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Aphaostracon pycnus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA GASTROPODA LITTORINIMORPHA HYDROBIIDAE

Scientific Name: Aphaostracon pycnus
Species Authority: Thompson, 1968
Common Name/s:
English Dense Hydrobe
Synonym/s:
Aphaostracon pycnum Thompson, 1968
Taxonomic Notes: Thompson (1968) described this species as Aphaostracon pycnus. This was later changed (possibly as a gender correction) by Turgeon et al. (1998) to A. pycnum. However, according to the ICZN (1999) the original spelling should stand as there has not been a genuine change in rank or combination (e.g., from subspecies to species or a genus shift); therefore A. pycnus remains the correct spelling (NatureServe 2009).

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2012
Date Assessed: 2012-03-14
Assessor/s: Cordeiro, J. & Perez, K.
Reviewer/s: Bohm, M., Collen, B. & Seddon, M.
Contributor/s: Dyer, E., Soulsby, A.-M., Whitton, F., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., McMillan, K., Collins, A., Offord, S., Duncan, C. & Richman, N.
Justification:
Aphaostracon pycnus has been assessed as Vulnerable under criterion D2, as it has a very restricted distribution with an estimated area of occupancy of less than 20 km2. While there are currently no documented declines with the speices occurring within a Florida National Forest, potential future threats are likely to affect the population significantly enough to cause severe and rapid declines over a timeframe of 10 to 15 years, thus threatening the survival of this species. The most likely threats are an increased frequency of drought events impacting the recharge of the groundwaters feeding the system, change in National Forest legislation with reduced protection to the location and nutrient loading from agricultural and urban runoff. While the species was considered for federal government listing, this was never put in place. However, the species would benefit from appropriate protection which buffers against potential future declines.
History:
1996 Vulnerable
1994 Indeterminate (Groombridge 1994)
1990 Indeterminate (IUCN 1990)
1988 Indeterminate (IUCN Conservation Monitoring Centre 1988)
1986 Indeterminate (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description: This species is endemic to Alexander Spring Run, Ocala National Forest, Lake County in Florida (Thompson 2004, NatureServe 2009). Shelton (2005) states that this species also occurs in Silver Glen Springs, around 20 km north of Alexander Springs. This record should be verified as it may constitute an important, and previously unknown, population of this species.
Countries:
Native:
United States (Florida)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is known only from one locality, and it is not known whether this represents a single or several populations (NatureServe 2009). Recent claims of a second location north of Alexander Springs require verification.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This species is restricted to forest springs.
Systems: Freshwater

Threats [top]

Major Threat(s): There are no current threats to this species. However, plausible future threats to this species are an increased frequency of drought events impacting the recharge of the groundwaters feeding the system, change in National Forest legislation with reduced protection to the location and nutrient loading from agricultural and urban runoff. Each of these has the potential to rapidly lead to significant declines in the population, ultimately leading to extinction of the species, within 10 to 15 years unless actions are taken to safeguard the species.

Other potential future threats might stem from tourism as the species occurs inside a National Forest. The US Forest Service website states that Alexander Springs is a "popular recreation area" (US Forest Service 2010). Melhop and Vaughn (1994) reported that swimmers temporarily displaced a related species, Aphaostracon monas, from a spring in Florida, although the snails repopulated the spring following the swimming season.

Vehicle pollution from Route 445, adjacent to Alexander Springs, may also be a threat. This species is likely to be vulnerable to small changes in water quality to its currently pristine habitat, similar to other hydrobiids (Melhop and Vaughn 1994).

Conservation Actions [top]

Conservation Actions: This species is listed as Vulnerable on the IUCN Red List (version 2.3 1996) under criterion D2 (very small or restricted population) (IUCN 2009). It has a Global Heritage Status of G1 (Critically Imperilled) (NatureServe 2009). The one known locality of this species is inside a National Forest (Ocala National Forest). The level of protection this awards to snails and freshwater habitats in general is unknown (NatureServe 2009).

Further work is needed to verify the second population recorded by Shelton (2005) at Silver Glen Springs, as this could be important for the long-term viability of this species. In addition, research is recommended to determine the status of the stream and surrounding habitat (e.g., riparian, forest) in which this species is found. The species and its habitat should also be incoporated into the National Forest management plans, and considered for State/Federal listing (NatureServe 2009). The US government considered listing this species in 1984, but it was never listed.
Citation: Cordeiro, J. & Perez, K. 2012. Aphaostracon pycnus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 24 April 2014.
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