Geographic location of collection sites for the three mormyrid specimens treated in this study. Description of this fish was deferred in the hope that more specimens would become available for study. pictus did not support a close relationship with Hippopotamyrus. However, an unpublished phylogenetic analysis of DNA sequences from the mitochondrial 12S, 16S, and cytochrome b genes added to a matrix of sequences from other mormyrid taxa including H. The head, body shape, and nearly equal median fins of the Moukalaba River specimen reminded us of Hippopotamyrus castor Pappenheim, 1906 from the Lokoundjé and Sanaga Rivers of Cameroon and to the Nilo-Sudanic species Hippopotamyrus pictus (Marcusen, 1864). The morphological distinctiveness of this fish was noted, but a second trip to the locality was unsuccessful in collecting more specimens. No EOD was recorded, but a tissue sample was taken. In July 2001 the first specimen ( MNHN 2003-0425) was collected in a gill net placed in the Moukalaba River close to its confluence with the Nyanga River in southern Gabon (Figs 1, 2).

In either case, we have little confidence that additional material will become available soon and believe description of these taxa should not be further postponed. The fishing effort required to produce these three individuals suggests that these species may be extremely rare in nature or that their precise habitat has yet to be discovered. Despite significant fish collection effort at a number of sites in Gabon since the late 1990s often specifically targeting mormyrid fishes, we know of no other specimens belonging to this unrecognized mormyrid lineage in museum collections. Here we describe two new species and a new genus of Mormyrinae, based on only three specimens collected over a period of 13 years at three widely separated localities in Gabon, West Central Africa. The division of Mormyridae into two subfamilies, Mormyrinae (19 genera) and Petrocephalinae (one genus), is supported by both morphological and molecular evidence ( Taverne 1972 Sullivan et al. There are currently 223 valid species of Mormyridae placed in 20 genera ( Sullivan and Lavoué 2015). 2002 Arnegard and Hopkins 2003 Hopkins et al. Due to their frequent species-specificity, recorded EOD waveforms can provide valuable characters for the taxonomy of these fishes ( Sullivan et al. In many mormyrids the waveform of each short (0.2–12 millisecond) pulse encodes the species identity and sex of the signaler while patterns in the timing of pulses convey motivational states ( Baker et al. The electric organ discharge, or EOD, is also used for communication. Using specialized electroreceptors distributed over the skin, mormyrids sense nearby objects and prey organisms as distortions to their self-produced electric field ( von der Emde and Schwarz 2002). Mormyrids are nocturnally active fishes endemic to the continental freshwaters of Africa that produce weak electric impulses from a muscle-derived organ located in the caudal peduncle, anterior to the caudal fin.

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