Iberochondrostoma olisiponensis

Scope: Global

Language: English

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Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
Animalia	Chordata	Actinopterygii	Cypriniformes	Cyprinidae

Scientific Name:

Iberochondrostoma olisiponensis (Gante, Santos & Alves, 2007)

Common Name(s):

English

–

Lisbon Arched-mouth Nase

Synonym(s):

Chondrostoma olisiponensis Gante, Santos & Alves, 2007

Assessment Information [top]

Red List Category & Criteria:	Critically Endangered B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) ver 3.1
Year Published:	2012
Date Assessed:	2010-08-19
Assessor(s):	Gante, H., Santos, C.D., Alves, M.J. & Rodrigues, J.
Reviewer(s):	Snoeks, J. & Pollock, C.M.
Justification: The Lisbon Arched-mouth Nase is restricted to three small rivers, with its extent of occurrence estimated to be less than 10 km² and area occupancy of ca. 3 km². Its distribution is highly fragmented with little or no contact between the three subpopulations. One of the subpopulations is known to be severely declining over the last two decades. Historical records in additional tributaries, where the species no longer exists, indicates a contraction of the extent of occurrence. The species is rare within its range and it is affected by high human pressure on water resources (including water extraction for agricultural purposes); presence of exotic species; industrial, domestic and agricultural sources of pollution; and land reclamation. These threats are especially problematic during extreme drought events, which lead to an overall degradation of habitat quantity and quality. Furthermore, the species was found to hybridize with a critically endangered sympatric relative (Iberochondrostoma lusitanicum) (Gante et al. 2010). Continued introgression from this comparatively more abundant species could lead to its genetic dilution.

Geographic Range [top]

Range Description:

This species occurs only in restricted areas of three small tributaries in the terminal portion of the Tagus (Tejo) River Basin in Portugal. These are Rio Trancão, Rio Maior and Ribeira de Muge (Gante et al. 2007, 2010). Material available in museum collections confirms its presence in historical times in two additional tributaries in which present day populations have not been found (Ribeira de Ulme and Ribeira de Magos) (Gante et al. 2007). This suggests that the species’ areas of occurrence and occupancy are likely regressing. Many other tributaries of the Tagus (Tejo) River have been sampled over the years but no additional subpopulations have been found. Further sampling effort in the tributaries where the species occurs was unsuccessful in finding more individuals, indicating a very restricted area of occupancy.

Conservative area calculations of the extent of occurrence (i.e., assuming that the species can be found in all of the extent of the basins where it was found) indicate an area below 10 km². The area of occupancy, based on proven occurrence or the presence of adequate habitat, is ca. 3 km².

Countries occurrence:

Native:

Portugal (Portugal (mainland))

Additional data:

♦ Estimated area of occupancy (AOO) - km2:	4	♦ Continuing decline in area of occupancy (AOO):	Yes
♦ Extreme fluctuations in area of occupancy (AOO):	No	♦ Estimated extent of occurrence (EOO) - km2:	4-10
♦ Continuing decline in extent of occurrence (EOO):	Yes	♦ Extreme fluctuations in extent of occurrence (EOO):	No
♦ Number of Locations:	3-4	♦ Continuing decline in number of locations:	Yes
♦ Extreme fluctuations in the number of locations:	No

Range Map:

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Population [top]

Population:

The exact size of subpopulations is unknown. However, since only few (one to five) individuals are collected at a given time from any locality, it is suspected the species is very rare. Only in extremely low water level conditions, when individuals were forced into isolated pools, have up to 20 individuals been collected at one time. Furthermore, the three subpopulations identified are most likely isolated from one another by the Tagus River main channel. Genetic data available for the known subpopulations reveal the existence of private alleles for both nuclear and mitochondrial DNA, supporting their low exchange of migrants in evolutionary times (Gante et al. 2010).

Current Population Trend:

Decreasing

Additional data:

♦ Continuing decline of mature individuals:	Yes
♦ Population severely fragmented:	Yes
♦ No. of subpopulations:	3

Habitat and Ecology [top]

Habitat and Ecology:	The species has been found in small order tributaries (creeks and streams) and marginal marshes/pools subject to seasonal flooding. Very little is known about its breeding ecology, except that it occurs in spring.
Systems:	Freshwater
Continuing decline in area, extent and/or quality of habitat:	Yes

Threats [top]

Major Threat(s):	The three subpopulations identified occur in an area of high human pressure on water resources, through water extraction for agriculture (especially in years of severe drought). It is also threatened by the presence of exotic species; industrial, domestic and agricultural sources of pollution; and land reclamation, which pose serious risks to the species’ long-term survival. Furthermore, the species was found to hybridize with a critically endangered sympatric relative (Iberochondrostoma lusitanicum) (Gante et al. 2010). Continued introgression from this relatively more abundant species could lead to its genetic dilution.

Major Threat(s):

The three subpopulations identified occur in an area of high human pressure on water resources, through water extraction for agriculture (especially in years of severe drought). It is also threatened by the presence of exotic species; industrial, domestic and agricultural sources of pollution; and land reclamation, which pose serious risks to the species’ long-term survival. Furthermore, the species was found to hybridize with a critically endangered sympatric relative (Iberochondrostoma lusitanicum) (Gante et al. 2010). Continued introgression from this relatively more abundant species could lead to its genetic dilution.

Conservation Actions [top]

Conservation Actions:	None of the three subpopulations are included in protected areas or benefit from conservation actions. A pilot ex-situ breeding program was initiated in July 2010.

Conservation Actions:

None of the three subpopulations are included in protected areas or benefit from conservation actions. A pilot ex-situ breeding program was initiated in July 2010.

Citation:	Gante, H., Santos, C.D., Alves, M.J. & Rodrigues, J. 2012. Iberochondrostoma olisiponensis. The IUCN Red List of Threatened Species 2012: e.T13160676A13160751. . Downloaded on 25 April 2018.
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