Characodon garmani

Characodon garmani
Characodon garmani
Characodon garmani
Original Description: 

  JORDAN, D. S. & B. W. EVERMANN (1898): The Fishes of North and Middle America. Bulletin - United States National Museum 1896-1900: pp 2831 - 2832

Etymology: 

The species is named for Prof. Samuel Garman in recognition of his valuable studies of the Cyprinodontiformes.

Holotype: 

  Collection-number: Museum of Comparative Zoology - Harvard University, Cat. No. MCZ-27704.

  The Holotype is a mature female of 27mm SL.

English Name: 
Parras Characodon
Mexican Name: 
Mexclapique de Parras
Synonyms: 

Characodon lateralis   Garman, 1895 (partially)

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 Characodon garmani has not been ascertained.

Size: 
The maximum SL is unknown.
Terra typica: 

The Holotype-location had been given by Jordan and Evermann as "Parras, Coahuila, Mexico".

Status after IUCN: 

Extinct

Status following other sources: 

Extinct; Comment: No records for more than 100 years

Distribution and ESU's: 

  This species is known only from springs and their outflows at Parras in the state of Coahuila, that flowed towards the now-dry laguna, terminus of the endorheic Río Nazas basin. Nothing is known about the complete distribution range of these fish. 

 

  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 three letters of the genus, followed by the first two letters of the species name and an ongoing number in each species.

 

  In Characodon garmani, we use the single ESU Chrga1 for the single specimen we know, characterizing the complete collection of this extinct species. 

Habitat: 

Characodon garmani inhabited springs near Parras in Coahuila. The springs disappeared by human influence before any information could be obtained.

Colouration: 

The colouration is only known from a single female in preservation. Jordan and Evermann described it as "olive to reddish brown, with scattered small spots of darker on the back, a darker band with or without spots of dark along the flank, more distinct posteriorly. Fins with fine dots of dark colour".

Biology: 

Nothing is known about this fish. Probably it had a similar life history pattern to Characodon lateralis and audax.

Diet: 

Nothing is known about its diet, but its feeding habits might probably have been similar to its congeners because of its similar dentition.

Remarks: 

The Parras valley is some three hundred kilometres northeast of the Río Mezquital. It is a desert area enclaved in the Chihuahua desert, far away from any locality where Goodeids live. The - in former times - beautiful springs have been damed up and well-staffed with common carps, and the water is used primarily for agriculture. Between 1880 and 1895, six endemic species have been described from this locality, all disappeared within the following years. Characodon garmani haven't been seen since 1953. There is only one specimen preserved, the Holotype.

 

Characodon garmani had been several times synonymized with Characodon lateralis though there are differences in the body shape (garmani is more elongated) and in size and shape of the fins.

 

Brian Kabbes has been in 2000 in a small town, 7km south of Durango city, named Parras del Fuente. Near this town, there is another town, Amado Nervo, where a Characodon has been detected, now refered to Characodon lateralis as Characodon lateralis "Amado Nervo". Comparing female fish from this locality with the Holotype of Characodon garmani, there is a conspicuous resemblance recognizable. Maybe there had been a misunderstanding concerning the type-locality.

 

Concerning distribution patterns of fish within the Río Nazas and the Río Mezquital, without wanting to predicate anything and excluding all endemic species (and therefore extinct species) of the type location of Characodon garmani, we find only a few species inhabiting both ríos. These are the Cyprinids Codoma ornata and Campostoma ornatum, and the Percid Etheostoma pottsi. Both genera have their closest relatives in the north of México, with the tendency to migrate southwards. On the other hand, we find some species in the Río Nazas basin, but not in the Río Mezquital. These are two species from the genus Cyprinella, one from Gila and one from Notropis (all Cyprinids), as well as Catostomus nebuliferus and Ictiobus niger, both Catostomidae. None of these genera can be found south of the Río Nazas. In the Río Mezquital, but not in the Río Nazas, we find (besides Characodon) the follwing species: Hybobsis aulidion (Cyprinidae), Gobiesox fluviatilis (Gobiesocidae), Menidia mezquital (Atherinopsidae) and Scartomyzon austrinus (Catostomidae). Without Scartomyzon (which is a genus with a not fully resolved taxonomy), all species (and genera) came from the south and are reaching the Río Mezquital as its northernmost geographic range. The only genus definitively living in both ríos with two different species is Cyprinodon (Cyprinodontidae) with the species Cyprinodon meeki in the Río Mezquital and Cyprinodon nazas in the Río Nazas. This genus reaches the Río Mezqutital from the north, surrounding the Chihuahua desert.

The conclusion of this is, that Characodon would be the only genus with a contrasting distribution range with relatives in the south (even if we take in consideration the relationship with the Empetrichthyinae, the closest relatives are livebearing Goodeids) and reaching the Río Nazas (the terminus of the river; in the river itself, there haven't been found any Characodon) in the north.

 

Some lines from James Langhammer to this topic: "The waters above the Falls can still today all be connected to one another during heavy raining seasons - and historically made a continuum northward to the basin that housed Characodon garmani. The historical distribution was a continuous channel that probably flowed year-round. The headwaters originated near the Los Pinos home range, flowed down to Guadalupe Aguilera and Chupaderos, then to the location where presently the High Falls pirated the system onto the Mezquital. Prior to the piracy the system turned northward and flowed to the confluence where El Toboso, Abraham Gonzales and 27 de Noviembre join it, and then flowed north to the presumed habitat of Characodon garmani and then merged with the boundary river (Río Grande del Norte) between the USA and México. This is fully documented in a hard-to-find paper on the distribution of Garter Snakes."

 

Garman, who caught the Holotype identified this species as Characodon lateralis, but Jordan & Evermann described it as a new species.

First Describer: 
Jordan & Evermann, 1898
Photos: 

Images 1 and 2: The only specimen ever caught of this species; preserved, female

Image 3: Drawing of this specimen

Copyright: Ruud Wildekamp

Image 4: For comparison: female Characodon lateralis from Amado Nervo

Copyright: Anton Lamboj