Characodon audax

Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Characodon audax
Original Description: 

  SMITH, M. L. & R. R. MILLER (1986): Mexican Goodeid Fishes of the Genus Characodon, with Description of a new Species. American Museum Novitates 2851: pp 1 - 14

Etymology: 

  The species name is derived from the Latin and means bold or daring, refering to the aggressive behaviour of this species.

Holotype: 

  Collection-number: University of Michigan Museum and Zoology, Cat. No. UMMZ-213302.

  The Holotype is a mature male of 38.5mm SL, collected by R. R. Miller, F. H. Miller et al, 16.03.1982. 

English Name: 
Bold Characodon, Black Prince
Mexican Name: 
Mexclapique del Toboso
Synonyms: 

Characodon sp.   Radda, 1984

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 audax, following Uyeno, Miller & Fitzsimons, 1983:

2n = 24    24M  

Terra typica: 

  The Holotype-location is a spring-fed pond called El Ojo de Agua de Las Mujéres, near the village of El Toboso (24°16'35'' N lat. and 104°34'50'' W long.), 10.4km N of HW 40 in the state of Durango.

Status after IUCN: 

  Critically endangered

Status following other sources: 

  Starus: Endangered

  Population development: Assigned new populations

Distribution and ESU's: 

  This species is known from springs and creeks along the upper part of the Río Mezquital (Río Tunal above the waterfalls of El Salto) in Durango. The northernmost population had ben found in the Río La Sauceda at Ciudad Canatán, the southernmost can be found in the Arroyo La Zorra at José María Pino Suaréz. The center of the distribution is around the town of Victoria de Durango.

 

  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.

 

  Within Characodon audax we can distinguish - with some uncertainties - seven different ESU's. Uncertainties because some of the populations included do not exist anymore, so there is no chance left to compare these fish with others. On the other hand, some scientists rank the red finned populations within Characodon lateralis though it is phylogenetically quite clear they do not belong there. However, a third group of scientists distinguish the red forms from audax and lateralis and would prefer to describe them as a separate species due to morphological grouping. We follow the taxonomy Omar Domínguez suggests which needs to rename the ESU abbrevaitions given by John Lyons, who groups them as Characodon lateralis as he wants to wait for final studies. We give both abbreaviations here, the original one in brackets. This is to do not mix up different ESUs finally. 

Chrau1 is restricted to the Ojo de Agua de las Mujéres spring, its ourflow and the damned lagoon at the tiny village of El Toboso, the Black Prince, how it is called. This is the only population we know (mostly) without red colour in captivity. However, wild fish show red fins, too. Chrau2 (Chrla1) summarizes the populations on the west bank of the Río Tunal, north of the Presa Peña de Aguila up to approximately San José de Gracia south of El Canatlán. We do honestly not know how far north or south we can find this ESU. It included (maybe) the extinct population at Cerro Gordo on the east bank of the Río Tunal, but there is no possibility left to figure this out. Chrau3 (Chrla2) encompasses the fish from the vicinity of El Canatlán which is named Los Pinos by aquarists. It is definitly different from fish of the east bank of the Río Tunal in its vicinity (Laguna Seca east of Guadalupe Aguilera), but we cannot say if there isnt a gradient from the former ESU leading to this one. This needs forther studies. Chrau4 (Chrla3) is used for populations on the east bank of the Río Tunal in the triangle between Guadalupe Aguilera, Venustiano Carranza and Colónia Anohuác, namely the Laguna Seca spring and some others in its vicinity. Chrau5 (Chrla4) is a very uncertain ESU. It encompasses from the north the spring at San Vicente de los Chupaderos to habitats south of Victoria de Durango. There are no living populations known, so there is little chance to figure out relationships. In contrary to the former ESU, the next on, Chrau6 (Chrla5) is clear. Fish from the spring area north of 27. de Noviembre called Ojo Garabato and the spring at Abraham Gonzales, but maybe also springs south of 27. de Noviembre belong to this ESU. The only known population far south of Victoria de Durango in the Arroyo la Zorra at Pino Suarez, an affluent of the Río Mezquital, forms up the last nown ESU, Chrau7 (Chrla6).

Habitat: 

  The habitats of Characodon audax aremostly spring-fed ponds and small creeks with currents slight to none and substrates made of sand, gravel and deep silty mud. The species prefers depths from 0.2 to 0.5m. The vegetation in the habitats comprises mainly green algae, Duckweed (Lemna), Pondweed (Potamogeton) and Nymphaea.

 

  On a survey of the GWG in January 2015 to Durango, we found this species in several, partly completely diverging habitats. Within the area of the Laguna Seca, we were able to find this species in several springs, all of them with substrates of sand and mud, segmented with big rocks and without plants except a short aufwuchs on the rocks. All of these biotops were sinks with several springs coming out of the ground, oxgen level around 10mg/l with clear or murky water by activity of Tilapias, that were present in most of the springs. Some of these springs were very small and the populations in danger to become extinct. In Abraham Gonzales, we were not able to find Characodon in the main spring which is inhabited by predatory Micropterus, but found them on one place over floaded lawn, water depth less than 20cm and full with decomposing grass and organic matter. In El Toboso, the Ojo de las Mujeres spring was superficially dry, water came trough the soil. The outflow was occupied by Gambusia senilis ansd didnt reveal any Characodon. We were able to find them in the subsequent lagoons, were the water temperature was lower than in the outflow (around 19°C). over substrates of mud and sand and loose stocks of Potamogeton. We were able to find this species in the spring area of 27. de Noviembre called Ojo Garabato in clear mud dark and brown water. The only plants were riperian grass and reed, giving shelter to the fish from predatory Micropterus and Lepomis. The water temperature ranged from 17 to 21°C. We couldnt find this species in the outflow of the spring area near 27. de Noviembre, maybe because of cold water, but this maybe dountful as we were able to find fully active fish in the Arroyo La Zorra near Pino Suaréz at 8.7°C. This habitat is a sandy and slow flowing creek fragmented in several pools that partly become dry over the summer period. West of the Río Tunal we have seen this species in a spring on a private property in milky water in dense vegetation, depth approximately 1.5m and in the Arroyo Las Moras in San Rafael. The water showed no hardness at all probably because of the washing of laundry. Garbage was everywhere and the fish were hiding in dense vegetation, probably a Ludwigia species. The creek was swift floating and had a depth of about 30cm. The habitats at Los Pinos (a shallow very slow floating creek occupied by green algae) and San Vicente de los Chupaderos (a spring pool with reed over mud, occupied with predatory Procambarus clarkii and Lepomis) didnt reveal any Characodon. The spring at Cerro Gordo was dry. 

Colouration: 

  Characodon audax shows different colour-varieties, mainly the colour of its unpaired fins in males and the sides. Males are coloured olivaceous-greyish to light brown, depending on the variety. Some specimens show silvery scales on the side, mainly specimens from El Toboso. Adult males of this form are dark grey or black on the back, on the upper sides of the head and the lower body from the pelvic fins to the caudal fin. The sides have a black back-ground that is broken into a reticulated pattern by the scales. Dorsal fin, caudal fin and anal fin are mostly black, pectoral and pelvic fins on the interradial membranes.

Fish from other locations show the fins coloured deep reddish, sometimes bright yellow, with or without broad black margins. The variaty from Los Pinos is coloured crimson reddish on the posterior half of the body. The underside of the head and sometimes the breast are light yellowish to deep orange, or sometimes salmon, depending on the location of the fish. Adult females have olivaceous to greenish sides, but in some varieties light brown, also on the top of the head and the back. The scale centers are pale silvery. The region between the pelvics and the anal fin is greenish blue, extending upward as a wedge for a short distance. The back is dark olive (or grayish-brown or brown), the belly pale to bluish gray. A midlateral series of irregular (or regular, or very few) melanistic blotches extends from the upper limit of the opercular cleft to the caudal-fin base. Number and region of the most spectacular blotches differs between the varieties. In very rare cases, these blotches coalesce to form a solid midlateral stripe. The median fins are mostly clear but have a yellowish cast at the base that extends sometimes over the whole fin. Some females from the form of El Toboso show black unpaired fins.

Biology: 

  When Smith and Miller collected the species on 16. March 1982, they detected no young fish, but ovaries of examined females were containing embryos.

Diet: 

  There are some facts about the dentition of this species, but an unclear situation concerning the diet. We find mostly bicuspid teeth in the outer series of adult Characodon audax (a few smaller ones are conical) and small conical in the inner series. This dentition suggests an omnivorous feeding habit. Young fish have only conical teeth. Concerning the gut, we find authors describing it as short (suggesting a carnivorous tendency), others describing it as long (suggesting a vegetarian tendency). These different statements and different observations of feeding preferences in captivity leed to a diversity of care sheets, but it seems like Characodon audax is prefering Daphnia or other small invertebrates. However, it has been seen feeding on green filamentous algae in the wild, too, so probably this species is feeding omnivorous indeed, maybe with changing preferences in the growing, as the changemnt of the dentition suggests. 

Remarks: 

  This species has been described by Smith & Miller in the late 1980's from the vicinity of El Toboso. The specimens from this location display dark black unpaired fins. In the recent years, several populations of the genus Characodon along the Río Mezquital have been examined and  - following O. Dominguez - some of these populations are very close to the species from El Toboso. His results suggest, that these - in contrary to the El Toboso variety - red-finned populations belong to Characodon audax. They have been thought before to belong to Characodon lateralis due to its red colour. The still existing few populations of Characodon audax are:

 

Characodon audax "El Toboso"

It comes from a small spring-fed pond beside the village of El Toboso. The habitat comprises a tiny spring, followed by a small creek and a shallow pool, where the water soaks into the ground. This location is the type-location of this species and the only known population with totally black fins in males. Juan Miguel Artigas Azas reported in 2011, that pool and creek have been dry and the spring has been populated by Gambusia senilis, but no Characodon. At the beginning of 2012, a few specimens have been found behind a dam. This population was thought to may have disappeared in the wild, but seems to persist for the moment in small numbers.

 

Characodon audax "Abraham Gonzales/27 de Noviembre"

The location is 27km NE from Durango city at HW 43, eastern of the town of Abraham Gonzales. The habitats are small ponds and a small creek crossing the HW and ending near the town of 27 de Noviembre. This population shows different fin-colours in males, red fins as well as yellow ones, mostly with a very broad terminal black band in the caudal fin. Typical for males from this location seem to be a black (not red) anal fin, that isn't shown in males from other locations. The females display a noticeable irregularity in the arrangement of blotches.

 

Characodon audax "Guadalupe Aguilera/ Laguna Seca"

The locality is near the town of Guadalupe Aguilera, some 60km N of Durango city, in the valley between Guadalupe Aguilera and Venustiano Carranza, at a place called Laguna Seca (dry pond). A spring fed tiny creek and a shallow pool. The spring at the base of a low mountain flows in a small creek and ends one hundred meters after the spring in a swampy area and finally in a shallow pond that is absorbed by the valley ground. Most of the fish inhabit the creek and the spring, very few can be found in the swamp or the lagoon. The reason therefore seem to be introduced Tilapia. The males from this population are coloured bright red, sometimes yellow. Females display a regular row of blotches down to very few. The number of blotches is very variable.

 

Characodon audax " Los Pinos"

It has been inhabiting the headwaters of the Río Canatlán, an upper affluent of the Río Tunal above the Penon del Aguila dam, about some 16km N of the town of Canatlán by HW 39. The whole habitat is a lame remnant of a creek not more populated with Characodon. This is the most northern population, coloured red from the tail anteriorly to the mid of the body with black blotches on the sides in both sexes and dark edged fins. Especially a broad black edged Dorsal fin in the male gender is noticable. The ground colour is lighter than in the very similar looking population from Guadalupe Aguilera, tending to a dark orange-red. The females resemble very close the females from Guadalupe Aguilera.

 

Characodon audax "Puente Pino Suarez"

Recently detected (in 2006). The location is about 25km south of Durango, at the highway from Durango to Mezquital. The location is called "El puente en el poblado de Pino Suarez" and is not exactly at the given GPS-location (23°52'43.5'' N; 104°31'54.7'' W). The rare photos show fish with silvery sides (without blotches) and red Caudal fins. At the Aqualab in Morelia have been kept two males for some time, but no females. At the moment, there are no more data available. In February 2012, James Langhammer reported from a new sampling there (pers. comm. 2012).

 

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 Los 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."

 

In the late 1990's, it was said, that some specimens from a population from San Vicente de los Chupaderos were collected by American aquarists and - after the population disappeared in the wild - a stock was still remaining. J. Langhammer, the greatest specialist for Characodon, examined photos of these fish and identified these fish as Characodon lateralis "Los Berros"(pers. 2010). Therefore, this variety of Characodon audax must be treated as extinct.

 

In December 2011, the Goodeid Working Group decided to create a project, called "Christmas for Characodon" to evaluate all known populations of Characodon, including both remaining species, and to concentrate efforts to save all existing populations and the remaining habitats. 

First Describer: 
Smith & Miller, 1986