Variación Morfológica en la Musculatura Cefálica de Diplobatis ommata y Narcine vermiculatus (Chondrychthyes: Narcinidae) / Morphological Variation in the Cephalic Musculature of Diplobatis ommata and Narcine vermiculatus (Chondrychthyes: Narcinidae)

Los trabajos realizados sobre batoideos han demostrado que existen grandes variaciones en la musculatura de la región cefálica ventral, estos cambios están asociados a los diferentes estilos de vida de los organismos y por tanto, a los mecanismos de alimentación. El objetivo de este trabajo fue llevar a cabo un estudio comparativo de la morfología de la musculatura cefálica dorsal y ventral de dos especies de la familia Narcinidae: Narcine vermiculatus y Diplobatis ommata. Se observó que ambas especies comparten un patrón morfológico común. Los músculos que mostraron mayores variaciones en la región dorsal fueron el depresor rostral, el preorbital lateral y el elevador rostral. La diferencia más importante en esta región, entre ambas especies, fue la ausencia del músculo cucularis en D. ommata. En la región ventral las principales diferencias se observaron en los músculos depresor mandibular, preorbital medial, interbranquial y depresor hiomandibular. Este último músculo está formado por dos paquetes en D. ommata, en tanto que en N. vermiculatus por uno. Se puede concluir que la morfología de la musculatura cefálica es constante; sin embargo, se observan diferencias importantes en el grado de desarrollo de los músculos tanto en la región dorsal como en la ventral.

SUMMARY: Works conducted on batoids have revealed large variations in the musculature of the ventral cephalic region, associated to the different lifestyles of these organisms and, therefore, to their feeding mechanisms. This work aimed to conduct a comparative study of the dorsal and ventral cephalic muscular morphology of two species of the family Narcinidae: Narcine vermiculatus and Diplobatis ommata. It was observed that both species share a common morphological pattern. Muscles with larger variations in the dorsal region were the rostral depressor, the lateral preorbital and the rostral elevator. The most relevant difference in this region between both species was the absence of the cucularis muscle in D. ommata. In the ventral region, the main differences were observed in the mandibular depressor, medial preorbital, interbranchial and hyomandibular depressor muscles. In D. ommata, the latter is formed by two packages, and by one in N. vermiculatus. It can be concluded that the cephalic musculature is constant; however, significant differences are observed in the muscle development degree in both the dorsal and the ventral regions.

APLICACIÓN DEL MODELO DE PÉRDIDA DE ADN PARA EL DISEÑO DE CEBADORES EN Potamotrygon magdalenae (POTAMOTRYGONIDAE) / Application of the model of DNA loss for desing of primers in Potamotrygon magdalenae (Potamotrygonidae)

RESUMEN El diseño de cebadores es fundamental para amplificar regiones de genes debido a que la especificidad que mantienen cebador-secuencia de interés puede causar el éxito o fracaso en la reacción de PCR. En relación a Potamotrygon magdalenae (especie de interés de acuerdo al PAN Tiburones-Colombia), existe poca información disponible de aspectos relacionados con la genética poblacional de esta Raya. El objetivo del presente trabajo consistió en diseñar cebadores bajo los criterios del Modelo de Pérdida de ADN (DNA-LM), que permitan evaluar el estado genético de las poblaciones de P. magdalenae. Alineamos secuencias de la superfamilia Dayastoidea, disponibles en el NCBI, de los genes mitocondriales Citocromo C Oxidasa 1 (MT-CO1) y Citocromo b (MT-CYB). Seguimos los parámetros Gap open penalty (5), Gap extension penalti (0,2) y Terminalgap penalties (0,1) y seleccionamos dos pares de cebadores de acuerdo con el DNA-LM. Estimamos el producto amplificado del gen MT-CO1 en 916 pb y del gen MT-CYB en 774 pb, en muestras de P. magdalenae procedentes de diferentes ciénagas del Magdalena medio. Discutimos los resultados desde la perspectiva de validar la especificidad de los cebadores diseñados, teniendo en cuenta la correspondencia e identidad de las secuencias de los genes considerados. Los cebadores aquí reportados pueden contribuir a ampliar el conocimiento de la genética poblacional, biogeografía y filogenética de la raya de agua dulce P. magdalenae.

ABSTRACT The primer design is critical for amplifying gene regions because the specificity that primer-sequence maintain can cause success or failure in the PCR reaction. Concerning Potamotrygon magdalenae (a species of interest according to the PAN Tiburones-Colombia), there is little information available about aspects related to population genetics of this river stingray. This study aimed to design primers under DNA Loss Model (DNA-LM) criteria, which will allow assessing the genetics status of populations of P. magdalenae. We aligned sequences from the superfamily Dayastoidea, available in the NCBI, of the mitochondrial genes Cytochrome C Oxidase 1 (MT-CO1) and Cytochromeb (MT-CYB). We followed the parameters Gap open penalty (5), Gap extension penalty (0.2) and Terminal gap penalties (0.1) and selected two pairs of primers according to the DNA-LM. We calculated the amplified product of the MT-CO1 gene in 916 pb and the MT-CYB gene in 774 pb in samples from different swamps of the middle Magdalena. We discussed the results from the perspective of validating the specificity of the primers designed, considering the correspondence and identity of gene sequences considered. The primers reported here will contribute to broadening the knowledge of population genetics, biogeography and phylogenetic of the river stingray P. magdalenae.

Variación morfológica del neurocráneo de ocho especies de batoideos (Chondrichtyes) / Morphological variation of the neurocranium of eight species of batoids (Chondrichthyes)

RESUMEN: Los estudios sobre sistemática y anatomía han revelado que las características del esqueleto de los batoideos muestran gran variabilidad y proporcionan información importante sobre las relaciones de parentesco de este grupo, es por ello que el objetivo de este trabajo fue describir la morfología del neurocráneo de ocho especies de batoideos. Los batoideos estudiados mostraron grandes variaciones principalmente en el rostrum, número de fontanelas, orientación de las cápsulas nasales y en la condición y desarrollo de los procesos pre y postorbitales. Las variaciones presentes en las especies estudiadas nos permitieron agrupar a los cráneos en tres morfotipos. El primero incluye a Narcine bancroftii; este morfotipo presenta características únicas, como son un rostrum cuadrado y cartílagos anterorbitarios ramificados; no presentan procesos preorbitales y postorbitales, cresta supraorbital ni apéndice rostral. El segundo morfotipo está formado por Rostroraja texana y Pseudobatus lentiginosus, los cuales tienen un rostrum bien desarrollado con un apéndice rostral en la región anterior, dos fontanelas, arcos yugales en la región occipital y procesos preorbitales y postorbitales poco desarrollados. El tercer morfotipo incluye a las especies de miliobatoideos los cuales tienen un rostrum reducido o ausente, un apéndice rostral separado del cráneo, con una fontanela y procesos preorbitales y postobitales desarrollados. La mayoría de las especies presentan variaciones morfológicas a lo largo de su desarrollo, por lo que al llevar a cabo estudios filogenéticos es importante utilizar caracteres de organismos adultos.

SUMMARY: Systematics and anatomy studies have revealed that characteristics of the batoids skeleton show significant variability and provide relevant information on the phylogenetic relationships of this group. Within this framework, our objective is describing the neurocranium morphology in eight species of batoids. Large variations were found, mainly in the rostrum, number of fontanelles, orientation of nasal capsules, and the condition and development of the pre- and post-orbital processes. These variations allowed us to group these craniums in three morphotypes. The first, including Narcine bancroftii, has unique characteristics, such as a squared rostrum and branched anterorbital cartilages; there are no pre-or post- orbital processes, supraorbital crest or rostral appendix. The second morphotype includes Rostroraja texana and Pseudobatus lentiginosus, which have a well-developed rostrum with a rostral appendix in the anterior region, two fontanelles, jugal arches in the occipital region, and pre- and post-orbital processes poorly developed. The third morphotype includes myliobatoids species, which have small or absent rostrum, rostral appendix separated from the cranium, one fontanelle, and developed pre- and post-orbital processes. Most species have morphological variations throughout their development; therefore, when conducting phylogenetic studies, using characters from adult specimens is fundamental.

Neuroanatomy of two species of genus Myliobatis (Chondrichthyes: Myliobatoidea) / Neuroanatomía de dos especies del género Myliobatis (Chondrichthyes: Myliobatoidea)

Several studies on the elasmobranchs neuroanatomy have shown that their brain is more complex than previously thought, and had significant intra and interspecific variations. The objective of this work was conducting a comparative encephalic neuroanatomy study of two species of genus Myliobatis. In total, 16 organisms of genera Myliobatis californica and Myliobatis longirostris, collected in the coasts of Kino Bay, Sonora, Mexico, were used. In Myliobatis, the brain has a long telencephalon and the posterior central nucleus is poorly developed. Their cerebellum is asymmetric, has several sulci, most of which are transversally oriented, with four lobes (anterior, medium and two posterior), a condition which has not been reported for any other species. It was observed that, despite the morphology of M. californica and M. longirostris is similar, there are some significant differences. Both species have moderate foliation, but M. californica has more sulci. In the diencephalon of M. californica, it was observed that the lobes of the infundibulum are oval-shaped and separated, while in M. longirostris, such lobes are rounded and near the medium line. It has to be highlighted that Myliobatis belongs to the most derived batoid group; nevertheless, its brain is considerably less complex, as compared to what has been reported for the most derived milyobatoids species.

Diversos estudios sobre la neuroanatomía de los elasmobranquios han demostrado que el cerebro es más complejo de lo que se pensaba y presenta considerables variaciones tanto intra como interespecíficas. El objetivo de este trabajo fue realizar un estudio de neuroanatomía comparada del encéfalo de dos especies del género Myliobatis. Se utilizaron un total de 16 organismos de Myliobatis californica y Myliobatis longirostris, los cuales fueron colectados en las costas de Bahía Kino, Son., México. El cerebro de Myliobatis tiene un telencéfalo largo, el núcleo central posterior está poco desarrollado; el cerebelo es asimétrico, presenta surcos que en su mayoría están orientados transversalmente, con cuatro lóbulos (anterior, medio y dos posteriores), condición que no ha sido reportada para otra especie. Se observó que, aunque M. californica y M. longirostris presentan una morfología similar existen ciertas diferencias. En ambas especies presentan una foliación moderada; sin embargo, en M. californica se observan más surcos. En el diencéfalo de M. californica se observa que los lóbulos del infundíbulo son ovalados y están separados, mientras que en M. longirostris son redondeados y se encuentran próximos a la línea media. Es importante señalar que, pese a que Myliobatis pertenece al grupo de batoideos más derivado, su cerebro es considerablemente menos complejo de lo que se ha reportado para las especies de miliobatoideos más derivadas.

Anatomía comparada del neurocráneo y el encéfalo de la raya mariposa Gymnura micrura (Batoidea: Gymnuridae) / Comparative anatomy of the neurocranium and encephalon of the butterfly ray, Gymnura micrura (Batoidea: Gymnuridae)

Mediante la comparación del neurocráneo de la "raya mariposa" Gymnura micrura con especies representantes de cinco familias de Batoidea, se reconoce que corresponde al patrón anatómico del orden Myliobatiformes, por la ausencia del rostro, la presencia de una sola fontanela y el mayor desarrollo de los procesos postorbitarios. La especie en estudio difiere de los Urotrygonidae y Dasyatidae por tener los procesos postorbitarios subdivididos. La organización del encéfalo de G. micrura corresponde al patrón anatómico de los Batoidea, sin embargo, a diferencia de los Rhinobatidae, Urotrygonidae y Dasyatidae, el cerebelo es simétrico; en contraste con los Myliobatidae los hemisferios cerebrales son reducidos; y la principal diferencia con relación a los Narcinidae es la ausencia de los lóbulos eléctricos.

By comparing the neurocranium of the "butterfly ray" Gymnura micrura with representative species of five families of Batoidea, it is recognized that it corresponds to the anatomical pattern of the order Myliobatiformes, because of the absence of the rostrum, the presence of a single fontanelle and the development of the postorbital processes. The species under study differs from the Urotrygonidae and Dasyatidae by having subdivided postorbital processes. The organization of the encephalon of G. micrura corresponds to the anatomical pattern of the Batoidea. However, unlike the Rhinobatidae, Urotrygonidae, and Dasyatidae, the cerebellum is symmetrical; in contrast with the Myliobatidae, the cerebral hemispheres are reduced; and, the main difference in relation to the Narcinidae, is the absence of electrical lobes.

Reproductive biology of Sympterygia bonapartii (Chondrichthyes: Rajiformes: Arhynchobatidae) in San Matías Gulf, Patagonia, Argentina

ABSTRACT This study estimates and analyses the reproductive parameters and cycle of Sympterygia bonapartii in San Matías Gulf, northern Patagonia, Argentina. A total of 827 males and 1,299 females were analysed. Males ranged from 185 to 687 mm of total length (TL) and females from 180 to 742 mm TL. Sexual dimorphism was detected; females were larger, heavier, exhibited heavier livers, wider discs and matured at lager sizes than males. Immature females ranged from 180 to 625 mm TL, maturing females from 408 to 720 mm TL, mature ones from 514 to 742 mm TL and females with egg capsules from 580 to 730 mm TL. Immature males ranged from 185 to 545 mm TL, maturing ones from 410 to 620 mm TL and mature males from 505 to 687 mm TL. Size at which 50% of the skates reached maturity was estimated to be 545 mm TL for males and 594 mm TL for females. According to the reproductive indexes analysed, S. bonapartii exhibited a seasonal reproductive pattern. Mating may occur during winter-early spring and the egg-laying season, during spring and summer.

RESUMEN El presente estudio estima y analiza los parámetros reproductivos y el ciclo reproductivo de Sympterygia bonapartii en el Golfo San Matías, Patagonia norte, Argentina. Se analizaron 827 machos y 1.299 hembras. Los machos midieron entre 185 y 687 mm de largo total (LT) y las hembras entre 180 y 742 mm LT. Se detectó dimorfismo sexual; las hembras fueron más grandes y pesadas que los machos y presentaron anchos de disco, pesos de hígado y tallas de madurez sexual mayores a los de los machos. Las hembras inmaduras midieron entre 180 y 625 mm LT, las hembras en maduración entre 408 y 720 mm LT, las maduras entre 514 y 742 mm LT y las hembras con cápsulas entre 580 y 730 mm LT. Los machos inmaduros midieron entre 185 y 545 mm LT, los machos en maduración entre 410 y 620 mm LT y los maduros entre 505 y 687 mm LT. La talla media de madurez sexual fue estimada en 545 mm LT para los machos y 594 mm LT para las hembras. De acuerdo con los índices reproductivos analizados, S. bonapartii se reproduce estacionalmente. El apareamiento ocurriría durante el invierno y la primavera y la temporada de puesta durante la primavera y el verano.

Compared morphology of the cephalic musculature in five species of genus Urotrygon (Chondrichthyes: Urolophidae) / Morfología comparada de la musculatura cefálica de cinco especies del género Urotrygon (Chondrichthyes: Urolophidae)

This work aims to describe the morphology of dorsal and ventral cephalic musculature in five species of genus Urotrygon. Muscular differences were observed, mainly in the development level. Muscles showing certain degree of variation in the dorsal region were the cucullaris and the ethmoideo-parethmoidalis. In ventral view, higher variation was observed. Muscles showing differences were the depressor rostri, the depressor hyomandibularis, the preorbitalis medial, the coracohioideus, and the depressor mandibularis. Urotrygon aspidurus was the species with the largest differences, as it has no mandibular depressor, and the rostral depressor is quite developed. The shape and arrangement of cephalic musculature in Urotrygon is similar to that reported for genus Urolophus and Dasyatis, however, it is different from that of most specialized myliobatoids.

El presente trabajo tiene por objetivo describir la morfología de la musculatura cefálica dorsal y ventral de cinco especies del género Urotrygon. En los músculos de la región cefálica dorsal y ventral se observaron diferencias, principalmente en el grado de desarrollo. Los músculos que mostraron cierto grado de variación en la región dorsal fueron el cucularis y el etmoideo paraetmoidal. En vista ventral los músculos que mostraron diferencias fueron el depresor rostral, el depresor hiomandibular, el preorbitalis medial, el coracohioideus y el depresor mandibular. Urotrygon aspidurus fue la especie que mostró mayores diferencias ya que no presenta el músculo depresor mandibular, y el depresor rostral está muy desarrollado. La forma y disposición de la musculatura cefálica de Urotrygon es similar a la reportada para especies de los géneros Urolophus y Dasyatis, sin embargo, es diferente a la de los miliobatoideos más especializados.

Estudio morfológico del cerebro y pares craneales de Diplobatis ommata (Elasmobranchii: Narcinidae) / Morphological study of the brain and cranial nerves of Diplobatis ommata (Elasmobranchii: Narcinidae)

El grupo de los Torpediniformes representa una de las líneas ancestrales de los batoideos cuya ruta evolutiva ha seguido una línea separada del resto de este grupo. No se han realizado estudios sobre la morfología del encéfalo de Diplobatis ommata, es por ello que el objetivo de este estudio fue describir la anatomía del encéfalo y pares craneales de esta especie. Los organismos fueron colectados en Zihuatanejo, Guerrero, México. El encéfalo se obtuvo por medio de la técnica de disección convencional. El encéfalo de Diplobatis ommata es similar al de los tiburones basales, sin embargo, presenta una vesícula eléctrica, característica de Torpediniformes. Las estructuras más grandes del encéfalo son los bulbos olfatorios y la médula oblongada. El telencéfalo es reducido y el cerebelo presenta simetría bilateral y es prácticamente liso. La disposición de los pares craneales es similar a la que presentan otros grupos de batoideos, sin embargo, la inervación de los pares craneales VII, IX y X se modifica, ya que además de inervar a las regiones descritas convencionalmente, inervan también a los órganos eléctricos.

The Torpediniformes group is one of the ancestral batoid lines, the evolution of which has followed a line separated from the rest of this group. No studies have been conducted on the brain morphology of Diplobatis ommata. This is why the objective of this work is describing the anatomy of the brain and the cranial nerves of this species. Organisms were collected in Zihuatanejo, Guerrero, Mexico. The brain was obtained through conventional dissection techniques. The brain of Diplobatis ommata is similar to that of basal sharks; however, it has the electric vesicle typical in Torpediniformes. The largest encephalic structures are the olfactory bulbs and medulla oblongata. The telencephalon is reduced, while the cerebellum has bilateral symmetry and is almost smooth. Disposition of cranial nerves are similar to other batoid groups; but innervation of pairs VII, IX and X is modified: they innervate regions conventionally described, but also electric organs.

Pesquería y biología de Rhinobatos percellens (Rajiformes: Rhinobatidae) capturados por la pesquería artesanal de playa La Pared, Venezuela / Fishery and biology of Rhinobatos percellens (Rajiformes: Rhinobatidae) caught by the artisanal fishery at La Pared beach, Venezuela

R. percellens is incidentally caught in Venezuela by the artisanal fishery using bottom gillnets. This species was classified by the IUCN as being near threatened, and there is poor knowledge about its biology and fishery in Venezuela. For this reason, we analyzed the specimens caught by the artisanal fleet in playa La Pared, once a week, from January to December 2007. We determined total length, sex and maturity for each captured specimen. A total of 210 specimens were analyzed, 159 females and 51 males. The 81% of all specimens caught were adults, but within this group 27% were pregnant. The average size of sexual maturity was found between 51 and 52cm for females and males, respectively. Adult females were found all year round, and pregnant females in seven of the months sampled; highest numbers were found between February-March and September. The analyzed females had a total of 96 embryos with a size range between 2 and 19cm, with a maximum fertility of four embryos per litter. February and June-July showed the maximum breeding time, and considering the broad range of embryos sizes and the frequency of pregnant females along the different months, allow us to believe that they reproduce throughout the year. Fishing regulation including minimum catch size in relation to maturity length and release of pregnant females in water is recommended.

Rhinobatos percellens es capturada en Venezuela por la flota artesanal que opera con redes de fondo. Está clasificada por la IUCN como casi amenazada, y no existen estudios sobre su biología o pesquería en el país. Por ello, se analizaron desembarques de la pesca artesanal de playa la Pared (isla de Margarita) durante enero-diciembre 2007. A cada ejemplar capturado se le determinó la longitud total, sexo y madurez. Fueron analizados 210 ejemplares, 159 hembras y 51 machos. El 81% de los ejemplares se encontraban maduros y un 27% de este grupo correspondió a hembras grávidas. La talla media de madurez sexual quedó ubicada en 51 y 52cm para hembras y machos, respectivamente. Se detectaron hembras maduras todo el año, y hembras grávidas en siete meses. Fueron analizados 96 embriones con tallas entre 2-19cm, siendo la fecundidad máxima cuatro embriones. La variación de las longitudes de los embriones entre los meses del año indican dos picos máximos de alumbramiento al año pero no existe una sincronía en la cópula ya que la especie se reproduce prácticamente todo el año. Se recomienda elaborar regulaciones pesqueras que incluyan una talla mínima de captura en función de la talla de madurez señalada y liberar las hembras grávidas al agua.

Relações filogenéticas dos tubarões-martelo (Elasmobranchii: Sphyrnidae) com ênfase em morfologia / Phylogenetic relationships of hammerhead sharks (Elasmobranchii: Sphyrnidae) with emphasis on morphology

A cabeça lateralmente expandida é a principal sinapomorfia da família Sphyrnidae, a qual compreende todos os tubarões-martelo. Apesar de haver trabalhos abordando esta família, sua anatomia interna tem sido negligenciada como fonte de caracteres para serem utilizados na taxonomia e filogenia dos Sphyrnidae, em especial acerca de seu cefalofólio. Além disso, outros caracteres permanecem pouco estudados na família, tais como os referentes à anatomia dentária, dentículos dérmicos e sistema de poros sensoriais do cefalofólio. As relações filogenéticas entre os Sphyrnidae, e desta família entre os demais Carcharhiniformes, ainda é controversa como sua taxonomia. As poucas hipóteses filogenéticas conhecidas, baseadas em morfologia, não foram testadas sob critérios sistemáticos. Já as poucas hipóteses moleculares existentes foram testadas mas são ainda mais controversas. O presente estudo apresenta uma revisão anatômica e taxonômica dos Sphyrnidae, construindo uma matriz de caracteres mais robusta para testar as relações filogenéticas entre os Sphyrnidae, contando com 3 gêneros relacionados no grupo externo: Carcharhinus, Rhizoprionodon e Negaprion. Os resultados posicionam S. tiburo na base da família, e E. blochii e S. tudes compondo um dos clados mais derivados. Espécies de maior porte e cefalofólio mais expandido compõem um clado formado por S. mokarran + (S. lewini + S. zygaena), ao paso que as de menor porte e com cefalofolio mais arredondado formam um grupo polifilético. Rhizoprionodon acutus aparece como monofilético à família Sphyrnidae quando incluído fora do grupo externo. As árvores de consenso (Strictus, Semistrictus, Majority-rule e Adams) apresentam os mesmos resultados. Os caracteres cranianos, sensoriais e de dentículo dérmico são os que mais suportaram os diversos clados. Após a revisão taxonômica da família, a filogenia com base em morfologia apresentou-se mais consistente e clara, embora controversa aos dados moleculares.

The laterally expanded head is the main synapomorphy of the family Sphyrnidae, which comprises all the hammerhead sharks. In spite of the existence of some works on this family, the internal anatomy have been neglected as a soured of characters to be used in the taxonomy and phylogeny of this family, especially about the cephalofoil. Additionally, other characters remains poorly studied in Sphyrnidae, such as the complete teeth anatomy, dermal denticles and sensorial system of pores in the cephalofoil. It is advocated here that the study of such sources of features would give new characters to construct a more robust matrix to be used in the phylogeny of this family. The interrelationships within the Sphyrnidae, as well as of this family among the other Carcharhiniformes is still controversial as their taxonomy. The few phylogenetical hypothesis based on morphology were never tested before, besides acceptted by many authors. In the other hand, the few hypothesis based on molecular data were tested but are even more controversial. The present study presents a anatomic and taxonomic review of the family Sphyrnidae, constructing a more robust matrix that were tested to verify the interrelationships within the family Sphyrnidae, using, for the first time, 3 related genera: Carcharhinus, Rhizoprionodon and Negaprion. The results show that S. tiburo is the most basal living sphyrnid, and E. blochii and S. tudes comprise one of the most derived clade. The large species with the most expanded cephalofoil comprise a monophyletic clade S. mokarran + (S. lewini + S. zygaena), while the small sized species with a more rounded cephalofoil are a polifiletic group. Rhizoprionodon acutus appeared as monophyletic to Sphyrnidae when included ouside the outgroup. The consensus trees (Strictus, Semi-strictus, Majority-rule and Adams showed the same relashionships. The cranial characters supported many clades, followed by sensorial and dermal denticle features...

A dorsal fold in Gymnura micrura (Bloch and Scheneider, 1801) (Chondrichthyes: Gymnuridae)

This paper reports a dorsal fold which is a membranous structure located on the tail of two juvenile butterfly rays, Gymnura micrura (Bloch & Scheneider, 1801), caught through artisanal fishery in the shallow waters of Maranhão State (Brazil).

Neste manuscrito registra-se uma nadadeira dorsal em dois espécimes juvenis de Gymnura micrura (Bloch and Scheneider, 1801) capturadas pela pesca artesanal em águas rasas do estado do Maranhão (Brasil).

Histological remarks of the oviduct and the oviducal gland of Sympterygia acuta Garman, 1877 / Observações histológicas do oviduto e da glândula oviducal de Sympterygia acuta Garman, 1877

The elasmobranchs constitute an important resource in Argentinian fishing and they show reproductive characteristics that make them susceptible to the pressure of fishing. In spite of the importance of the resource our knowledge about the species of the Southwestern Atlantic is scarce. In this work we study the microanatomy of the oviduct and the oviducal gland of Sympterygia acuta. The results show a very folded oviduct with mucous and ciliated cells. The oviducal gland depicts the same zonation as other batoids, showing the typical four regions (club, papillary, baffle and terminal). The epithelium lining the glandular lumen is simple columnar with ciliated and glandular cells. The four zones show simple or ramified tubular gland the secretions of which constitute the egg's envelopes. The club and baffle zones are similar to those present in other species. The papillary one depicts a different pattern of secretions that other Rajiformes and the last zone of the gland is characterized by mixed adenomers. The information here exposed constitutes the first report on the microanatomy of the genital tract of S. acuta.

Os elasmobranchii constituem um importante recurso pesqueiro na Argentina e mostram características reprodutivas que os fazem suscetíveis à pressão de pesca. Apesar da importância do recurso, nosso conhecimento sobre as espécies do Atlântico do Sudoeste é escasso. Neste trabalho, estudamos a microanatomia do oviduto e da glândula oviducal de Sympterygia acuta. Os resultados mostram um oviduto muito dobrado, com células mucosas e células ciliadas. A glândula oviducal apresenta as mesmas zonas que outros batóideos, mostrando as quatro regiões típicas (club, papillary, baffle e terminal). O epitélio que reveste o lúmen glandular é simples, com células ciliadas e células glandulares. As quatro zonas mostram glândulas tubulares simples ou ramificadas e suas secreções constituem os envelopes do ovo. As zonas do club e baffle são semelhantes aquelas presentes em outras espécies. A papilar tem um padrão de secreção diferente de outros Rajiformes e a última zona da glândula é caracterizada por adenômeros mistos. A informação aqui exposta constitui o primeiro relato sobre a microanatomia do trato genital de S. acuta.

Tiburones y rayss (subclase elasmobranchii) desartados por la flota de arrastrre camaronero en el caribe de Colombia / Sharks and Rays (Subclass Elasmobranchii) Discarded from Commercial Shrimp Trawlers at the Caribbean Sea of Colombia

Con el fin de obtener una aproximación a la estructura del ensamblaje de peces cartilaginosos extraídos por la flota de arrastre camaronero en la costa norte de Colombia, se evaluó la composición y abundancia de tiburones y rayas descartados en dos sectores del Caribe colombiano, entre agosto y noviembre de 2004. Mensualmente se analizaron lances de la flota de arrastre camaronero al interior de cada sector (norte: La Virgen y Portete; sur: Barú, cabo Tiburón, Cascajal, Cispatá, Morrosquillo, Ceycén, Mestizo, río Cedro, Tigua y Tortuguilla). Observadores a bordo de la flota comercial de arrastre camaronero muestrearon 1/5 de la captura previamente homogenizada, tomada al azar de una de las cuatro redes de la embarcación. En 30 lances se registró la presencia de 47 peces cartilaginosos, correspondientes a seis familias y ocho especies. La mayor Captura por Unidad de Esfuerzo (CPUE) en términos de biomasa se registró en ambas zonas durante septiembre, la menor en noviembre en la zona sur; el mayor valor del número de individuos se presentó en septiembre en la zona sur y el menor en noviembre, lo cual puede atribuirse a la mayor disponibilidad del recurso objetivo que está asociado al periodo de mayores lluvias que enriquece las aguas de los ambientes costeros y son usados como hábitat y zonas de alimentación por los peces cartilaginosos.

In order to have an approximation to the cartilaginous fishes assemblage structure exploited by commercial shrimp trawlers from the north coast of Colombia, composition and abundance of the discarded sharks and rays on two zones of the Colombian Caribbean, between August and November of 2004 were evaluated. Each month, a number of trawls were analyzed in each zone (north: La Virgen and Portete; south: Barú, Cabo Tiburón, Cascajal, Cispatá, Morrosquillo, Ceycén, Mestizo, Cedro river, Tigua and Tortuguilla). Observers were placed on board commercial shrimp trawlers, sampling 1/5 from the total capture, previously homogenized, which was randomly taken from one of the four nets of the vessel. Within 30 trawls, there were 47 cartilaginous fishes registered, belonging to six families and eight species. The largest capture per effort unit (CPUE) in biomass was registered on September in both zones, whereas the smallest happened on November in the south one. The greatest value in number of units was in September within the south zone and the opposite occurred in November, registering the smallest values. This could explain the great availability of the objective resource, directly associated with the heavier rainy season that enriches the waters of the coastal environment and characterizes the region, probably used as habitat and feeding grounds for the cartilaginous fishes.

Hábitos alimentares de tubarões-martelo jovens, Sphyrna zygaena (Carcharhiniformes: Sphyrnidae), no litoral sul do Brasil / Feeding habits of young smooth hammerhead sharks, Sphyrna zygaena (Carcharhiniformes: Sphyrnidae), in the Southern Coast of Brazil

O presente estudo foi conduzido em duas comunidades da pesca artesanal nas cidades Guaratuba (Paraná) e Itapoá (Santa Catarina), no sul da costa brasileira. Os conteúdos estomacais de indivíduos Sphyrna zygaena foram identificados, sendo os itens alimentares agrupados em três categorias. As categorias mais importantes foram teleósteos (78,6 por cento) e cefalópodes (60,7 por cento), representados pela sardinha Harengula clupeola e a lula Loligo sp., ambos considerados como principais itens alimentares de S. zygaena na região estudada.

The present study was conducted in two artisan fishing communities in the cities Guaratuba (Paraná) and Itapoá (Santa Catarina), in the South Brazilian coast. Stomach contents of Sphyrna zygaena specimens were identified, showing three categories of food items. The most important feeding categories were teleosts (78.6 percent) and cephalopods (60.7 percent), represented by the sardine Harengula clupeola the squid Loligo sp., both considered the main food items of S. zygaena in the studied region.

Aspects of the reproductive biology of the shortfin mako, Isurus oxyrinchus (Elasmobranchii Lamnidae), in the Southeastern region of Brazil

Uteri from four pregnant females and two newborn of shortfin mako, Isurus oxyrinchus, were collected in the southeastern region of Brazil, during September, October, and November of 1993 and 1994. All embryos were near-term with developing dentition and inner organs. Total length ranged from 64.5 to 72.0 cm, and the maximum number of embryos observed in a litter was 20. These observations further confirmed oophagy as a form of nutrition in this species, and its periodicity. The presence of teeth in the embryos' stomachs suggest that tooth replacement begins in the uterine phase.

Quatro úteros provenientes de quatro fêmeas prenhas e dois indivíduos recém-nascidos de anequim, Isurus oxyrinchus, foram coletados na região Sudeste do Brasil durante os meses de setembro a novembro de 1993 e 1994. Todos os embriões estavam bem desenvolvidos, próximos ao estágio de nascimento, apresentando a dentição e órgãos internos bastante desenvolvidos. O comprimento total desses embriões variou entre 64,5 e 72,0 cm, e o maior número de embriões observado no interior de uma única fêmea foi 20. As observações aqui realizadas confirmam a oofagia como forma de nutrição dos embriões dessa espécie e sua periodicidade. A presença de dentes no estômago dos embriões sugere que a substituição dos dentes se inicia na fase uterina.