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Ephemeroptera: Ephemerellidae of Gunnison County, Colorado

Ephemerella excrucians
Pale Morning Dun, PMD, Pale Olive Quill

Walsh, 1862

Updated 20 Jun 2020
TSN 101276


This mayfly was discussed in many fishing books and scientific papers from the late 20th century as Ephemerella inermis as well as Ephemerella excrucians.

Good Links

On this website:
Ephemerella Introduction

Other Websites:
Discussion and Photos of Ephemerella excrucians or Pale Morning Dun from Troutnut.com


Alexander,LC; Delion,M; Hawthorne,DJ; Lamp,WO and Funk,DH 2009 Mitochondrial lineages and DNA barcoding of closely related species in the mayfly genus Ephemerella (Ephemeroptera: Ephemerellidae). Journal of the North American Benthological Society, 28(3) 584-595. PDF
     Abstract: "We compared genetic lineages in the mayfly genus Ephemerella (Ephemeroptera: Ephemerellidae) identified from mitochondrial DNA (mtDNA) to current taxonomy in 9 morphological taxa, including 2 geographically widespread species, Ephemerella invaria ( = E. inconstans, E. rotunda, E. floripara) and Ephemerella dorothea ( = E. infrequens). Maximum likelihood and parsimony analyses of the mtDNA sequences placed E. inconstans and E. invaria in a well-supported clade; however, mean Kimura 2-parameter genetic distance between the lineages was high (5.2%) relative to distance within lineages (1.3%). The phylogenetic relationships of synonyms E. rotunda and E. floripara were not resolved, but estimates of mean genetic distance to E. invaria were high for both (8.5% and 11.6%, respectively). Populations of E. dorothea were grouped in 2 well-supported clades (12.9% mean divergence) that did not include the synonym E. infrequens (20.9% mean divergence, based on a single sample). A large genetic distance (18.6%) also was found between eastern and western populations of Ephemerella excrucians. Western samples of Ephemerella aurivillii were so genetically distant from all other lineages (32.2%) that doubt about its congeneric status is raised. mtDNA data have been useful for identifying genetic lineages in Ephemerella, but our results do not support use of cytochrome oxidase I (COI) as a DNA barcode to identify species in this genus because we also found evidence of incomplete mtDNA lineage sorting in this gene. Use of the barcoding gene rediscovered some old taxonomic problems in Ephemerella, a result that emphasizes the importance of completing empirical systematic description of species before using single-character systems for identification."

Argyle,DW; Edmunds,GF 1962 Mayflies (Ephemeroptera) of the Curecanti Reservoir Basins Gunnison River, Colorado. University of Utah Anthropological Papers 59 8, 178-189.
     Quote from page 187: "This is the most widespread species in the entire drainage. The nymphs were collected from all of the streams and all but a few of the collection stations. All specimens of this species complex are being studied by R.K. Allen and G.F. Edmunds who are attempting to revise this taxonomically difficult complex. One specimen seems to be different from the other nymphs collected."

Buchwalter,DB; Cain,DJ; Clements,WH; Luoma,SN 2007 Using biodynamic models to reconcile differences between laboratory toxicity tests and field biomonitoring with aquatic insects. Environmental Science and Technology 41, 4821-4828.
     Abstract: "Aquatic insects often dominate lotic ecosystems, yet these organisms are under-represented in trace metal toxicity databases. Furthermore, toxicity data for aquatic insects do not appear to reflect their actual sensitivities to metals in nature, because the concentrations required to elicit toxicity in the laboratory are considerably higher than those found to impact insect communities in the field. New approaches are therefore needed to better understand how and why insects are differentially susceptible to metal exposures. Biodynamic modeling is a powerful tool for understanding interspecific differences in trace metal bioaccumulation. Because bioaccumulation alone does not necessarily correlate with toxicity, we combined biokinetic parameters associated with dissolved cadmium exposures with studies of the subcellular compartmentalization of accumulated Cd. This combination of physiological traits allowed us to make predictions of susceptibility differences to dissolved Cd in three aquatic insect taxa: Ephemerella excrucians, Rhithrogena morrisoni, and Rhyacophila sp. We compared these predictions with long-term field monitoring data and toxicity tests with closely related taxa: Ephemerella infrequens, Rhithrogena hageni, and Rhyacophila brunnea. Kinetic parameters allowed us to estimate steady-state concentrations, the time required to reach steady state, and the concentrations of Cd projected to be in potentially toxic compartments for different species. Species-specific physiological traits identified using biodynamic models provided a means for better understanding why toxicity assays with insects have failed to provide meaningful estimates for metal concentrations that would be expected to be protective in nature. "

Buchwalter,DB; Cain,DJ; Martin,CA; Xie,L; Luoma,SN; Garland,JT 2008 Aquatic insect ecophysiological traits reveal phylogenetically based differences in dissolved cadmium susceptibility. Proceedings of the National Academy of Sciences 105 24, 8321-8326.

Corkum LD. 1980 Carnivory in Ephemerella inermis Eaton nymphs (Ephemeroptera: Ephemerellidae). Entomological News 91(5):161-163. PDF

Edmunds Jr, GF. 1995 Habitat differences between northern and southern populations of mayflies of the western United States. Pages 171-176 in Corkum LD; Ciborowski JJH. Current Directions in Research on Ephemeroptera. Canadian Scholars' Press, Inc. Toronto.
     Discussed as E. inermis

Gilpin,BR and Brusven,MA 1970 Food habits and ecology of mayflies of the St. Maries River in Idaho. Melanderia 4:19-40. PDF

Hamilton,H and Clifford, F 1983 The seasonal food habits of mayfly (Ephemeroptera) nymphs from three Alberta, Canada, streams, with special reference to absolute volume and size of particles ingested. Arch. Hydrobiol., Suppl, 65(2/3), 197-234. PDF
      Discussed as Ephemerella inermis.

Jacobus,LM and McCafferty,WP 2003 Revisionary contributions to North American Ephemerella and Serratella (Ephemeroptera: Ephemerellidae). Journal of the New York Entomological Society 111:174-193. PDF

Johnson,SC 1978 Larvae of Ephemerella inermis and E. infrequens (Ephemeroptera:Ephemerellidae). Pan-Pacific Entomologist 54, 19-25.
     After the Ephemerella revision by Jacobus and McCafferty in 2003, this paper could be titled "Larvae of Ephemerella excrucians and E. dorothea infrequens.". Discussed as Ephemerella inermis.

Leonard,JW 1949 The nymph of Ephemerella excrucians Walsh. Canadian Entomologist 81(6):158-159. PDF

McCafferty,WP; Durfee,RS; Kondratieff,BC 1993 Colorado mayflies (Ephemeroptera): an annotated inventory. Southwestern Naturalist 38 3, 252-274. PDF
     Discussed as Ephemerella inermis. Quote from page 266: "This evidently is one of the most common ephemerellids in Colorado; however it is easily confused with E. infrequens McDunnough, and caution must be taken in distinguishing the larvae of the two species (see Johnson 1978)."

McCafferty,WP and Provonsha, AV The Mayflies of North AmericaSpecies List (Version 8Feb2011)
     Here is the geographic range and synonyms:
Ephemerella excrucians Walsh, 1862 [CAN:FN,NE,NW;USA:NE,NW,SE,SW]
    * Ephemerella argo Burks, 1947 (syn.)
    * Ephemerella crenula Allen & Edmunds, 1965 (syn.)
    * Ephemerella excurcians Walsh, 1862 (spell.)
    * Ephemerella inermis Eaton, 1884 (syn.)
    * Ephemerella lacustris Allen & Edmunds, 1965 (syn.)
    * Ephemerella ora Burks, 1949 (syn.)
    * Ephemerella rama Allen, 1968 (syn.)
    * Ephemerella rossi Allen & Edmunds, 1965 (syn.)
    * Ephemerella semiflava McDunnough, 1926 (syn.)

Stewart,KW and Szczytko,SW 1983 Drift of Ephemeroptera and Plecoptera in two Colorado rivers. Freshwater Invertebrate Biology. 2(3)117-131. PDF

Underwood, L 2004 The Greatest Fishing Stories Ever Told: Twenty-Eight Unforgettable Fishing Tales. The Lyons Press 288pgs.
     Fishing story that mentions Ephemerella inermis (now Ephemerella excrucians).

Walsh, BD 1862 List of the Pseudoneuroptera of Illinois contained in the cabinet of the writer, with descriptions of over forty new species, with notes on their structural affinities. Proceedings of the Academy of Natural Sciences Philadelphia 14:361-402.
     Walsh described Ephemerella excrucians in this paper.
Walsh 1862 described the mayfly species Ephemerella excrucians in this paper on page 377 Walsh 1862 continued his description of the mayfly species Ephemerella excrucians in this paper on page 378

Brown, Wendy S. 2004 Mayflies (Ephemeroptera) of Gunnison County, Colorado, USA