Girardinichthys multiradiatus

Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Girardinichthys multiradiatus
Original Description: 

  MEEK, S. E. (1904): The fresh-water fishes of Mexico north of the Isthmus of Tehuantepec. Publication. Field Columbian Museum 93, Zoological Series 5: pp 1 - 252

Etymology: 

  This species-name is derived from the Latin and means "with many rays". The species was first grouped within Characodon and differed by having much more fin-rays than its congeners.

Holotype: 

  Collection-number: Field Columbian Museum, Cat. No. FCM-4523.

  The Holotype has got a TL of 39.6mm.

English Name: 
Darkedged Splitfin
Mexican Name: 
Mexclapique de Zempoala
Synonyms: 

Girardinichthys innominatus   Evermann & Goldsborough, 1902 (wrong identified)

Characodon multiradiatus   Meek, 1904

Lermichthys multiradiatus   Hubbs, 1926

Girardinichthys limnurgus   Jordan & Evermann, 1927

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 multiradiatus, following Uyeno, Miller & Fitzsimons, 1983:

2n = 48    10st/  38t  

Size: 
The maximum known SL is 55mm (Miller e al, 2005).
Terra typica: 

The Holotype comes from the Lago de Lerma, basin of the Río Lerma.

Status after IUCN: 

Vulnerable

Status following other sources: 

Threatened; Comment: Stable since 2000

Distribution and ESU's: 

This species comes from the Pacific Slope, accurately from the upper parts of the ríos Lerma and Balsas basins and from the lagunas de Zempoala in the states México, Michoacán and Morelia.

Habitat: 

The darkedged Splitfin lives in quiet to sligthly moving waters of small lakes, spring-fed ponds and ditches and near banks of pools of cool streams. It can be found over substrates of silt, mud, clay, sand, gravel and rocks. Like all known Goodeids, it prefers clear to muddy water and depths of less than 1m, frequently 0.6m or less. The vegetation comprises green algae, Lemna, Salvinia, Nasturtium, Potamogeton, Scirpus and Juncus.

Irrigation channel near Ciudad Hidalgo IIrrigation channel near Ciudad Hidalgo II

Colouration: 

Both sexes are coloured greyish-yellow to bright yellow. Typically, a gravity spot can be seen in both sexes, too. The upper half of the body is darker, the venter can be coloured cream-yellow to yellow. Males show dark pigmented unpaired fins, nearly blackish in some populations. On its base, they show small or bigger sized yellowish to golden areas. In some populations, the fins appear brightly yellow to orange or golden coloured with dark edges. Both sexes show several bars on the upper half of their sides, with the origin behind the opercle, reaching the caudal base and becoming more prominant posteriorly. In some females, these bars fade and the fish appear totally yellow or golden. The paired fins are clear, also unpaired fins in females, sometimes becoming slightly grayish.

Biology: 

Captures of gravid females with eyed embryos and newborn young (6 to 8mm SL) indicate a reproduction period from at least December to May.

Diet: 

Meek denoted incisor-like bicuspid teeth, but made no statements concerning the length of its gut. In contrary to its congener Girardinichthys viviparus, the mouth is bigger and the cleft not vertical, so we might have here - taking all known facts in consideration - a more omnivorous species than the Mexcalpique.

Remarks: 

Meek discovered, that some specimens identified as Girardinichthys innominatus (now viviparus) from the Río Lerma belong to another species and described this species as a member of the genus Characodon as Characodon multiradiatus, pointing at the fact, that this species resembles the species innominatus, with which it has been previously identified. Even Hubbs and Turner (1939) pointed at the fact, that Lermichthys multiradiatus - its new generic name since 1926 - "is a close relative of Girardinichthys, and probably a derivative." Finally, in 1971, Miller and Fitzsimmons synonymized Lermichthys with Girardinichthys.

 

The variability within this species is remarkable. Not even the colouration differs, there are also populations known with extended rays of the anal and dorsal fin in males, giving the fish a fringed shape.

 

The habitats of this species are characterized by water with different parametres. The range goes from soft to hard water and from acidic water with pH 6.0 to alkaline water with pH 9.0. This is the highest range of water parametres tolerated by Goodeids, that is measured in the wild.

 

Another superlative is to be reported about Girardinichthys multiradiatus. This species inhabits among others the isolated lagunas de Zempoala, 2.800m above sea level. This habitat is the highest situated Goodeid-habitat noted.

 

From many of the historic sites of this species it has disappeared in the last century, and remaining populations are often small and isolated. Few populations are still healthy, and  the future of this species is definitively uncertain.