Stephanostomum minankisi n. sp. (Digenea: Acanthocolpidae) from dusky flounder Syacium papillosum (Paralichthydae) from southern Gulf of Mexico: A new species without spines?

A new species of the genus Stephanostomum is described for the southeastern Gulf of Mexico based on morphological and nucleotide evidence. Stephanostomum minankisi n. sp. infects the intestine of the dusky flounder Syacium papillosum in the Yucatan Continental Shelf, Mexico (Yucatan Peninsula). Sequences of the 28S ribosomal gene were obtained and compared with available sequences of the other species and genera of the families Acanthocolpidae and Brachycladiidae from GenBank. A phylogenetic analysis was conducted, including 39 sequences, 26 of which represented 21 species and six genera of the family Acanthocolpidae. The new species is characterized by the absence of circumoral spines and spines on the tegument. Nonetheless, scanning electron microscopy consistently revealed the pits of 52 circumoral spines distributed in a double row with 26 spines each, and forebody spined. Other distinctive features of this species are testes in contact (sometimes overlapping), the vitellaria running along the body lateral fields to the mid-level of the cirrus-sac, pars prostatica and ejaculatory duct similar in length, and uroproct present. The phylogenetic tree showed that the three species found as parasites of dusky flounder (the new adult species and two in metacercaria stages) were grouped into two different clades. S. minankisi n. sp. was the sister species of Stephanostomum sp. 1 (Bt = 56) and formed a clade with S. tantabiddii, supported by high bootstrap values (100).

Population structure of mud flounder Paralichthys orbignyanus from the south-western Atlantic Ocean.

The mud flounder Paralichthys orbignyanus (Pleuronectiformes, Paralichthyidae) inhabits shallow waters of low salinities and mud bottoms in the temperate marine coastal regions of the Bonaerensean Ecoregion of the Argentinean Biogeographic Province in the south-western Atlantic Ocean. Specimens of P. orbignyanus were collected from Lagoa dos Patos (LDP) (southern Brazil), Mar Chiquita (MCH) and Marisol (MAR) both located in Buenos Aires (Argentina), and San Antonio Oeste (SAO) in the San Matías Gulf, Rio Negro (Argentina). A fragment of the mitochondrial DNA of the Control Region and seven microsatellite loci were characterized. In the Control Region, P. orbignyanus showed high variability, low nucleotide diversity, mild population expansion and a coalescence time of 35,000 years before the present. Flounders provided evidence of a genetic structure between the sampling sites LDP, MCH, MAR vs. SAO. On the other hand, P. orbignyanus displayed a lower to moderate contemporary genetic structure among all samples except between LDP and MCH. With no evidence of isolation by distance, this analysis supports a model of limited gene flow that is likely to be associated with a consistent larvae retention in all sampling sites. In addition, the present connectivity is ascribed to a lower migration process from SAO in the San Matías Gulf congruent with the prevailing littoral drift.

Functional Groups of Metazoan Parasites of the Dusky Flounder (Syacium papillosum) as Bioindicators of Environmental Health of the Yucatan Shelf.

We aimed to compare the percentage of explained variance given by the relationship of species and functional groups of metazoan parasites of the dusky flounder Syacium papillosum and environmental variables from water and sediments in the Yucatan shelf (YS). Parasite data were obtained from 127 S. papillosum specimens collected from 17 of 67 stations. At each station, 46 environmental variables were measured, including hydrocarbons, heavy metals, and physicochemical variables from water and sediments. Fifteen functional groups were defined based on biological characteristics of 48 parasite species. Our multivariate statistical analyses showed that species and functional groups produced similar explained variance values (47.3% and 50% respectively). However, using functional groups the time and financial resources were minimal compared with those used for morphological and molecular identification to produce the species composition matrix. Thus, functional groups are the best choice from the point of view of saving time and money.

Use of a species-rich and highly eutrophic tropical estuary in the South Atlantic by Pleuronectiformes (Teleostei: Acanthopterygii) / Uso de um estuário tropical rico em espécies e altamente eutrofizado no Atlântico Sul por Pleuronectiformes (Teleostei: Acanthopterygii)

Abstract: A total of 1,471 specimens of 16 species of flatfishes (Pleuronectiformes) were caught during 48 sampling campaigns between July 2005 and June 2007 at ten stations in Guanabara Bay, Rio de Janeiro, Brazil. Paralichthyidae was the dominant family, with Etropus crossotus as the dominant species. The outer stations, especially those on the western side of the lower estuary, were distinguished as a result of their higher abundance of flatfishes and number of species. The spatial distribution of E. crossotus and its population structure indicate that this species is an estuarine resident despite the apparent reduction in its area of occupation within the estuarine complex. Among the other species, nine were classified as marine stragglers (Achirus declivis, Bothus ocellatus, Cyclopsetta chittendeni, Etropus longimanus, Paralichthys orbignyanus, P. patagonicus, Syacium micrurum, Symphurus diomedeanus and Trinectes paulistanus) and three as estuarine opportunists (Bothus robinsi, Citharichthys macrops and Syacium papillosum); another three could not be classified due to the small number of captures or lack of previous data (S. tessellatus, A. lineatus and C. spilopterus).

Resumo: Um total de 1.471 espécimes de 16 espécies de linguados (Pleuronectiformes) foram capturados durante 48 campanhas de amostragem entre julho de 2005 e junho de 2007 em dez estações na Baía de Guanabara, Rio de Janeiro, Brasil. Paralichthyidae foi a família dominante, com Etropus crossotus como a espécie dominante. As estações externas, especialmente aquelas no lado ocidental do baixo estuário, foram distinguidas como resultado de sua maior abundância de linguados e número de espécies. A distribuição espacial de E. crossotus e sua estrutura populacional indicam que esta espécie é uma residente estuarina, apesar da aparente redução em sua área de ocupação dentro do complexo estuarino. Dentre as outras espécies, nove foram classificadas como migrantes marinhos (Achirus declivis, Bothus ocellatus, Cyclopsetta chittendeni, Etropus longimanus, Paralichthys orbignyanus, P. patagonicus, Syacium micrurum, Symphurus diomedeanus e Trinectes paulistanus) e três como oportunistas estuarinos (Bothus robinsi, Citharichthys macrops e Syacium papillosum); outras três não puderam ser classificados devido ao pequeno número de capturas ou falta de dados prévios (S. tessellatus, A. lineatus e C. spilopterus).

External morphology, postcranial and appendicular osteology of three southwestern Atlantic flatfishes ( Paralichthys, Paralichthyidae), and comparisons with other congeneric species

Comparisons of the external morphology and analysis of osteological features of the postcranial and appendicular skeletons of three southwestern Atlantic flatfish species of the genus Paralichthys (P. isosceles, P. orbignyanus and P. patagonicus) were carried out. Bones are described, and detailed morphological, morphometric and meristic characteristics of these flounders are given in order to provide information about the external and internal morphology of three species of Paralichthys occurring in the south-west Atlantic waters that add new information and will help regarding within the framework of a phylogenetic study of the group. Interspecific differences were found in the number of vertebrae and intermuscular bones, as well as in the morphology and morphometry of vertebrae, caudal skeletons, pectoral and pelvic girdle bones. Relationships between bones are discussed and bone characteristics compared with those found in other species of Paralichthys and in other pleuronectiform species. The position of Paralichthys isosceles within Paralichthys is discussed, along with other congeners such as P. triocellatus and P. oblongus.(AU)

Se llevaron a cabo comparaciones de la morfología externa y el análisis de las características osteológicas de los esqueletos postcraneal y apendicular de tres especies de peces planos del Atlántico sudoccidental del género Paralichthys (P. isosceles, P. orbignyanus y P. patagonicus). Se describen los huesos, y se proporcionan características morfológicas, morfométricas y merísticas detalladas de estos lenguados con el fin de aportar información sobre la morfología externa e interna de tres especies de Paralichthys presentes en el Atlántico sudoccidental. Esta nueva información contribuirá al marco de un estudio filogenético del grupo. Se encontraron diferencias interespecíficas en el número de vértebras y huesos intermusculares, así como en la morfología y morfometría de las vértebras, los esqueletos caudales, los huesos de las cinturas pectoral y pélvica. Se discuten las relaciones entre los huesos y las características óseas en comparación con las encontradas en otras especies de Paralichthys y de otros Pleuronectiformes. Se discute la posición de Paralichthys isosceles dentro del género Paralichthys, junto con otros congéneres como P. oblongus y P. triocellatus.(AU)

External morphology, postcranial and appendicular osteology of three southwestern Atlantic flatfishes ( Paralichthys, Paralichthyidae), and comparisons with other congeneric species

Comparisons of the external morphology and analysis of osteological features of the postcranial and appendicular skeletons of three southwestern Atlantic flatfish species of the genus Paralichthys (P. isosceles, P. orbignyanus and P. patagonicus) were carried out. Bones are described, and detailed morphological, morphometric and meristic characteristics of these flounders are given in order to provide information about the external and internal morphology of three species of Paralichthys occurring in the south-west Atlantic waters that add new information and will help regarding within the framework of a phylogenetic study of the group. Interspecific differences were found in the number of vertebrae and intermuscular bones, as well as in the morphology and morphometry of vertebrae, caudal skeletons, pectoral and pelvic girdle bones. Relationships between bones are discussed and bone characteristics compared with those found in other species of Paralichthys and in other pleuronectiform species. The position of Paralichthys isosceles within Paralichthys is discussed, along with other congeners such as P. triocellatus and P. oblongus.(AU)

Se llevaron a cabo comparaciones de la morfología externa y el análisis de las características osteológicas de los esqueletos postcraneal y apendicular de tres especies de peces planos del Atlántico sudoccidental del género Paralichthys (P. isosceles, P. orbignyanus y P. patagonicus). Se describen los huesos, y se proporcionan características morfológicas, morfométricas y merísticas detalladas de estos lenguados con el fin de aportar información sobre la morfología externa e interna de tres especies de Paralichthys presentes en el Atlántico sudoccidental. Esta nueva información contribuirá al marco de un estudio filogenético del grupo. Se encontraron diferencias interespecíficas en el número de vértebras y huesos intermusculares, así como en la morfología y morfometría de las vértebras, los esqueletos caudales, los huesos de las cinturas pectoral y pélvica. Se discuten las relaciones entre los huesos y las características óseas en comparación con las encontradas en otras especies de Paralichthys y de otros Pleuronectiformes. Se discute la posición de Paralichthys isosceles dentro del género Paralichthys, junto con otros congéneres como P. oblongus y P. triocellatus.(AU)

Phylogenetic analysis of the order Pleuronectiformes (Teleostei) based on sequences of 12S and 16S mitochondrial genes

The fish order Pleuronectiformes, composed of 14 families, has two suborders: Psettodoidei (with one family) and Pleuronectoidei (with thirteen families). The relationships among families of Pleuronectoidei and among the genera of their families have extensively been debated and a consensus has not yet been reached. In the present study, partial sequences of the 12S and 16S mitochondrial rRNA genes were obtained from 19 species belonging to the families Achiridae, Bothidae, Cynoglossidae, Paralichthyidae, Pleuronectidae, Scophthalmidae, and Soleidae. Additional sequences of 42 pleuronectiform species were obtained from GenBank. Phylogenetic analyses were conducted by the methods of maximum-parsimony, maximum-likelihood and Bayesian inference. Our results corroborate the monophyletic status of all families, excluding Paralichthyidae. In the family Achiridae, the genus Catathyridium (freshwater) was the sister group of Trinectes (saltwater), and Hypoclinemus (freshwater) was the sister group of Achirus (saltwater). Assuming that the putative ancestor of achirids lived in saltwater, it is suggested that the freshwater habitats in South America were colonized independently by different achirid lineages.

Ambicoloration and morphological aberration in the sole Achirus declivis (Pleuronectiformes: Achiridae) and two other cases of color abnormalities in achirid soles from southeastern Brazil

Three cases of color abnormalities and one of morphological aberration in flatfishes of the genus Achirus are described from the Piraquê-Açú River estuary, Espírito Santo, Brazil. One specimen of A. declivis has 75% of the blind side with coloration like that of the ocular side. Another specimen of the same species is strongly hypomelanistic. A third specimen has incomplete eye rotation and a hooked dorsal fin. An ambicolored A. lineatus is also described.

Três casos de anormalidades pigmentares e um caso de malformação morfológica são descritos em linguados do gênero Achirus do estuário do Rio Piraquê-Açú, Espírito Santo, Brasil. Um espécime de A. declivis tem 75 % do lado cego com coloração idêntica àquela do lado oculado. Um outro indivíduo desta mesma espécie tem hipomelanização acentuada. Um terceiro espécime tem rotação incompleta do olho e início da nadadeira dorsal em formato de gancho. Um espécime de A. lineatus ambicolorido é também descrito.

Ambicoloration and morphological aberration in the sole Achirus declivis (Pleuronectiformes: Achiridae) and two other cases of color abnormalities in achirid soles from southeastern Brazil

Three cases of color abnormalities and one of morphological aberration in flatfishes of the genus Achirus are described from the Piraquê-Açú River estuary, Espírito Santo, Brazil. One specimen of A. declivis has 75% of the blind side with coloration like that of the ocular side. Another specimen of the same species is strongly hypomelanistic. A third specimen has incomplete eye rotation and a hooked dorsal fin. An ambicolored A. lineatus is also described.

Três casos de anormalidades pigmentares e um caso de malformação morfológica são descritos em linguados do gênero Achirus do estuário do Rio Piraquê-Açú, Espírito Santo, Brasil. Um espécime de A. declivis tem 75 % do lado cego com coloração idêntica àquela do lado oculado. Um outro indivíduo desta mesma espécie tem hipomelanização acentuada. Um terceiro espécime tem rotação incompleta do olho e início da nadadeira dorsal em formato de gancho. Um espécime de A. lineatus ambicolorido é também descrito.