Adontosternarchus
Adontosternarchus is a genus of ghost knifefishes found in Amazon and Orinoco river basins in tropical South America. They have blunt snouts, a dark-spotted or -mottled pattern on a pale background (however, spotting/mottling can be so dense that individuals appear almost all dark) and reach up to  in total length. They feed on zooplankton and can be found quite deep, with A. devenanzii recorded down to . Species
There are currently six recognized species in this genus:

 Adontosternarchus balaenops (Cope, 1878)
 Adontosternarchus clarkae Mago-Leccia, Lundberg & Baskin, 1985
 Adontosternarchus devenanzii Mago-Leccia, Lundberg & Baskin, 1985
 Adontosternarchus duartei de Santana & Vari, 2012
 Adontosternarchus nebulosus Lundberg & Cox Fernandes, 2007
 Adontosternarchus sachsi (W. K. H. Peters, 1877)

References

Apteronotidae
Fish of South America
Freshwater fish genera
Taxa named by Max Mapes Ellis