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Ptychobranchus greenii

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA BIVALVIA UNIONOIDA UNIONIDAE

Scientific Name: Ptychobranchus greenii
Species Authority: (Conrad, 1834)
Common Name(s):
English Triangular Kidneyshell
Synonym(s):
Ptychobranchus greeni (Conrad, 1834)
Taxonomic Notes: Spelling of Ptychobranchus greenii is correct (Turgeon et al. 1998). This species exhibits variable shell morphology and may be confused with some species of Pleurobema. Ecomorphs of the species are best identified by process of elimination (USFWS 1993). Furthermore, it appears that there may be at least three species existing under this name. Genetic studies are planned to resolve this problem (P. Hartfield pers. comm. 1997). Potentially, this species will be split into Ptychobranchus greenii (Black Warrior and Tombigbee basins) and Ptychobranchus foremanianus (I. Lea 1842) (Alabama, Cahaba, Coosa basins).

A list of synonyms for this species can be found on The MUSSEL project web site (Graf and Cummings 2011).

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(iii) ver 3.1
Year Published: 2012
Date Assessed: 2012-03-12
Assessor(s): Cordeiro, J. & Cummings, K.
Reviewer(s): Bohm, M., Seddon, M. & Collen, B.
Contributor(s): Dyer, E., Soulsby, A.-M., Whitton, F., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., Collins, A., McMillan, K., Duncan, C., Offord, S. & Richman, N.
Justification:
Ptychobranchus greenii has been assessed as Endangered under criteria B1ab(iii). This is a declining regional endemic that is rare throughout most of its range, however, most of the declines have been historical so that the species is unlikely to qualify for a listing under criterion A. It has a restricted extent of occurrence of less than 5,000 km2 and probably closer to 1,000 km2, occurs in less than five locations, and rivers in the Mobile Basin are still under threat from impoundments and pollution, leading to a decline in the area and quality of habitat. Further research is recommended on population status and ecology of the species, together with continued monitoring of remaining populations, to ensure that any further declines are noticed in time for preventive conservation action.

In 1996, the previous assessment was made by Bogan, who considered that there had been a decline of more than 80% in known range (and hence populations) (A. Bogan pers. comm. 1996).
History:
1996 Critically Endangered
1994 Endangered (Groombridge 1994)

Geographic Range [top]

Range Description: The type locality for Ptychobranchus greenii is the headwaters of the Black Warrior River, Alabama. Additional records include the Black Warrior River and tributaries (Mulberry Fork, Locust Fork, North and Little Warrior Rivers, Brushy Creek, Sipsey Fork). McGregor et al. (2000) reported it absent from the Cahaba River, Alabama. However, records from the remainder of the Mobile Basin are now recognized as Ptychobranchus foremanianus, including Cahaba River specimens (Williams et al. 2008). Its extent of occurrence is likely to be close to 1,000 km2, and no larger than 5,000 km2 (NatureServe 2009). It is extant in isolated localized populations only (Williams et al. 2008), and unlikely to occur in more than five locations (NatureServe 2009).
Countries:
Native:
United States (Alabama)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species was known to inhabit the Sipsey Fork and tributaries (Winston/Lawrence County, Alabama) and Locust Fork (Blount County, Alabama) of the Black Warrior River; Cahaba River (Bibb County, Alabama); and Coosa tributaries, Shoal Creek, Kelly Creek (Shelby Co., Alabama), Terrapin Creek (Cherokee Co., Alabama), Big Canoe Creek, Conasauga River (Murray/Whitfield Co., Georgia, Bradley Co., Tennessee), Holly Creek (Murray Co., Georgia), Coosawattee River (Gordon Co., Georgia), and Oostanaula River (Floyd/Gordon Co., Georgia) (Parmalee and Bogan 1998, USFWS 2000, 2004). Numerous surveys have targeted this species (USFWS 1993, Pierson 1992, J. Williams pers. comm. 1997). Healthy populations appear to remain in two streams in Banhhead National Forest and very small, isolated populations exist in the Sipsey Fork and Locust Fork tributaries of the Black Warrior basin, Cahaba River, and upper Coosa River system (Mirarchi et al. 2004). However, it now exists in the Black Warrior River, Alabama, with specific records including the Black Warrior River and tributaries (Mulberry Fork, Locust Fork, North and Little Warrior Rivers, Brushy Creek, Sipsey Fork). Records from the remainder of the Mobile Basin are now recognized as Ptychobranchus foremanianus, including Cahaba River specimens (Williams et al. 2008) 

Populations are small and localized in the Sipsey Fork drainage and in the Conasauga River and a single fresh dead shell is the only evidence of the species in the Cahaba River. The species is rarely found in the Locust Fork tributary of the Black Warrior River (USFWS 2000, 2004).

Population estimates are unknown and numbers typically are low. This species has been extirpated from the Alabama River, and from primary channels of the Black Warrior and Coosa Rivers (USFWS 2004).

Historically, this species was fairly common in stretches of the Conasauga River flowing through Tennessee and northern Georgia but appears to be extirpated in the Tennessee stretch of the Conasauga River today (Parmalee and Bogan 1998).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species appears most prevalent in sections of river three feet in depth and having a good current and a firm substrate as opposed to coarse gravel and sand (Parmalee and Bogan 1998), specifically in shoals and runs of small rivers and large streams (USFWS 2000).
Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is not utilized.

Threats [top]

Major Threat(s): Loss of habitat due to impoundments is the primary reason for the decline of the species. It may also be threatened by overutilization for commercial, recreational, scientific and educational purposes (USFWS 1993). Disappearance from significant portions of its range are primarily due to changes in river and stream channels because of dams, dredging, or mining, and historic or episodic pollution events. The species is not known to survive in impounded waters and more than 1,700 km of large and small river habitat in the Basin have been impounded by dams for navigation, flood control, water supply, and/or hydroelectric production purposes (USFWS 2004).

In the Mobile River basin, the greatest threats are dams (for navigation, water supply, electricity, recreation, and flood control), channelization (causing accelerated erosion, altered depth, and loss of habitat diversity, substrate stability, and riparian canopy), dredging (for navigation or gravel mining), mining (for coal, sand, gravel, or gold) in locally concentrated areas, pollution- point source (industrial waste effluent, sewage treatment plants, carpet and fabric mills, paper mills and refineries in mainstem rivers), pollution- nonpoint source (construction, agriculture, silviculture, urbanization) (USFWS 2000).

The extremely limited range and low numbers of the species make it very vulnerable to actual and potential threats. Isolated imperiled populations in the Mobile River basin are probably vulnerable to random accidents, such as toxic spills, and to naturally catastrophic events, such as droughts and floods, even if land use and human populations were to remain constant within isolated watersheds (USFWS 2000).

Conservation Actions [top]

Conservation Actions: This species was listed as federally endangered in the U.S. in 1993. Williams et al. (2010) list this species as Endangered according to the AFS assessment.

A specific recovery plan has been created for the Mobile River basin (USFWS 2000) which contains the following objectives: (1) protect habitat integrity and quality of river and stream segments that currently support or could support imperiled aquatic species; (2) consider options for free-flowing river and stream mitigation strategies that give high priority to avoidance and restoration; (3) promote voluntary stewardship as a practical and economical means of reducing nonpoint pollution from private land use; (4) encourage and support community based watershed stewardship planning and action; (5) develop and implement programs and materials to educate the public on the need and benefits of ecosystem management, and to involve them in watershed stewardship; (6) conduct basic research on endemic aquatic species and apply the results toward management and protection of aquatic communities; (7) develop and implement technology for maintaining and propagating endemic species in captivity; (8) reintroduce aquatic species into restored habitats, as appropriate; (9) monitor listed species population levels and distribution and periodically review ecosystem management strategy; (10) coordinate ecosystem management actions (USFWS 2000).

Critical habitat has been designated in Alabama in the Sipsey Fork, North River, Locust Fork, Cahaba River, Coosa River, Hatchet Creek, Kelly Creek, Shoal Creek, Yellowleaf Creek, Big Canoe Creek, and the lower Coosa River; in Georgia in Oostanaula complex; and in Tennessee in Oostanaula complex (641 occuppied, 297 unoccuppied km) (USFWS 2003).

The population on the Sipsey Fork and Brushy Creek, upper Black Warrior River drainage are in streams which originate and flow through the Bankhead National Forest. Portions of the Conasauga River flow through the Cherokee National Forest. The U.S. Forest Service has strengthened stream management zone guidelines for streams under its jurisdiction in Alabama (USFWS 2000). Critical habitat has been designated in Alabama in the Sipsey Fork, North River, Locust Fork, Cahaba River, Coosa River, Hatchet Creek, Kelly Creek, Shoal Creek, Yellowleaf Creek, Big Canoe Creek, and the lower Coosa River; in Georgia in Oostanaula complex; and in Tennessee in Oostanaula complex (641 occupied, 297 unoccupied km) (USFWS 2003).

Further research is recommended on population status and ecology of the species, together with continued monitoring of remaining populations, to ensure that any further declines are noticed in time for preventive conservation action.

Citation: Cordeiro, J. & Cummings, K. 2012. Ptychobranchus greenii. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 24 July 2014.
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