Stenacron
Introduction '''''Stenacron''''' is a genus of mayfly in the family Heptageniidae (the flat-headed mayflies), with a distribution across eastern North America.
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.
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 of ''"The Biology of Mayflies"'''','' 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.List of the currently valid species as of 2014:* ''Stenacron candidum'' (Traver, 1935) i c g b* ''Stenacron carolina'' (Banks, 1914) i c g b* ''Stenacron floridense'' (Lewis, 1974) i c g b* ''Stenacron gildersleevei'' (Traver, 1935) i c g b (Gildersleeve's Stenacron Mayfly)* ''Stenacron interpunctatum'' (Say, 1839) i c g b (Stenacron Mayfly)* ''Stenacron minnetonka'' (Daggy, 1945) i c g b* ''Stenacron pallidum'' (Traver, 1933) i c g bData sources: i = ITIS, c = Catalogue of Life, g = GBIF, b = Bugguide.netSynonym forms that make up the interpunctatum complex. *''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
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