Leptocephalus Larvae of the Tribe Callechelyini (Anguilliformes, Ophichthidae, Ophichthinae) in the Western North Atlantic

Larvae of Aprognathodon platyventris, Callechelys bilinearis, C. perryae, C. muraena, C. sp. cf. springeri, Callechelys sp., Letharchus vellifer, a callechelyin (genus and species unknown), and a bascanichthyin (genus and species unknown) are described and figured. Larval identification is based on position of the dorsal fin, gill-arch osteology, caudal osteology, number of nephric myomeres, and total number of myomeres. Members of Callechelyini have the fourth hypobranchial present as larvae and adults. Two groups are recognized in Callechelys. Larvae of the first group are distinguished by having the fourth hypobranchial separate from the fifth ceratobranchial, gut morphology, and pigment pattern; adults have a split urohyal and two rod-shaped elements in the pectoral girdle. Larvae of the second group are characterized by having the fourth hypobranchial fused with the fifth ceratobranchial, gut morphology, and pigment pattern; adults have a simple urohyal and one or two rod-shaped elements in the pectoral girdle.