Aquatic Insects of Michigan
by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan
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- Keys/Identification
- Aquatic Insects of Michigan
Ephemeridae of Michigan - Identification
Introduction
[under construction]
Adults (adapted from Burks 1953 and Edmunds et al. 1976)
| 1a | a. Pronotum of male shortened, about three times as wide as long | Pentagenia vittigera (Walsh) |
| b. Penes long and tubular | ||
| c. Caudal filaments of female shorter than body | ||
| also: large rivers | ||
| 1b | a. Pronotum of male well developed, no more than twice as wide as long | 2 |
| b. Penes variable, not long and tubular | ||
| c. Caudal filaments of female longer than body | ||
| 2a(1b) | a. Crossveins of wings crowded together near bullae | Ephemera Linnaeus, 3 |
| b. Fore wings with distinct pattern of dark markings | ||
| c. Terminal filament as long as cerci | ||
| 2b | a. Crossveins of wings not crowded near bullae | 4 |
| b. Wings without pattern of dark markings although crossveins may be darkened | ||
| c. Terminal filament vestigial or distinctly shorter than cerci | ||
| 3a(2a) | a. Hind wing with small, dark clouds surrounding the discal crossveins, making the wing appear spotted |
Ephemera simulans Walker |
| b. Penis lobes of male relatively broad | ||
| 3b | a. Hind wing not spotted, discal crossveins not surrounded by dark clouds as above | Ephemera varia Eaton |
| b. Penis lobes of male relatively narrow | ||
| 4a(2a) | a. Head with frons greatly expanded below eyes |
Litobrancha recurvata (Morgan) |
| b. Scutellum with only a shallow medioapical notch | ||
| c. Penes of male recurved ventrally | ||
| d. Wing uniformly tinted with dark drown | ||
| 4b | a. Head with frons not extending below eyes | Hexagenia Walsh, 5 |
| b. Scutellum with a deep medioapical notch | ||
| c. Penes of male nor recurved | ||
| d. Wing membrane hyaline or with dark spots or clouds, but never uniformly pigmented as above | ||
| 5a(4b) | Males | 6 |
| 5b | Females | 8 |
| 6a(5b) | In dorsal view, mesal margin of penis lobes with an anteapical protuberance |
Hexagenia bilineata (Say) |
| 6b | In dorsal view, mesal margin of penis lobe without an anteapical protuberance | 7 |
| 7a(6b) | Apexes of penis lobes sharply incurved |
Hexagenia limbata (Serville) |
| 7b | Apexes of penis lobes elongate and arcuate, tapering gradually to apices | Hexagenia rigida McDunnough |
| 7c | Apexes of penis lobes arcuate, but short and blunt | Hexagenia atrocaudata McDunnough |
| 8a(5b) | Hind wing with a broad, reddish or purplish-brown band at the posterior margin |
Hexagenia atrocaudata McDunnough |
8b |
Hind wing with a relatively narrow, sometimes discontinuous, dark brown band at the posterior margin, and two relatively large, brown sports in the disc of the wing |
Hexagenia bilineata (Say) |
| also: Each discal crossvein surrounded by a small, brown cloud | ||
| 8c | Hind wing without a darkened continuous posterior margin as above | 9 |
| 9a(8c) | a. Hind wing membrane and veins hyaline, discal crossveins black | Hexagenia rigida McDunnough |
| b. Abdomen white or cream colored, with dorsal color pattern of dull red markings | ||
9b |
a. Hind wing membrane hyaline, veins partly or entirely yellowish or tan, and cross-veins black or brown both in discal and marginal areas of wing | Hexagenia limbata (Serville) |
| b. Abdomen yellow, tan or light brown, with a drown color pattern | ||
Nymphs (adapted from McCafferty 1975)
| 1a | a. Mandibular tusks with a distinct lateral keel that is more or less toothed, and with some spurs |
Pentagenia vittigera (Walsh) |
| b. Femora of prothoracic legs produced posteroproximally ventral to trochanters | ||
| c. Terminal segment of labial palpi club-shaped, being broadly rounded apically | ||
| 1b | a. Mandibular tusks without a distinct toothed keel | 2 |
| b. Femora of prothoracic legs not produced proximally as above | ||
| c. Terminal segment of labial palpi not club-shaped | ||
| 2a(1b) | a. Frontal process of head distinctly bifurcate | Ephemera Linnaeus, 3 |
| b. Small group of spurs basally and laterally on mandibular tusks | ||
| c. Tibiae of prothoracic legs never emarginate apically, and not greatly flattened | ||
| also: Abdomen with dark, longitudinal markings at least on some abdominal sternites, not appearing flattened or broadened dorsoventrally; caudal filaments no more than one-half the length of the body | ||
| 2b | a. Frontal process of head rounded or somewhat truncate, never bifurcate | 4 |
| b. Tusks without any spurs or spines | ||
| c. Tibiae of prothoracic legs slightly to distinctly emarginate along the distal margin | ||
| 3a(2a) | Both fore and hind wing pads heavily blotched with dark markings |
Ephemera simulans Walker |
| 3b | Hind wing pads without dark blotches | Ephemera varia Eaton |
| also: Dark, longitudinal streaks sometimes discernible laterally along abomen | ||
| 4a(2b) | a. Antennal segments without whorls of long setae over most of its length, with only short setae | Litobrancha recurvata (Morgan) |
| b. Small unfringed gills on Ab1 single, not branched | ||
| c. Frontal process of head somewhat angulate with lateral margins slightly divergent from base | ||
| 4b | a. Antennae with whorls of long setae on most segments | Hexagenia Walsh, 5 |
| b. Small unfringed gills on Ab1 forked | ||
| c. Frontal process of head rounded, conical or truncate | ||
| 5a(4b) | a. Frontal process more or less truncate, often slightly emarginate | Hexagenia atrocaudata McDunnough |
| b. Pairs of round or somewhat elliptical, pale, dark margined spots sometimes apparent on both tergites and sternites of abdomen | ||
| 5b | a. Frontal process not truncate, if anterior margin approaching straight, then lateral margins distinctly convergent anteriorly | 6 |
| b. Never both abdominal tergites and sternites with pairs of pale, dark margined spots | ||
| 6a(5b) | a. Frontal process narrowly conical | Hexagenia rigida McDunnough |
| b. Nymph of mature male with distinctive, nearly straight, developing penes | ||
| 6b | a. Frontal process more or less rounded or broadly conical | 7 |
| b. Nymph of mature male with developing penes curved | ||
| 7a(6b) | a. Mesotarsal claws swollen for most of their length |
Hexagenia bilineata (Say) |
| b. Developing penes of mature male nymph angulate and beak-like | ||
| c. Frontal process sometimes somewhat conical | ||
| 7b | a. Mesotarsal claws slender for most of their length | Hexagenia limbata (Serville) |
| b. Developing penes of mature male nymph more evenly curved | ||
| c. Frontal process usually evenly rounded | ||
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Burks BD. 1953. The mayflies, or Ephemeroptera, of Illinois. Illinois Natural History Survey Bulletin 26(1):1-216.
Edmunds GF, Jensen SL, Berner L. 1976. The mayflies of North and Central America. University of Minnesota Press: Minneapolis, MN. x + 330 p.
McCafferty WP. 1975. The burrowing mayflies of the United States (Ephemeroptera: Ephemeroidea). Transactions of the American Entomological Society 101:447-504.
Page created: June 16, 2003; Last edited: November 06, 2013 (EB)