|Scientific Name:||Pachypanchax varatraza Loiselle, 2006|
Pachypanchax sp. nov. 'Varatraza'
|Taxonomic Source(s):||Loiselle, P.V. 2006. A review of the Malagasy Pachypanchax (Teleostei: Cyprinodontiformes, Aplocheilidae), with descriptions of four new species. Zootaxa 1366: 1-44.|
|Taxonomic Notes:||This species was submitted as Pachypanchax sp. nov. 'Menambery' and subsequently changed to Pachypanchax sp. nov. 'Varatraza' on recommendation of Paul Loiselle and published on The IUCN Red List in 2004. The species was subsequently formally described and named (Loiselle 2006).|
|Red List Category & Criteria:||Endangered B1ab(iii) ver 3.1|
|Assessor(s):||Ravelomanana, T. & Sparks, J.S.|
|Reviewer(s):||Raminosoa, N., Randrianizahaisa, H. & Rasoloariniaina, R|
This species has been recorded from rivers on the eastern slopes of Madagascar from the Manambato to the Ampanobe. It has a restricted range (extent of occurrence is less than 5,000 km²), and is known from less than five locations. With habitat degradation (deforestation of the catchment area) also reported in some parts of its range this species is assessed as Endangered.
|Previously published Red List assessments:|
|Range Description:||Endemic to Madagascar, Pachypanchax varatraza is native to the basins of the Menambery, Fanambana and Ampanobe rivers in northeastern Madagascar (Loiselle 2006). Andriantsoa (pers. comm.) reported some subpopulations from the Loky and Manambato rivers.|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species has a restricted range and has been recorded from rivers on the eastern slopes of Madagascar from the Manambato to the Ampanobe.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:|
Pachypanchax varatraza inhabits a wide range of habitats. The Menambery population was collected from the Andampy, a small stream flowing under relatively intact forest cover at an altitude of 70 m above sea level. At this point, the stream consists of a series of quiet pools with clay/sand bottoms, interspersed with short stretches of flowing water over sand/gravel bottoms. The water was very turbid, with ca. 20.0 cm visibility, slightly acidic (pH: 6.5), soft (general hardness < 18.0 ppm, carbonate hardness 36.0 pp), with a conductivity of 49.0 ìS/cm². Extensive stands of Marsilea sp. were present in the shallows of flowing stretches of the stream. Neither filamentous algae nor other aquatic macrophytes were observed. Representatives of the Ampanobe basin population were collected from the Mahazava, a small stream flowing through modified low-altitude rain forest at an altitude of 30 m above sea level. The bottom was clay/sand, interspersed with patches of bedrock. The water was clear and the current moderate. No aquatic macrophytes or attached algae were observed (Loiselle, 2006).
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Movement patterns:||Not a Migrant|
|Use and Trade:||No use or trade information is available for this species.|
This species has been extirpated from the lower reaches of the Menambery, Fanambana and Ampanobe rivers by an exotic predator, Channa maculata. It persists in one high-gradient tributary of the upper Menambery, whose watershed lies in a surviving patch of forest. As a result of deforestation, the remaining headwaters tributaries of this river are devoid of water during the dry season, and thus are no longer viable Pachypanchax habitats. The basin of the Fanambana is subject to the same sharply seasonal pattern of precipitation, but as its watershed is not deforested to the same degree as that of the Menambery, habitat loss has not affected P. varatraza as seriously. Ampanobe River watershed benefits from a less seasonal pattern of rainfall and retains most of its forest cover. While the presence of G. holbrooki in the middle and upper reaches of the Ampanobe is cause for concern, the dominance of vanilla culture in the local economy strongly discourages extensive deforestation. This should prevent the large-scale habitat loss that has negatively impacted P. varatraza in the Fanambana drainage and threatens its survival in the Menambery (Loiselle, 2006).
|Conservation Actions:||Part of the population is included in Loky-Manambato protected Area.|
|Citation:||Ravelomanana, T. & Sparks, J.S. 2016. Pachypanchax varatraza. The IUCN Red List of Threatened Species 2016: e.T44485A58307388.Downloaded on 26 September 2018.|
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