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Montana Field Guide

Montana Field Guides

White Sand-river Mayfly - Pseudiron centralis

Native Species

Global Rank: G5
State Rank: SNR

Agency Status


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General Description
This mayfly species is a member of the large prairie river, sand-dwelling invertebrate assemblage of eastern Montana. It should occur in the long streches of shifting sandbar habitat between cobble riffles and runs of the Milk, Powder, lower Missouri and Yellowstone Rivers. Many large prairie rivers have been dammed affecting the substrate dynamics preffered by this globally uncommon and rare assemblage of insects dominated by mayflies (see also Lachlania saskatchewanensis, Aneperous rusticus, Macdunnoa nipawinia, Homoeoneuria alleni).

Range Comments
Rangewide this species occurs throughout eastern and central North America, and has been known as far west as Alberta (Pescador, 1985) and Utah (Edmunds and Musser, 1960) and California (McCafferty and Meyer, 2007). In Montana, we have only one occurrence record from the Milk River near the Canadian Border where the river still has its natural flow regime and large sand bars.

Observations in Montana Natural Heritage Program Database
Number of Observations: 1

(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 large, shallow perennially flowing prairie rivers with shifting sand dominated reaches.

Pseudoiron centralis may be declining in the state along with the other sand-dwelling mayflies due to siltation and habitat changes brought on by the building of dams on the large prairie rivers and the low-flow effects of the previous drought in Montana.

Threats or Limiting Factors
All forms of river quality degradation pose potential threats to this species. Particularly, siltation and hydrological alteration from dams, diversions or withdrawal of excess water for human use that alter natural sand bar formation.

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Citation for data on this website:
White Sand-river Mayfly — Pseudiron centralis.  Montana Field Guide.  .  Retrieved on , from