|Scientific Name:||Bellamya trochlearis Martens, 1892|
Bellamya unicolor ssp. trochlearis (Martens, 1892)
Vivipara trochlearis Martens, 1892
|Taxonomic Notes:||In the combined consensus cladogram (Maximum Likelihood, Maximum Parsimony and Bayesian inference) of the African viviparidae, constructed by Sengupta et al. (2009), the specimens identified as Bellamya trochlearis nest at different places between other Lake Victoria endemic 'species'. The whole species group in Lake Victoria, a lake that is geologically very young, seems hence to be genetically inseparable from each other. Sengupta et al. (2009) therefore state that their findings support the conclusion of Mandahl-Barth (1954), namely that these 'species' actually represent different eco-phenotypic morphs of the same species, adapted to different microhabitats. Bellamya trochlearis is retained here provisionally as a classical species until the Victorian forms of Bellamya are officially revised and it has been decided if these should be given the status of subspecies or mere ecological forms.
It is possible that in recent surveys, the ecophenotypic morphs 'Bellamya trochlearis' and 'Bellamya constricta' have been confused.
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Van Damme, D. & Lange, C.|
There is insufficient information on the present distribution to make a Red List assessment of this species, since there have been no records from the Tanzanian part over the last 30 years, though the type locality is Sirwa Island at the southern shore (Tanzania). This species was previously assessed as Endangered (Brown 1996) and has since been changed to Data Deficient (Lange 2010). Uncertainties in taxonomy (or confusion with B. constricta) may have led to misidentification and therefore, misinformation about its present range. Therefore, it is assessed as Data Deficient.
|Previously published Red List assessments:|
|Range Description:||This species is endemic to Lake Victoria. According to Mandahl-Barth (1954) it was restricted to the western and southwestern part of the lake, where he collected it at Entebbe, Damba Island, Katebo, Salisbury Channel, Bukone (Uganda), Bukoba, Ilemera and Mwanza (Tanzania). Lange et al. (2013) mention it from a 2002-2004 survey at Mbita (Winam Gulf, Kenya) and Sengupta et al. (2009) from Bukakata, Lambu, Kivindi, Ngombe and Lugala (Uganda). Its present range (i.e., since 1980) in Tanzania is unknown, and Ngupula and Kayanda (2010) do not mention this species from their extensive 2008 survey in the Tanzanian and Ugandan sector.|
The rather contradictory distribution data may indicate that the presence of this morphotype depends on the availability of its microhabitat. If that shifts to other areas this morphotype appears in that new area and vanishes from the foregoing. Its range is therefore highly unstable. Though this species quite probably still occurs in the lake, we hence do not possess any reliable data about the present range.
Native:Kenya; Tanzania, United Republic of; Uganda
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No information is available on the population. It is apparently not abundant (Lange et al. 2013).|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||This is a benthic species dredged offshore to a depth of 30 m (Brown 1994). The carinas on the shells and the depth to which it can occur suggest that this form lives on muddy bottoms. Lange et al. (2013) state that in Kenya it is rare and restricted to areas that are not severely disturbed.|
|Use and Trade:||This species is not used.|
|Major Threat(s):||No information is available on threats to this species. It is possibly affected by pollution, sedimentation and other types of human disturbances.|
|Conservation Actions:||No information is available on conservation actions.|
|Amended reason:||Point locality records for this species were recently compiled by D. Van Damme. As a result of these records, there has been a slight extension to the previously published distribution range for this species. These point locality records are also now displayed on the distribution map.|
|Citation:||Van Damme, D. & Lange, C. 2017. Bellamya trochlearis (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T2753A110765622.Downloaded on 23 January 2018.|
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