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Egg cases of the narrowmouthed catshark Schroederichthys bivius were recorded entangled with sponges, corals and tubeworms at different sites in the south-west Atlantic Ocean. This work sheds light on the importance of benthic invertebrates in the life cycle of oviparous chondrichthyan species. [ABSTRACT FROM AUTHOR]

The total lengths ( LT) at which 50% were mature of Psammobatis rudis and Psammobatis normani, in the south-west Atlantic were: P. rudis, 428 mm for males and 414 mm for females and P. normani, 443 mm for males and 403 mm for females. Clasper length in mature males was greater in P. normani than in P. rudis, whereas oviducal gland width was not different between species. Females of P. normani with egg cases were found in every month sampled, and in January, March, April and July in P. rudis, although insufficient samples were available to identify peak oviposition times. Geographic variation in size frequency and maturity were found. The effects of oceanographic conditions and fishing pressure are discussed. Size at 50% maturity in both species was >74% of the maximum LT, indicating late sexual maturity and low potential stock recovery rate. [ABSTRACT FROM AUTHOR]

Logistical ogives gave an estimated LT50 value (i.e. the total length at which 50% individuals are sexually mature) of 635 mm for female and 650 mm for male Sympterygia bonapartii. Mature individuals of both sexes had significantly larger livers than immature ones and females had a significantly heavier liver than males. Clasper elongation was the first step in male maturation, followed by clasper calcification and the development of alar thorns. In mature females, the right ovary was larger than the left, which was apparently due to differences in stroma tissue. Gonadosomatic index and diameter of ovarian follicles of mature females peaked in late spring and was at a minimum from late summer and through the winter. Juvenile S. bonapartii were more abundant near estuarine areas during winter, and adults appeared in estuaries by late spring and summer. Females carrying egg-cases were found near the shore in late spring and egg-cases were found in benthic samples only in shallow waters suggesting that S. bonapartii deposits egg-cases in shallow waters during late spring-summer and that nursery areas are in outer estuarine zones. In the southern part (38°–42° S) of the study area S. bonapartii showed a strong movement to shallow waters in late spring and summer, spreading over the entire coastal area in winter. These movements are discussed in relation to water temperature and trophic interactions. Copyright 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

Longnose skates have great economic importance in South American fisheries, and in order to preserve them, it is important to have a well-defined taxonomic status of their species. Dipturus lamillai was recently described for Malvinas Islands waters based on morphological and molecular comparisons with Zearaja chilensis . Although D. lamillai has been compared with several congeneric species, it was not properly compared with the morphologically similar Zearaja brevicaudata , the most abundant longnose skate in the Southwest Atlantic. Here, these species were compared by morphological and molecular analyses in order to evaluate their conspecificity. Linear morphometric variables of holotype and paratypes of D. lamillai and 69 specimens of Z. brevicaudata were compared and investigated using Principal Component Analysis. In addition, thorn patterns, denticle distributions, color, and clasper morphology were compared. No body proportions or other single character that could differentiate D. lamillai from Z. brevicaudata were found. Molecular analyses comprised of the comparison of the Cytochrome oxidase subunit I ( COI ) and the NADH dehydrogenase subunit 2. The results of the Maximum Likelihood (ML) carried out for each molecular marker showed that sequences from D. lamillai clustered together with those of Z. brevicaudata , and the molecular distance determined by Kimura two-parameter were lower than the expected for different species. Additionally, the Automatic Barcode Gap Discovery method and the Bayesian implementation of the Poisson tree processes were carried out with COI sequences to explore species limits, and their results were consistent with ML analyses. In summary, the results obtained showed that there are no morphological or molecular differences between these nominal species of the valid skate genus Zearaja , leading to the conclusion that they are conspecific. Therefore, we designated Z. brevicaudata as a senior synonym of D. lamillai .

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., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Environmental pollution affects the quality of the natural environment where major and trace elements have been commonly found to accumulate in biotic and abiotic matrices. The purposes of this research were (1) to assess the accumulation and distribution of 24 major and trace elements in water, sediments, and muscle and gills of ten native fishes from two natural areas with different degree of protection in the Atlantic Rainforest, (2) to discuss potential origin of the elements related to the land use, and (3) to assess the human health risk for water and muscle fish consumption in general and fisher populations. Major and trace elements were determined by inductively coupled plasma mass spectrometry. Concentrations of Ag, Cu, and Se in water and Cr, Cu, Hg, Mn, Ni, and Zn in sediment were higher than the international guidelines for the aquatic biota protection. Muscle Cr, Cu, Ni, Pb, Hg, and Zn from several species (both studied areas) were above guidelines for human consumption. The bioaccumulation factor (< 6936) was higher in gills than in muscle, and indicated that Andromakhe saguazu, Andromakhe paris, Gymnogeophagus lipokarenos, and Steindachnerina biornata were macroconcentrators of Zn, and Australoheros ykeregua, G. lipokarenos, and Hemiancistrus fuliginosus were macroconcentrators of Se and Sr. The hazard index and target hazard quotient indicated that there is no risk from chronic consumption of water or fish. The results show the need to reduce the entry of pollutants into streams, paying special attention to reducing runoff in deforested areas., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

We conducted a revision of the Neotropical genus Acrobrycon . A previous study synonymized the species, A.ipanquianus , distributed from the western portion of the Amazon River to the north-western region of the La Plata River Basin, and A.tarijae , with type locality in the Lipeo River in Bolivia. We revisited this result by collecting new morphometric, meristic, and genetic data ( COI mitochondrial gene) for 24 individuals distributed along La Plata River Basin in Argentina, and discussed our results in the context of multiple biogeographic processes of isolation in that basin. Our results revealed a more complex history of diversification and geographic distribution across Acrobrycon species than previously suspected, probably associated with multiple biogeographic processes of isolation in La Plata River Basin. We present new evidence that led us to reconsider the validity of A.tarijae , which is distinguishable from A.ipanquianus by the number of vertebrae (37-39 vs. 41-42) and pleural ribs (12-13 vs. 14). These results were also supported by our molecular analyses that revealed a genetic divergence >4% between A.ipanquianus and A.tarijae . We also identified two main genetic clusters within A.tarijae : the first cluster consisted of specimens from the Bermejo, Pilcomayo, Itiyuro and Juramento river basins (northern Argentina); and the second cluster included specimens from the southernmost basins, such as the Salí River in Tucumán, Cuarto River in the province of Cordoba and the Quinto River in the province of San Luis. Our results suggest that the genetic structure observed in A.tarijae is the result of the type of drainage (endorheic vs. exorheic) and geographical distance., (Yanina F. Briñoccoli, Sergio Bogan, Dahiana Arcila, Juan J. Rosso, Ezequiel Mabragaña, Sergio M. Delpiani, Juan Martín Díaz de Astarloa, Yamila P. Cardoso.)

Optimising conservation efforts requires an accurate record of the extant species as well as their geographic distributions. Nevertheless, most current conservation strategies start from an incomplete biodiversity inventory. Argentina has an extraordinary diversity of species, however, until now an updated inventory of its fauna has not been carried out. In this context, the main objective of this work is to present the results of the first national inventory of vertebrate species. Experts from each major vertebrate taxonomic group assembled and compiled its respective inventory. The information gathered included taxonomic rank, conservation status, endemism and geographic distribution. Species richness and representativeness were calculated for each taxonomic group, distinguishing between native, endemic and exotic, for each Argentinian province. Our results show Argentina harbours 3,303 species: 574 marine fish, 561 freshwater fish, 177 amphibians, 450 reptiles, 1,113 birds, and 428 mammals. Native species constitute 98.1% of the total taxa. The results achieved were spatially represented showing a pattern of higher richness from north to south and from east to west. Species considered as threatened account for 17.8% and 15.2% are endemic. There are five Extinct species. These results provide key information on developing strategies and public policies at the national and provincial levels and constitute a tool for the management and conservation of biodiversity., (Valeria Bauni, Claudio Bertonatti, Adrián Giacchino, Facundo Schivo, Ezequiel Mabragaña, Ignacio Roesler, Juan José Rosso, Pablo Teta, Jorge D. Williams, Agustin M. Abba, Guillermo H. Cassini, María Berta Cousseau, David A. Flores, Damián M. Fortunato, María Emilia Giusti, Jorge Pablo Jayat, Jorge Liotta, Sergio Lucero, Tomás Martínez Aguirre, Javier A. Pereira, Jorge Crisci.)

The Atlantic Rainforest is among the main biodiversity hotspots in the world, the Yabotí Biosphere Reserve (YBR) being one of the most important remaining areas. Agriculture practices could lead to intensive usage of pesticides resulting in a risk to the environment and human health. Water, suspended particulate matter (SPM), sediment, and fish (Andromakhe paris and Andromakhe saguazu) samples were collected from four streams with different degrees of protection of the YBR in two periods in order to assess the distribution of 18 organochlorine pesticides. Legacy and current-use pesticides were found in the different environmental matrices of the stream headwaters in non-anthropized areas within the buffer zone that drains the intangible area. A similar occurrence pattern of pesticides was found in all matrices. Levels of DDTs (<3.63 ng/L) and endosulfans (<21.8 ng/L) in surface water were above international guidelines for the protection of aquatic life in several streams for both sampling periods. HCHs, DDTs, endosulfans, and chlorpyrifos were detected in SPM and sediments from three streams, while γ-HCH (<60.3 ng/g lipid weight), chlorpyrifos (<698 ng/g lw), p,p´-DDD (<367 ng/g lw), and α-endosulfans (<209 ng/g lw) were detected in fish muscle in several streams. Chlorpyrifos and endosulfans were associated with current use, while DDx/DDT ratios suggested an old use. The concentration of pesticides found would not represent a risk to human health; however, it highlights the need to establish better regulation and action guidelines to reduce the anthropogenic effect on natural reserves., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)

Along many decades, protected environments were targeted by the scientific community for ecological research and for the collection of scientific information related to environmental aspects and biodiversity. However, most of the territory in hotspot regions with weak or even non legal protection has been left aside. These non-protected areas (NPA) could host high biodiversity values. This paper addresses how scientific effort on a NPA (CIAR) of 700 ha from the Atlantic Rain Forest, generates new information and tools for large-scale environmental and biodiversity management in NPAs. Information published during the last decade was summarized and complemented with subsequent novel data about biodiversity (new species, first records, DNA and chemical analyses, etc.). The results showed: 1 new genus (arachnid), 6 new species and several putative new species (fish and arthropod), 6 vulnerable species (bird and mammal) and 36 first records for Argentina (fish, arthropod, platyhelminth and fungi). When compared with protected natural areas of the same biome, the CIAR showed highly valuable aspects for fauna and environment conservation, positioning this NPA as a worldwide hotspot for some taxa. Indeed, when compared to international hotspots in a coordinated Malaise trap program, the CIAR showed 8,651 different barcode index numbers (∼species) of arthropods, 80% of which had not been previously barcoded. Molecules like Inoscavin A, with antifungal activity against phytopathogens, was isolated for the first time in Phellinus merrillii fungi. The study of major threats derived from anthropic activities measured 20 trace elements, 18 pesticides (i.e. endosulfans, chlorpyrifos, DDTs, HCHs) and 27 pharmaceuticals and drugs (i.e. benzoylecgonine and norfluoxetine) in different biotic and abiotic matrices (water, sediment, fish and air biomonitors). This integrated data analysis shows that biodiversity research in NPA is being undervalued and how multidisciplinary and multi-taxa surveys creates a new arena for research and a pathway towards sustainable development in emerging countries with biodiversity hotspots.

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. Molecular analysis revealed 100% of agreement between morphological identification and molecular identity. Odontesthes argentinensis, Odontesthes platensis, Odontesthes smitti, Odontesthes nigricans and Odontesthes incisa were assigned to five different barcode index numbers (BINs). Maximum-likelihood analysis showed that all marine species of Odontesthes clustered separately in a unique monophyletic phylogroup, comprising five well defined haplogroups, with genetic divergence between groups ranging from 2.75 to 7.11%. The genetic analysis including freshwater congeners showed that O. incisa clustered alone occupying a basal position. The F st pairwise comparisons within O. argentinensis support the existence of three population groups: one conformed by Mar Chiquita Lagoon (MCh) specimens, and the others by Mar del Plata/Mar Chiquita coast and San Blas Bay coastal specimens, respectively. The AMOVA showed significant overall differentiation (F st  = 0.238; p = 0.00001) for the entire data set. The previous/present evidence is discussed, and strongly suggests that incipient speciation is occurring in O. argentinensis argentinean populations, and specimens from MCh would be considered at present as the leading candidate of a marine to freshwater incipient speciation event.

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. chilensis, 47 individuals from SWA and 22 from SEP were examined. By comparing external morphology, spinulation pattern, clasper, egg cases, and mitochondrial cytochrome c oxidase I (COI) sequence data, differences between groups were found. Adults from SWA presented longer snout length and shorter tail than those from SEP. Dermal denticles were restricted to the rostral area in SWA skates, whereas in SEP skates most of the dorsal surface was covered with denticles. Marked differences in the morphology of several components of clasper were noticeable. Egg cases of SWA skates had thinner lateral keels than those of SEP. Molecular analysis revealed two well-defined cohesive clusters, corresponding to SWA and SEP specimens, respectively. Average K2P distance between groups was 3.4%, higher than expected for intraspecific differences, and sequences were assigned to different BINs. These integrative approaches strongly support that specimens from SWA known as Z. chilensis correspond to a different nominal species than those from SEP. Herein, Z. brevicaudata (Marini 1933) is resurrected from synonymy with Z. chilensis., (Copyright © 2018 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.)

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., Competing Interests: The authors have declared that no competing interests exist.

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. The aim of this study was to infer boundaries among: (A) Odontesthes bonariensis and O. argentinensis at species level, and intermediate morphs; (B) the population of O. argentinensis of Mar Chiquita Lagoon and its marine conspecifics. To achieve this, we integrated, meristic, Geometrics Morphometrics and DNA Barcode approaches. Four groups were discriminated and subsequently characterized according to their morphological traits, shape and meristic characters. No shared haplotypes between O. bonariensis and O. argentinensis were found. Significative-meristic and body shape differences between the Mar Chiquita and marine individuals of O. argentinensis were found, suggesting they behave as well differentiated populations, or even incipient ecological species. The fact that the Odontesthes morphotypes shared haplotypes with both, O. argentinensis and O. bonariensis, but also possess meristic and morphometric distinctive traits open new questions related to the origin of this morphogroup., (Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.)

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. However, its broad application is impeded by the need to construct a comprehensive reference sequence library for all fish species. Here, we make a regional contribution to this grand challenge by calibrating the species discrimination efficiency of barcoding among 125 Argentine fish species, representing nearly one third of the known fauna, and examine the utility of these data to address several key taxonomic uncertainties pertaining to species in this region., Methodology/principal Findings: Specimens were collected and morphologically identified during crusies conducted between 2005 and 2008. The standard BARCODE fragment of COI was amplified and bi-directionally sequenced from 577 specimens (mean of 5 specimens/species), and all specimens and sequence data were archived and interrogated using analytical tools available on the Barcode of Life Data System (BOLD; www.barcodinglife.org). Nearly all species exhibited discrete clusters of closely related haplogroups which permitted the discrimination of 95% of the species (i.e. 119/125) examined while cases of shared haplotypes were detected among just three species-pairs. Notably, barcoding aided the identification of a new species of skate, Dipturus argentinensis, permitted the recognition of Genypterus brasiliensis as a valid species and questions the generic assignment of Paralichthys isosceles., Conclusions/significance: This study constitutes a significant contribution to the global barcode reference sequence library for fishes and demonstrates the utility of barcoding for regional species identification. As an independent assessment of alpha taxonomy, barcodes provide robust support for most morphologically based taxon concepts and also highlight key areas of taxonomic uncertainty worthy of reappraisal.