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
English Name: 
Darkedged Splitfin
Mexican Name: 
Mexclapique de Zempoala
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

Holotype: 

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

  The Holotype has got a TL of 39.6mm.

Terra typica: 

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

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.

Synonyms: 

Girardinichthys innominatus   Evermann & Goldsborough, 1902 (wrong identified)

Characodon multiradiatus   Meek, 1904

Lermichthys multiradiatus   Hubbs, 1926

Girardinichthys limnurgus   Jordan & Evermann, 1927

Distribution and ESU's: 

  The Darkedged Splitfin is endemic mainly to the Mexican federal states of Mexico and Michoacán, but reaching on the fringe of its distribution also the federal states of Querétaro, Morelos and even Hidalgo. The centre of its historical distribution is the upper Río Lerma drainage, where it occured mainly in channels, dams, creeks, ponds and lakes along the river. The habitats closest to the Lerma river sources are the Laguna Chignahuapán and swamps near Xalatlaco S of Toluca de Lerdo. The distribution includes also habitats along some of upper Lerma main affluents like the ríos Las Minas and Cachiví and the Arroyo Jaltepec. The westernmost habitat along the Río Lerma is the San Miguel spring in Maravatío de Ocampo, only 45km E of the Laguna Cuitzeo but about 150km NW (both distances beeline) from the Río Lerma sources. Additionally to the Río Lerma drainage, Girardinichthys multiradiatus managed on several points to occupy two more big drainages. One is in the S the Río Balsas drainage with the Arroyo El Zarco in the headwaters of the Río Turundeo W of Ciudad Hidalgo (the westernmost known habitat in general), 30km SW of Maravatio de Ocampo, the endorheic Presa El Bosque S of the town of Heroica Zitácuaro and dams within the headwaters of the Río Tiloxtoc, all these localities within the Río Cutzmala basin. The eastern- and southernmost known habitats in general about 25km SW of Mexico City are the endorheic Lagunas Zempoalas within the Río Amacuzac basin, also Río Balsas drainage, the only known habitats within the state of Morelos. The third big drainage where this species occurs is the Río Pánuco drainage in the N of the Río Lerma. The distribution encompasses several smaller dams in the headwaters of the Arroyo Characol SW of San Juan del Río (e.g. La Goleta and San Martins dam) in the state of Querétaro, the Presa Huapango and smaller dams near Polotitlán de la Illustración, Río San Juan headwaters in the state of Mexico and the only known habitat in the state of Hidalgo, a small dam about 6km NE of Polotitlán, draining into the Arroyo Casas Viejas, a Río San Francisco affluent. Mercado-Silva confirmed its presence in the Tonatiahua and Zempoala lakes in Morelos through suveys in 2016 and 2017 and the habitats in the Río Balsas and Pánuco drainages are partly still populated with this species (Lyons, 2011; Domínguez-Domínguez, 2005). The distribution and abundance declined substantially over the 20th century (Lyons, 2011), leaving remnant stocks. A new stock has been discovered on a survey by Köck et al. W of Ciudad Hidalgo (2017). According to its appearance in four different drainages, four subpopulations can be distinguished: The Río Lerma subpopulation (type subpopulation), the Río Pánuco subpopulation, the Río Cutzmala subpopulation and the Lagunas de Zempoala subpopulation. The underlined names are the ones officially used by the Instituto Nacional de Estadística y Geografía; nevertheless, other ones might be more often in use or better known and therefore prefered.

 

      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.

 

  Actually, we distinguish two ESU`s in Girardinichthys multiradiatus. Girmu1 for the population in the Lagunas de Zempoala and Girmu2 for all the other ones, including the ríos Lerma, Pánuco and Balsas.

 

  Maximum Extent of Occurence of Girardinichthys multiradiatus:

Maximum EOO of Girardinichthys multiradiatus

Status : 

  International Union for Conservation of Nature (IUCN): vulnerable

 

  Conservation status and population trends of Mexican Goodeids (Lyons, 2011): vulnerable/stable? – This species was known historically from about 16 locations located just northwest, west, and south of greater Mexico City including 13 streams and wetlands in the upper the Lerma River basin and single sites in the headwaters of the Balsas River basin on the Pacific slope, the endorheic (no outlet) Lake Zempoala system, and the Taxingu Reservoir in the upper Pánuco River basin on the Atlantic slope (Domínguez-Domínguez et al. 2005b). Distribution and abundance of G. multiradiatus declined substantially in the Lerma basin over the 20th century, and the seven remaining populations there are now small and isolated, but these populations seem to have been stable since the late 1990s. The Balsas, Zempoala, and Taxingu populations also still persist.

 

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

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

Maravatio I

Maravatio II

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.

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

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.

Locations