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Homopus signatus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Testudines Testudinidae

Scientific Name: Homopus signatus (Gmelin, 1789)
Common Name(s):
English Speckled Dwarf Tortoise, Speckled Cape Tortoise, Speckled Padloper, Speckled Tortoise
French Homopode marqué
Spanish Tortuga Manchada
Synonym(s):
Chersobius peersi Archer, 1968
Chersobius signatus — Hewitt, 1937
Testudo signata Gmelin, 1789
Taxonomic Notes: Two subspecies have been recognised, namely Homopus signatus signatus and H. s. cafer, with a zone of intergradation in the eastern part of the range in the western Great Karoo (Boycott 1986, 1989; Bour 1988; Iverson 1992; Branch 1998; Boycott and Bourquin 2000; Loehr 2008). However, a range-wide study by Daniels et al. (2010) evaluated the genetic distinctiveness of the two putative subspecies as well as intergrades and found limited differentiation within the species. It was concluded that H. s. cafer is not a valid taxon, rendering H. signatus monotypic. However, the status of a population from the Pofadder area requires further investigation (Daniels et al. 2010). Colour patterns previously used to distinguish the two subspecies appear to be related to crypsis on different substrates.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2acd ver 3.1
Year Published: 2017
Date Assessed: 2013-05-16
Assessor(s): Baard, E.H.W. & Hofmeyr, M.D.
Reviewer(s): Bauer, A., Rhodin, A.G.J. & van Dijk, P.P.
Justification:
This species is assessed as Vulnerable as it has undergone an inferred population reduction of over 30% in the past three generations (75 years) due to anthropogenic land transformation, where the causes of destruction may not have ceased, based on direct observation [A2a], a decline in AOO, EOO and habitat quality [A2c], and actual levels of exploitation [A2d]. These declines are considered likely to continue into the future.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Endemic to South Africa, occurring mainly along the West Coast region of the Western Cape and Northern Cape, from Piketberg and around Citrusdal in the south, northwards across the Olifants River into the Namaqualand Hardeveld to the Springbok-Steinkopf area. Eastwards, the distribution reaches as far inland as the Klipwerf-Loeriesfontein-Calvinia area of the Roggeveld-Bokkeveld region in the Northern Cape. The most northerly records are from the Richtersveld (Bauer and Branch 2003 [2001]) and from just north of Pofadder (Branch et al. 2007). Griffin (2003) did not substantiate any Homopus signatus records from Namibia, including a record from the Fish River Canyon Park (Boycott and Bourquin 2000). Earlier records of this species from Namibia (Mertens 1955, 1971) are referable to H. solus (Branch 2007).
Countries occurrence:
Native:
South Africa (Northern Cape Province, Western Cape)
Additional data:
Estimated area of occupancy (AOO) - km2:2730Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:97213
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:4-6Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):1000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:No information on population size is currently available, but there is evidence of a population decline.
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:3Continuing decline in subpopulations:Yes
All individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:Occurs predominantly in the winter rainfall region of the northwestern Succulent Karoo and Fynbos biomes along the West Coast and adjacent inland of South Africa. Found from a few metres above sea level on the West Coast to elevations of around 1,000 m in the interior at Loeriesfontein-Calvinia and the Cederberg Range (Boycott 1989). Shows a particular preference for rocky terrain, which includes typical Namaqualand and Hardeveld granite koppies (hills) in the north, and typical Sandveld and Cederberg sandstone koppies and rocky ridges in the south. Occurs in low to medium-high Namaqualand succulent shrubland (blomveld) and heuweltjieveld, and fynbos and strandveld shrub vegetation, both in the Succulent Karoo and Fynbos biomes. Prefers to shelter in rock crevices or under medium to large boulders and rock slabs, a behaviour that provides protection against temperature extremes and predation.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):25
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: Some illegal off-take has taken place during the past decades for the pet trade. The extent and trend of this is unknown.

Threats [top]

Major Threat(s): Listed as Restricted by Boycott (1988) and as Lower Risk/near threatened in the 1996 IUCN global listing (IUCN 1996). Currently considered Vulnerable, mainly due to human-induced habitat degradation and destruction and the international reptile pet trade. Observations and focused research throughout the known range indicate that this species is intolerant of habitat modification. There appears to be a strong correlation between population status and habitat quality. Severe habitat fragmentation has resulted from extensive agricultural development throughout the range and especially in the Sandveld region. This includes the irreversible alteration of the inter-koppie (small hill) habitat—a zone that probably plays an important role in inter-population gene flow. Overgrazing by domestic stock, especially goats, further degrades and threatens remaining natural koppie habitats. There is illegal collection for export to the international pet trade, although this is infrequent. Midgley et al. (2005) recorded the imminent threat and potential impact of global climate change on the western parts of South Africa. Loehr (2008) clearly demonstrated that the expected changes in rainfall pattern and temperature across the range is likely to severely impact growth rates and fecundity of individuals, and consequently the survival of the species.

Conservation Actions [top]

Conservation Actions: This species is listed on CITES Appendix II. 

Conservation actions recommended include:
  • Continue research into the life history of the species.
  • Develop a species Biodiversity Management Plan (BMP-S). 
  • Cultivate conservation stewardship arrangements that include more natural habitat (throughout the range) in formal conservation arrangements.
  • Be vigilant for illegal collection of specimens for the pet trade.

Citation: Baard, E.H.W. & Hofmeyr, M.D. 2017. Homopus signatus. The IUCN Red List of Threatened Species 2017: e.T10241A110342315. . Downloaded on 20 October 2017.
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