Ingo Seidel posted on CRC: Amatitlania and of Australoheros are indeed closely related. According to the current analyses based on molecular data (e.g. López- Fernández et al. 2010) these genera are even 'sister' taxa (means the most close related genus of Amatitlania is Australoheros).
Here's a link to that work:
http://aquaticecology.tamu.edu/files/2012/07/Lopez-Fernandez-et-al.-2010-MPE.pdf
Some good discussion:
The genus Australoheros, although restricted in its distribution
to southern South America’s Paraná-La Plata basins, has been
shown to be deeply nested among Central American taxa by all
molecular studies. But, the position of Australoheros is far from congruent
among these studies. While we recover the genus nested
within amphilophines and weakly related to Amatitlania and part
of ‘Cryptoheros’, Hulsey et al. (2004) found it as sister to ‘Cichlasoma’
festae and at the base of a clade including Caquetaia umbrifera,
tomocichlines and herichthyines (sensu this paper). Similarly to
Hulsey, Concheiro Pérez et al. (2006), found Australoheros at the
base of Astatheros and the herichthyines, whereas Rican and Kullander
(2006) found it as sister to a clade of amphilophines and
our caquetaines, and Rican et al. (2008) placed it at the base of
all Central American cichlids in their combined molecular trees
and MP analysis of genes and morphology (Rican et al., 2008,
Figs. 1–3, 6). Interestingly, Rican et al.’s (2008) morphological analysis
weakly grouped Australoheros with ‘Cryptoheros’ panamensis
and placed it close to Cryptoheros sensu lato, Archocentrus and Herotilapia,
further suggesting extensive morphological homoplasy
within amphilophines (see above). Given the variable position of
Australoheros and the fact that Rican et al. (2008) included the largest
number of species from the genus, we interpret our results with caution. This is especially true from a biogeographic point of view,
since interpretation of the origin of Australoheros and its current
geographic distribution seems more difficult on the basis of our
topology (i.e. nested within an otherwise Central American clade)
than that of Rican et al. (i.e. from a basal position with respect to
all Central American taxa). Overall, all studies coincide in placing
Australoheros within the Central American assemblage, and most
studies place the genus in a position near to or inside amphilophines.
Further study is needed to establish the position of Australoheros
and to infer its biogeographic history.
Matt