Chapalichthys peraticus
Álvarez del Villar, J. (1963): Ictiologia Michoacána. 3. Los Peces de San Juanico y de Tocumbo. Anales de la Escuela Nacional de las Ciencias Biológicas 12 (1-4): pp 111 - 138
Álvarez del Villar assigned no Collection number. The Holotype had been an adult female of 63.4 mm SL, caught in the Presa de San Juanico by I. Barreca, 30.05.1963.
The Holotype had been caught at the Presa de San Juanico, in the vicinity of Cotija, about 15km NW of Tocumbo in Michoacán.
The name "peraticus" is derived from the Greek and means “odd" or "unfamiliar". Álvarez del Villar had chosen that species name, because he has been thinking about the circumstances, why the habitat of this fish is out of the typical distribution range of the genus. So the species name means something like "untypical distribution".
Chapalichthys pardalis Uyeno, 1983 (?)
This species is only known from the chain of lakes of Presa de San Juanico, about 15km NW of Tocumbo in Michoacán.
ESU ist short for Evolutionarily Significant Unit. Each unit expresses an isolated population with different genetic characteristics within one species. ESU's can be defined by Molecular genetics, Morphology and/or Zoogeography and help in indicating different phylogenetic lineages within a species. The abbreviation for an ESU is composed of the first 3 letters of the genus, followed by the first 2 letters of the species name and an ongoing number in each species.
Following modern phylogenies, we have to distinguish two ESU's within this species, whereas the first abbreaviation, Chapa1 is taken for fish from the Manatial de Tocumbo. The second one, Chapa2 is in use for fish from the Presa de San Juanico, that are run as Chapalichthys peraticus on this Website. This will be changed in a review of the genus Chapalichthys, finally revealing only two species, encaustus and pardalis.
Its habitats are pools and ponds with partially dense aquatic vegetation, mainly Ceratophyllum and Eichhornia, as well as dense reed on the shore. The substrates are mainly silt, mud, gravel and rocks. The species prefers depths of less than 1m. The water is clear to turbid. Radda measured a water-temperature of 24°C on 17.02.1982 in a depth of 0.1m, but the temperature of the waterbody itself doesn't go higher than 20°C.
There is not much information about this species available. Maybe because it was treated as pardalis most of the time, there is information about this species refered to pardalis. Álvarez del Villar collected individulas of 18 and 19mm in late May and early January in 1963, suggesting a protracted breeding season.
Chapalichthys peraticus is very close related to encaustus and pardalis, so the feeding habits might be similar, comprising aufwuchs, algae, insects from the water surface and small aquatic invertebrates.
Silvery grey in both sexes with a yellowish-greenish or yellowish-brownish glimmer. The fins are coloured clear to yellowish with broad terminal yellow bands in the caudal fin. The fish show many small dots, somehow appearing elongated. The colour pattern resembles very close the colouration of pardalis, appearing maybe more yellowish or brownish in ground colour and presenting more and in comparison smaller dots.
Chapalichthys peraticus has been synonymized several times with pardalis.
The identification of the "real" peraticus is complicated by the fact, that besides coorectly identified fish with collection data, two other, and sometimes different fish named peraticus are distributed in the hobby. A smaller one with a prominent midlateral band and without blotches (and absolutely different to pardalis and encaustus), and a bigger one, similar to pardalis with the collection data: "Tocumbo, Presa de San Juanico", which comprises both type-localities. The latter are maybe wrongly denoted pardalis, but might be indeed peraticus, at least in some cases; the former ones are wrongly denoted Xenotoca, either a form of variata, or specimens from an undecsribed species, but surely no Chapalichthys. This fact is supported by the wrongly identified form called Chapalichthys sp."La Mintzita" in the hobby, that comprises indeed an undescribed Xenotoca, being in description already in honour of the late Ivan Dibble (pers. comm. Domínguez, 2011).
Following the original description of pardalis and peraticus by Álvarez del Villar, both Chapalichthys are barely distinguishable, and the future will reveal, if peraticus will persist valid (Domínguez, pers. comm. 2011).
R.R. Miller (2005) reported this species as "no more collected since 1964", and Uyeno et al.(1983) thought this species to be extinct. Hieronimus et al. in contrary had no problems to catch some specimens in 1989 in a channel to the Presa, but all males. Meanwhile collections have been successful again.