Stenacron
Stenacron interpunctatum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Ephemeroptera
Family: Heptageniidae
Genus: Stenacron
Jensen, 1974

Stenacron is a genus of mayfly in the family Heptageniidae (the flat-headed mayflies),[1] with a distribution across eastern North America.[2]

Life History

Although larvae can be found in many different conditions, they have some basic and preferred requirements. They tend to cling to the underside of rocks that are a minimum of 8 X 8 inches and 2 inches thick. Larger rocks contain greater populations of Stenacron species. They are seldom found in the faster riffle waters, but instead at the slower moving banks, typically with a water depth of no less than 3 inches and up to 16 inches deep. Stenacron can live in waters that are not moving and low in Dissolved Oxygen (DO), although they prefer stable and moderate DO levels, in which greater populations will occur. Documented in "Taxonomy and ecology of Stenonema mayflies", Phillip A. Lewis showed that the form Stenacron interpunctatum / heterotarsale historically carried an EBI (Empirical Biotic Index) rating of a level 7, showing a high tolerance level to pollution, both Toxic and Organic.[3]

Taxonomy

History

Thomas Say first documented the species interpunctatum in 1839 in Indiana from 20 holotypes and 14 paratypes. Hagan, in 1861, confirms and expands the geographical range of the species with the collection of others in Virginia that concurred with Say’s haplotypes. Dr. J.R. Traver, the second author[4] of "The Biology of Mayflies"[5], said there are three distinct groups in the genus Stenonema in 1933. The interpunctatum group later became the genus Stenacron. Steven L Jensen listed the genus as Stenacron in 1974.

Species

Although there are 7 recognized species in the genus, the variation amongst populations of S. interpunctatum forms the Stenacron interpunctatum complex, which comprises 16 closely related subspecies.[6]

List of the currently valid species as of 2014:

Data sources: i = ITIS,[7] c = Catalogue of Life,[8] g = GBIF,[9] b = Bugguide.net[10]

Synonym forms that make up the interpunctatum complex.[11]

  • Stenacron interpunctatum / affine
  • Stenacron interpunctatum / areion
  • Stenacron interpunctatum / canadense
  • Stenacron interpunctatum / conjunctum
  • Stenacron interpunctatum / frontale
  • Stenacron interpunctatum / heterotarsale
  • Stenacron interpunctatum / majus
  • Stenacron interpunctatum / ohioense
  • Stenacron interpunctatum / proximum

Larval development

“No experimental evidence exists to indicate how much or how little coloration of the imaginal individuals of this genus is independent of the environment in which the nymphs develop. Circumstantial evidence Spieth (1938) indicates, and such evidence is constantly accumulating, that the environment may play a part in determining the degree of coloration of the adults”

— Spieth, Herman T., Taxonomic Studies on the Ephemeroptera IV. The Genus Stenonema

When confronted with a large series, especially from the areas around the Great Lakes, more “intermediate” than “typical” specimens are invariably found

— Speith, Herman T., Taxonomic Studies on the Ephemeroptera IV. The Genus Stenonema

References

  1. ↑ "Genus Ephemeroptera Heptageniidae Stenacron". www.macroinvertebrates.org. Retrieved 2023-07-01.
  2. ↑ Murray, Tom (2006). "Genus Stenacron". BugGuide - Genus Stenacron Info Page.
  3. ↑ Lewis, P. A. (1974). The Taxonomy and Ecology of Stenonema Mayflies. National Environmental Research Center.
  4. ↑ Mosely, Martin E. (August 1936). "The Biology of Mayflies". Nature. 138 (3484): 223–224. doi:10.1038/138223a0. ISSN 0028-0836.
  5. ↑ "The biology of mayflies, with a systematic account of North American species, by James G. Needham ... Jay R. Traver ... [and] Yin-chi Hsu ... assisted by specialists ..." HathiTrust. Retrieved 2023-10-16.
  6. ↑ Traver, J. D. (1935). Biology of a Mayfly.
  7. ↑ "Stenacron Report". Integrated Taxonomic Information System. Retrieved 2018-03-24.
  8. ↑ "Browse Stenacron". Catalogue of Life. Retrieved 2018-03-24.
  9. ↑ "Stenacron". GBIF. Retrieved 2018-03-24.
  10. ↑ "Stenacron Genus Information". BugGuide.net. Retrieved 2018-03-24.
  11. ↑ "Taxonomy and ecology of Stenonema mayflies (Heptageniidae: Ephemeroptera) / by Philip A. Lewis". HathiTrust. Retrieved 2023-10-16.
  • Chinery, Michael (1986). Collins Guide to the Insects of Britain and Western Europe. London: Collins. ISBN 0-00-219170-9.

Further reading

  • Media related to Stenacron at Wikimedia Commons
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