Characodon audax

First Describer: 
Smith & Miller, 1986
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Original Description: 

SMITH, M.L. & MILLER, R.R. (1986): Mexican Goodeid Fishes of the Genus Characodon, with Description of a New Species. Am. Mus. Novit. 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: 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
Synonyms: 

Characodon sp.   Radda, 1984

Karyotype: 

2n = 24    24M   (following Uyeno, Miller & Fitzsimmons, 1983)

Terra typica: 

The Holotype-location is a spring-fed pond called El Ojo de Agua de Las Mujeres, 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 after J.Lyons (2011): 

Endangered; Comment: Assigned new populations

Distribution: 

This species is only known from some locations along the upper part of the Río Mezquital (above the waterfalls of El Salto) in Durango.

Habitat: 

The habitats of Characodon audax are mostly 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.

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. 

Photos: 

Image 1: male from El Toboso

Copyright by Frank Kroenke

Image 2: male from El Toboso, pond raised

Image 3: male from El Toboso

Copyright by Omar Domínguez Domínguez

Image 4: female from El Toboso

Copyright by Omar Domínguez Domínguez

Image 5 and 6: males from El Toboso

Image 7: male from El Toboso

Image 8: male from El Toboso

Image 9: female from El Toboso

Images 10 and 11: females from El Toboso

Images 12 and 13: males from Guadalupe Aguilera

Copyrights by Frank Kroenke

Image 14: male from Guadalupe Aguilera

Copyright by Gunter Teichmann

Image 15: male from Guadalupe Aguilera

Image 16: yellow-finned male from Guadalupe Aguilera

Copyright by Gunter Teichmann

Images 17 and 18: red and yellow caudal fins from males from Guadalupe Aguilera

Copyright by Gunter Teichmann

Images 19, 20 and 21: spawning pair from Guadalupe Aguilera

Copyrights by Frank Kroenke

Images 22 and 23: group of fish from Guadalupe Aguilera

Copyright by Gunter Teichmann

Images 24 and 25: females from Guadalupe Aguilera

Copyright by Frank Kroenke

Images 26 and 27: males from Abraham Gonzales

Copyrights by Gunter Teichmann

Image 28: fish from Abraham Gonzales

Copyright by Gunter Teichmann

Image 29: female from Abraham Gonzales

Copyright by Gunter Teichmann

Image 30: male from Abraham Gonzales

Image 31: pair from Abraham Gonzales

Images 32 and 33: male from Abraham Gonzales

Image 34: female from Abraham Gonzales

Image 35: male from Los Pinos

Copyright by Gunter Teichmann

Image 36: female from Los Pinos

Copyright by Gunter Teichmann

Image 37: male from Los Pinos? more probably from Puente Pino Suarez

Image 38: young male from Abraham Gonzales

Copyright: Anton Lamboj

Image 39: young female from Los Pinos, but rather probably Puente Pino Suarez

Copyright: Anton Lamboj

Images 40 and 41: male from Los Pinos (?), rather probably Puente Pino Suarez

Copyright: Anton Lamboj

Images 42 - 44: males from Los Pinos

Copyright: Anton Lamboj

Images 45 - 47: females from Los Pinos

Copyright: Anton Lamboj