"Xenotoca" cf. melanosoma

Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Xenotoca melanosoma
Original Description: 

  undescribed species

English Name: 
Northern Black Splitfin
Mexican Name: 
Mexclapique negro del norte
Status after IUCN: 

  not assessed

Status following other sources: 

  assessed as "Xenotoca" melanosoma: Threatened; Comment: Stable since 2000

Distribution and ESU's: 

  This undescribed species is widely distributed but sparse on the Pacific Slope, inhabiting the ríos Grande de Santiago and Ameca. Furthermore, it can be found in the endorheic basins of Etzatlán, Magdalena, Zacoalco, San Marcos, Atotonilco and Zapotlán. All habitats are in Jalisco. The populations from the ríos Ayuquila (Armería basin) and Tamazula and Tuxpán (Coahuayana basin) represent a distinct line and encompass the "true" melanosoma.

 

  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.

 

  In "Xenotoca" cf.  melanosoma we are able to distinguish several ESU's. Xenme1 is used for nearly all populations from the endorheic basins of Etzatlán and Magdalena as well as for the ríos Grande de Santiago and Ameca populations. We have to be careful as fish from Etzatlán and Magdalena look very different, so this ESU is in need of evaluation. Xenme4 is restricted to the spring of Estancia de Ayones, but it resembles the Magdalena populations though the colouration is more distinct. This population has to be included in an evaluation as well. Xenme2 seems to be clear and encompasses all populations from the endorheic basins from Atotonilco down to Zapotlán, more or less all the Sayula valley populations. Xenme3 is in use for the "true" melanosoma from the ríos Ayuquila, Tamazula and Tuxpán.  

Habitat: 

  This species lives in ponds, streams and lakes with clear to muddy water (sometimes badly polluted) over substrates of mud, sand, gravel, rocks, boulders and bedrock. There is eiher no vegetation or green algae, Armoracia, Cyperus, Eleocharis, Potamogeton, water hyacinths, Lemna, Nasturtium, Scirpus and Typha. The currents are none to moderate.

 

  On a survey in 2016, we found representatives of this species in a clear spring on a private property in la Estancia de Ayones between waterplants of the genera Potamogeton, Eleocharis and Myriophyllum. The diameter of the spring was about ten meters. Other species were Goodea atripinnis, Zoogoneticus purhepechus, Poeciliopsis cf. infans and Tilapia. In an artificial fish pond opposite Palo Verde lagoon, the species lived in plantless muddy water together with Zoogoneticus purhepechus, Goodea atripinnis, Allotoca maculata, Poeciliopsis infans and again Tilapia and Pseudoxiphophorus bimaculatus. A similar habitat was the spring pool at the Hacienda San Sebastian, the type location of "Xenotoca" doadrioi. At Almoloya spring we found a single specimen in brownish and little murky water. The species was associated with Ameca splendens, "Xenotoca" doadrioi, Zoogoneticus purhepechus and Goodea atripinnis as well as Pseudoxiphophorus bimaculatus and Tilapia. Another habitat was the Presa Quemada north of the Magdalena lake. We found the species over gravel in turbid water, moved by strong winds. It was associated with Goodea atripinnis, Poeciliopsis infans and Tilapia.

Like most of the Goodeids, it prefers depths of less than 1m. It seems to be not very abundant in the habitats as it is rarely observed, though in  the Presa Quemada and San Sebastian spring, we were able to count a high number of individuals.

 

Balneario Al Moloya IBalneario Al Moloya II

 

Manantial en La Estancia de Ayones IManantial en La Estancia de Ayones II

 

Presa Quemada IPresa Quemada II

 

Pool at Palo Verde IPool at Palo Verde II

 

Hacienda San Sebastian IHacienda San Sebastian II

Colouration: 

  The colouration can be very similar to the one we see in "Xenotoca" melanosoma, at least in populations from the endorheic area of Etzatlán. Populations from the endorheic Magdalena basin are brighter in colour, sometimes light grey or tan (Almoloya, San Sebastian) to even silvery white (Presa Quemada), all of them with a small number of vertical dark grey bares on the caudal peduncle. The upper half of the body is darker, the belly can be almost white. The population from la Estancia de Ayones differs by feamles showing even in big individuals a reticular dark brown pattern in tan ground, when afraid reducing it to the obliagte bars on the peduncle. Males reduce this pattern to dark  blotches on the back on tan ground and rows of black edges scales on the sides, the back overlaid by a bluish glance. Both sexes show a dark broad band on the peduncle. All in all, this species has got different looks depending on the habitat. Even the body shape varies from slender and brawny (La Estancia de Ayones)  to more delicate but high bodied (Presa Quemada), or sometimes high bodied and brawny (Etzatlán).  

Biology: 

  Young have been captured late spring, indicating a reproduction from at least March to May.

Diet: 

  The dentition is similar to "Xenotoca" eiseni suggesting an omnivorous feeding behaviour, nevertheless feeding predominantly on aquatic animals and lesser amounts of algae.

Husbandry: 

  Looking on the habitats of "Xenotoca" cf. melansoma, they suggest the species is not in need of a special habitat structure as many of the locations show no or little vegetation but murky water. Nevertheless, it may prefer dense vegetation and roots (in the aquarium even dense artificial staff) to hide. In the wild, the species occurs in rivers, ponds and springs, but always prefering the quiet parts with little current, so it won't be necessary in the aquarium to have strong current. In the aquarium, the fish often hide in the shelter, but courting and impressing males as well as fighting fish of both sexes can often be seen in the open water. Fry is eaten in many cases, rarely not, so it may depend on the quantity and quality of food and on the number of space to hide. When several different stages of juveniles occur, fry is often neglected, so it makes sense to add separate brought up fry to the group with a size of 1.5 or 2cm to provide these stages and get a flock breeding colony.

  The recommended tank size is at least 150 liters, bigger ones are better for sure. Dense vegetation combined with many roots and wood and free space areas for the males to impose and fight make sense. The current should be low.

  In the wild, the species seem to feed as a typical omnivore from small and middle sized invertebrates, aufwuchs, algae, organic matter, smal fish and insects from the surface. "Xenotoca" cf. melanosoma can be fed in the aquarium with food of different sources, composed of different small or middle sized frozen or freeze dried invertebrates (Daphnia, Bloodworms, Artemia), small and middle sized livefood (e.g. Nauplia, Cyclops, Daphnia, Bloodworms. little rainworms, little fish) and good flake food or tablets respectively granulat food. Fish of the "Xenotoca" melanosoma - complexe feed from less vegetarian sources than representatives of the "Xenotoca" eiseni - complexe.

   Concerning water quality, this species is in need of greater water changes (60 - 80% every week), so an automatic water changing system can be helpful. Otherwise, in combination with constant temperatures higher than 24°C, fish may get sick, lose resistance against diseases and burn themselves out. So, mainly for keeping the strain healthy and strong, give the fish a rest during winter time with temperatures lower than 20°C for 2 or 3 months so they stop producing fry. In spring, when the temperature slowly increases, they will start spawning at 20 or 21°C and won't stop until it gets colder again or gets too warm (25°C?).

  This species does very well when is kept in the open from spring to fall, starting when the temperature exceeds 17°C water temperature and cold periods are no longer expected. During the warm summer, reproduction will stop and may occur again in fall. Bring the fish in before the temperature goes below 15°C water temperature and keep them cool for the first days, then slowly raise the temperature but try to stay below 20°C over the winter time.

 

 

 

 

Locations