Aequidens Eigenmann & Bray

Synonymy

Astronotus (Aequidens) Eigenmann & Bray, 1894. Ann. N.Y. Acad. Sci. 7: 616 (type by original designation Acara tetramerus Heckel). — Masculine.

Diagnosis

Aequidens is recognized for a group of Cichlasoma like cichlids, differing from Cichlasoma in naked dorsal and anal fins and long caudal peduncle including 2-3 vertebrae instead of none.

Aequidens was long a catch-all group for South American cichlids with three anal fin spines and lacking conspicuous characters. The genus was reviewed by Kullander (1983), who distinguished a number of species groups. Most of these species groups have since been recognized as genera: Bujurquina, Tahuantinsuyoa and Laetacara in Kullander (1986), and Krobia and Cleithracara in Kullander & Nijssen (1989). Also Guianacara species have traditionally been included in Aequidens. Nonetheless, Aequidens 'sensu stricto', remains vaguely diagnosed.

The type species, A. tetramerus, which attains 160 mm SL, is one of the most widespread South American cichlids, and is recorded from most of the Amazon, Tocantins, and Orinoco basins, and Guianan rivers. It was recently redescribed by Kullander (1986) on the basis of western Amazonian material, by Kullander & Nijssen (1989) on Surinamese material, and by Kullander (1995) on specimens from the Aripuanã drainage. The other species reach 100-120 mm SL and are much more limited in distribution.

Aequidens plagiozonatus, live specimen collected near Cuiabá, Brazil. Photo: A. Kullander

Key to species

There is no published key available. Please refer to Kullander (1986), Kullander & Nijssen (1989), Kullander & Ferreira (1991), and Kullander (1995) for identification guides. More than half a dozen undescribed species are known from museum material.

Etymology

Aequidens is formed from the Latin adjective aequus meaning same or equal, and the Latin noun dens, meaning tooth, referring to the even-sized teeth in contrast to Astronotus with enlarged anterior teeth.

Geographical distribution

Tropical cis-Andean South America, including the Guianas, the Orinoco drainage, the Tocantins drainage, the Parnaíba drainage, the Amazon drainage and the uppermost Paraguay drainage.

Included species

Aequidens chimantanus Inger, 1956

Aequidens diadema (Heckel, 1840)

Aequidens epae Kullander, 1995

Aequidens gerciliae Kullander, 1995

Aequidens mauesanus Kullander, 1997

Aequidens metae Eigenmann, 1922

Aequidens michaeli Kullander, 1995

Aequidens pallidus (Heckel, 1840)

Aequidens duopunctata Haseman, 1911

Aequidens paloemeuensis Kullander & Nijssen, 1989

Aequidens patricki Kullander, 1984

Aequidens plagiozonatus Kullander, 1984

Aequidens potaroensis Eigenmann, 1912

Aequidens rondoni (Ribeiro, 1918)

Aequidens tetramerus (Heckel, 1840)

Chromys uniocellata Castelnau, 1855.

?Aequidens stollei Ribeiro, 1918.

Acaronia trimaculata Allen in Eigenmann & Allen, 1942.

Aequidens tubicen Kullander & Ferreira, 1991

Aequidens viridis (Heckel, 1840)

Aequidens awani Haseman, 1911

References

EIGENMANN, C.H. & W.L. BRAY. 1894. A revision of the American Cichlidae. Ann. N.Y. Acad. Sci. 7: 607-624.
KULLANDER, S.O. 1986. Cichlid fishes of the Amazon River drainage of Peru. Swedish Museum of Natural History, Stockholm, 431 pp.
KULLANDER, S.O. 1995. Three new cichlid species from southern Amazonia: Aequidens gerciliae, A. epae and A. michaeli. Ichthyological Exploration of Freshwaters 6:149-170.
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.
KULLANDER, S.O. & H. NIJSSEN.1989. The cichlids of Surinam. E.J. Brill, Leiden and other cities, XXXIII+256 pp.