Morphological comparison between Doryteuthis pleii and D. sanpaulensis (Cephalopoda, Myopsida, Loliginidae) from Brazil

The distinction of squid species in the genus Doryteuthis is not easy due to their morphological similarity, lack of conspicuous specific characters, and overlap geographical occurrence. This difficulty has leading to an almost exclusive molecular approach, and a premature neglect of the morpho-anatomy. To emphasize that the squid phenotypic features can be useful to identify, as well as to perform any comparative analyses (such as taxonomy and phylogeny), two close species were selected as outset. Doryteuthis pleii and D. sanpaulensis are common sympatric squids in Brazilian waters, commonly used in fisheries, not so difficult to distinguish by external features of the adult specimens. The samples were analyzed from biometric data to dissections, and the found most expressive characters to distinguish them are the mantle-fin ratio; morphology of the tentacle club, its ratio compared to the mantle length; hectocotylus morphology and nidamental gland morphology.

Morphological comparison between Doryteuthis pleii and D. sanpaulensis (Cephalopoda, Myopsida, Loliginidae) from Brazil

The distinction of squid species in the genus Doryteuthis is not easy due to their morphological similarity, lack of conspicuous specific characters, and overlap geographical occurrence. This difficulty has leading to an almost exclusive molecular approach, and a premature neglect of the morpho-anatomy. To emphasize that the squid phenotypic features can be useful to identify, as well as to perform any comparative analyses (such as taxonomy and phylogeny), two close species were selected as outset. Doryteuthis pleii and D. sanpaulensis are common sympatric squids in Brazilian waters, commonly used in fisheries, not so difficult to distinguish by external features of the adult specimens. The samples were analyzed from biometric data to dissections, and the found most expressive characters to distinguish them are the mantle-fin ratio; morphology of the tentacle club, its ratio compared to the mantle length; hectocotylus morphology and nidamental gland morphology.(AU)

Morphological analysis of the oviduct, oviducal gland and isthmus of the blue shark Prionace glauca (Linnaeus, 1758) (Elasmobranchii: Carcharhiniformes)

Oviducal gland present in elasmobranchs is correlated to the organism's reproductive strategy, and its functions are to produce mucus, to form the egg's tertiary envelope and to store sperm. The gland contains four zones: club, papillary,baffle and terminal. The structures of the oviduct, oviducal gland and isthmus of blue shark Prionace glauca were described using macroscopic, light microscopy and scanning electron microscopy techniques. The epithelium of the oviduct and isthmus is folded and is a simple, columnar, ciliated lining epithelium with glandular cells. In the oviducal gland, the lining tissues in the four zones are similar to the oviduct and isthmus lining. The terminal zone shows the presence of sperm in the lumen of the secretory tubules, which remains stored even in the absence of recent copulation. Here, these organs were studied and their connections in an attempt to elucidate the mechanisms of reproduction in the blue shark, showing the three-dimensional aspects, thus adding morphological information important for the understanding of the structure and functioning of these organs of fundamental importance in the life of the majority of elasmobranchs.(AU)

A glândula oviducal presente nos elasmobrânquios está correlacionada com a estratégia reprodutiva, cuja função é de produzir o muco, formar o envelope terciário do ovo e armazenar espermatozóides. A glândula contém quatro zonas: club, papilar, baffle e terminal. Foi descrita a estrutura do oviduto, glândula oviducal e istmo do tubarão-azul, Prionace glauca , pelas técnicas macroscópica, microscópica de luz e eletrônica de varredura. Foi observado que no oviduto e istmo o epitélio é pregueado de revestimento simples, colunar, ciliado com células glandulares. Na glândula oviducal o tecido de revestimento é semelhante ao oviduto e istmo nas quatro zonas. Na zona terminal observou-se a presença de espermatozoides no lúmen dos túbulos secretores que permanecem estocados mesmo na ausência de copula recente. Aqui, estudaram-se esses órgãos e suas conexões na tentativa de elucidar os mecanismos da reprodução no tubarão azul, apresentando os aspectos tridimensionais, desta forma agregando informações morfológicas importantes para o entendimento da estrutura e funcionamento desses órgãos de fundamental importância na vida da maioria dos elasmobrânquios.(AU)