Alasmidonta wrightiana (Ochlockonee Arcmussel)

[sebbe67]

Alasmidonta wrightiana

From Florida and Georgia, extinct.

[another specialist]

Red List Category & Criteria EX ver 2.3 (1994)
Year Assessed 2000
Assessor/s Bogan, A.E. (Mollusc Specialist Group)
Evaluator/s Seddon, M.B. (Mollusc Red List Authority)
Justification A. wrightiana was listed as Critically Endangered in 1996 (Baillie and Groombridge 1996) due to uncertainty about whether surveys had been carried out. More recent information concludes that it is Extinct.
History 1990 - Indeterminate (IUCN 1990)
1994 - Indeterminate (Groombridge 1994)
1996 - Critically Endangered (Baillie and Groombridge 1996)

www.iucnredlist.org/search/details.php?species=778

[another specialist]

Taxonomic Comments: Considered a synonym of A.TRIANGULATA (= A. UNDULATA) by Clench and Turner (1956).

Reasons: Very restricted range and reduced numbers and lack of specimens since 1931 make the species' existence questionable. More thorough searches of the Ochlockonee River may reveal this species to be extant.

Estimated Number of Element Occurrences Comments: Known only from 2 EOs < 20 km apart on the Ochlockonee River, Gadsden/Leon counties, Florida. Total of 15 specimens known. Despite repeated efforts by numerous collectors, the species has not been collected live since 1931.

Global Short Term Trend Comments: Considered by many researcher to be extinct. However, there is still the possibility that this species is still extant in the Ochlockonee River, eventhough extensive survey efforts in 1993 found no specimens (Brim Box pers. comm. 2000). Recent (late 1990's) search efforts have been hampered by very low water levels. Much of its original habitat may have been inundated by Lake Talquin.

Global Inventory Needs: Various sections of the upper and lower Ochlockonee River were surveyed in July of 1993, by Jayne Brim-Box. This species was not found. More intensive surveys of the Ochlockonee in Florida and Georgia, particularly the lower mainstem downstream of Lake Talquin, are needed to ascertain present status.

www.natureserve.org/

[sebbe67]

This species is known only historically from 2 occurrences < 20 km apart on the Ochlockonee River (Ochlockonee River system), Gadsden/Leon counties, Florida (Clench and Turner, 1956; Johnson, 1967). Athearn (1998) examined the headwaters of the Ochlockonee River and concluded the species is extirpated there. A total of 15 specimens is known. Despite repeated efforts by numerous collectors, the species has not been collected live since 1931.

[Sebbe]

This species has been recorded only from the Ochlockonee River, Florida, USA, from 2 occurrences < 20 river km apart, above Lake Talquin (an impoundment where it has not been found since 1931) (Clench and Turner, 1956; Johnson, 1967; Athearn, 1998). Athearn (1998) identified four specimens in his collection from a tributary of the Flint River, Thomaston, Upson Co., Georgia, that he attributed to Alasmidonta wrightiana based upon mophological features "which perfectly match the type figure) from Walker's (1901) original locality but Johnson (1967) determined that Walker's specimens are actually Alasmidonta triangulata so Athearn's are likely this species also. Despite repeated attempts, it has not been found since. Johnson (1967) state that examination of the type and subsequently collected specimens has clearly shown that Alasmidonta wrightiana of the Ochlockonee River, Florida, is distinct from Alasmidonta triangulata of the Apalachicola River system of Georgia and Florida

This species is known only historically from 2 occurrences < 20 km apart on the Ochlockonee River (Ochlockonee River system), Gadsden/Leon counties, Florida (Clench and Turner, 1956; Johnson, 1967). Athearn (1998) examined the headwaters of the Ochlockonee River and concluded the species is extirpated there. A total of 15 specimens is known. Despite repeated efforts by numerous collectors, the species has not been collected live since 1931.

explorer.natureserve.org/servlet/NatureServe?sourceTemplate=tabular_report.wmt&loadTemplate=species_RptComprehensive.wmt&selectedReport=RptComprehensive.wmt&summaryView=tabular_report.wmt&elKey=110077&paging=home&save=true&startIndex=1&nextStartIndex=1&reset=false&offPageSelectedElKey=110077&offPageSelectedElType=species&offPageYesNo=true&post_processes=&radiobutton=radiobutton&selectedIndexes=110077

[surroundx]

Williams, James D., Bogan, Arthur E., Butler, Robert S., Cummings, Kevin S., Garner, Jeffrey T., Harris, John L., Johnson, Nathan A. and Watters, G. Thomas. (2017). A revised list of the freshwater mussels (Mollusca: Bivalvia: Unionida) of the United States and Canada. Freshwater Mollusk Biology and Conservation 20: 33-58.

[Sebbe]

Status of Freshwater Mussels in the Ochlockonee River Basin of Georgia and Florida.

Recent and comprehensive surveys of Ochlockonee River basin mussel fauna are lacking, particularly in the lower portion of the basin which historically has been undersampled. We present the results of surveys conducted between 2006 and 2017 to assess the status of freshwater mussels in the Ochlockonee River basin, and examine historical survey records to assess changes in mussel distribution and population status in recent decades. We gave particular attention to the current status and distribution of 3 federally endangered mussels, Hamiota subangulata (Shinyrayed Pocketbook), Medionidus simpsonianus (Ochlockonee Moccasinshell), and Pleurobema pyriforme (Oval Pigtoe), and 1 threatened mussel, Elliptoideus sloatianus (Purple Bankclimber). During the 12-year period, 3 agencies made 257 collections throughout the basin, encountering 19 of the basin's 22 native mussel species. Shinyrayed Pocketbook and Oval Pigtoe were not detected and are possibly extirpated from the basin. Alasmidonta wrightiana (Ochlockonee Arcmussel), a basin endemic, was not found during the surveys. It has not been collected in more than 85 years, suggesting that the species is likely extinct. A remnant population of Ochlockonee Moccasinshell, also a basin endemic, was detected in a 23-km reach of the lower Ochlockonee River. Although encountered in most of their respective historical ranges, Cyclonaias infucata (Sculptured Pigtoe) and Purple Bankclimber appear to have declined in some areas of the upper basin. Watershed alterations in the basin that may have adversely impacted the mussel fauna include the conversion of forests to agricultural and urban lands, impoundment of the mainstem by Jackson Bluff Dam, introduction of Corbicula fluminea (Asian Clam), and the effects of droughts and water use by humans. Although we detected a relatively intact fauna in the lower Ochlockonee River, our findings suggest declines in 5 mussel species in the basin since 2000, including the 4 federally listed mussels.

bioone.org/journals/southeastern-naturalist/volume-20/issue-1/058.020.0101/Status-of-Freshwater-Mussels-in-the-Ochlockonee-River-Basin-of/10.1656/058.020.0101.short

[Melanie]

It is possible that the Ochlockonee River endemic Alasmidonta wrightiana became extinct due to construction of Jackson Bluff Dam in 1927. It may have been dependent on a migratory fish host that was blocked by the dam. The last collections of this presumably short-lived anodontine were made in 1931 directly upstream of Lake Talquin (Williams and Butler 1994).

Source: Freshwater Mussels of Florida Johnson, Nathan A., Warren, Gary L., Butler, Robert S., Williams, James D. Published by The University of Alabama Press, 2014