Xenoophorus captivus

Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Xenoophorus captivus
Original Description: 

  HUBBS, C. L. (1924): Studies of the Fishes of the Order Cyprinodontes. V. Notes on Species of Goodea and Skiffia. Occasional Papers of the Museum of Zoology University of Michigan No 148: pp 1 - 8

Etymology: 

  The species name is derived from the Latin and means "captured". Hubbs didn't explain, why he had chosen that name, but he wrote about the habitat in the original description: "...from which (rem.: Goodea atripinnis) it has doubtless been derived by isolation following stream capture." He indicates on the origin of this fish from the Río Lerma and the change in the current of the Río Panuco, that the Río Panuco has captured  - metaphorically spoken - this species from the Río Lerma.

Holotype: 

  Collection-number: Field Museum of Natural History, Cat. No. FM-5557.

  The Holotype is an adult male of 46mm SL, collected by S.E. Meek in 1907.

English Name: 
Relict Splitfin
Mexican Name: 
Mexclapique viejo
Synonyms: 

Goodea atripinnis   Meek, 1907 (partially, for specimens from Jesus Maria)

Goodea captiva   Hubbs, 1924

Xenoophorus erro   Hubbs & Turner, 1937

Xenoophorus exsul   Hubbs & Turner, 1939

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 Xenoophorus captivus, following Uyeno, Miller & Fitzsimons, 1983:

2n = 48    2sm/ 4st/ 42stt  

Size: 
The maximum known SL is 66mm (Miller et al, 2005).
Terra typica: 

  The Holotype comes from "a small stream at Jesus Maria, which belongs to the Río Panuco system" in San Luis Potosí.

Status after IUCN: 

  Endangered

Status following other sources: 

Endangered; Comment: Declining since 2000

Distribution and ESU's: 

  This species comes from the Atlantic Slope and from endorheic basins, more precisely spoken from headwaters of the Río Santa María above Santa María del Río ( Río Panuco basin), a small spring-fed stream near the northern end of Valle San Luis Potosí and at Illescas, northeast of Zacatecas in San Luis Potosí and Zacatecas.

Habitat: 

  The habitats are springs and their outflows, small streams and ditches. This species lives over substrates of silt, mud, clay, sand, gravel and rocks in clear to murky water. It prefers depths of less than 1m with currents slight to moderate. Aquatic vegetation is comprised of the ubiquitous green algae and Lemna, Eichhornia, Ceratophyllum, Nasturtium and Potamogeton. Concerning water temperatures, there are given different details, correlated with different habitats. Lundell et al (1934) reported a cold mountain stream (Agua del Medio) and cold habitats near Venado and Moctezuma, whereas Fitzsimons reported in 1979 many springs with "for reproduction convenient temperatures".

 

Moctezuma IMoctezuma II

 

Moctezuma IIIMoctezuma IV

 

Venado IVenado II

 

Venado IIIVenado IV

Colouration: 

  Males are coloured dark-brown to black, throat and venter are lighter. The unpaired fins are dark-grayish to nearly black, the caudal fin has a thin clear to yellowish terminal band. The scales on the sides, but mainly on the caudal peduncle, have a striking green glimmer. Pectorals and Pelvic fins of courting males have a bluish appearance. Young, but mature males and females show a midlateral dusky band, superimposed by glimmering scales in older males. A second dark band has got its origin behind the anal fins and ends on the caudal peduncle. It is also superimposed in older females by green glimmering scales.

Biology: 

  Indicated from collections, the reproduction period extends from February to July. In populations inhabiting warm springs, young may be born year-round (Fitzsimons 1979).

Diet: 

Xenoophorus captivus is a species with vegetarian feeding habits, suggested by the much convoluted intestine and the incisor-like teeth in the outer row.

Remarks: 

Hubbs and Turner described two additional species (though they indicated in 1939, that they may be seen as subspecies after more detailed examination), namely exsul and erro. These "species" differ mainly in size and shape of the head. Too less details to see them as distinct species, and following Artigas-Azas, some of the habitats of the 3 types are connected in the wet season. The name erro means "wanderer", because it left away from the Río Lerma, the center of Goodeid distribution, and exsul "in exile". So both names have similar meanings as the name given by Hubbs in 1924. This indicates the selection of the name captivus in the original description of this species.

 

Xenoophorus captivus has been described from specimens Meek collected in 1907 and refered to Goodea atripinnis. Hubbs detected the mistake and described this species about 15 years later.

 

Though the Karyotype of this species is similar to Goodea (and it has been also placed in the vicinity of this genus), the nearest relative may be Xenotoca variata.

 

Samplings in 2003 revealed that only 4 from the historical documented 7 sites are still inhabited with small populations. Decreases in the water level and the drying of springs coupled with water pollution are probably the main reasons for the species' decline.

Husbandry: 

  Looking on the habitats of Xenoophorus captivus, they suggest the species may prefer dense vegetation and roots (in the aquarium even dense artificial staff) to hide. In the wild, there was little or swift current to observe in the biotops, so it will be necessary to provide some in the aquarium as well. In the aquarium, the fish often hide deep in the shelter, but courting and impressing as well as fighting males can often be seen in the open water. Fry is eaten in some cases, in others 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 80 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 from algae and aufwuchs. Xenoophorus captivus was observed at Moctezuma feeding from algae and/ or aufwuchs in a depth of about one meter in swift current, at Vendo it was hidden in dense vegetation in very shallow water (10cm), but not in the open water (Köck, 2014). In the aquarium, the food should be composed of different small frozen or freeze dried invertebrates (Daphnia, Bloodworms, Artemia), small livefood (e.g. Nauplia, Cyclops, Daphnia) and good flake food or tablets respectively granulat food. However, the main source should be vegetarious and the quanitity of bloodworms quite low. A good solution to produce algae balls is to place stones in a bowl with water in front of the window. Best is to take water from a pond or an aquarium. When algae and aufwuchs grow, put one of these stones to the Xenoophorus and they will feed from it. When articila food is taken, wafers or tablets for Loricarids are very good, also flake food with a high percentage of fibre and reduced fat and proteine.

 

  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 was found in the wild at very low temperatures, sometimes not even 10°C (Kabbes, Slaboch).

 

  This species does very well when is kept in the open from spring to fall, starting when the temperature exceeds 15°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 10°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