Ephemeroptera: Heptageniidae of Gunnison County, ColoradoIntroduction to the mayfly genus Epeorus Eaton 1881 |
| Trait | Male | Female |
| Eyes | Large, touching in the middle | Small, widely spaced, not touching |
| Forelegs | Extremely Long (used to clasp females) | About the same length as the other legs |
| Abdomen | Claspers between tails | No claspers |
The stonefly Megarcys signata appears to be chasing an Epeorus nymph who is swimming away. These animals were caught and released from the upper East River on the 17th of July 2009.
Good Links
On this website:Introduction to Iron
Heptageniidae Introduction
Other Websites:
Photos of Epeorus larvae from the McKenzie River, Oregon http://zebu.uoregon.edu/~dmason/Mckenzie/bugs/epeorus.html
This animal was under a rock in a stream in the upper East River Valley 18 July 2007.
References
Allan,JD 1978 Diet of brook trout (Salvelinus fontinalis Mitchell) and Brown Trout (Salmo trutta L.) in an alpine stream. Internationale Vereinigung für Theoretische und Angewandte Limnologie Verhandlungen 20, 2045-2050.Allan,JD and Flecker,AS 1989 The mating biology of a mass-swarming mayfly. Animal behavior 37, 361-371.
Buchwalter,DB and Luoma,SN 2005 Differences in dissolved cadmium and zinc uptake among stream insects: mechanistic explanations. Environmental Science and Technology 39, 498-504.
Eaton,AE 1881 An announcement of new genera of the Ephemeridae. Entomologist's Monthly Magazine 18:21-27.
The genus Epeorus is described on page 26.
Edmunds,GF and Allen,RK 1964 The Rocky Mountain species of Epeorus (Iron) Eaton (Ephemeroptera: Heptageniidae). Journal of the Kansas Entomological Society 37 (4) 275-288. PDF
Abstract: "The North American mayflies variously assigned to the genus Iron or the genus Epeorus present a perplexing problem in generic classification and this problem, as yet, has no clear solution. The type species of Epeorus (E. torrentis Eaton) and Iron (I. longimanus Eaton) appear to be as distinct in both the adult and nymphal stages as are other genera in the Heptageniidae. Lestage (1917), on the basis of nymphal characters, even placed these genera in separate subfamilies. In Europe the two types appear to retain their identity as distinct genera, but some of the New World species have uncertain generic placement. The North American species can be separated into two genera by the character of the tarsal claws in the male imago; however, the nymphal stages do not conform to this arrangement. The penes of the males of the known species are extremely diverse, and again, the groupings of the nymphal stages are not consistent with groupings based on the forms of the male genitalia. It is apparent that a clarification of the relationship of these species must await a general revision of the complex. Epeorus torrentis has a different type of penis than any of the North American species, including those assigned to Epeorus, and therefore we are placing Iron as a subgenus of Epeorus, including all of the species assigned by Traver (1935) to this name. The nymphs of Ironopsis (Traver) are so fundamentally similar to the nymphs of Epeorus (Iron) longimanus that we also regard it as a subgenus of Epeorus rather than as a distinct genus. The nymphs of Ironodes (Traver) are readily distinguished by the presence of dorsal abdominal tubercles, but the penes of the male imagoes are so similar to those of the subgenus Ironopsis that this group also seems best placed as a subgenus of Epeorus. This classification has been previously proposed by Burks (1953), Edmunds and Traver (1954) and Demoulin (1958); however, for a final clarification, a detailed study must be completed for the Asian species, including Bleptus, allies of Iron reported by Traver (1933a), and other Asian forms as yet undescribed."
Ellsworth,SD 2000 Influence of substrate size, Cladophora, and caddisfly pupal cases on colonization of macroinvertebrates in Sagehen Creek, California. Western North American Naturalist, pp.311-319. PDF
Abstract: "Colonization of stream macroinvertebrates onto artificial substrates was examined in Sagehen Creek California, during 1993. Substrate size and presence or absence of pupal cases of the caddisfly Anagapetus (Glossosmatidae) were examined as possible influences on macroinvertebrate colonization. Macroinvertebrates were collected from substrates after 60 d of incubation and identified to the lowest feasible taxonomie unit. Dry weight of the filametous green alga Cladophora also was determined for each substrate.
A general linear model indicated a significant positive relationship between both substrate size and presence pupal cases on richness (P < 0.001). There was no significant effect of cases on the E5 evenness index, which supports the passive sampling model as a mechanism giving rise to the effect of cases on richness. A multivariate general linear model indicated a significant positive effect of Anagapetus cases on Micrasema bactro, Epeorus, and Rhyacophila sp and of substrate size on Hydropsyche occidentalis and Epeorus. Neither cases nor substrate size had a significant effect on Cladophora density (P > 0.05). There were significant negative correlations between Cladophora density and both Shannon H' and J' indices. There were significant positive relationships between Cladophora density with Baetis, Simulium, and Chironomidae density. Combined main effects of substrate size, Anagapetus pupal cases, and Cladophora have dynamic influences on this macroinvertebrate fauna. This study demonstrates the complex interplay of biotic abiotic factors that determine macroinvertebrate distribution and abundance in this system."
Gill,BA; Harrington,RA; Kondratieff,BC; Zamudio,KR; Poff,NL and Funk,WC 2014 Morphological taxonomy, DNA barcoding, and species diversity in southern Rocky Mountain headwater streams. Freshwater Science 33(1) 288-301.
Working in wadeable streams on the Front Range of Colorado, they found a cryptic species of Epeorus alongside E. albertae, deceptivus and longimanus.
Jensen,SL 1966 The Mayflies of Idaho (Ephemeroptera). M.S. Thesis, University of Utah, Utah. 364 p.
Quote from page 161: " The following combinations of characters serve to distinguish this genus from all other genera of Heptageniidae occurring in Idaho: Male Imagos. (1) Basal segment of the foretarsi equal to or slightly longer than the second segment. Female Imagos. Either (1) the subanal plate is broadly rounded with only a shallow posterior margin of the head deeply emarginate; or (2) the subanal plate with the postero-median emargination usually well developed, and with the basal crossveins of forewings weakly developed, appearing detached anteriorly (Fig 65). Nymphs. (1) Two caudal filaments present, the median terminal filiment absent (fig. 62)."
Lehmkuhl,DM 1968 Observations on the life histories of four species of Epeorus in western Oregon (Ephemeroptera: Heptageniidae). Pan-Pacific Entomologist 44(2):129-137. PDF
Li,R; Lei,Z; Li,W; Zhang,W and Zhou,C 2021 Comparative mitogenomic analysis of heptageniid mayflies (Insecta: Ephemeroptera): Conserved intergenic spacer and trna gene duplication. Insects, 12(2), p.170.
Abstract: "Large intergenic spacers and tRNA gene duplications have been reported in several insect groups, although little is known about mitogenomes of mayflies. Here, we determined complete mitogenomes of ten heptageniid species and systemically analyzed their mitogenomic features. Both a conserved intergenic spacer (IGS) and trnM duplication were detected in those mitogenomes. The IGS, which was observed in heptageniids, could be further folded into a stable stem-loop structure. The tRNA gene duplication was found in almost all analyzed mitogenomes, and a unique gene block trnI-trnM-trnQ-trnM-ND2 was also discovered. Our analysis demonstrates that the heptageniid gene arrangement pattern can be explained by the tandem duplication-random loss (TDRL) model. Phylogenetic analyses using both Bayesian inference (BI) and maximum likelihood (ML) methods based on the nucleotide and amino acid sequence data recovered the genus Epeorus as monophyletic with strong support. Our results provide a better understanding of mitogenomic evolution in Heptageniidae, as well as novel molecular markers for species identification of mayflies."
Ma,Z; Li,R; Zhu,B; Zheng,X and Zhou,C 2022 Comparative mitogenome analyses of subgenera and species groups in Epeorus (Ephemeroptera: Heptageniidae). Insects, 13(7), p.599. PDF
AbstTronstad,LM; Hotaling,S; Giersch,JJ; Wilmot,OJ and Finn,DS 2020 Headwaters fed by subterranean ice: potential climate refugia for mountain stream communities?. BioRxiv, p.788273. ract: "Epeorus Eaton, 1881 is a diverse mayfly genus in Heptageniidae comprising more than 100 species which are further divided into nine subgenera and several species groups. However, the classification and the phylogenetic relationships among them are still uncertain. Here, 15 complete mitochondrial genomes of Epeorus were sequenced and compared together with six available ones of same genus in the NCBI database. Based on morphological classification, the 21 mitogenomes were classified into six subgenera (Proepeorus, Epeorus s.str., Belovius, Iron, Caucasiron and Siniron) and four species groups (G1, G2, montanus and longimanus). Among all analyzed mitogenomes, the gene rearrangement of trnI-trnM-trnQ-NCR-ND2 was first found occurring in three species of group G1, whereas the gene block trnI-trnM-trnQ-trnM-ND2 was observed in all other mitogenomes of Epeorus. Furthermore, the genetic composition and codon usage of species in group G1 were also significantly different from all other Epeorus species, except group longimanus. The intergenic spacer between trnA and trnR, which has the stem-loop secondary structure, occurred in all 21 mitogenomes, and the sequences of stems and loops were conserved within species groups. Furthermore, the phylogenetic analyses strongly support the monophyly of all species groups, although three of six recognized subgenera Proepeorus, Belovius, and Iron, were shown as the non-monophyletic groups."
Mebane,CA; Dillon,FS and Hennessy,DP 2012 Acute toxicity of cadmium, lead, zinc, and their mixtures to stream-resident fish and invertebrates. Environmental Toxicology and Chemistry, 31(6), 1334-1348. PDF
Tronstad,LM; Hotaling,S; Giersch,JJ; Wilmot,OJ and Finn,DS 2020 Headwaters fed by subterranean ice: potential climate refugia for mountain stream communities? Western North American Naturalist, 80(3), pp.395-407. PDF
Abstract: "Near-term extirpations of macroinvertebrates are predicted for mountain streams worldwide as a warming climate drives the recession of high-elevation ice and snow. However, hydrological sources likely vary in their resistance to climate change and thus streams fed by more resistant sources could persist as climate refugia for imperiled biota. In 2015-2016, we measured habitat characteristics and quantified macroinvertebrate community structure along six alpine streams in the Teton Range, Wyoming, USA. Strong differences in habitat characteristics (e.g., temperature, bed stability, conductivity) confirmed three major stream sources: surface glaciers, perennial snowfields, and subterranean ice. Subterranean ice-fed streams - termed "icy seeps" - appear common in the Teton Range and elsewhere yet are globally understudied. Midges in the family Chironomidae dominated our study sites, representing 78.6% of all specimens sampled, with nematodes, caddisflies (Neothremma), and mayflies (Epeorus) also common. At the community-scale, glacier-and snowmelt-fed streams differed significantly in multivariate space, with icy-seep communities intermediate between them, incorporating components of both assemblages. Because the thermal environment of subterranean ice, including rock glaciers, is decoupled from large-scale climatic conditions, we predict that icy seeps will remain intact longer than streams fed by surface ice and snow. Furthermore, our results suggest that icy seeps are suitable habitat for many macroinvertebrates occupying streams fed by vulnerable hydrological sources. Thus, icy seeps may act as key climate refugia for mountain stream biodiversity, an idea in need of further investigation."
The United States Geological Survey (USGS) National Water Quality Assessment Data Warehouse (NAWQA) shows this species is present in Gunnison County. Data as of 1Sep2005
Webb,JM and McCafferty,WP 2006. Contribution to the taxonomy of Eastern North American Epeorus Eaton (Ephemeroptera: Heptageniidae). Zootaxa 1128: 57-64.
Wellnitz,TA; Poff,NL; Cosyleón,G and Steury,B 2001 Current velocity and spatial scale as determinants of the distribution and abundance of two rheophilic herbivorous insects. Landscape Ecology, 16(2), 111-120. PDF
Abstract: "Organisms frequently show marked preferences for specific environmental conditions, but these preferences may change with landscape scale. Patterns of distribution or abundance measured at different scales may reveal something about an organism's perception of the environment. To test this hypothesis, we measured densities of two herbivorous aquatic insects that differed in body morphology and mobility in relation to current velocity measured at different scales in the upper Colorado River (Colorado, USA). Streambed densities of the caddisfly larva Agapetus boulderensis (high hydrodynamic profile, low mobility) and mayfly nymph Epeorus sp. (low hydrodynamic profile, high mobility) were assessed at 3 spatial scales: whole riffles, individual cobbles within riffles, and point locations on cobbles. Riffles were several meters in extent, cobbles measured 10-30 cm in size, and the local scale was within a few centimeters of individual larvae (themselves ca. 0.5-1.0 cm in size). We also quantified the abundance of periphytic food for these herbivores at the cobble and riffle scales. Agapetus favored slow current (<30 cm s-1) across all scales. Epeorus, by contrast, favored fast current (60-80 cm s-1) at the local and riffle scale, but not at the cobble scale. Only Agapetus showed a significant relationship to current at the cobble scale, with greatest larval densities occurring at velocities near 30 cm s-1. We had predicted an inverse correlation between grazer density and periphytic abundance; however, this occurred only for Agapetus, and then only at the cobble scale. These data suggest that organisms respond to environmental gradients at different spatial scales and that the processes driving these responses may change with scale, e.g., shifting from individual habitat selection at local and cobble scales to population responses at the riffle scale. This study also highlights the importance of using the appropriate scale of measurement to accurately assess the relationship between organisms and environmental gradients across scale. "
Zitnan,D; Zitnanová,I; Spalovská,I; Takác,P; Park,Y and Adams,ME 2003 Conservation of ecdysis-triggering hormone signalling in insects. The Journal of Experimental Biology 206, 1275-1289. Full Text
One of their study animals was Epeorus sp.