Characodon lateralis

Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Characodon lateralis
Original Description: 

  GUENTHER, A. (1866): Catalogue of the Physostomini. Catalogue of Fishes of the British Museum 6: pp 1 - 368

Etymology: 

  The species name is derived from the Latin. It means "on the sides" and refers to the lateral stripe in the colour pattern (mainly visible in preservation).

Holotype: 

  Collection-number (probably): British Museum of Natural History, Cat. No. BMNH-1855-9-19.

  The Holotype is a female of 56mm total length, collected by B. Seeman.

English Name: 
Rainbow Characodon
Mexican Name: 
Mexclapique arcoiris
Synonyms: 

Characodon garmani   Meek, 1904

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 lateralis, following Uyeno, Miller & Fitzsimons, 1983:

2n = 24    24M  

Size: 
The maximum known SL is about 63mm (Miller et al, 2005).
Terra typica: 

The Holotype comes from - following Guenther " Southern Central America". This is definitely wrong. 

Status after IUCN: 

Critically endangered

Status following other sources: 

Endangered; Comment: Lost populations to C. audax

Distribution and ESU's: 

  Characodon lateralis is distributed in habitats along the lower part of the Río Tunal below the waterfalls of El Salto in Durango. One center is between the Río Tunal and the Río de Nombre de Díos, the second one was more eastern at Amado Nervo.

 

  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 lateralis we are able to distinguish twoESU's. The first one, Chrla1 (Chrla7) is in use for the fish of the more northen and bigger area of distribution, including populations of springs in San Juan, Los Berros, La Constancia and Nombre de Díos (concerning the abbreaviations in brackets, please get the explanation from Characodon audax). Some of these populations are extinct, but at least the ones in Los Berros and La Constancia remained. The sond ESU, Chrla2 (Chrla8) was found in a small spring and its outflow in Amado Nervo, a small town east of Nombre de Díos. It has to be treated as extinct in the wild.

Habitat: 

The habitats are similar to the ones, Characodon audax inhabits: Marshy pools, spring-fed ponds, springs and their outflows with abundant submergent vegetation (Myriophyllum, Ceratophyllum, Potamogeton and Scirpus). Concerning the substrates predominate silt, clay, mud, sand, soft marl, gravel and rocks. The currents are usually slight to none, occassionally moderate, the water is clear to turbid. The Rainbow Characodon prefers depths of less than 0.5m.

Colouration: 

Characodon lateralis is a very colourful species. The population from Los Berros is olive-brown in both sexes. Females show 2 to 7 prominent dark blotches in the midline, mostly not reaching the caudal peduncle. The lower part of the head until the origin of the anal fin is coloured creme or yellowish, the opercle has got a green glimmer, the belly is bluish. The fins are yellowish in adults with a black terminal band and clear in younger females. The males show red unpaired fins, changing the colour before the black terminal band into yellow. The body sides are coloured reddish, becoming deep red in older males. The scales are bluish-green. Older males appear more red than younger ones. The midline shows very few dusky and diffuse blotches and a broad and dusky lateral band. The area behind the opercle is more prominent dark. The belly from the snout to the origin of the anal fin is coloured mainly creme or yellowish, the opercle with a greenish glimmer. The population from Amado Nervo is coloured greenish-gray in both sexes, the red-finned males have a red caudal fin and the base of anal fin and dorsal fin coloured red, fadding to the end. The area above the anal fin is coloured red. A lateral band, formed by irregular blotches extends from the opercle to the caudal fin, becoming more prominent posteriorly and forming a black area on the caudal base. Clear-finned males and females appear totally greenish-gray without colourful markings. Both show 3 to 11 black blotches on the sides with the origin in the mid of the body and extending posteriorly. The opercle has got a greenish glimmer.

Biology: 

Young were captured from 0.8 to 11mm SL between 13 March and 2 September. This indicates a protracted reproductive season extending from at least early March through August. At least in one habitat (Ojo de agua de San Juan), the fish moved about in large aggregations in shallow water, retreating to deeper places when disturbed (Fitzsimmons 1972).

Diet: 

There are some facts about the dentition of this species, but an unclear situation concerning the diet. We find mostly bicuspid teeth (and tricuspid) in the outer series of adult Characodon lateralis (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). Günther mentioned 1866 the inestinal tract "but slightly convoluted" (suggests omnivorous feeding habits). These different statements and different observations of feeding preferences in captivity lead to a diversity of care sheets, but it seems like Characodon lateralis is prefering Daphnia or other small invertebrates. However, it has been seen feeding on green filamentous algae (Spirogyra, Ulothrix) in the wild, too (Fitzsimmons 1972), so probably this species is feeding omnivorous indeed, maybe with changing preferences in the growing, as the changement of the dentition suggests. Intestinal content has been made of filamentous chlorophytes, cyanophytes, pennate diatoms and oligochaets.

Remarks: 

This fish disappeared from a large part of its original range by pollution of the Río Mezquital through the big company Celulosas de México. As far as we know, there are only two location centers left:

 

Characodon lateralis " Los Berros"

Characodon lateralis inhabits 3 springs in the vicinity of Los Berros: The springs El Ojo de agua de San Juan (23°57'102'' N lat. and 104°16'121" W long.), El Ojo de Agua Los Berros and the tiny spring La Constancia. Water is abundant and clear and pollution is unlikely in the San Juan-spring. The spring is 100 x 20m in diameter, full of aquatic vegetation and used for picnic places. La Constancia is not much bigger than a bathtub, located on a private area and definitely used as a bathing pool.

 

The aquarium strain of Characodon lateralis cannot be assigned to one locality and might be mixed up from different localities. Some strains show very red males whereas wild-caught males often display red only on the venter (at least the population of Ojo de Agua Los Berros).

 

Characodon lateralis "Amado Nervo"

This population lives only in a small creek, that is running among large trees, over a bed of sand and mud and crossing the town of Amado Nervo. The habitat is strongly polluted. There is no aquatic vegetation except green algae. This is a very interesting population. Not only because of its resemblance of Characodon garmani, but also because there can be found two different colour varieties in males. Few males with a red caudal fin and red colour on the base of anal and dorsal  fin, and the majority coloured yellowish-gray without bright colour markings in the fins and resembling females in colour pattern. The social behaviour of this species is poorly understood. Certainly in nearly all red finned populations of Characodon audax, we can find different coloured males, encompassing individuals with red coloured fins as well as brown-grayish ones with yellow fins, or sometimes even brownish fins.

 

This population is in high danger of extinction in the wild. In 2011, the creek has been nearly completely overwhelmed by terrestrial vegetation and only one juvenile male could be collected. Probably, after last samples in 2012 revealed not a single fish, it is extinct in wild already.

 

Last presumptions deal with the possibility of this population being a distinct species. New studies on Characodon should reveal the relationship among the members of the whole genus and the position of this form.

 

Characodon lateralis "Nombre de Díos", former living in a spring W of the town of Nombre de Díos disappeared out of unknown reasons. It must be treated extinct like many other populations of Characodon lateralis.

 

Günther described this species from specimens at the British Museum in "Dr. B. Seeman's collection, who obtained them from Southern Central America" and himself, in 1869, he remarked on the inadequacy of the localities of Seeman's collection. J. M. Fitzsimons suspected in 1972, that this wrong given locality led finally to the "unnecessary" (he synonymized garmani and lateralis) description of Characodon garmani from Parras by Jordan & Evermann in 1898, and again by Meek in 1904 for specimens from Durango.

 

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: 
Günther, 1866