A recent review of the chanchito cichlids of the Uruguay and Paran river drainages (in Argentina, southern Brazil, Paraguay and Uruguay) has recognised eight species, four of which are described as new.
This study by Old ich ~an of the University of South Bohemia and Sven Kullander of the Swedish Museum of Natural History is published in a recent issue of the journal Zootaxa.
Australoheros facetus, A. kaaygua, A. scitulus, and A. tembe are the four species recognized, with an additional four species described as new: A. charrua, A. forquilha, A. guarani and A. minuano.
Australoheros charruaPreviously given the working name of Australoheros sp. Pirapo, this species is most similar to A. scitulus, from which it is distinguished in having fewer dorsal (16 vs. 17) and anal (7 vs. 8"9) fin spines, more dorsal-fin rays (10 vs. 9), shorter head, greater interorbital distance, and without the blotches and the head and body usually present in A. scitulus.
This species is named after the indigenous people of the Charrua, which inhabited an area in which the type locality (in the Uruguay River drainage in Rio Grande do Sul, Brazil) is situated.
Australoheros forquilhaThis species is distinguished from other members of the genus in having dark markings below the orbit along the posterolateral border of the suborbital series, checkerboard spotted dorsal, anal and caudal fins and more than 14 caudal vertebrae in some specimens, 25"26 (vs. 24"25) E0 scales, a downward pointing subterminal mouth, the shortest interorbital and longest preorbital distances, and a unique scale cover of the base of the dorsal fin with two cover scales corresponding to one transverse scale row.
Previously given the working name of Australoheros sp. Forquilha, this species is endemic to the tributaries of the upper and middle Uruguay River drainage in Brazil and Argentina. The species is named after the Forquilha River, the type locality.
Australoheros guaraniThis species is distinguished from other members of the genus in having the largest sclaes between the dorsal fin and the upper lateral line.
The colour pattern of this species is most similar to A. forquilha and A. tembe, but itcan be further separated from these two species in having fewer (13 vs. 14 or more) caudal vertebrae, a shorter caudal peduncle, shorter scale cover of the dorsal fin, and a smaller interorbital distance.
This species is the only Australoheros known from Paraguay (where it is found in the upper Paran River drainage), and is named after the Guaran (an indigenous tribe).
Australoheros guarani was previously given the working name of Australoheros sp. Paraguay.
Australoheros minuanoPreviously given the working name of Australoheros sp. Uruguai, Australoheros minuano can be distinguished from other members of the genus in the dominant males being pink to red.
It further differs from congeners except A. kaaygua in mostly having 12 pectoral-fin rays, and is distinguished from A. facetus, A. cf. facetus and A. guarani in mostly having six rakers on the lower arm of the first gill arch.
It is also distinguished from A. facetus and A. cf. facetus in not having an upwards directed mouth and a longer dorsal fin scale cover, covering bases of 7"8 last spines (vs. only 2"3).
The colour pattern of A. minuano is similar to A. kaaygua in having yellowish ground color, but it lacks the red corners of the caudal fin typical for A. kaaygua, and is further distinguished from this species by being more slender.
This species is found in the middle and lower Uruguay River drainage in southern Brazil (Rio Grande do Sul) and Uruguay. It is named after the Minuano, an indigenous tribe that lived in Rio Grande do Sul.
Based on molecular data, four species groups within Australoheros are recognised: the facetus group (A. facetus, A. guarani); the forquilha group (A. forquilha, A. tembe); the kaaygua group (A. kaaygua, A. minuano) and the scitulus group (A. charrua, A. scitulus).
For more information, see the paper: ~an, O and SO Kullander (2008) The Australoheros (Teleostei: Cichlidae) species of the Uruguay and Paran River drainages. Zootaxa 1724, pp. 1"51.