A new species of Hoplias malabaricus species complex (Characiformes: Erythrinidae) from the Crepori River, Amazon basin, Brazil.

A new species belonging to the Hoplias malabaricus complex from the Amazon basin, Brazil, is described. The new species is characterized by 15-16 predorsal scales, 37-39 lateral-line scales, 5 scales from dorsal fin to lateral line, 38-39 vertebrae, iii-iv, 7-8 anal-fin rays, ii-iv, 12-15 caudal-fin rays, last vertical series of scales on the base of caudal-fin rays forming a straight line, 6-7 dark bands in anal fin and no distinctive dark bands or blotches on flanks. The new species is also distinguished from other congeners of the H. malabaricus species-group by means of landmark-based morphometrics and DNA Barcoding (Cytochrome c Oxidase I gene). An identification key to species of the H. malabaricus species complex is provided.

Phylogenetic relationships, genetic diversity and biogeography of menhadens, genus Brevoortia (Clupeiformes, Clupeidae).

Brevoortia Gill 1861 is a genus of the Clupeidae (Teleostei) that includes six species of fishes commonly known as menhadens in eastern North America and "savelhas" or "saracas" in southeastern South America. Species of Brevoortia are important components of the marine food web of coastal ecosystems in the Atlantic and contribute significantly to fisheries. In this study, the first phylogenetic and biogeographic hypotheses including all species of Brevoortia are presented. A total of 113 specimens were analyzed using three molecular markers (two mitochondrial: COI and 16s; and one nuclear: RAG2). Maximum Parsimony, Maximum Likelihood and Bayesian Inference were employed to estimate phylogenetic relationships. A Bayesian multispecies coalescent approach was used to estimate a dated phylogeny, which supported biogeographic analyses of ancestral geographic ranges. Results corroborate previous hypotheses that the four North Atlantic species are grouped in two clades, one composed of B. tyrannus (Latrobe, 1802) and B. patronus Goode, 1878, and the second including B. smithi Hildebrand, 1941 and B. gunteri Hildebrand, 1948. The South Atlantic B. aurea (Spix and Agassiz, 1829) and B. pectinata (Jenyns, 1842) form a third clade, which is sister to the clade composed of B. smithi and B. gunteri. The monophyly and validity of the six nominal species of Brevoortia were not supported. Results also indicate that Brevoortia originated in the North Atlantic during the middle Miocene (about 15 Mya). A cooling event of the tropical Atlantic at around 10 Mya likely facilitated the range expansion of the genus to the South Atlantic, whereas a significant warming of the tropical Atlantic waters during the late Miocene at 6-7 Mya possibly promoted the isolation between the northern and southern counterparts of that ancestral lineage. The relevance of the Florida Peninsula in association with sea level fluctuations for the diversification within Brevoortia is also discussed.

Embryonic development timeline in skates (Chondrichthyes: Rajiformes): Sympterygia acuta as the first case study in the family Arhynchobatidae.

Oviparous elasmobranch embryos (Chondrichthyes) have been the focus of several embryological studies; they are useful models for studying early ontogeny in vertebrates, as can help explore the existence of common developmental patterns among species. Skates (Rajiformes) are the most speciose order of oviparous elasmobranchs, however, few studies are focused on embryo development and only based on one skate family: Rajidae. Here, we extended the study of embryo development to other skate family, Arhynchobatidae, which represent about 1/3 of all skate species. Three adult female bignose fanskates (Sympterygia acuta) were held in captivity in order to provide the first complete embryonic development timeline for any species within the Arhynchobatidae family. Our results allowed further comparisons at the embryonic scale of different oviparous elasmobranch families, providing an updated cross-species overview of the early ontogeny. Incubation in S. acuta lasted 97 ± 1.4 days at 11-21.7 °C, and hatching size was 93.2 ± 0.2 mm in total length and 49.2 ± 0.3 mm in disc width. Early embryos of S. acuta were anatomically similar to other oviparous elasmobranch embryos, with several structures appearing at the same time, but late embryonic development was comparatively delayed. The late resorption of both the external yolk sac and the external gill filaments, and also the delay in the slit opening could indicate a low metabolic demand in S. acuta, which would probably be coupled with its seasonal reproductive cycle. Some structures such as external gill filaments and claspers appeared at a similar time in some species of Rajidae and also in Arhynchobatidae, but at different times in species of the same family, showing an inconsistency also found within shark families. Although the sequential scheme remained relatively constant, small heterochronies would be present within skates, within sharks, and also between skates and sharks.

A continental-wide molecular approach unraveling mtDNA diversity and geographic distribution of the Neotropical genus Hoplias.

With an estimate of around 9,000 species, the Neotropical region hosts the greatest diversity of freshwater fishes of the world. Genetic surveys have the potential to unravel isolated and unique lineages and may result in the identification of undescribed species, accelerating the cataloguing of extant biodiversity. In this paper, molecular diversity within the valuable and widespread Neotropical genus Hoplias was assessed by means of DNA Barcoding. The geographic coverage spanned 40 degrees of latitude from French Guiana to Argentina. Our analyses revealed 22 mitochondrial lineages fully supported by means of Barcode Index Number, Automatic Barcode Gap Discovery and phylogenetic analyses. This mtDNA survey revealed the existence of 15 fully supported mitochondrial lineages within the once considered to be the continentally distributed H. malabaricus. Only four of them are currently described as valid species however, leaving 11 mitochondrial lineages currently "masked" within this species complex. Mean genetic divergence was 13.1%. Barcoding gap analysis discriminated 20 out of the 22 lineages tested. Phylogenetic analyses showed that all taxonomically recognized species form monophyletic groups. Hoplias malabaricus sensu stricto clustered within a large clade, excluding the representatives of the La Plata River Basin. In the H. lacerdae group, all species but H. curupira showed a cohesive match between taxonomic and molecular identification. Two different genetic lineages were recovered for H. aimara. Given the unexpected hidden mitochondrial diversity within H. malabaricus, the COI sequence composition of specimens from Suriname (the type locality), identified as H. malabaricus sensu stricto, is of major importance.

Integrative taxonomy reveals disjunct distribution and first record of Hoplias misionera (Characiformes: Erythrinidae) in the Amazon River basin: morphological, DNA barcoding and cytogenetic considerations

The Hoplias malabaricus group encompasses six valid species and still is believed to harbors cryptic diversity. In this work, an integrative approach including morphological, DNA barcoding, and cytogenetic considerations was conducted to characterize a population of H. malabaricus from the Amazon basin that was recently allocated in the same mitochondrial lineage with H. misionera, a species originally described from La Plata basin. The DNA barcoding analysis revealed that the Amazon population nested together with H. misionera specimens from the La Plata basin (BIN AAB1732) in the same cluster. The intragroup distance (0.5%) was 12 times lower than the nearest neighbor (6%) distance. The morphometric analysis demonstrated slightly variation between Amazon and La Plata populations, being the former composed by larger specimens. Further morphological data supported the molecular evidence of H. misionera inhabiting Amazon basin. The karyotype characterization of H. misionera in the Amazon population showed 2n=40 and karyotypic formulae 20m+20sm, that added to C-banding, Ag-NOR and 18S results are suggestive of the similarity to karyomorph C of H. malabaricus. This work reveals the first record of H. misionera outside of La Plata basin and expands the species distribution for 2500 km northward until the Marajó Island, estuary of Amazonas River.(AU)

O grupo Hoplias malabaricus compreende seis espécies válidas e ainda acredita-se que abriga diversidade críptica. Neste trabalho, uma abordagem integrativa incluindo considerações morfológicas, de DNA barcoding e de citogenética foi conduzida para caracterizar uma população de H. malabaricus da bacia amazônica que foi recentemente alocada na mesma linhagem mitocondrial de H. misionera, uma espécie originalmente descrita para a bacia La Plata. A análise molecular por DNA barcoding revelou que essa população amazônica forma um clado monofilético com espécimes de H. misionera provenientes da bacia La Plata (BIN AAB1732). A distância genética intragrupo (0,5%) é 12 vezes menor do que para o vizinho mais próximo (6%). A comparação morfométrica demonstrou pequena variação entre as populações amazônica e La Plata, sendo os primeiros ligeiramente maiores. Entretanto, os dados morfológicos corroboram com evidência molecular e confirmam a ocorrência de H. misionera na bacia amazônica. A caracterização cariotípica de H. misionera na população amazônica apresentou 2n=40 e fórmula cariotípica 20m+20sm, que aliada aos resultados de banda C, Ag-NOR e 18S sugerem que seja similar ao cariomorfo C de H. malabaricus. Esse trabalho revela o primeiro registro de H. misionera fora da bacia La Plata e estende a distribuição da espécie por mais de 2500 km ao Norte, até a Ilha do Marajó, estuário do rio Amazonas.(AU)

Marine biodiversity in the Atlantic and Pacific coasts of South America: knowledge and gaps.

The marine areas of South America (SA) include almost 30,000 km of coastline and encompass three different oceanic domains--the Caribbean, the Pacific, and the Atlantic--ranging in latitude from 12∘N to 55∘S. The 10 countries that border these coasts have different research capabilities and taxonomic traditions that affect taxonomic knowledge. This paper analyzes the status of knowledge of marine biodiversity in five subregions along the Atlantic and Pacific coasts of South America (SA): the Tropical East Pacific, the Humboldt Current,the Patagonian Shelf, the Brazilian Shelves, and the Tropical West Atlantic, and it provides a review of ecosystem threats and regional marine conservation strategies. South American marine biodiversity is least well known in the tropical subregions (with the exception of Costa Rica and Panama). Differences in total biodiversity were observed between the Atlantic and Pacific oceans at the same latitude. In the north of the continent, the Tropical East Pacific is richer in species than the Tropical West Atlantic, however, when standardized by coastal length, there is very little difference among them. In the south, the Humboldt Current system is much richer than the Patagonian Shelf. An analysis of endemism shows that 75% of the species are reported within only one of the SA regions, while about 22% of the species of SA are not reported elsewhere in the world. National and regional initiatives focusing on new exploration, especially to unknown areas and ecosystems, as well as collaboration among countries are fundamental to achieving the goal of completing inventories of species diversity and distribution.These inventories will allow accurate interpretation of the biogeography of its two oceanic coasts and latitudinal trends,and will also provide relevant information for science based policies.

Gross morphology and surface ultrastructure of the gills of Odontesthes argentinensis (Actinopterygii, Atherinopsidae) from a Southwestern Atlantic coastal lagoon.

Odontesthes argentinensis was collected from Mar Chiquita Coastal Lagoon, the Southernmost coastal Atlantic Lagoon of Argentina. The morphology of the gills was analyzed by scanning electron microscopy. The morphology of the superficial structures of the gill filaments and pharyngeal region of the gill arch was discussed and related to their functional aspects. The gills arches are structurally similar to those of other teleosts and bring out the osmoregulatory capacity of this species. The epithelium that covers the surface of the filaments and the pharyngeal region of the gill arch is formed by polygonal pavement cells with conspicuous microridges. These folds in the membrane are not denoted in the epithelium of the respiratory lamellae. Apical crypts of chloride cells are present on the afferent and interlamellar filament surfaces, but are absent elsewhere on the gill arch. The highest density of mucous cells is observed into the gill filament and the pharyngeal region which indicates the existence of a protective strategy of the respiratory lamellae and the pharynx. The epithelium of the gill arches and the rakers is studded with spines. There are taste buds along the whole pharyngeal region that may be associated with their participation in tasting at this zone.

Estudio preliminar de las larvas (nematoda: ascaridida) parásito de paralichthys orbignyanus (Valenciennes, 1839) y paralichthtys patagonicus (pisces: pleuronectiformes) / Preliminary study on parasitic nematode larvae in paralichthtys orbignyanys and paralichthys patagonicus (pisces: pleuronectiformes)

The present paper deals with a preliminary study of different larvae of nematoda found in two species of fish Paralichth orbignyanus and Paralichthys patagonicus. In P. orbignyanus the genus Terranova type a was found. Both Anisakis type I and Hysterothylacium were present in P. patagonicus. Different types of larvae belonging to genera Terranova (B and B'), Contracaecum (A and B) and Raphidascaris occurred in both P. patagonicus and P. orbignyanus. The specimens of Nematoda were described and the corresponding morphometric indexes were determined. The abundance of Nematoda obtained in relation to the diet of the flounders led us to conclude that P. orbignyanus feeds basically on crabs and fish, while P. patagonicus has a more diverse diet