Hybridization is strongly constrained by salinity during secondary contact between silverside fishes (Odontesthes, Atheriniformes).

This study investigates a contact zone between two silverside fish species (marine Odontesthes argentinensis and freshwater O. bonariensis) in the estuarine Mar Chiquita lagoon along the Atlantic coast in Argentina (MChL), in which intermediate morphs had been reported. It has been suggested that admixture and introgression occur in MChL between these two species, but direct genetic evidence is lacking.

Prejuveniles of Mugil liza (Actinopterygii; Fam. Mugilidae) show digestive and metabolic flexibility upon different postprandial times and refeeding.

Many animals face periods of feeding restrictions implying fasting and refeeding. The determination of digestive/metabolic and body condition parameters at different times of food deprivation and after refeeding allows to evaluate the postprandial dynamics, the transition from feeding to fasting and the capacity to reverse digestive and metabolic alterations. In spite of its physiological importance, studies on estuarine-dependent detritivore fish are lacking.

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.

Understanding the early ontogenetic stages of Mugil liza (Mugilidae): Morphological traits and digestive/metabolic profile of pre-juveniles after recruitment.

The family Mugilidae consists mainly of diadromous species, whose reproduction occurs in offshore waters. Pre-juveniles shift their diet in the surf zone (zooplanktophagous to iliophagous). Later, during their recruitment into estuaries, huge changes take place in their digestive system.

Biogeography, habitat transitions and hybridization in a radiation of South American silverside fishes revealed by mitochondrial and genomic RAD data.

Rivers and lake systems in the southern cone of South America have been widely influenced by historical glaciations, carrying important implications for the evolution of aquatic organisms, including prompting transitions between marine and freshwater habitats and by triggering hybridization among incipient species via waterway connectivity and stream capture events. Silverside fishes (Odontesthes) in the region comprise a radiation of 19 marine and freshwater species that have been hypothesized on the basis of morphological or mitochondrial DNA data to have either transitioned repeatedly into continental waters from the sea or colonized marine habitats following freshwater diversification. New double digest restriction-site associated DNA data presented here provide a robust framework to investigate the biogeographical history of and habitat transitions in Odontesthes.

Evidence of a landlocked reproducing population of the marine pejerrey Odontesthes argentinensis (Actinopterygii; Atherinopsidae).

In South America, the order Atheriniformes includes the monophyletic genus Odontesthes with 20 species that inhabit freshwater, estuarine and coastal environments. Pejerrey Odontesthes argentinensis is widely distributed in coastal and estuarine areas of the Atlantic Ocean and is known to foray into estuaries of river systems, particularly in conditions of elevated salinity. However, to our knowledge, a landlocked self-sustaining population has never been recorded.

Inferring boundaries among fish species of the new world silversides (Atherinopsidae; genus Odontesthes): new evidences of incipient speciation between marine and brackish populations of Odontesthes argentinensis.

Species of new world silversides (Actinopterygii; Atherinopsidae; genus Odontesthes) possess economic relevance, biological interest and ecological importance. In the present paper we: (A) investigate the molecular diversity in marine species of Odontesthes from the South West Atlantic Ocean (SWAO), and analyse their interspecific relationships and divergence by means of DNA Barcoding, including its freshwater congeners, as well. (B) Explore the suitability of DNA Barcoding to analyse the diversity and distribution of haplotypes in Odontesthes argentinensis, the only well documented marine species from the SWAO that exhibit putative estuarine and marine populations.

Almost a century of oblivion: Integrative taxonomy allows the resurrection of the longnose skate Zearaja brevicaudata (Marini, 1933) (Rajiformes; Rajidae).

Zearaja chilensis has been reported from Southern Brazil in the Southwest Atlantic (SWA) to northern Chile in the Southeast Pacific (SEP), and it was listed as vulnerable by the IUCN. Recent molecular studies have called into question the conspecificity between specimens from these opposite coasts of South America, which can have implications for the conservation status of the species. To verify the identity of specimens identified as Z.

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.

Transcriptomic differentiation underlying marine-to-freshwater transitions in the South American silversides and (Atheriniformes).

Salinity gradients are critical habitat determinants for freshwater organisms. Silverside fishes in the genus have recently and repeatedly transitioned from marine to freshwater habitats, overcoming a strong ecological barrier. Genomic and transcriptomic changes involved in this kind of transition are only known for a few model species.

Surfing among species, populations and morphotypes: Inferring boundaries between two species of new world silversides (Atherinopsidae).

Atherinopsidae are widespread freshwater and shallow marine fish with singular economic importance. Morphological, genetical and life cycles differences between marine and estuarine populations were already reported in this family, suggesting ongoing speciation. Also, coexistence and interbreeding between closely related species were documented.

Merluccius tasmanicus Matallanas & Lloris 2006 is a junior synonym of M. australis (Hutton 1872) (Gadiformes: Merluciidae) based on morphological and molecular data.

The high intraspecific variation among and the conservative external morphology of Merluccius spp. have resulted in serious identification difficulties. Four hundred and twenty fresh and preserved specimens of Merluccius were analyzed, including the type series of Merluccius australis, M.

DNA barcoding identifies Argentine fishes from marine and brackish waters.

Background: DNA barcoding has been advanced as a promising tool to aid species identification and discovery through the use of short, standardized gene targets. Despite extensive taxonomic studies, for a variety of reasons the identification of fishes can be problematic, even for experts. DNA barcoding is proving to be a useful tool in this context.

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.