (cited by Radujkovic B.M., Orecchia P., Paggi L. 1989: Acta Adriat. 30: 137–187), reported as Sterrhurus musculus in the same host in the Canary Islands (Gijon-Botella H., LopezRoman R. 1989: Rev. Iber. Parasitol. 49: 137–138), and in the north-east Atlantic (Sproston N.G. 1939: Trav. Stn. Biol. Roscoff 16: 33–58), there are no definite reports of this hemiurid fluke occurring in conger eels nor are there data on the degree of parasitism in fish of the genus Conger (but see Paniagua E., Vilas R. 2001: Acta Parasitol. Port. 8: 166). In this study, we examined 156 conger eels, from the spring of 1999 to the summer of 2001. The fish were caught in the Ria de Arousa (a coastal embayment in Galicia, northwestern Spain). During this time we detected only 15 individuals obtained from six conger eels that could have been L. musculus, and of these helminths, 5 were subjected to morphometric analysis. The trematodes were stained with iron acetocarmine and mounted in Canada balsam. Comparison of the measurements made on these helminths and those made on a sample taken from A. anguilla caught in the same area are

Allozyme analysis of two polymorphic enzymes in a natural population of Lecithochirium musculus.

Genetic variability among 112 individuals of Lecithochirium musculus from Anguilla anguilla from northwestern Spain was examined using allozyme analysis. Starch-gel electrophoresis was used to investigate the genetic variation in two polymorphic enzymes, glucose phosphate isomerase (GPI) and phosphoglucomutase (PGM). The banding patterns obtained for GPI were consistent with a dimeric structure for this enzyme and with single-locus control. The inferred genotype frequencies did not significantly differ as compared with those predicted by the Hardy-Weinberg equation. Two PGM loci were detected (Pgm-1 and Pgm-2). Pgm-1 was polymorphic and showed a striking departure from Hardy-Weinberg predictions (total absence of heterozygotes for alleles in high frequencies), raising the possibility of the existence of two reproductively isolated populations. However, other reasons for this observation are discussed.