Chapalichthys pardalis (including peraticus)

Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Chapalichthys pardalis
Original Description: 

  Álvarez del Villar, J. (1963): Ictiologia Michoacána. 3. Los Peces de San Juanico y de Tocumbo. Anales de la Escuela Nacional de la Ciencias Biológicas 12 (1-4): pp 111 - 138

Etymology: 

  The name "pardalis" (gr.) means “spotted like a Panther”. It described the colour pattern of this species, that Álvarez del Villar saw disjunctive to related species.

Holotype: 

  Álvarez del Villar gave no Collection-number in the description.

  The Holotype is an adult female of 37.4mm SL, caught by J. Álvarez in Tocumbo, 23.09.1961.

English Name: 
Polka-dot Splitfin
Mexican Name: 
Pintito de Tocumbo
Synonyms: 

  Chapalichthys peraticus  Álvarez del Villar (1963)

Karyotype: 

  The Karyotype describes the number and appearance of chromosomes during the phase of condensation, classified by the position of the centromere (Levan et al., 1964).

The following abbreviations are employed:

 

M = large metacentric chromsome (a result of Robertsonian fusion)

m = small metacentric chromsome (centromere at medium position)

sm = submetacentric chromsome (centromere at submedian position)

smst = submetacentric-subtelocentric chromosome (continous series)

st = subtelocentric chromosome (centromere at subterminal region)

stt = subtelocentric-acrocentric chromosome (continous series)

t = acrocentric chromosome (centromere at terminal region)

 

The Karyotype of Chapalichthys pardalis, following Uyeno, Miller & Fitzsimons, 1983:

2n = 36    12M/ 2sm/ 8st/ 14t  

Size: 
The maximum known SL is 85mm (Miller et al, 2005).
Terra typica: 

  The Holotype had been caught in the manantial de Tocumbo, about 40km S of the Lago de Chapala in Michoacán.

Status : 

  International Union for Conservation of Nature (IUCN): not assessed

 

  Conservation status and population trends of Mexican Goodeids (Lyons, 2011): critically endangered/stable – This species is known from only two areas in the upper Balsas River basin, the San Juaníco Lake and the Tocumbo Springs, located about 25 km downstream on the outlet of the lake (Miller et al. 2005). For many years the San Juaníco population was considered a separate species, C. peraticus (e.g., Domínguez-Domínguez et al. 2005b), but recent genetic and morphological analyses (Miller et al. 2005; Kyle Piller, Southeastern Louisiana University, Hammond, Louisiana, USA, personal communication) indicate that the there are insufficient differences between the two populations to warrant separate species status. The Tocumbo population is small and is limited to a spring system that has been heavily modified as a swimming area. The San Juaníco population is larger and occupies a bigger area, but is nonetheless still small.

 

  NOM-059-SEMARNAT-2010: no categoría de riesgo (no category of risk)

Distribution and ESU's: 

  This species is only known from a spring-fed alberca (swimming pool) and its outlet at Tocumbo near the Río Balsas in Michoacán. In the last years, a population (?) from the Lago de la Magdalena, halfway between Tocumbo and the Presa de San Juanico, has been introduced in the hobby. Confronting Omar Domínguez with this location (in 2011), he indicated that this former lake is dry and there is no water at all, so this might be an erronous given location. The collector couldn't have been traced already, so this riddle will have not be solved.

 

    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.

Habitat: 

  The manatial de Tocumbo is are clear spring and its outflow creek, now almost entirely modified into a concrete pool. The depths where they can be found are not more than 1.0-2.0m, but originally they prefer about 0.5m. The natural substrates (now concrete) were silt, mud, gravel, rocks and boulders, concerning vegetation can be found green algae and sparse water hyacinth in the outlet. Miller wrote about the spring temperatures varying from 21 to 24°C. In the Presa de San Juanico, they live in 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 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.

Colouration: 

  Silvery gray in both sexes with a yellowish-greenish glimmer. The fish show an irregular and close pattern of dark blotches, more prominent on the lower part of the body. The dorsal part shows smaller blotches or points, in males somewhat dusky superimposed. The blotches in the midline are forming an irregular lateral band. The fins are yellowish-gray in females and dark-gray in males. The caudal fin shows a bright yellow terminal band in males, delimited from the dusky part of the fin by a small dark line. Fins and opercle are non-spotted. The opercle is silvery coloured. Young specimens show few blotches evenly distributed over the sides.

Biology: 

  This fish probably has a long reproductive period as 13mm young were taken on 23 September (Álvarez del Villar 1963), 18mm on 17 February and "all size classes" were noted on 20 April by Kingston (1979). Individuals as small as 18 and 19mm (from the close related Chapalichthys peraticus Álvarez del Villar) also were collected in late May and early January, suggesting a protracted breeding season (Álvarez del Villar 1963). 

Diet: 

  At Tocumbo, it was seen feeding on algae and aufwuchs and was attracted to insects at the surface, so it might be omnivorous.

Remarks: 

  The population of Tocumbo, now virtually confined to a concrete pool, is classified as threatened because of its very restricted distribution and the impacts from people swimming and washing in its greatly modified habitat. Following Omar Domínguez Domínguez (pers. com. 2017), the popularion might be already extirpated due to cleaning prosesses of the spring. However, confirmations therefore are needed, but this population might be extinct in the wild.

 

Chapalichthys peraticus, originally described by the same author in the same paper (Álvarez del Villar, 1963) from the Presa de San Juanico, about 15km N of Tocumbo, has been synonymized several times with pardalis and revalidated in the the same way. Recent (2016) phylogenetical tests revealed finally, that both populations belong to the same species and have to be named Chapalichthys pardalis. Following the original description of pardalis and peraticus by Álvarez del Villar, both Chapalichthys are barely distinguishable.

Locations