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Paralarvae morphology and ecology of early development is unknown in most cephalopod species. We describe the early development, size abundance, and temporal and spatial distribution of Pterygioteuthis hoylei (Pfeffer, 1912) paralarvae (PL) along with abundance and distribution of adults in the Gulf of California, Mexico. Pterygioteuthis hoylei represents the most abundant squid species in plankton collections from the Gulf of California, and juveniles and adults of this species have an important role as the main cephalopod prey for jumbo flying squid Dosidicus gigas. Paralarvae were collected during eight oceanographic cruises done along the Gulf of California, from 2004 to 2007 using oblique tows which covered all seasons of the year. These were morphologically identified and development series was completed to the juvenile stage. A sample of paralarvae was identified with genetic methods using cytochrome c oxidase subunit (COI). Adults were identifiedfrom collection at the Museum of Natural History of Santa Barbara, California, USA, based among other characteristics, on the arrangement of 15 ocular photophores of the species. Almost all paralarvae morphological structures followed an increasing size/count trend. The first ocular photophore was observed at 0.8 mm of mantle length (ML) while the complete set of photophores (15) was recorded at 4.7 mm ML. Male hectocotylus was found completely developed at 5.0 to 7.0 mm gladius length (GL), while full pigmentation pattern in tentacles was completed at 16 mm GL indicating the beginning of the juvenile-adult stage. Most of the P. hoylei paralarvae were captured during March and May with densities up to 1,694 PL/1000 m³ (71.8% of total paralarvae abundance) indicating a well defined reproductive season. Size abundance analysis showed a significant high abundance of recently hatched paralarvae particularly at 1.1-2.0 mm ML covering the gulf area from Bahía Concepción south to Bahía de La Paz also in March and May (39.7% and 32.1%, respectively). The rest of the size classes and the adults in general, distributed in the same regions, with considerably low abundance at the Entrance zone of the gulf and were absent at the Archipelago zone or Northern gulf indicating its tropical zoogeographic affinit. We conclude that reproductive activity of P. hoylei occurs mostly along the Southern region of the Gulf of California during late winter and spring, representing a significant reproductive and hatching area for this species.

Palabras clave: DNA; Spawning season; size abundance; Morphology; hatching area; squid

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