ONTOGENY AND DISTRIBUTION OF HYGOPHUM-BENOITI (PISCES, MYCTOPHIDAE) OF THE NORTH-WESTERN MEDITERRANEAN

Two species of the lantern fish genus Hygophum, H. benotti and H. hygo mii, are present in the Mediterranean. Differentiation of the larvae f rom these two species has been problematic. An attempt to identify suc h larvae in the plankton samples of the North Western Mediterranean le d to a broader study that included the examination of a large number o f plankton samples collected in the region since 1976. The large numbe r of Hygophurum larvae obtained during July 1992 in the North Western Mediterranean (that proved to be H. benoiti), together with collection s of larvae from different geographic areas (especially H. hygomii fro m the Southwest Indian Ocean). allowed a detailed morphometric compari son of the larvae of H.benoiti and H. hygomii. Developmental stages of H. benoiti from yolk sac to post-flexion larvae are described. Inform ation on the temporal occurrence of H.benoiti in the plankton, as well as the spatial distribution of this species during the survey of peak abundance (June/July 1992) in the North Western Mediterranean, is pre sented.