Resumen del producto

The morphology and ecology of squid and octopus paralarvae during early development is unknown in most cephalopod species, particularly in tropical areas. We describe for the first time the morphological changes of the paralarvae of Onychoteuthis sp. 1, probably Onychoteuthis horstkottei, based on the analysis of 63 cephalopod paralarvae of the Family Onychoteuthidae. Zooplankton samples were collected with oblique tows (505 ?m) carried out from 2004 to 2008 in the Gulf of California and Gulf of Tehuantepec, México. All samples were fixed in 96% ethyl alcohol. Descriptions and drawings of the morphological characters were made through the study of seven of the best-shaped paralarvae specimens (2.7-7.4 mm gladius length, GL). The dorsal and ventral head chromatophore patterns (DHCP, VHCP respectively), the mantle chromatophores, and the presence, shape, and size of the ocular and visceral photophores, were the most important morphological taxonomic characters to identify Onychoteuthis sp. 1 paralarvae in our samples. In the specimens examined, the mantle was relatively broad at midpoint, sharply pointed posteriorly, and often constricted anteriorly. The gladius had a characteristic posterior spike outside the mantle. The DHCP and VHCP showed a basic pattern (1+2+4 and 2+2 respectively) observed at the smallest size that was conservative through the size range analyzed, with the addition of a few chromatophores with increasing size. The paired chromatophores observed on the dorsal midline of the mantle increased in number with size. A single ocular photophore was observed on each eye at 2.0-6.3 mm GL, while a second ocular photophore was present on specimens at 7.4 mm GL. The adults of two or three other Onychoteuthis species have distribution records in the tropical Mexican Pacific. However, only O. horstkottei has two ocular photophores in each eye. In paralarvae, the conservative head chromatophore patterns and the paired ocular photophores are the best morphological characters to use to identify Onychoteuthis horstkottei. In addition, the locality of collection of paralarvae in front of Bahía de Banderas was very close to the Type Locality of O. horstkottei, located at the Revillagigedo Islands. Tissue samples from paralarvae and one adult collected at surface (505 ?m) in 2004 are being processed for DNA identification.

Palabras clave: Cephalopods paralarvae; Onychoteuthis

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx