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Montana Field Guide

Montana Field Guides

A Mayfly - Caenis youngi


Global Rank: G4
State Rank: S3
* (see State Rank Reason below)

Agency Status
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State Rank Reason (see State Rank above)
This species had few occurrence records and a perceived limited distribution in Montana. It was added to the Species of Concern list as an S2 in 1987 for “undocumented reasons” (MNHP 2015). However, more recent macroinvertebrate surveys across various regions of the state have greatly increased the number of occurrences to 29, and it is now considered to be less habitat-restricted with a statewide range extent (MNHP 2015). We updated the Nature Serve model to factor in this species’ wider-ranging distribution and its revised rank is an S3. In light of this, MNHP has removed it from the SOC list.
 
General Description
This mayfly species has been reported from slow-moving vegetated streams, sloughs or wetlands across Montana. The larvae are small and brown with protective opercules over their gills to protect them from silt and sediment.

Diagnostic Characteristics
The larvae are small and brown with protective opercules over their gills to protect them from silt and sediment.

Species Range
Montana Range

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Range Comments
Locations and habitat presented in the original species description indicated that this species was limited to slow moving waters in the Yellowstone Park area of Montana (Roemhild 1984). However, more recent macroinvertebrate surveys across various regions of the state have greatly increased the number of occurrences to 29, and it is now considered to be less habitat-restricted with a statewide range extent (MNHP 2015).

Summary of Observations Submitted for Montana
Number of Observations: 31

(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)



Migration
This species is not known to migrate as adults and the larvae are fairly sedentary.

Habitat
This mayfly species has been reported from slow-moving vegetated streams, sloughs or wetlands across Montana.

References
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Citation for data on this website:
A Mayfly — Caenis youngi.  Montana Field Guide.  .  Retrieved on , from