Estudio sobre la anatomía y algunos aspectos de la biología de los congrios que habitan el Mar Argentino y adyacencias.
On the base of samples of congrid eels captured in the South Western Atlantic Ocean, between 34 degree S to 40 degree S and 30m to 400m depth, from research cruises, commercial fleet (low scale and coastal fishing) and specimens preserved in ichthyological collections, four species were determined: Ariosoma opistophthalmum, Conger orbignyanus, Bassanago albescens and Bassanago nielseni. The latter is the first record in the region. Diagnosis of taxa from Family Congridae to species is given. Morphology, reproduction, feeding and distribution of the fish species found from the region are compared and discussed, as well as those from other parts of the world. On the other hand, numerous samples of ichthyoplankton were obtained from research cruises carried out by both foreign and Argentinian research vessels in the 'Mar Argentino' and adjacent waters, in order to detect spawning and breeding areas. In the samples, leptocephali of the Order Anguilliformes and one unknown leptocephalus were found. On the base of the distribution and morphology of the adult Anguilliform specimens and reported literature (Smith, 1979 and Bohlke, 1989) the following species were determined. Family Congridae: A.opistophthalmum, B.dubius, C.orbignyanus and B.albescens, Family Muraenesocidae: Cynoponticus savanna?, Family Chlopsidae: Chlopsis bicolor, Family Muraenidae: Gymnothorax conspersus, Family Ophichthidae: Ophichthus gomesii and one specimen of the Subfamily Myrophinae, Family Nettastomatidae: Saurenchelys stylura and Hoplunnis tenuis an unknown Family with one specimen that Smith (1989k) names 'Type I species A' whose adult is unknown. Most of the larvae occurred in the northern part of the region, probably carried by the warm southward Brazil current. The only exception was that the larvae of the congrid eel B.albescens inhabited northern Patagonian shelf and slope, in front of Buenos Aires Province, region influenced by the cold northward Malvinas current. Regarding larvae, both morphological and morphometric data are given, and in relation to the adult, systematic, ecological and biogeographical subjects are discussed. Caudal skeleton is useful as a taxonomic character as well as a 'link' among larvae and adult forms.