aggregations. A number of breeding strategies exist in the genus. Some species breed in polygamous harems, while other species form monogamous pairs. Three of the described species, A. barlowi, A. megastoma and A. pantalone, practice mouthbrooding, either by both parents or only by the female. In most cases, regardless of the breeding strategy, the female is more highly involved with care of the eggs and fry, whilst the male defends a territory from predators. The sex of the fry is affected by the water conditions: In all species where it has been studied warmer water results in more males and in some species more acidic water (lower pH) also results in more males. Taxonomy and species Apistogramma is part of Geophagini and its closest relatives are Apistogrammoides and Taeniacara. There are currently 93 recognized Apistogramma species, making it the most species-rich genus of cichlid in the Americas, together with Crenicichla. New species of Apistogramma are regularly described, and undescribed species—sometimes cryptic—are known to exist in the genus. Several of the recognized species occur in more than one form, and some of these actually may represent separate species, as appears to be the case for the "Papagayo" and "Pebás" forms, both typically included in A. ortegai. A comprehensive taxonomic review of the genus is necessary. The genus is sometimes divided into subgroups based on the appearance and phylogenetic relationship of the various species. Apistogramma acrensis Staeck, 2003 Apistogramma agassizii (Steindachner, 1875) Apistogramma aguarico Römer & Hahn, 2013 Apistogramma alacrina S. O. Kullander, 2004 Apistogramma allpahuayo Römer, Beninde, Duponchelle, Vela Díaz, Ortega, Hahn, Soares, Díaz Cachay, García-Dávila, Sirvas-Cornejo & Renno, 2012 Apistogramma amoena (Cope, 1872) Apistogramma angayuara S. O. Kullander & E. F. G. Ferreira, 2005 Apistogramma arua Römer & Warzel, 1998 Apistogramma atahualpa Römer, 1997 Apistogramma baenschi Römer, Hahn, Römer, Soares & Wöhler, 2004 Apistogramma barlowi Römer & Hahn, 2008 Apistogramma bitaeniata Pellegrin, 1936 Apistogramma borellii (Regan, 1906) Apistogramma brevis S. O. Kullander, 1980 Apistogramma cacatuoides Hoedeman, 1951 Apistogramma caetei S. O. Kullander, 1980 Apistogramma caudomaculata Mesa_Salazar & Lasso, 2011 Apistogramma cinilabra Römer, Duponchelle, Vela Díaz, García-Dávila, Sirvas-Cornejo, Díaz Cachay & Renno, 2011 Apistogramma commbrae (Regan, 1906) Apistogramma cruzi S. O. Kullander, 1986 Apistogramma diplotaenia S. O. Kullander, 1987 Apistogramma eleutheria Varella & Britzke, 2016 Apistogramma elizabethae S. O. Kullander, 1980 Apistogramma eremnopyge Ready & S. O. Kullander, 2004 Apistogramma erythrura Staeck & I. Schindler, 2008 Apistogramma eunotus S. O. Kullander,