INVESTIGADORES
BARON pedro Jose
artículos
Título:
The paralarvae of two squid species from South American waters: Loligo gahi and Loligo sanpaulensis
Autor/es:
BARÓN, PEDRO J.
Revista:
JOURNAL OF PLANKTON RESEARCH
Editorial:
Oxford University Press
Referencias:
Año: 2003 p. 1347 - 1358
ISSN:
0142-7873
Resumen:
Two loliginid squid inhabit coastal and continental shelf waters of the south-west Atlantic off
Argentina: Loligo gahi DOrbigny, 1835 and Loligo sanpaulensis Brakoniecki, 1984. Even though
L. gahi is associated with colder and deeper waters than L. sanpaulensis, both are sympatric in part
of their geographic and bathymetric ranges of distribution. As in many other cephalopod species,
there are no detailed descriptions of the paralarvae (planktonic larvae of the cephalopods) of these
species useful for identification of individuals captured in plankton samples. In this study, size,
morphometry and patterns of chromatophore abundance and distribution were characterized for
hatchlings (hatching paralarvae) of these two species obtained in the laboratory after egg incubation
at different temperatures. Paralarvae from both species were captured in preliminary plankton
surveys conducted off the coast of Central Argentina, and were characterized on the basis of their
morphometry. Differences were observed in the dorsal mantle lengths of the hatchlings of L. gahi
(2.33.7 mm) and L. sanpaulensis (1.41.7 mm). Average size and number of dark chromatophores
at hatching were negatively correlated with incubation temperature in L. gahi. Although most
morphometric indices showed between-species differences, fin length to mantle length ratio was
markedly higher in L. sanpaulensis. Patterns of chromatophore abundance and distribution allow
the hatchlings of both species to be differentiated from each other and from those of other Loligo
species. Hatchlings of L. sanpaulensis have two red chromatophores on the cheek patches areas,
while those of L. gahi have three to five. On the dorsal surface, the hatchlings of L. gahi display
dark brown chromatophores, which were absent in L. sanpaulensis. Hatchlings of L. gahi were
found at outer shelf and costal stations off Northern Patagonia. Paralarvae of L. sanpaulensis were
found at coastal stations off the Buenos Aires Province and off Northern Patagonia.