Summary ³

The northern riffleshell, scientific name Epioblasma torulosa rangiana, is a subspecies of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels.

Distribution ⁴

Global Range: (250-5000 square km (about 100-2000 square miles)) This entity replaces Epioblasma torulosa torulosa in the headwaters of the Ohio River drainage; its counterpart in the headwaters of the Tennessee River System is Epioblasma torulosa gubernaculum. As with most naiads, its present range is a remnant of its former distribution. Historically, this entity was recorded from the mainstem of the Ohio River (Stansbery and Cooney, 1985) but has apparently been extirpated from there. The Ohio State University Museum of Zoology has records for the White and Wabash Rivers in Indiana but it has not been collected there in recent times (Clark, 1976; Cummings et al., 1991). Taylor and Hughart (1981) presumed that it was no longer present in the Elk River of West Virginia. Currently extant in only seven streams; the Green River in Kentucky, French and LeBoeuf Creeks and the Allegheny River in Pennsylvania, the Detroit River in Michigan (possibly extirpated- see below), and Big Darby Creek in Ohio (USFWS, 1993), and recently discovered in at least one additional river in Ontario (Metcalfe-Smith et al., 1998). Staton et al. (2000) lists historical and present distribution. Recently found in Conewanto Creek near Warren, Warren Co., Pennsylvania, where it was previously thought to be extirpated (Evans and Smith, 2005). In Illinois, it formerly occupied the Vermilion, Wabash, and Ohio Rivers but is now extirpated in the state (Cummings and Mayer, 1997). Recently this species has been confirmed to be likely extirpated from the main channel of the Detroit River between Lake St. Clair and Lake Erie, Michigan/Ontario; due to zebra mussel invasion (Schloesser et al., 2006).

Habitat ⁵

Habitat Type: Freshwater

Comments: Ortmann (1919: 334) reported that this species was "always found...on riffles, on a bottom of firmly packed and rather fine gravel, in swiftly flowing, shallow water or coarse gravel" and Clarke (1981: 362) gave its habitat as "highly oxygenated riffle". Preferred habitat appears to require swiftly moving water. The high oxygen concentrations in swift streams may be necessary for survival. It is a species of riffle areas of smaller streams, and as such has fared better than larger river species, which have been heavily impacted by dredging and impoundment. Of the eleven or so species of naiads thought to be extinct in 1971 by Stansbery, most were from this latter type of habitat and all were species of Epioblasma.

Iucn red list assessment ⁶

• Needs updating

Assessor/s

• 1996
  Critically Endangered (CR)
• 1994
  Endangered (E)
• 1990
  Endangered (E)
• 1988
  Endangered (E)
• 1986
  Endangered (E)
• 1983
  Endangered (E)

Nature serve conservation status ⁷

Rounded Global Status Rank: T2 - Imperiled

Reasons: Historically occurred throughout much of the Ohio River watershed but range has been dramatically reduced to eight to ten populations scattered over four states and one province with only three that are considered viable.

Intrinsic Vulnerability: Highly vulnerable

Comments: Due to slow growth and relative immobility, establishment of sustainable, viable populations requires decades of immigration and recruitment, even where suitable habitat exists (Neves, 1993). Mussel recruitment is typically low and sporadic, with population stability and viability maintained by numerous slow-growing cohorts and occasional good year classes (Neves and Widlak, 1987).

Environmental Specificity: Very narrow. Specialist or community with key requirements scarce.

Comments: The decline in the overall range of this species suggests that it is not tolerant of poor water quality. Individuals are sensitive to pollution, siltation, habitat perturbation, inundation, and loss of glochidial hosts.

Sources and Credits

1. (c) Femorale, some rights reserved (CC BY-NC), http://www.femorale.com/shellphotos/detail.asp?species=Epioblasma%20torulosa%20rangiana%20(Lea,%201839)
2. (c) dshelton, some rights reserved (CC BY-NC)
3. Adapted by rkkessler from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Epioblasma_torulosa_rangiana
4. (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28852277
5. (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28852285
6. (c) International Union for Conservation of Nature and Natural Resources, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/34447087
7. (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28852270

More Info

• iNat taxon page
• Animal Diversity Web
• Biodiversity Heritage Library
• BOLD Systems BIN search
• Global Biodiversity Information Facility (GBIF)
• SeaLifeBase
• World Register of Marine Species

Range Map

(c) NatureServe, some rights reserved (CC-BY-NC)

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