New species of Guidus Ivanov, 2006 (Cestoda: Phyllobothriidea) from Bathyraja magellanica (Philippi) from the Patagonian Continental Shelf of Argentina.

Specimens representing two new species of Guidus Ivanov, 2006 were collected from the Magellan skate (Bathyraja magellanica [Philippi]) in the Patagonian Continental Shelf of Argentina, Southwestern Atlantic Ocean. Guidus francoi sp. n. and Guidus magellanicus sp. n. differ from their congeners by a particular combination of features, including type of bothridia, worm length, number of testes, and distribution of vitelline follicles. Guidus francoi sp. n. is distinguished from G. magellanicus sp. n. by having fewer proglottids, fewer testes and a higher ratio between the cirrus sac length and the proglottid width. The microthrix pattern of species of Guidus from the Southwestern Atlantic is described, based on specimens of G. francoi sp. n., Guidus magellanicus sp. n., and newly collected specimens of Guidus argentinense Ivanov, 2006. These three species share the presence of wide aristate gladiate spinitriches on the proximal bothridial surface, narrow gladiate spinitriches on the bothridial rim, and filitriches on the distal bothridial surface. The diagnosis of Guidus is revised to include several features exhibited by the new species (i.e., presence of bothridial indentations and bothridial stalks, distribution of vitelline follicles, and eggs grouped in cocoons). The discovery of G. francoi sp. n. and G. magellanicus sp. n. from B. magellanica increases the number of species of Guidus collected from batoids in the Southwestern Atlantic from one to three. The specificity exhibited by the species herein described reinforces the tight association between rays in the genera Guidus and Bathyraja.

The complete mitochondrial genome of Eaton's skate, Bathyraja eatonii (Rajiformes, Arhynchobatidae).

The complete mitochondrial genome of Eaton's skate Bathyraja eatonii was studied using the long-read technology, PacBio Sequel System. The complete mitochondrial genome form of B. eatonii was 16,698 bp and it's comprised of 13 protein-coding genes, 22 tRNA and 2 rRNA. The base composition of B. eatonii is analyzed 31.94% for A, 33.94% for T, 13.49% for G, 20.64% for C, the result of GC content was 33.94%. Phylogenetic analysis showed that B. eatonii was closely related to Bathyraja meridionalis in Arhynchobatidae family, and this first mitochondrial genome of Antarctic skate would provide fundamental information to the evolutional relationship of Antarctic fishes.

Reproductive biology of the eyespot skate Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae) an endemic species of the Southwestern Atlantic Ocean (34ºS - 42ºS)

Atlantoraja cyclophoraé uma patim endémica para a plataforma continental do Sudoeste do Oceano Atlântico (22ºS-47ºS) e uma espécie de captura acessória na pesca comercial de arrasto de fundo. As relações morfométricas, o tamanho na maturidade e o ciclo reprodutivo desta espécie foram analisados, com amostras coletadas entre 34ºS e 42ºS. A faixa de tamanho foi de 190 a 674 mm de comprimento total (TL) para machos e de 135 a 709 mm para fêmeas. O dimorfismo sexual entre as relações TL - largura do disco e TL - peso total foi encontrado, com as fêmeas mais largas e mais pesadas que os machos. O tamanho médio na maturidade para machos foi estimado em 530 mm TL e para fêmeas em 570 mm TL. O índice gonadossomático (IGS) em fêmeas maduras variou sazonalmente e apresentou o maior valor em dezembro. O diâmetro folicular máximo e a largura da glândula do oviduto não apresentaram nenhum padrão sazonal. Fêmeas com ovos no útero estavam presentes a maior parte do ano. A atividade reprodutiva nos machos seria contínua ao longo do ano, evidenciada pela falta de variação do IGS entre as estações do ano. Os resultados obtidos sugerem queA. cyclophora pode passar por um ciclo reprodutivo anual, em coincidência com o relatado para esta espécie em populações brasileiras.(AU)

Atlantoraja cyclophoraUma raya endémica das continentais continentais do Océano Atlántico Sudoccidental (22ºS-47ºS) que se captura incidentalmente nas pescarias comercias de arrastre de fondo. Se estuda as relações morfométricas, o ciclo reprodutivo e se considera o longitude de madurez sexual de esta espécie com multidões entre 34º e 42ºS. Um poço de fumeiro 190 a 674 mm de comprimento total (LT) em machos e 135 a 709 mm LT em hembras. Se observó dimorfismo sexual entre as relações LT - ancho de disco y LT - peso total, siendo as hembras más e as pesadas que os machos. A altura de corte é estimada em 530 mm LT para machos e 570 mm LT para hembras. El índice gonadosomático (IGS) en hembras maduras varió estacionalmente, con la valor mais alto en Diciembre. No se registrou variación estacional respect on diámetro máximo folicular y al ancho de la glándula oviductal. Seçandoon hembras con huevos en úteros durante a maior parte do ano. La actividad reproductiva en los machos sería continua durante todo o ano, dada a falta de variação do IGS entre estaciones. Se sugiere queA. cyclophora experimenta un ciclo reproductivo anual, similar a reportado para esta espécie em aguas do Brasil.(AU)

Growth and reproduction in captivity unveils remarkable life-history plasticity in the smallnose fanskate, Sympterygia bonapartii (Chondrichthyes: Rajiformes)

We analyzed growth and reproduction of captive-born smallnose fanskates Sympterygia bonapartii. Egg cases were obtained from oviposition of two females caught in the wild and held at Temaikèn Aquarium. Following hatching, growth was analyzed in 13 females and 21 males until sexual maturity. Pattern of oviposition activity and reproductive performance were evaluated in six of the captive-reared females. Four models were fitted to growth data, among which the logistic function was the one attaining the best fit. The highest growth rate for both sexes was recorded during the first year of life, whereas growth was significantly higher in females than in males during the second year. Size at first oviposition was 61.7 ± 3.5 cm TL, similar to wild specimens. However, captive-reared females reached maturity before two years of age, i.e. much earlier than wild skates, implying a significant phenotypic plasticity in this species. The similarity in size at maturity and the difference in age at maturity between captive and wild specimens indicate that there is a decoupling of both parameters mediated through growth rates. Captive-born skates reproduced successfully and yielded viable offspring, indicating that the environment at Temaikèn Aquarium is suitable for S. bonapartii to attain its full life cycle.(AU)

Analizamos el crecimiento y la reproducción de ejemplares de raya marmorada, Sympterygia bonapartii nacidas en cautiverio. Se obtuvieron ovicápsulas a partir de la oviposición de dos hembras capturadas en la naturaleza y mantenidas en el Acuario Temaikèn. Posteriormente a la eclosión, se analizó el crecimiento en 13 hembras y 21 machos hasta la madurez sexual. Se evaluó el patrón de oviposición y la performance reproductiva en seis de las hembras criadas en cautiverio. Se ajustaron cuatro modelos a los datos de crecimiento, entre los cuales la función logística fue la que logró el mejor ajuste. Para ambos sexos, la mayor tasa de crecimiento se registró durante el primer año de vida. Durante el segundo año, la tasa de crecimiento fue significativamente mayor en hembras que en machos. La talla de primera oviposición fue de 61,7 ± 3,5 cm LT, similar a la estimada en rayas silvestres. Sin embargo, las hembras criadas en cautiverio alcanzaron la madurez antes de los dos años de vida, es decir mucho antes que en el ambiente natural, lo que implica una plasticidad fenotípica significativa en esta especie. La similitud en la talla de madurez y la diferencia en la edad de madurez entre individuos cautivos y silvestres indican que hay un desacople de ambos parámetros mediado por la tasa de crecimiento. Los individuos nacidos en cautiverio se reprodujeron exitosamente y dejaron descendencia viable, lo que indica que el ambiente del Acuario Temaikèn es adecuado para que S. bonapartii complete su ciclo de vida.(AU)

Complete mitochondrial genome and the phylogenetic position of the Leadhued skate Notoraja tobitukai (Rajiformes: Arhynchobatidae).

In this study, the complete mitochondrial genome of the Leadhued skate Notoraja tobitukai (Rajiformes: Arhynchobatidae) was determined. It was a circular molecule (16, 799 bp), consisted of 37 genes with a typical gene order in vertebrate mitogenome. In the whole mitogenome, there were 24 bp short intergenic and 26 bp overlaps. The nucleotide composition was 32.3% A, 22.6% C, 13.1% G and 32.0% T. Two start codons (GTG and ATG) and two stop codons (TAG, TAA/T--) were used in the protein-coding genes. The 22 tRNA genes ranged from 65 bp (tRNA-Cys) to 75 bp (tRNA-Leu1). The phylogenetic result showed that N. tobitukai was clustered with the Pavoraja nitida.

Complete mitochondrial genome and the phylogenetic position of the Leadhued skate Notoraja tobitukai (Rajiformes: Arhynchobatidae).

In this study, the complete mitochondrial genome of the Leadhued skate Notoraja tobitukai (Rajiformes: Arhynchobatidae) was determined. It was a circle molecular (16, 799 bp), consisted of 37 genes with a typical gene order in vertebrate mitogenome. In the whole mitogenome, there were 24 bp short intergenic and 26 bp overlaps. The nucleotide composition was 32.3% A, 22.6% C, 13.1% G and 32.0% T. Two start codons (GTG and ATG) and two stop codons (TAG, TAA/T) were used in the protein-coding genes. The 22 tRNA genes ranged from 65 bp (tRNA-Cys) to 75 bp (tRNA-Leu1). The phylogenetic result showed that N. tobitukai was clustered with the Pavoraja nitida.