Holotype (male): VENEZUELA: Amazonas: “Puerto Ayacucho (40 km S)/ El Tobogán, Caño Coromoto/ 26 January 1989/ CL2388, John T. Polhemus/ side stream/ head of lower falls” (USNM) Paratypes (2): Same data as holotype (1, USNM); same locality but leg. M. Balke (1, SEMC; DNA voucher SLE 734).

Crucisternum toboganensis is nearly indistinguishable from C. ouboteri based on external characters beyond coloration (uniform along the body in C. toboganensis, paler pronotum in C. ouboteri). They can be recognized by characters of the aedeagus: the apical third of the parameres gradually narrow towards the apex, with straight outer margins in C. toboganensis (Fig. 6C), whereas in C. ouboteri the apical third of the parameres is parallel-sided and has sinuate outer margins (Fig. 6A, B).

Body length 2.1–2.4 mm, width 1.2–1.3 mm. General coloration uniformly brown along body regions. Elytra with punctures rather sharply marked. Aedeagus (Fig. 6C) fusiform, widest slightly beyond mid length; median lobe gradually narrowing from basal fifth towards apical region; gonopore on apical region of median lobe; apical third of parameres gradually narrowing towards apex, with straight outer margins.

Named after the type locality: El Tobogán de la Selva in Venezuela.

Venezuela (Amazonas). See Fig. 7.

Nothing is known about the biology of this species except that it was collected from the margin of the Rio Coromoto, the infamous locality for many water beetle species including the family Meruidae (see Spangler and Steiner 2005).