Ellipse (Venustaconcha ellipsiformis)

Overview

Overview

Ellipse (Venustaconcha ellipsiformis), a mussel presently listed as Threatened in Wisconsin. This species prefers shallow, flowing, clean small streams with stable substrate in the eastern and southern part of the state. It has also been recorded from localized populations in the western part of the state. The host fish are mostly small stream species including the rainbow darter, Johnny darter and mottled sculpin.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Ellipse (Venustaconcha ellipsiformis). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.

Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.

Species guidance

Note: a species guidance document is not available at this time. Information below was compiled from publication PUB-ER-085-99 (now out-of-print).

Identification: Shell is elliptical, heavy and rough having a sharp crease near the posterior ridge. The outside of the shell is greenish-yellow with numerous wavy, continuous rays of dark green. Pseudocardinal and lateral teeth are heavy. Umbro sculpture consists of three or four fine double looped concentric ridges. The nacre is bluish-white to white. The ellipse is small, up to 89 mm (3.5 inches) long.

Habitat: Inhabits small to medium sized streams with good current, in shallow water, on sand or gravel bottoms.

State Distribution: Occurs in the following rivers in Wisconsin: Ashippun, Bark, Crawfish, Manitowac, Meeme, Milwaukee, Mukwonago, Mullet, Oconomowoc, Pigeon, south fork of the Popple, Rock, Sugar, and Yellow. Also found in Cedar Creek, Jericho Creek, O'Neil Creek, Sugar Creek. This species may yet be found in rivers for which only historical records now exist. Refer to the species map.

Phenology: Breeding occurs in late summer and fall but glochidia are not shed until the late spring or early summer of the next year. The host fish are darters.

Management Guidelines: Because it inhabits small streams and headwaters, this mussel is particularly vulnerable to siltation and pollution from runoff. Habitat protection and water quality improvements would benefit this species. Increased development along waterways in southeast Wisconsin is of particular concern for the continued existence of the species.

Other resources

Links to additional Ellipse information

• Michigan Natural Features Inventory [PDF exit DNR]
• MN Department of Natural Resources [exit DNR]
• Illinois Natural History Survey [exit DNR]

Other links related to mussels and clams

• NatureServe Explorer
• Illinois Natural History Survey [exit DNR]
• The Field Museum [exit DNR]
• Conchologists of America [exit DNR]
• EPA Biological Criteria [exit DNR]
• Milwaukee Public Museum: Mathiak Collection of Freshwater Mussels of Wisconsin [exit DNR]

Photos/Video

Photos

Click to view a larger version. Please considering donating a photo to the Natural Heritage Conservation Program for educational uses. Photo use

Wildlife Action Plan

Natural community (habitat) associations

The table below lists the natural communities that are associated with Ellipse. Only natural communities for which Ellipse is "high" (score=3) or "moderate" (score=2) associated are shown. See the key to association scores for complete definitions. Please see the Wildlife Action Plan to learn how this information was developed.

Ecological landscape associations

The table below lists the ecological landscape association scores for Ellipse. The scores correspond to the map (3=High, 2=Moderate, 1=Low, 0=None). For more information, please see the Wildlife Action Plan.

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Landscape-Community combinations of highest ecological priority*

Ecological priorities are the combinations of natural communities and ecological landscapes that provide Wisconsin's best opportunities to conserve important habitats for a given Species of Greatest Conservation Need. The 10 highest scoring combinations are considered ecological priorities and are listed below. More than 10 combinations are listed if multiple combinations tied for 10th place. For more information, please see the Wildlife Action Plan.

* Ecological priority score is a relative measure that is not meant for comparison between species. This score does not consider socio-economical factors that may dictate protection and/or management priorities differently than those determined solely by ecological analysis. Further, a low ecological priority score does not imply that management or preservation should not occur on a site if there are important reasons for doing so locally.

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Issues/threats and conservation actions

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.

Threats/issues and conservations actions for rare animals

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