Chapalichthys pardalis

First Describer: 
Álvarez del Villar, 1963
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Original Description: 

Álvarez del Villar, J. (1963): Ictiologia Michoacána. 3. Los Peces de San Juanico y de Tocumbo. Mich. Ann. Esc. Nat. Cienc. Biol. 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: 

none

Karyotype: 

2n = 36    12M/ 2sm/ 8st/ 14t   (following Uyeno, Miller & Fitzsimmons, 1983)

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

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

Status after IUCN: 

not mentioned

Status after J.Lyons (2011): 

Endangered; Comment: Stable since 2000

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 wait to be unraveled.

Habitat: 

Its habitats are clear springs and their 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.

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 fish, 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.

 

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. The identification of the "real" peraticus is complicated by the fact, that besides correctly identified fish with collection data, two other, and in some cases 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 desription 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).

Photos: 

Image 1: young female

Image 2: male from Tocumbo

Copyright by Omar Domínguez Domínguez

Image 3: female from Tocumbo

Copyright by Omar Domínguez Domínguez

Image 4: pair from Tocumbo

Copyright by Omar Domínguez Domínguez

Images 5 and 6: male

Images 7 and 8: female

Image 9: newborn fry

Images 10, 11 and 12: males

Images 13 and 14: groups