Engaewa pseudoreducta 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Malacostraca Decapoda Parastacidae

Scientific Name: Engaewa pseudoreducta Horwitz & Adams, 2000
Common Name(s):
English Margaret River Burrowing Crayfish

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii) ver 3.1
Year Published: 2010
Date Assessed: 2010-06-01
Assessor(s): Burnham, Q.
Reviewer(s): Collen, B. & Richman, N.
Contributor(s): Livingston, F., Soulsby, A.-M., Batchelor, A., Dyer, E., Whitton, F., Milligan, H.T., Smith, J., Lutz, M.L., De Silva, R., McGuinness, S., Kasthala, G., Jopling, B., Sullivan, K. & Cryer, G.
Engaewa pseudoreducta has been assessed as Critically Endangered using criterion B1ab(iii). This species has an estimated extent of occurrence of less than 100 km ², and has a severely fragmented distribution. This range of this species is in decline, and it is now extirpated from the type locality. This species is being threatened by soil compaction due to its reliance on a specific type of clay, water abstraction, and agriculture. It is present in a nature reserve, but there are no species-specific management plans in place for its protection. Urgent action is required to protect the land on which this species is found. The restricted nature of this species could result in its near-future extinction with one significant threatening event.

Geographic Range [top]

Range Description:This species is endemic to Western Australia, and has a restricted distribution being found only in one locality in two creeklines (Q.Burnham, pers. comm. 2008). The type locality for this species has been altered and no longer contains any individuals of this species (Q. Burnham pers. comm. 2008). This species is found in fragmented sites on the edge of a nature reserve (Q. Burnham pers. comm. 2008). The distribution of this species is unlikely to be significantly greater, due to other crayfish species being present in close proximity, but not overlapping (Q. Burnham pers. comm. 2008). It is unknown whether altitude is potentially a limiting factor in the distribution of this species. It appears this species is limited to the clay soils found in the Treeton area (Q. Burnham, pers. comm. 2008). The extent of occurrence of this species has been estimated to be less than 100 km2.
Countries occurrence:
Australia (Western Australia)
Additional data:
Number of Locations:1
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Populations of this species are estimated to have been higher before anthropogenic disturbance. According to Q. Burnham (pers. comm. 2008), this is the most difficult Engaewa species to find.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species is generally found in heathlands dominated by myrtaceous shrubs, and where the level of the water table never comes above the surface (Horowitz and Adams 2000). More precisely, this species usually burrows in silty, sandy-clay soils, where the water table may or may not reach the surface (Q. Burnham pers. comm. 2008). This species appears to be closely associated with certain hydrological processes and potentially soil types, while responding poorly to disturbance. They are limited to habitats that constitute a small component of the range through which they are found (Q. Burnham, pers. comm. 2008).

Threats [top]

Major Threat(s): This species has a highly restricted geographical range and is presumed to be susceptible to agricultural practices (Q. Burnham, pers. comm. 2008). The swampy headwater creek habitat of the only known population has been substantially altered by clearing of native vegetation, cattle grazing, draining, afforestation practices and small dam construction (Horwitz and Adams 2000). Any alterations to the natural condition of the soil, for example soil compaction by cattle grazing, is a major threat to this species due to its close relationship with clay soils in this area (Q. Burnham, pers. comm. 2008). Rapid changes in land use within their combined distribution areas have affected surface and ground water conditions in the southwest, destroying their natural habitat (Naturebase 2007). Any large scale perennial extraction of groundwater therefore falls into one of the major categories of threats posed to this crayfish of the region (Morgan and Beatty 2005).

Conservation Actions [top]

Conservation Actions: This species is listed as threatened under Western Australian state legislation. This species is also present in a nature reserve (Q. Burnham, pers. comm. 2008) which may afford some protection. Horwitz and Adams (2000) recommend this species should be listed as Critically Endangered. Further research into the abundance and appropriate conservation measures are required for this species.

Citation: Burnham, Q. 2010. Engaewa pseudoreducta. The IUCN Red List of Threatened Species 2010: e.T153710A4535220. . Downloaded on 20 September 2018.
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