Sven O Kullander


Aequidens tubicen Kullander & Ferreira


Aequidens tubicen Kullander & Ferreira, 1991. Zool. Scr. 19, p. 427, fig. 4 (Brazil, Estado do Pará, Rio Trombetas drainage, Reserva Biológica de Trombetas, igarapé at km 4 on the road to Perimetral Norte).

Aequidens tubicen. Holotype, MZUSP 15887, 103.8 mm SL. Photo © A. Kullander
Aequidens tubicen. Holotype, MZUSP 15887, 103.8 mm SL, ethanol preserved specimen from the Reserva Biológica de Trombetas. Photo: A. Kullander.


A moderately large (to almost 120 mm) Aequidens species with triserial predorsal scale pattern, relatively long pectoral fin (32.5-37.7% of SL) and 25-26 scales in the E1 row. It is most similar toA. pallidus, with which it shares an enhanced, wide, light spot anterior to the caudal spot, lateral band high on side, posteriorly positioned midlateral spot and high vertebral number (usually 14+13=27). It differs from A. pallidus in colour pattern characteristics that are unique for the genus: The cheek spot common in Aequidens and Cichlasoma species is wanting, instead there is an irregularly rounded blackish spot at the corner of the preopercle and adjacent cheek. The lateral band running from head to dorsal margin of caudal peduncle is interrupted by a large, elongate midlateral spot and subdivided into two or three elongate spots posteriorly; midlateral spot contiguous with or only narrowly separated from a wide dark bar running dorsally to the base of the dorsal fin, the spot and bar together forming a strongly oblique, backwards slanting vertical marking. (Modified after Kullander & Ferreira, 1991.)


MZUSP 15887. An adult female, 103.8 mm SL. Brazil, Estado do Pará, Rio Trombetas drainage, Reserva Biológica de Trombetas, igarapé at Km 4 on the road to Perimetral Norte. 20 Jul 1979. R. M. Corrêa e Castro.


tubicen — Latin noun meaning trumpeter, alluding to the name of the river drainage, the Trombetas, to which the species seems to be restricted. the Portuguese trombetas means trumpets.

Geographical distribution

Restricted to the Rio Trombetas drainage, all collecting sites in a restricted area close to Rio Trombetas just upstream of the Cachoeira Porteira, including streams along the BR-163 and the river margin, and Igarapé do Patauá which is a tributary of the lower Rio Mapuera.

Natural history

Aequidens tubicen is collected in small clearwater fast flowing forest streams, near small waterfalls and rapids, always associated with rocky or sand bottom. Specimens collected on the banks of the Rio Trombetas were taken in rocky pools formed when the river level drops and which are not connected to the river. Stomachs of a few specimens taken from a small steram contained small fishes, insects and plant debris (Kullander & Ferreira, 1991).

Local names

Not recorded.


KULLANDER, S.O. & E.J.G. FERREIRA. 1991. A new Aequidens species from the Rio Trombetas, Brasil, and redescription of Aequidens pallidus. Zool. Scr. 19: 425-433.