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Montana Field Guide

Montana Field Guides

A Mayfly - Siphlonurus autumnalis

Special Status Species
Native Species

Global Rank: G2G4
State Rank: SNR

Agency Status

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General Description
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Range Comments
This valid species has been known historically only from western Canada (McDunnough, 1931), Washington and Montana (Jacobus and McCafferty, 2002) . It occurs in western Montana in Crazy Beaver Spring and Cut Bank Spring and Wally Spring, Flathead County; Fisher Cap Lake, Swiftcurrent Lake, Waterton Lake, and Josephine Lake in Glacier National Park, Glacier County (McCafferty and Newell, 2007).

Observations in Montana Natural Heritage Program Database
Number of Observations: 6

(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 has been taken from rocky but somewhat quiet edgewaters along relatively large rivers in the Northwest (Jacobus and McCafferty, 2002)

Threats or Limiting Factors
All forms of stream quality degradation pose potential threats. These include siltation; pollution from agricultural and industrial waste; and hydrological alteration from drainage, dams, or withdrawal of excess water for human use.

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Citation for data on this website:
A Mayfly — Siphlonurus autumnalis.  Montana Field Guide.  .  Retrieved on , from