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Montana Field Guide

Montana Field Guides

A Sand-dwelling Mayfly - Anepeorus rusticus
Other Names:  Acanthomola pubescens

Species of Concern

Global Rank: G2
State Rank: S1
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:


 

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State Rank Reason (see State Rank above)
This sand-dwelling mayfly is currently listed as "S1" Species of Concern in MT due to extremely limited and/or rapidly declining population numbers, range and/or habitat, making it highly vulnerable to extirpation in the state. This large river species has probably lost miles of habitat due to dams on the Milk, Tongue, Bighorn, and Missouri Rivers. This species is limited by intact large, prairie river habitat and potentially may be threatened by coal bed natural gas (CBNG) development in the Powder River basin of Wyoming (Stagliano 2012).
 
General Description
This predaceous, little 2-tailed mayfly species (most mayflies have 3 tails) prefers large, warm water sandy rivers in the prairie regions of Saskatchewan and the Western Prairie States. It is an indicator species of a largely intact Large Prairie River Ecological System that is being lost in North America. It is fairly unique in the Ephemeroptera order by being predaceous; most mayfly species are herbivorous feeders on algae, diatoms and other plant materials. It "runs" along underwater sandbars searching for prey in a similar fashion to tiger beetles on terrestrial sandbars. It is a rare and uncommonly collected mayfly because of it's fast swimming ability and the use of the river current to escape. Acanthomola pubescens is a synonym of Anepeorus rusticus (Wang and McCafferty 2004).

Species Range
Montana Range

Click the legend blocks above to view individual ranges.
 


Range Comments
Rangewide, A. rusticus is known to occur in Saskatchewan and the Intermountain West (Montana, Alberta), but extirpated from Utah (NatureServe 2015). In Montana, A. rusticus has been reported from 2 (5 samples) sites on the Powder River and could potentially be found in the lower Yellowstone River.

Summary of Observations Submitted for Montana
Number of Observations: 7

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

Recency

 

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



Habitat
This species is associated with larger, perennially flowing prairie rivers with sand-dominated bottoms (shifting sandbars) and cobble riffles.

Food Habits
It is fairly unique in the Ephemeroptera order by being predaceous; most mayfly species are herbivorous feeders on algae, diatoms and other plant materials. It "runs" along underwater sandbars searching for prey in a similar fashion to tiger beetles on terrestrial sandbars.

Management
Anepeorus rusticus is seriously declining in the state probably due to siltation and habitat changes brought on by the building of dams on the large prairie rivers and long-standing drought in Montana.

Threats or Limiting Factors
Threats to this species include the loss of large river shifting sandbar habitat due to flow reductions and modification caused by dams, drought and water diversions. This species is limited by intact large, prairie river habitat and potentially may be threatened by coal bed natural gas (CBNG) development in the Powder River basin of Wyoming (Stagliano 2012).

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