Ontogenetic evidence supporting a relationship between Brotulotaenia and Lamprogrammus (Ophidiiformes: Ophidiidae) based on the morphology of exterilium and rubaniform larvae

Analysis of the "Dana" collection of larval fishes yielded 36 exterilium larvae and 17 rubaniform larvae, referable to the Ophidiidae. Both larval types reach large sizes before transformation and are characterized by an exterilium gut, although it is less strongly expressed in rubaniform larvae. Both have early-forming, elongate, descending processes of the coracoid that serve to support the trailing intestines. Both have a greatly reduced pelvic girdle attached to a stalkiike cartilaginous structure, resulting in a pelvic fin origin well posterior to the cleithral symphysis, a position that is without precedent in the family Ophidiidae. Both of these larval types also strongly display an anterior to posterior developmental sequence, lose the pelvic fin rays at transformation, and have extraordinarily elongate proximal radials supporting their dorsal and anal fins and modified proximal radials supporting the anterior dorsal fin rays. After examination of these larvae and reference to 5 previously described exterilium larvae and 1 previously described rubaniform larva, we conclude that they belong to Lamprogrammus (three species) and Brotulotaenia (four species), respectively. The most recent classification of the Ophidiidae places Brotulotaenia in the monotypic subfamily Brotulotaeniinae, and Lamprogrammus in the subfamily Neobythitinae along with 37 other genera. The latter subfamily is an unwieldy assemblage for which monophyly has never been established. Ontogenetic evidence suggests a closer relationship between Brotulotaenia and Lamprogrammus, and the most economical reorganization of the ophidiids would involve incorporating the latter genus into the Brotulotaeniinae.