Heptageniidae
Guides
Arthroplea bipunctata
flatheaded mayfly
Arthroplea bipunctata is a species of flatheaded mayfly in the family Heptageniidae (sometimes historically placed in Arthropleidae). It is known from North America, with records from the Nearctic region. The species was described by McDunnough in 1924, originally as Cinygma bipunctata. Like other flatheaded mayflies, it belongs to a group adapted to clinging in fast-flowing waters.
Cinygma dimicki
Cinygma dimicki is a species of flat-headed mayfly in the family Heptageniidae, described by James Halliday McDunnough in 1934. It belongs to a genus of North American mayflies characterized by distinctive head morphology adapted for clinging to substrates in flowing water. The species is known from the Nearctic region, though specific ecological details remain poorly documented in published literature.
Cinygma integrum
Cinygma integrum is a North American mayfly species in the family Heptageniidae. It is one of three Cinygma species on the continent. The life history has been studied in Oregon, where nymphs occupy submerged wood habitats year-round and adults emerge from mid-May to mid-July. The nymph is the only described member of its genus in North America.
Cinygma lyriforme
Cinygma lyriforme is a species of flatheaded mayfly in the family Heptageniidae, originally described as Ecdyonurus lyriformis by James Halliday McDunnough in 1924. The species name "lyriforme" refers to the lyre-shaped pattern characteristic of this taxon. Like other members of Heptageniidae, it possesses dorsoventrally flattened nymphs adapted for clinging to substrates in flowing water. The genus Cinygma is a small Nearctic genus with limited species diversity.
Cinygmula
Cinygmula is a genus of flatheaded mayflies (Heptageniidae) comprising at least 30 described species. The genus is characterized by distinctive morphological features in some species, including pointed claws and a distinct frontal fold on the imago. Species occur in high-altitude alpine habitats across central Asia and the eastern Himalaya. The genus has been studied for its potential use as a bioindicator of aquatic contamination.
Cinygmula reticulata
Cinygmula reticulata is a species of mayfly in the family Heptageniidae, first described by McDunnough in 1934. It is a member of the Nearctic fauna, occurring in North America. Like other members of the genus Cinygmula, it is associated with running water habitats where the aquatic nymphs develop. The species is represented by limited observation records, with only four observations documented on iNaturalist.
Cinygmula subaequalis
flatheaded mayfly
Cinygmula subaequalis is a flatheaded mayfly species in the family Heptageniidae. It is distributed across northern North America, including Alaska, northern Canada, and the eastern United States. The species belongs to a genus characterized by distinctive head morphology. Limited observational data suggests it is rarely encountered.
Ecdyonurus
Ecdyonurus is a genus of mayflies in the family Heptageniidae, comprising approximately 66 described species distributed primarily across Europe and parts of North Africa and Asia. The genus is taxonomically well-studied, with multiple species described in recent decades from mountain regions including the Carpathians, Crimean Peninsula, and Aurès Mountains. Species within this genus are typically associated with running waters and have been subjects of ecological studies on larval growth and thermal biology.
Epeorus albertae
flatheaded mayfly
Epeorus albertae is a flatheaded mayfly in the family Heptageniidae, distributed across northern and western North America. Laboratory studies indicate that nymphal growth rate and activity are strongly temperature-dependent, with optimal growth occurring at 15°C compared to slower development at lower temperatures. Nymphs exhibit behavioral thermoregulation by seeking refugia at cold temperatures, suggesting adaptation to thermally variable stream environments.
Epeorus fragilis
flatheaded mayfly
Epeorus fragilis is a species of flatheaded mayfly in the family Heptageniidae, first described by Morgan in 1911. It is distributed across North America. As a member of the order Ephemeroptera, it undergoes aquatic larval development before emerging as a short-lived adult.
Epeorus longimanus
flatheaded mayfly
Epeorus longimanus is a flatheaded mayfly species in the family Heptageniidae. Nymphs inhabit stream riffles and show specific microhabitat preferences, being more abundant in areas with smaller sediment sizes, higher live periphyton biomass, and lower densities of invertebrate predators. The species is distributed across western North America from Alaska through the western United States to southwestern and northern Canada.
Epeorus pleuralis
Quill Gordon
Epeorus pleuralis, commonly known as the Quill Gordon, is a flatheaded mayfly in the family Heptageniidae. It is native to North America and is recognized as an important species in aquatic entomology and fly fishing. The species is known for its relatively early emergence in the spring, making it a significant hatch for anglers in eastern North American streams.
Epeorus punctatus
Epeorus punctatus is a species of flat-headed mayfly in the family Heptageniidae. The species was originally described by McDunnough in 1925 under the genus Iron before being transferred to Epeorus. It is known from North America within the Nearctic region. Like other members of the genus, it likely inhabits flowing water environments where the nymphs cling to submerged substrates.
Heptagenia adaequata
Heptagenia adaequata is a species of flatheaded mayfly in the family Heptageniidae. Described by James Halliday McDunnough in 1924, it is a Nearctic species found in North America. Like other members of its genus, it is associated with running water habitats. The species is represented by relatively few observations in biodiversity databases.
Heptagenia flavescens
flatheaded mayfly
Heptagenia flavescens is a species of flatheaded mayfly in the family Heptageniidae. The species has been documented in North America and Central America, with records indicating a southwestern range extension. As with other members of Heptageniidae, it possesses the characteristic flattened head morphology associated with this group of mayflies.
Heptagenia marginalis
Margined Flat-headed Mayfly
Heptagenia marginalis is a species of flatheaded mayfly in the family Heptageniidae, first described by Banks in 1910. It belongs to a family characterized by dorsoventrally flattened body forms adapted to clinging in fast-flowing water. The species is known from North America, though detailed biological information remains limited in available literature.
Heptagenia pulla
dusky flat-headed mayfly
Heptagenia pulla is a species of flat-headed mayfly in the family Heptageniidae, commonly known as the dusky flat-headed mayfly. The species was described by Clemens in 1913 and is native to the Nearctic region. Like other members of its genus, it is associated with flowing freshwater habitats. The specific epithet "pulla" refers to the dusky or dark coloration characteristic of this species.
Ironodes
Ironodes is a genus of mayflies in the family Heptageniidae, first described by Traver in 1935. Members of this genus are part of the diverse Heptageniidae family, commonly known as flat-headed mayflies due to their distinctive head morphology. The genus is represented by relatively few observations, suggesting it may be uncommon, geographically restricted, or underreported in surveys.
Ironodes nitidus
Ironodes nitidus is a species of flat-headed mayfly in the family Heptageniidae. The species was described by Eaton in 1885. It belongs to a genus of mayflies found in North America, with records from the Nearctic region including Middle America and North America. The genus Ironodes is part of the diverse Heptageniidae family, which contains many species adapted to running water habitats.
Leucrocuta aphrodite
Leucrocuta aphrodite is a species of flatheaded mayfly in the family Heptageniidae. It inhabits freshwater streams and rivers in eastern North America. The species was described by McDunnough in 1926.
Leucrocuta hebe
flatheaded mayfly
Leucrocuta hebe is a species of flatheaded mayfly in the family Heptageniidae. This species is found across parts of North America, including the northern and southeastern United States and northern Canada. As a member of the order Ephemeroptera, it has an aquatic larval stage and a short-lived adult stage.
Leucrocuta jewetti
Jewett's Flat-headed Mayfly
Leucrocuta jewetti is a species of flatheaded mayfly in the family Heptageniidae. It is known from southeastern Canada and the northwestern United States. As a member of the Heptageniidae, it belongs to a family of mayflies commonly associated with running water habitats. The species was described by Allen in 1966.
Leucrocuta juno
Leucrocuta juno is a species of flatheaded mayfly in the family Heptageniidae, described by McDunnough in 1924. It belongs to the order Ephemeroptera, a group of aquatic insects known for their brief adult lifespan. The species is native to North America and is part of a genus characterized by distinctive morphological features typical of heptageniid mayflies.
Leucrocuta minerva
Leucrocuta minerva is a species of mayfly in the family Heptageniidae, described by McDunnough in 1924. It belongs to a genus of small to medium-sized flat-headed mayflies commonly known as "little yellow quills" or similar vernacular names. Species in this genus are typically associated with running water habitats. The specific epithet "minerva" refers to the Roman goddess of wisdom, though the etymological reasoning behind this choice is not documented in available sources.
Leucrocuta thetis
Leucrocuta thetis is a species of flatheaded mayfly in the family Heptageniidae. It is known from North America. As a member of the Heptageniidae, it belongs to a group of mayflies commonly associated with running water habitats. The species was described by Traver in 1935.
Maccaffertium
flatheaded mayflies
Maccaffertium is a genus of mayflies in the family Heptageniidae, commonly known as flatheaded mayflies. The genus was established by Bednarik in 1979 and contains approximately 19–20 described species. Like other members of Heptageniidae, these mayflies are characterized by their flattened, streamlined bodies adapted for life in flowing water. The genus is found in North America, with species distributed across various freshwater habitats.
Maccaffertium mediopunctatum
flat-headed mayfly
Maccaffertium mediopunctatum is a species of flat-headed mayfly in the family Heptageniidae. It occurs in Southeastern Canada and the Eastern United States. The species has two recognized subspecies: M. m. arwini and M. m. mediopunctatum. Like other members of its genus, it exhibits the unique mayfly developmental trait of having a fully winged subadult stage (subimago) that requires one additional molt to reach sexual maturity.
Maccaffertium mediopunctatum arwini
A subspecies of mayfly in the family Heptageniidae. Like other members of its genus, it exhibits the characteristic subimago stage—fully winged but sexually immature—unique among insects. Adults are short-lived, emerging from aquatic habitats to mate. The subspecific epithet honors an individual, following the pattern of other Maccaffertium subspecies.
Maccaffertium mediopunctatum mediopunctatum
Maccaffertium mediopunctatum mediopunctatum is a subspecies of mayfly in the family Heptageniidae. The genus Maccaffertium was established to accommodate species formerly placed in Heptagenia and related genera, distinguished by particular features of the male genitalia and wing venation. This subspecies is part of a group of flatheaded mayflies commonly found in North American streams and rivers. Subimagos (subadults) of this species exhibit the characteristic pale, milky-white coloration and opaque wings typical of the genus, with sexual dimorphism in eye size and abdominal claspers.
Maccaffertium meririvulanum
fresh flat-headed mayfly
Maccaffertium meririvulanum is a species of flatheaded mayfly in the family Heptageniidae, characterized by its distinctive flattened head morphology typical of this group. The species is known from North America, where it inhabits freshwater lotic environments. As with other members of the genus, it undergoes the unique mayfly developmental pattern involving a winged subadult (subimago) stage that molts once more to reach sexual maturity.
Maccaffertium mexicanum
flatheaded mayfly
A flatheaded mayfly species in the family Heptageniidae. Adults are attracted to light sources near aquatic habitats. The species possesses the unique mayfly trait of developing fully functional wings during the subimago (sub-adult) stage, requiring one additional molt to reach sexual maturity. Two subspecies are recognized: M. m. integrum and M. m. mexicanum.
Maccaffertium modestum
flatheaded mayfly
Maccaffertium modestum is a species of flatheaded mayfly in the family Heptageniidae. It occurs in North America, specifically in the eastern United States and southeastern Canada. The species exhibits the characteristic subimago stage typical of mayflies, where fully functional wings develop before the final molt to adulthood.
Maccaffertium pudicum
flatheaded mayfly
Maccaffertium pudicum is a species of flatheaded mayfly in the family Heptageniidae. It is found in North America. The species exhibits the characteristic subimago stage typical of mayflies, where fully functional wings develop before the final molt to adulthood.
Maccaffertium smithae
Maccaffertium smithae is a species of flatheaded mayfly in the family Heptageniidae, described by Traver in 1937. As a member of the Heptageniidae family, it possesses the characteristic flattened head shape typical of this group. The species is known from North America, though specific details about its biology and ecology remain limited in the available literature.
Maccaffertium terminatum
flatheaded mayfly
Maccaffertium terminatum is a species of flatheaded mayfly in the family Heptageniidae. It is widely distributed across Canada and the Nearctic region. The species possesses the characteristic subimago stage typical of mayflies, where sexually immature adults with opaque, milky-white wings emerge from water before undergoing a final molt to the reproductive adult stage. Two subspecies are recognized: M. t. terminatum and M. t. placitum.
Maccaffertium terminatum placitum
Maccaffertium terminatum placitum is a subspecies of mayfly in the family Heptageniidae. Like other members of the genus, it exhibits the unique mayfly developmental trait of having a functional winged sub-adult stage (subimago) prior to the final molt to sexual maturity. The subimago is characterized by milky-white, opaque wings and paler body coloration compared to the transparent-winged adult. This subspecies is part of the Nearctic fauna of North America.
Macdunnoa
Macdunnoa is a genus of mayflies in the family Heptageniidae, established by Lehmkuhl in 1979. The genus belongs to the order Ephemeroptera, a group of aquatic insects known for their brief adult lifespan. Very few observations of this genus have been recorded, with only a single documented observation in iNaturalist. As a member of Heptageniidae, it is part of a diverse family of flat-headed mayflies commonly found in running water habitats.
Nixe
Nixe is a genus of mayflies in the family Heptageniidae, established by Flowers in 1980. These aquatic insects belong to the order Ephemeroptera, characterized by their short adult lifespan and complex life cycles involving aquatic nymphal stages. The genus has been documented in 451 iNaturalist observations, indicating moderate levels of citizen science engagement. As heptageniid mayflies, members of this genus likely inhabit flowing water environments where their nymphs develop.
Nixe inconspicua
Nixe inconspicua is a species of flatheaded mayfly in the family Heptageniidae, first described by McDunnough in 1924. As a member of the Heptageniidae, it possesses the characteristic dorsoventrally flattened body form typical of this family. The species is known from North America, though specific details about its biology and ecology remain limited in the available literature.
Nixe lucidipennis
clear-winged flat-headed mayfly
Nixe lucidipennis is a species of flat-headed mayfly in the family Heptageniidae, distributed across North America. The species was described by Clemens in 1913. It is known from a limited number of observations, with records indicating presence in the Nearctic region. As a member of the genus Nixe, it belongs to a group of mayflies characterized by their flattened head morphology and association with running water habitats.
Pseudiron centralis
White Sand-river Mayfly
Pseudiron centralis is a predaceous mayfly species endemic to sandy freshwater river habitats in North America. It exhibits a univoltine summer life cycle with an extended egg stage lasting 9–10 months. Larvae are active epibenthic predators specialized for feeding on psammophilous chironomid larvae, with distinct microhabitat shifts during development: early instars occupy marginal sands, while later instars inhabit shifting sand dunes in main channel areas. The species shows low population density but also low mortality, with random dispersion patterns in mature larvae.
Raptoheptagenia cruentata
predaceous flat-headed mayfly
Raptoheptagenia cruentata is a mayfly species originally described as Heptagenia cruentata by Walsh in 1863, later reclassified into the new genus Raptoheptagenia based on distinctive larval morphology. The genus was established because the larvae differ markedly from other Heptagenia species, having been previously misidentified as belonging to the genus Anepeorus. Adult males were successfully reared from these larvae, confirming the adult-larval association. This species belongs to the family Heptageniidae, commonly known as flat-headed mayflies.
Rhithrogena
March Browns, Olive Uprights
Rhithrogena is a genus of flatheaded mayflies in the family Heptageniidae, commonly known as March Browns or Olive Uprights. The genus contains approximately 153 species distributed across the Holarctic region. Larvae are primarily scrapers that feed on periphyton from stones in running waters. Several species serve as important food sources for fish and have been studied for their bioindicator potential in freshwater monitoring.
Rhithrogena hageni
Western Black Quill
Rhithrogena hageni is a mayfly species in the family Heptageniidae, first described by Eaton in 1885. It is known from the Nearctic region, specifically North America. The species is commonly referred to as the Western Black Quill. Like other members of the genus Rhithrogena, it is associated with lotic (flowing water) habitats where its nymphs develop.
Spinadis simplex
Wallace's Deepwater Mayfly
Spinadis simplex is a species of mayfly in the family Heptageniidae, commonly known as Wallace's Deepwater Mayfly. It is a North American species first described by Walsh in 1863. The genus Spinadis is distinguished within the Heptageniidae by specific morphological characteristics related to wing venation and genitalia structure. Like other members of the family, S. simplex has aquatic nymphal stages and winged adult stages with brief adult lifespans.
Stenacron carolina
Carolina flat-headed mayfly
Stenacron carolina is a species of flatheaded mayfly in the family Heptageniidae. It is found in North America. The species was described by Banks in 1914. Like other members of the genus Stenacron, it is associated with aquatic habitats.
Stenacron floridense
Stenacron floridense is a species of flatheaded mayfly in the family Heptageniidae, first described by Lewis in 1974. It is part of a genus of mayflies characterized by dorsoventrally flattened bodies adapted for clinging to substrates in flowing water. The species is recorded from North America, though specific details about its biology remain limited in published literature.
Stenacron minnetonka
flatheaded mayfly
Stenacron minnetonka is a species of flatheaded mayfly in the family Heptageniidae, first described by Daggy in 1945. It is known from North America. The species belongs to a genus of aquatic insects whose larvae inhabit flowing freshwater environments. Limited observational data are available for this species specifically.
Stenonema
Stenonema is a genus of mayflies in the family Heptageniidae. Species within this genus are aquatic insects found in freshwater environments, with nymphs inhabiting both riffle and pool habitats. The genus has been extensively studied in ecological and toxicological research, particularly regarding morphological variation, behavioral responses to environmental cues, and sensitivity to pollutants. Multiple species, including S. modestum, S. tripunctatum, and S. vicarium, serve as bioindicators for water quality assessment.
Stenonema femoratum
Dark Cahill
Stenonema femoratum, commonly known as the Dark Cahill, is a mayfly species in the family Heptageniidae. It is native to North America and has been documented in the Nearctic region, including the northeastern United States. The species is part of the diverse mayfly fauna associated with freshwater systems.