Garden Eel Leptocephali: Characters, Generic Identification, Distribution, and Relationships

More than 30 species of garden eels (Anguilliformes, Congridae, Heterocongrinae) are now known worldwide, including several that are undescribed. The leptocephali of Heteroconger Bleeker have been described from the Atlantic and East Pacific, but little is otherwise known of the early life history of these eels. Study of the large collection of garden eel larvae in the Dana collections, Copenhagen (around 600 specimens), and other material, now allows the larval form of Gorgasia Meek and Hildebrand to be identified, and the distribution of several Indo-west Pacific species to be mapped. Heteroconger leptocephali have midlateral melanophores on the myotomes as in the larvae of most genera of Congrinae, and Paraconger and Chiloconger in the Bathymyrinae. Those of Gorgasia have a different pigmentation pattern consisting mainly of compact melanophores on the myosepta below the midlateral level. A third larval type, Leptocephalus maculatus Della Croce and Castle, 1966 has scattered melanophores over the body surface and is identified with Heteroconger hassi (Klausewitz and Eibl-Eibesfeldt, 1959), The pigment pattern of Gorgasia, though distinctive, is similar to that of the bathymyrine Ariosoma and its closer allies, to Benthenchelys and other Ophichthidae and unexpectedly to Muraenesox, Additionally, some skeletal characters and the common use of tail-first burrowing behavior suggest that a more comprehensive study of the relationship between the heterocongrines, the bathymyrines and the Ophichthidae in particular, is warranted.