Resumen del producto

Cephalopod paralarvae (PL) of the Family Gonatidae were obtained from samples collected with oblique Bongo and Meter net (505µm) tows during eight oceanographic cruises carried out from 2004 to 2007 in the Gulf of California, México. Temperature at 10 m depth was obtained from CTD casts made in each zooplankton station. Morphometric indexes, chromatophore patterns, and morphology were analyzed in all specimens. The mantle, dorsal and ventral head chromatophore patterns (MCP, DHCP, VHCP respectively), the presence of ocular photophores, and the radula, were the most important morphological taxonomic characters to identify species of this Family in our samples. Two species: Gonatus sp. 1 (7.7 mm ML) and Gonatus sp. 2 (7.2 mm ML) were identified at paralarval stage, and the developmental changes of Gonatus pyros PL through study of the morphology of 12 specimens (4.7-15.7 mm ML) is described by the first time. In G. pyros PL allometric growth was observed. Eye diameter remained relatively constant, and mantle width and tentacle length decreased while fins and arms II tended to increase with size. The MCP was consistent throughout development with an increasing trend in chromatophore numbers with size. The DHCP and VHCP were conservative and species specific taxonomic criteria throughout its development. Large ocular photophores (one inner at each eye) were observed at 8.7-15.7 mm ML specimens. Consistent chromatophore patterns through development and ocular photophores indicated these specimens belong to G. pyros whose adults are, to the date, the only gonatid species to have ocular photophores in the Family. The PL of G. pyros were collected only during the coldest months of January and March (15.0°-18.5° C and 19.2°-22.8° C, respectively) although cruises in the Gulf of California were also conducted in the months of May, July, September and November. The PL were distributed mostly in the deepest central sampling stations of the Gulf, from south of the Great Islands Archipelago to the mouth of the Gulf. Its presence inside the Gulf of California represents a range extension for the species, previously recorded at its southern zoogeographic limit at 32°N, off the west coast of the Baja California Peninsula.[br]

Palabras clave: Paralarval assemblages; Gonatus pyros paralarvae; Morphology

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