Girardinichthys viviparus

Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Girardinichthys viviparus
Original Description: 

  BUSTAMANTE y SEPTIÉN, M. (1837): Descripción del Mexcalpique (Cyprinus viviparus). El Mosaico Mexicano vo 2: p 116

Etymology: 

  This species name is derived from the Latin and means "livebearing". It was the first species of Cyprinodonts, where livebearing has been observed.

Holotype: 

no Holotype deposited 

English Name: 
Chapultepec Splitfin
Mexican Name: 
Mexclapique
Synonyms: 

Cyprinus viviparus   Bustamante, 1837
Lucania sp.   Girard, 1859
Girardinichthys innominatus   Bleeker, 1860 
Limnurgus variegatus   Günther, 1866 
Mollienesia sp.   Gill, 1882 
Lucania richi   Goode, 1891
Characodon geddesi   Regan, 1904
Limnurgus innominatus   Regan, 1907

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 Girardinichthys viviparus, following Uyeno, Miller & Fitzsimons, 1983:

2n = 48    10st/ 38t  

Size: 
The maximum known SL is 65mm (Miller et al, 2005).
Terra typica: 

The terra typica has been given with Mexico City.

Status after IUCN: 

Critically endangered

Status following other sources: 

Endangered; Comment: Only remnant populations

Distribution and ESU's: 

This species is only known from the endorheic basin of Valle de México.

Habitat: 

This species inhabits quiet water of lakes, ponds, canals and ditches over mud substrate. It prefers clear to murky water and depths between 0.3 and 0.6m. Vegetation is abundant, mainly green algae, Potamogeton, water hyacinths, Lemna and Chara.

Colouration: 

Males are silvery gray, marbled sligthly blackish-gray. The unpaired fins are dark, becoming darker at the edge and completely black in dominant males. During courtship the males become totally blackish to black. The paired fins are clear. Females are silvery-gray with the upper half of the body darker, the venter brighter. Sometimes, females show a gravity spot. The fins are clear to somehow dusky-grayish. Females show an indefinite number of dusky bars on the caudal peduncle and the upper half of the body, fading anteriorly. These bars are only sligthly darker than the body sides and sometimes not clearly visible. A bluish glimmer can be seen with some specimens.

Biology: 

According to Díaz Pardo and Ortíz Jiménez (1986), the reproduction occurs continuously from at least February to October as indicated by captures of newborn young and individuals 8 to 14mm SL from February to May, with young appearing into October.

Diet: 

S.E. Meek noted a not-coiled intestinal canal, about the length of the body and small, pointed teeth, all indicates of a carnivorous nutrition. The cleft is nearly vertical, so this species might be specialized in feeding from a special kind of small invertebrates (Copepods?).

Remarks: 

The Mexcalpique inhabited originally the endorheic basin of the Lago de Texcoco. Most parts of this Lake disappeared during the last decades, and with this parts disappeared also Girardinichthys viviparus. Miller reported 2005 (denoting that he died in 2003, but his book about Mexican fish had been published posthum), that through a canal, this species reached the Río Tula basin, where it could be found now in the Laguna de Zumpango. He reported this species also from collections in ditches south of San Juan Teotihuacán in 1977 and a small population persisting in Lago Xochimilco (2003).

Meanwhile, a study from Salgado et al (2004) revealed that in 2 of 5 known habitats, including the Laguna de Zumpango and the Requena Reservoir, this species has disappeared again and has survived only in the three lagos de Chapultepec in Mexico City. Further examinations in this 3 habitats showed a different abundance and threat of the species. In Lago Viejo, the situation was best with about 20 specimens per m² and no parasites. In Lago Menor, this species has been infected with Lernaea (about 48% of the specimens). The abundance has been about 15 specimens per m². The worst situation has been in Lago Mayor with only 2 specimens per m² and nearly all fish infected with Lernaea and Bothriocephalus acheilognathi, a tapeworm typical for asian cyprinids. Lagos Menor and Mayor had been populated with Cyprinus carpio (probably the reason for the infection with the tapeworrm and Lernaea), Lago Mayor with Tilapia, too.

In Viviparous fishes (Uribe & Grier, 2005) Domínguez et al. published results of "recent annual systematic samples", where this species has been found in the lagos de Xochimilco and Zumpango, but very rarely, and the most likely largest population in the Lago Mayor. 

 

In 2008, Miranda et al. reported about a high abundance of Girardinichthys viviparus in the Lago de Tecocomulco, northeastern of México City, where it hasn't been reported before. It might have been overlooked there, though this lake has been studied well. Another possibility may have been the introduction by man. 

 

Girardinichthys viviparus has been the first cyprinodontiform fish, where livebearing has been observed, probably as early as 1769. Following T. Gill - who translated a letter in 1882 from Don Joseph Anthony de Alzate y Ramirez, who observed the transit of the Venus in 1769 - this Don Alzate forwarded some preserved viviparous scaly fishes in 1772 to the Royal Academy of Sciences in Paris. Gill translated further, that Don Alzate had told the academy before about this odd species, he stated the locality of this new species with Mexico City and he wrote the following most interesting lines: "If you press the belly with your fingers, you force out the fry before their time, and upon inspecting them through the microscope, you may discern the circulation of blood, such as it is to be when the fish is grown up. If you throw these little fishes into water, they will swim as well as if they had been long accustomed to live in that element." Doubtlessly, this fish had been Girardinichthys vivparus.

 

Guenther (1866) had chosen the scientific name Limnurgus variegatus to "purge the barbarous" name Girardinichthys innominatus, given by Bleeker six years before. This is of course not legimitated. However, the species had been already described in 1837 by S. Bustamante as Cyprinus viviparus, so this species name had to be accepted finally.

Photos: 
Image 1: male
Copyright by Frank Kroenke
Image 2: gravid female
Copyright by Frank Kroenke
Image 3: male and few young females
Copyright by Frank Kroenke
Image 4: competiting males
Copyright by Susanne Schleussner
Image 5 and 6: pond raised fish
Copyrights by Martin Ravn Tversted/ Lars Vig Jensen