Bioelectric fields of the African marbled lungfish Protopterus aethiopicus (Sarcopterygii: Protopteridae), African ( Heterotis niloticus ) and South American silver ( Osteoglossum bicirrhosum ) arowanas (Actinopterygii: Osteoglossidae): Primitive electrogenesis?

Sporadic weak electric discharges were recorded from the African marbled lungfish ( Protopterus aethiopicus ), African arowana ( Heterotis niloticus ) and South American silver arowana ( Osteoglossum bicirrhosum ). In all species, the discharges were registered from a pair of freely swimming individuals left for several hours in an experimental tank, or evoked by tactile stimulation in the lungfish and the African arowana. Maximum amplitudes of recoded pulses ranging from 1.5 mV in Osteoglossum to 10 mV in Protopterus and Heterotis , as well as the coordinated discharge patterns, allow us to suggest the existence of anatomically and physiologically specialized electrogenic tissue in these species. The phylogenetic and evolutionary significance of primitive electrogenesis in the lobe-finned and bony-tongue fishes is discussed.