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Montana Field Guide

Montana Field Guides

A Sand-dwelling Mayfly - Macdunnoa nipawinia

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Species of Concern
Native Species

Global Rank: G3
State Rank: S2
(see State Rank Reason below)

Agency Status

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State Rank Reason (see State Rank above)
This sand-dwelling mayfly is currently listed as an "S2" species of concern in Montana because they are potentially at risk of extirpation in the state, due to limited and/or declining numbers, range and/or habitat, even though it may be abundant in some areas.
General Description
As with most Heptagenid mayflies, this species has a flattened body shape and head. Gills alongside the abdomen may be slightly oriented underneath the body and gill #7 is minute compred to those on segments 1-6. This species was, until recently, known only from Saskatchewan (Lehmkuhl 1979), where it was found on gravel beds and submerged woody debris in the South Saskatchewan River. This species was reported as present in Montana, with 2 records from one site on the lower Yellowstone River (Gustafson 2006). A preliminary global ranking has been given to this species (NatureServe 2015), and we placed it on the state’s SOC list

Species Range
Montana Range Range Descriptions


Range Comments
This species was, until recently, known only from Saskatchewan (Lehmkuhl 1979), where it was found in the South Saskatchewan River. It was also recently discovered in Montana (MNHP March 2006). A preliminary global ranking is given to this species; however, a current faunistic survey being conducted throughout Saskatchewan may yield additional records.

Observations in Montana Natural Heritage Program Database
Number of Observations: 3

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

This species is associated with larger, perennially flowing warmwater prairie rivers with sand-gravel dominated bottoms with cobble riffles.

M. nipawinia is seriously in decline in the state probably due to siltation and habitat changes brought on by the long-standing drought in Montana.

Threats or Limiting Factors
Threats to this species include dams and diversions and excessive siltation that smothers their sandy bottom habitats.

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Citation for data on this website:
A Sand-dwelling Mayfly — Macdunnoa nipawinia.  Montana Field Guide.  .  Retrieved on , from