Xenotaenia resolanae

Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
Xenotaenia resolanae
English Name: 
Leopard Splitfin
Mexican Name: 
Mexclapique leopardo
Original Description: 

  TURNER, C. L. (1946): A contribution to the Taxonomy and Zoogeography of the Goodeid Fishes. Occasional Papers of the Museum of Zoology University Michigan No. 495: pp 1-15

Holotype: 

  Collection-number: University of Michigan Museum of Zoology, Cat. No. UMMZ-143024.

  The Holotype is a mature female of 34mm SL, collected by B. C. Turner, 29.03.1939.

Terra typica: 

  The Holotype comes from a tributary to the Río Purificación, the Río Resolana, about 25 miles SW of the town of Autlan in Jalisco.

Etymology: 

  The species is named after the type-locality, the Río Resolana in Jalisco.

Synonyms: 

  none

Distribution and ESU's: 

  This species comes from the Pacific Slope, from the basins of riós Cuitzmala, Purificación and Chacala (= Cihuatlán or Marabasco) in the states of Jalisco and Colima.

 

  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.

 

  Xenotaenia resolanae inhabits two river systems being isolated from each other. Those systems lead to two different ESU's. Fish from the southern one, the Río Marabasco with its tributaries (ríos Cuautitlan and San Antonio, and the arroyos Las Marias and El Durazno) belong to Xenre1, whereas fish from the northern one, the Río Purificacíon (with Río Resolana and the arroyos Tecolote and El Conejo) belong to Xenre2.

Status : 

  International Union for Conservation of Nature (IUCN): not assessed

 

  Conservation status and population trends of Mexican Goodeids (Lyons, 2011): vulnerable/stable –This species is known historically from a total of 16 locations. Within the Purificación River basin, water pollution from sugar mill discharges, human sewage, and animal wastes had eliminated or reduced most populations by the 1980s, but since then remaining populations seem to have stabilized (Lyons and Navarro-Pérez 1990; Lyons 1996; Domínguez-Domínguez et al. 2005b). In the upper Marabasco River basin, which has less human development, the species has seen little decline, although most populations are small. Overall, about 10 total populations still exist.

 

  NOM-059-SEMARNAT-2010: no categoría de riesgo (no category of risk)

Habitat: 

  Xenotaenia resolanae can be typically found in pools of clear to turbid streams, over substrates of silt, mud, sand, rocks, leaves and bedrock or boulders. Except  green and brown algae and Potamogeton, Eichhornia and Ceratophyllum, there can be usually found no aquatic-vegetation. The currents are none to slight or moderate. It prefers depths less than 1m, typically not under 0.5m. The temperature in March and April 1975 had been between 22.8 and 25.6°C. Miller described a habitat of this species shadowed by trees.

Biology: 

  Miller caught young fish in March and April (1975), 13 and 14mm long. In captivity, it produces every month except August and December (Kingston 1979), suggesting a long reproductive period.

Diet: 

  The gut is relatively short (0.85% of the total length) and the teeth, as well as the jaws are very strong. The anterior row is bifid. The gut suggests a carnivorous feeding habit, the teeth might be an indication for omnivorous feeding habits, however with prefering small invertebrates.

Size: 
The maximum known SL is 76mm (Miller et al, 2005).
Colouration: 

  The ground-colour is greenish-vellow, the dorsal part more greenish, the venter yellow. In younger specimens the posterior halves of the scales are darkened by brown and black pigment cells above the lateral line for the entire length of the body and in the belly region for some distance. Along the lateral line there are about 15 irregular patches. In older specimens, these dark patches often become broken up or disappear, whereas the markings upon the individual scales dorsal to the lateral line become more conspicuous. The posterior edges of the scales on the upper part of the body have a metallic glimmer. There are 3 irregular, vertical brownish bars on the caudal fin with many whitish dots between them . The posterior margin of the dorsal fin is edged sparsely with light brown and the tips of the pelvic fins are white. Pectoral fins and anal fin are clear.

Remarks: 

  Turner noted, that the head is unusually long in proportion to the total length and that the caudal peduncle differs little from the other species in proportion to the length. These facts together indicate, that the body in relation is much shorther than in other species.

 

  Xenotaenia resolanae is closely related to Ilyodon and Allodontichthys species and comprises the western-most distributed representative of Goodeids.

 

  Water pollution is threatening this species, too, and it has disappeared from several main localities in the Río Purificación basin.

 

  I observed several times males slowly spreading one of its striking white ventrals, but never seeing doing this during courtship. But nevertheless it might be used as a way to attract females. Further observations could be interesting in this context. 

Locations