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The Tropical Indo-Pacific (TIP) includes about two thirds of the world’s tropical oceans and harbors an enormous number of marine species. The distributions of those species within the region is affected by habitat discontinuities and oceanographic features. As well as many smaller ones, the TIP contains seven large recognized biogeographic barriers that separate the Red Sea and Indian Ocean, the Indian from the Pacific Ocean, the central and eastern Pacific, the Hawaiian archipelago, the Marquesas and Easter Islands. We examined the genetic structuring of populations of Cirrhitichthys oxycephalus, a small cryptic species of reef fish, across its geographic range, which spans the longitudinal limits of the TIP. We assessed geographic variation in the mitochondrial cytb gene and the nuclear RAG1 gene, using 166 samples collected in 46 localities from the western to eastern edges of the TIP. Sequences from cytb show three well-structured groups that are separated by large genetic distances (1.58–2.96%): two in the Tropical Eastern Pacific (TEP), one at Clipperton Atoll another occupying the rest of that region and the third that ranges across the remainder of the TIP, from the central Pacific to the Red Sea and South Africa. These results indicate that the ~4,000 km wide Eastern Pacific Barrier between the central and eastern Pacific is an efficient barrier separating the two main groups. Further, the ~950 km of open ocean that isolates Clipperton Atoll from the rest of the TEP is also an effective barrier. Contrary to many other cases, various major and minor barriers from the Central Indo-Pacific to the Red Sea are not effective against dispersal by C. oxycephalus, although this species has not colonized the Hawiian islands and Easter Island. The nuclear gene partially supports the genetic structure evident in cytb, although all haplotypes are geographically mixed.

Threatened shark species are caught in large numbers by artisanal and commercial fisheries and traded globally. Monitoring both which shark species are caught and sold in fisheries, and the export of CITES-restricted products, are essential in reducing illegal fishing. Current methods for species identification rely on visual examination by experts or DNA barcoding techniques requiring specialist laboratory facilities and trained personnel. The need for specialist equipment and/or input from experts means many markets are currently not monitored. We have developed a paper-based Lab-on-a-Chip (LOC) to facilitate identification of three threatened and CITES-listed sharks, bigeye thresher (Alopias superciliosus), pelagic thresher (A. pelagicus) and shortfin mako shark (Isurus oxyrinchus) at market source. DNA was successfully extracted from shark meat and fin samples and combined with DNA amplification and visualisation using Loop Mediated Isothermal Amplification (LAMP) on the LOC. This resulted in the successful identification of the target species of sharks in under an hour, with a working positive and negative control. The LOC provided a simple "yes" or "no" result via a colour change from pink to yellow when one of the target species was present. The LOC serves as proof-of-concept (PoC) for field-based species identification as it does not require specialist facilities. It can be used by non-scientifically trained personnel, especially in areas where there are suspected high frequencies of mislabelling or for the identification of dried shark fins in seizures.

Background The lack of barriers in the marine environment has promoted the idea of panmixia in marine organisms. However, oceanographic conditions and habitat characteristics have recently been linked to genetic structure in marine species. The Tropical Eastern Pacific (TEP) is characterized by dynamic current systems and heterogeneous oceanographic conditions. The Gulf of Panama (part of the equatorial segment for the TEP) is influenced by a complex current system and heterogeneous environment, which has been shown to limit the gene flow for shoreline species. Next Generation Sequencing (NGS) has contributed to detect genetic differences in previously reported panmictic species by the assessment of loci associated with selection and to understand how selection acts affects marine populations. Lutjanus guttatus is a species distributed in the TEP for which previous studies using mitochondrial data recovered a panmictic pattern along its distributional range. In this study, we used SNP data of L. guttatus individuals sampled along its range to evaluate population genetic structure and investigate whether oceanographic factors influence the species’ genetic architecture. Finally, we assessed the role of adaptive selection by evaluating the contribution of outlier and neutral loci to genetic divergence. Methods The RADcap method was used to obtain 24 million paired reads for 123 individuals of L. guttatus covering nearly all its distributional area. Genetic variation was assessed using both spatial and non-spatial methods by comparing three different data sets: (i) a Combined Loci (CL dataset = 2003 SNPs); a search for putative loci under selection allowed the evaluation of (ii) Neutral Loci (NL dataset = 1858 SNPs) and (iii) Outlier Loci (OL dataset = 145 SNPs). We used the estimating effective migration surface (EEMS) approach to detect possible barriers to gene flow. Results Genetic differences were found in the OL dataset, showing two clusters (Northern and Southern), whereas NL showed no differences. This result may be related to the Selection-Migration balance model. The limit between the Northern and Southern groups was in the Gulf of Panama, which has been previously identified as a barrier to gene flow for other species, mainly due to its heterogeneous oceanographic conditions. The results suggest that selection plays an important role in generating genetic differences in Lutjanus guttatus. A migration corridor was detected that coincides with the Costa Rica Coastal Current that flows from Central America to the Gulf of California, allowing the homogenization of the northern population. In the Southern cluster, a migration corridor was observed with the OL from Panama to Colombia, which could be associated with the currents found in the Gulf of Panama. Genetic variation found in the OL of Lutjanus guttatus highlights the usefulness of NGS data in evaluating the role of selection in population differentiation.

Hemigrammus unilineatus (Gill, 1858) (Characidae) is rediscovered in Yasuní National Park, eastern Ecuador, where it has not been reported since 1987. We present a detailed taxonomic description, including measurements and photographs, as well as a distribution map of this species in Ecuador. Based on our new evidence, we confirm the presence of H. unilineatus in the Ecuadorian Amazon.

Los estudios sobre hábitos alimentarios de comunidades acuáticas ayudan a entender cómo estas inter-actúan, y considerando que los peces de páramo han sido muy poco investigados, se analizó la dieta y se contribuyó al entendimiento de la ecología trófica de Grundulus quitoensis, especie endémica de los andes del Ecuador. Se estudió el contenido estomacal de 26 ejemplares de la laguna El Voladero. Se iden-tificaron doce categorías de presa, de las cuales, el género Bosmina (Crustacea: Cladocera) (Ni = 2410; Fo = 22) y entidades de la familia Chironomidae (Insecta: Diptera) (Ni = 466; Fo = 46) presentan la mayor abundancia. El factor de condición alométrico (K) obtuvo valores entre 0,11–0,77, significando que los ejemplares se encontraban en condiciones de poca alimentación. Aunque la dieta de esta especie es am-plia, consume en gran cantidad insectos y microcrustáceos. Es necesario preservar la laguna El Voladero para conservar su biodiversidad única.

A review of the species of the genus Mylossoma Eigenmann & Kennedy, 1903 found in the Ecuadorian Cis-Andean region was conducted. Two species were recognized: M. albiscopum (Cope, 1872) from the Putumayo, Napo, and Tigre river basins and M. aureum (Agassiz, 1829) from the Napo river basin. A map of geographical distribution and radiographs for both species are provided. Historical records of M. duriventre (Cuvier, 1818) were not confirmed in this geographical distribution.

ABSTRACT A new species of catfish is described from the Esmeraldas River Basin, Pacific slope, northern Ecuador. Tentatively included in Microglanis, represents the second species of the genus inhabiting the Trans-Andean region. The new species is distinguished from known congeners by a unique combination of external characteristics: head and body color pattern, uniform, pale brown, yellowish or grayish, without any kind of blotches, bands or dots, only a lunate transverse band, dark or black, at caudal-fin origin; adipose-fin origin and forward without lighter or luminous areas. Compared with M. variegatus, the new species has morphometric differences, such as the distances between dorsal and pelvic fins, and between posterior nostrils. Some osteological characteristics are compared with those observed in species of Pseudopimelodidae inhabiting the Pacific versant of Colombia and Ecuador and with some other species of Microglanis.

An annotated list of the freshwater fishes of the Limoncocha Lagoon, in the Limoncocha Biological Reserve in the northern Amazon region of Ecuador is presented. Fishes were captured between March and July of 2012, and we combined these results with previous studies to provide a comprehensive list of fishes in the Limoncocha Biological Reserve. Thirty-three species belonging to 14 families distributed in 7 orders were collected. The most representative orders in number of species and specimens were Characiformes, Siluriformes, and Perciformes, respectively, being Characiformes as the most important in terms of richness and abundance of species. Characidae (Characiformes) exhibited the greatest abundance and broadest distribution in our samples. A short morphological description and morphometric measurements of each species are also presented.

La fecundidad relativa en peces es la estimación de la cantidad de ovocitos de una hembra por desove. Este aspecto se investigó en especímenes topotipos de Grundulus quitoensis de la laguna altoandina El Voladero, Ecuador. Se identificó el estadio de madurez gonadal (maduro e inmaduro) a través de la observación directa, se calculó la fecundidad relativa al peso (FRP) y a la longitud total (LT). Las hembras estudiadas tuvieron en promedio una LT de 63,9 mm. El rango de ovocitos varió entre 75 y 716 por hembra y en total se contaron 5691 ovocitos para 16 hembras. El PT varió entre 0,5 g y 4,7 g; mientras que la LT varió entre 36,7 mm a 63,9 mm. La fecundidad relativa se observó comprendida entre 1,6 y 14,3 ovocitos por mm de LT del animal (X ̅= 6,9 ± 3,6 mm-1) y entre 47,2 y 319,1 ovocitos por g de peso total (X ̅= 148,9 ± 74,9 g-1). Es importante conocer el ciclo de vida e historia natural de una especie, porque contribuyen al conocimiento ecológico de los peces que habitan las lagunas altoandinas, como es el caso del estudio aquí desarrollado en G. quitoensis.

The leucism is an aberration in pigmentation, resulting from a genetic abnormality and occurs in all vertebrate groups in which the fish are included. In Ecuador it has not reported such anomalies in fish. Is presented for the first time a case of partial leucism in an individual of Andean Catfish (Astroblepidae), observed in a spring located near the Lake San Pablo Canton Otavalo, Imbabura Province, Ecuador.

We report collections of several specimens of Sicydium in 2013 and 2014 from the Jubones and Santa Rosa Rivers in southwestern Ecuador. These collections substantially expand the known range of the genus southward. The specimens are tentatively identified as Sicydium cf. rosenbergii based on their morphology. Small differences in morphology among specimens from the two rivers are noted, as are discrepancies with the type description. A museum database search uncovered two additional records of the genus south of their previously recognized range including one record from northwestern Peru.

Neotropical mountain streams are important contributors of biological diversity. Two species of the characid genus Rhoadsia differing for an ecologically important morphological trait, body depth, have been described from mountain streams of the western slopes of the Andes in Ecuador. Rhoadsia altipinna is a deeper-bodied species reported from low elevations in southwestern Ecuador and northern Peru, and Rhoadsia minor is a more streamlined species that was described from high elevations (>1200 m) in the Esmeraldas drainage in northwestern Ecuador. Little is known about these species and their validity as distinct species has been questioned. In this study, we examine how their body shape varies along replicated elevational gradients in different drainages of western Ecuador using geometric morphometrics and the fineness ratio. We also use sequences of the mitochondrial cytochrome oxidase c I gene and the second intron of the S7 nuclear gene to examine whether genetic data are consistent with the existence of two species. We found that body depth varies continuously among populations within drainages as a function of elevation, and that body shape overlaps among drainages, such that low elevation populations of R. minor in the Esmeraldas drainage have similar body depths to higher elevation R. altipinna in southern drainages. Although a common general trend of declining body depth with elevation is clear, the pattern and magnitude of body shape divergence differed among drainages. Sequencing of mitochondrial and nuclear genes failed to meet strict criteria for the recognition of two species (e.g., reciprocal monophyly and deep genetic structure). However, there was a large component of genetic variation for the COI gene that segregated among drainages, indicating significant genetic divergence associated with geographic isolation. Continued research on Rhoadsia in western Ecuador may yield significant insight into adaptation and speciation in Neotropical mountain streams.