The complete mitochondrial genome of the threatened Neotropical catfish Lophiosilurus alexandri (Silurifomes: Pseudopimelodidae) and phylogenomic analysis indicate monophyly of Pimelodoidea.

Lophiosilurus alexandri is an endemic catfish from the São Francisco River Basin (Brazil) popularly known as pacamã, which has economic potential for aquaculture farming. The mitochondrial genome was sequenced for the threatened Neotropical catfish L. alexandri. Assembly into scaffolds using MIRA and MITObim software produced the whole, circularized mitochondrial genome, which comprises 16,445 bp and presents the typical gene arrangement of Teleostei mitochondria. A phylogenomic analysis was performed after the concatenation of all proteins obtained from whole mitogenomes of 20 Siluriformes and two outgroups. The results confirmed the monophyly of nine families of catfishes and also clustered L. alexandri as a sister group to the family Pimelodidae, thus confirming the monophyly of the superfamily Pimelodoidea. This is the first mitochondrial phylogenomics study for Pimelodoidea and the first mitogenome described for the Pseudopimelodidae family, representing an important resource for phylogeography, evolutionary biology, and conservation genetics studies in Neotropical fishes.

The complete mitochondrial genome of the southern purple-spotted gudgeon Mogurnda adspersa (Perciformes: Eleotridae) through pyrosequencing.

The complete mitochondrial genome of the Critically Endangered southern purple-spotted gudgeon, Mogurnda adspersa, was determined for the first time using 1/8 of a 454 pyrosequencing plate. The mitogenome was assembled using the bioinformatic software MIRA. The M. adspersa genome organization was very similar to most vertebrates, being 16,523 bp in length. It contained 13 protein-coding genes, 22 transfer RNA, 2 ribosomal RNA genes, and 1 non-coding control region. The current methodology was effective to assemble the whole mitogenome using 2008 mitochondrial reads representing 0.23% of total genomic reads produced and providing average mitogenome coverage of 17.4 reads per site. The whole mitogenome sequence provided here is deposited in NCBI with the accession number KJ130031 and may benefit systematics studies and conservation programs of M. adspersa.

Reproduction of pimelodus maculatus (siluriformes: pimelodidae) in three section of grande river basin, downstream Porto Colombia dam, south-eastern Brazil

The alterations to the hydrologic regime downstream from hydroelectric dams may cause an impact on the reproductive success of fishes. This study aimed to analyse the influence of the physical and chemical parameters of the water of the Grande and Pardo Rivers on gonadal maturation, oocyte diameter, follicular atresia and biological indices of Pimelodus maculatus collected from three river sections: Grande River, downstream from the Porto Colômbia dam (S1), Grande River, downstream from the confluence with the Pardo River (S2) and in the Pardo River channel (S3). Males and females captured in S1 presented significantly higher average values for total length and body weight than those captured in S2 and S3. The gonadosomatic index values were significantly higher in fish collected in S3 and the Fulton condition factor did not show significant differences in fish collected from the three sections. The oocyte diameter, the follicular cells height and the zona pellucida thickness did not show any statistical differences between the sections. Conductivity presented a significant difference between S1 and S3 and during the reproductive period, water transparency presented similar values in the two sampling sections of the Grande River, but a much lower value in the Pardo River. A low frequency of fish with reproductive activity was registered in S1, whereas in S2 and S3 higher frequencies were recorded, emphasising the need of preserving the tributaries for the reproductive success of P. maculatus of the Grande River in south-eastern Brazil.

A jusante das barragens hidrelétricas ocorrem alterações no regime hidrológico que podem causar impactos sobre o processo reprodutivo dos peixes. O objetivo do presente estudo foi analisar a influência de parâmetros físico-químicos da água do rio Grande e rio Pardo sobre a maturação gonadal, diâmetro ovocitário, atresia folicular e índices biológicos de Pimelodus maculatus coletados em três trechos: a jusante do reservatório de Porto Colômbia (P1), a jusante da confluência do rio Grande com rio Pardo (P2) e na calha do rio Pardo, a aproximadamente 100 km de P2 (P3). Machos e fêmeas capturados no ponto 1 apresentaram valores médios de comprimento total e peso corporal significativamente maiores do que aqueles capturados nos pontos 2 e 3. Os valores de IGS foram significativamente maiores nos peixes coletados no ponto 3 e o fator de condição de Fulton não apresentou diferenças significativas entre os peixes coletados nos três pontos. O diâmetro ovocitário, a altura das células foliculares e a espessura da zona pelúcida dos ovócitos vitelogênicos não mostraram diferenças estatísticas entre os pontos. A condutividade apresentou diferença significativa entre os pontos 1 e 3 e a transparência da água durante o período reprodutivo apresentou valores próximos nos dois pontos amostrais do rio Grande, e valor bem menor no ponto amostral do rio Pardo. Em P1 registrou-se baixa frequência de peixes em atividade reprodutiva, e em P2 e P3 maiores frequências de peixes reproduzindo. Os resultados encontrados enfatizam a necessidade de conservação de tributários para o sucesso reprodutivo de P. maculatus, do rio Grande no sudeste do Brasil.

Profiles of sex steroids, fecundity and spawning of a migratory characiform fish from the Paraguay-Paraná basin: a comparative study in a three-river system.

This study investigated for the first time the reproductive biology of Prochilodus lineatus in a system of rivers in southeastern Brasil, relating it to the role of tributary rivers in the reproductive success of this important commercial fish in the Upper Paraná River basin, where a cascade of hydroelectric dams were deployed. Specimens were caught bimonthly in three river sites: (S1) Grande River, downstream from the Porto Colômbia dam; (S2) Pardo River; and (S3) Mogi Guaçu River. Sex steroid plasma levels, fecundity, follicular atresia, oocyte diameter and gonadosomatic index (GSI) were compared among sites. In S1, fish exhibited changes in the reproductive parameters: lower GSI, oocyte diameter and fecundity and higher follicular atresia index, when compared to S2 and S3. Frequency of maturing fish was higher in S3 and spawning was only registered in S3. In sites S2 and S3, plasma concentrations of testosterone and 17ß-estradiol in females and testosterone in males showed wide variations following gonadal maturation. Fish from S1 showed few significant variations in sex steroid concentrations throughout the gonadal cycle. These results indicate that P. lineatus does not reproduce in Grande River (S1), but probably uses the Pardo River (S2) as a migratory route towards the Mogi Guaçu River (S3) where they complete gonadal maturation and spawning. Our findings contribute for understanding the reproductive biology of P. lineatus and to highlight the importance of tributaries in impounded rivers as a favourable environment for migration and spawning of fish.