endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (Zero (no occurrences believed extant)) Pleurobema altum (= Pleurobema fibuloides) was apparently restricted to the Coosa River drainage in Alabama and Georgia (Williams et al., 2008). In the Coosa River basin in Georgia, it is known historically from the Etowah, Oostanaula, and Conasauga River drainages but has not been collected there recently and is considered extinct (Williams and Hughes, 1998). It has not been encountered in nearly 100 years. As a result it is not currently recognized by the USFWS (as P. altum or otherwise) as threatened or endangered; most authors consider it extinct (Mirarchi et al., 2004).
Habitat Type: Freshwater
Comments: Nothing is known of microhabitat preferences or reproductive ecology although this species is known from the Coosa and Conasauga Rivers.
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 0 (zero)
Comments: This species has not been encountered in nearly 100 years. As a result, Pleurobema altum (= Pleurobema fibuloides) is not currently recognized by the USFWS as threatened or endangered; most authors consider it extinct (Mirarchi et al., 2004). It occurred in the Coosa River in Shelby County, Alabama, and upstream to the Upper Coosa and Conasauga Rivers in Georgia (Evans, 2001; Gangloff, 2003). Historically it occurred from the headwaters of the Coosa River drainage downstream through its middle reaches with the most recent dated museum material collected from the Conasauga River in 1958 (Williams et al., 2008). FLMNH has specimens from the Coosa River in Shelby Co., Alabama, collected in 1913 and undated (older) material from the Coosa River in Floyd Co., Georgia, and Conasauga River in Georgia.
Zero, no individuals known extant
Life History and Behavior
Nothing is known of microhabitat preferences or reproductive ecology. The glochidial host is not known.
National NatureServe Conservation Status
Rounded National Status Rank: NX - Presumed Extirpated
NatureServe Conservation Status
Rounded Global Status Rank: GX - Presumed Extinct
Reasons: This species has not been encountered in nearly 100 years except for a single lot collected in 1958. As a result, it is not currently recognized by the USFWS as threatened or endangered; but most authors consider it extinct although the name originally attributed to it is now considered a nomen dubium with Pleurobema fibuloides proposed as a replacement.
Intrinsic Vulnerability: Unknown
Environmental Specificity: Unknown
Comments: Nothing is known of microhabitat preferences or reproductive ecology.
Global Short Term Trend: Relatively stable (=10% change)
Global Long Term Trend: Decline of >90%
Comments: The most recent dated museum material collected from the Conasauga River in 1958 (Williams et al., 2008).
Degree of Threat: Unknown
Global Protection: None. No occurrences appropriately protected and managed
Names and Taxonomy
Comments: The classification of the Gulf Coast species of Pleurobema is unsettled. Current researchers are recognizing what appears to be clinal variation in the group and as a result many species are being synonomized. This research is still in progress and will likley result in the recognition of fewer species-level taxa in this genus (Kandl et al., 2001). The species to which the name Pleurobema altum has previously been applied is Pleurobema fibuloides (see Williams et al., 2008). Simpson (1900; 1914) included P. fibuloides in the synonym of P. altum. Conrad (1854) described Unio altum, giving the type locality as "one of the western states, probably Tennessee". However the brief description was incomplete, omitting details about the umbo cavity (an important diagnostic feature of Mobile Basin Pleurobema). The type specimen of U. altum has been lost. Without comment or discussion, Simpson (1900) gave the distribution of P. altum as Conasauga River, Georgia, and later (Simpson, 1914) gave the type locality as "Tennessee?" Most subsequent authors have recognized P. altum as a Coosa River drainage endemic (e.g. Frierson, 1927; Hurd, 1974; Stansbery, 1976). However, with incomplete description, vague type locality, and absence of a type specimen, recognition of U. altum is unjustified and considered a nomen dubium (Williams et al., 2008).
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