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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- Acanthametropodidae
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- Keys/Identification
- Aquatic Insects of Michigan
Baetidae (Small Minnow Mayflies) of Michigan - Identification
Key to Adult Baetidae of Michigan
(adapted from Waltz and Burian 2008, Jacobus and Wiersema 2014)
| 1a | a. Hind wings present and with a blunt costal projection and 10 or more crossveins | Callibaetis Eaton |
| b. Abdomen with distinct dark speckles | ||
| c. Forewings of most species patterned | ||
| 1b | a. Hind wings present or absent, if present, then usually with less than 6 crossveins | 2 |
| b. Abdomen variable, rarely with speckles | ||
| c. Forewings of most species without patterns | ||
| also: Costal projection of hind wings never blunt, either pointed, hooked, or absent | ||
| 2a(1b) | a. Marginal intercalaries of forewings occur singly | 3 |
| b. Hind wings present or absent, if present, hind wings with costal projection hooked or recurved | ||
| 2b | a. Marginal intercalaries of forewings occur in pairs | 6 |
| b. Hind wings present or absent, if present, costal projection of hind wings variable, rarely hooked | ||
| 3a(2b) | a. Males with spine-like process present between the forceps of most species | Anafroptilum Kluge, Neocloeon Traver |
| b. Terminal segment of forceps elongate | ||
| 3b | a. Males without a spine-like process between forceps | 4 |
| b. Terminal segment of forceps variable | ||
| 4a(3b) | a. Hind wings absent and male genitalia with distinct coniform penes cover between the forceps bases | Cloeon Leach |
| b. Terminal segment of forceps small, rounded | ||
| c. Females with brownish pigment at the pterostigma of forewings | ||
| 4b | a. Hind wings present or absent, and male genitalia with rounded or rectangular penes cover between forceps bases | 5 |
| b. Terminal segment of the forceps usually elongate | ||
| c. Females without brownish pigment at the pterostigma of forewings | ||
| 5a(4b) | Segment 2 of male forceps with a distinct inner swelling or bulge |
Pseudocentroptiloides usa Waltz and McCafferty |
| 5b | Segment 2 of male forceps without distinct swelling or bulge | Procloeon Bengtsson |
| 6a(2b) | a. Anterior process of mesothorax coniform, projecting dorsally |
7 |
| b. Hind wings present or absent, if present, hind wings without a costal process | ||
| 6b | a. Anterior process of mesothorax not coniform and not projecting dorsally | 8 |
| b. Hind wings, when present, with or without a costal process | ||
| 7a(6a) | Hind wings minute, without veins |
Heterocloeon curiosum (McDunnough) |
| 7b | Hind wings present or absent, when present, with 2 longitudinal veins | Acentrella Bengtsson |
| 8a(6b) | a. Hind wings without a costal process, or with costal process greatly reduced |
Pseudocloeon Klapálek |
| also: Distinct plate present between forceps bases of male; terminal segment of forceps small and rounded | ||
| 8b | a. Hind wings present or absent, if present, hind wings with a costal process | 9 |
| 9a(8b) | Hind wings with a second longitudinal vein forked, vertex or fork proximad and toward wing base | Diphetor hageni (Eaton) |
| also: Terminal segment of male forceps elongate | ||
| 9b | Hind wings present or absent, if present, hind wings with second vein simple, or if forked, vertex or fork occurs distally beyond the middle of the hind wing | 10 |
| 10a(9b) | Costal process of hind wing acute, prominent, with a curbed anterior margin preceding the costal process |
Acerpenna Waltz and McCafferty |
| also: Beyond the costal process, anterior margin of hind wing undulate; terminal segment of male forceps approximately 4x long as wide | ||
| 10b | Hind wings present or absent, if present, hind wing costal process variable, not as acute or prominent as above | 11 |
| also: Terminal segment of male forceps variable | ||
| 11a(10b) | Hind wings present |
Baetis Leach (in part) |
| 11b | Hind wings absent or, if present, small, slender, with only 2 longitudinal veins | 12 |
| 12a(11b) | a. Small species, maximal forewing length 2.5-4.5 mm | Paracloeodes minutus (Daggy) |
| b. Terminal segment of male forceps elongate, cylindrical, with terminal segment of forceps about 2.5-3.0x longer than wide | ||
| c. Male genitalia without small rectangular plate between forceps bases | ||
| 12b | a. Larger species, forewing length generally > 4.0 mm | 13 |
| b. Terminal segment of male genitalia not elongate, only about as long as wide | ||
| c. Male genitalia with a small rectangular plate between forceps bases | ||
| 13a(12b) | a. Forceps of male strongly curved |
Plauditus Lugo-Ortiz and McCafferty |
| b. Ab3-4 terga strongly pigmented in red medially, with Ab5-6 terga washed in red | ||
| c. Rectangular plate present between male forceps bases | ||
| 13b | a. Forceps of male not strongly curved as above | Baetis Leach (in part) |
| b. Abdominal terga not pigmented as above | ||
| c. Rectangular plate usually absent between male forceps bases | ||
Key to the mature nymphs of Baetidae in Michigan
(adopted from Waltz and Burian 2008, Jacobus and Wiersema 2014)
| 1a | a. Apex of the labial palpi simple and truncate |
2 |
| b. Trachae of gills palmate, or asymmetrical with most branches on median side | ||
| c. Tails with a distinct dark band every third to fifth segment | ||
| d. Gills simple, or with dorsal flaps on one or more abdominal segments | ||
| 1b | a. Apex of the labial palpi variable, but not truncate as above | 6 |
| b. Trachae variable | ||
| c. Tails rarely banded as above | ||
| d. Gills simple, or large and compound | ||
| 2a(1a) | a. Labrum with a deep triangular median notch at the distal margin |
Pseudocentroptiloides usa Waltz and McCafferty |
| b. Paraglossae broad, longer than the glossae | ||
| c. Claws longer than their respective tarsi | ||
| d. Gills simple | ||
| 2b | a. Labrum with a small median notch along the median margin | 3 |
| b. Paraglossae subequal to the glossae | ||
| c. Claws usually shorter than their respective tarsi | ||
| d. Gills simple, or with dorsal flaps | ||
| 3a(2b) | a. Mandible incisors usually deeply cleft to the base, or united less than 0.5x the height of the incisors |
4 |
| b. Length of segment 3 of the maxillary palp subequal to segment 2 | ||
| c. Laterla bristles of the caudal filaments present on proximal three-fourths, apices of the filaments without bristles | ||
| d. Gills simple | ||
| 3b | a. Mandible incisors united above the base, or fused to the apex | Procloeon Bengtsson |
| b. Length of segment 3 of the maxillary palp, when present, shorter than segment 2 | ||
| c. Laterla bristles of the caudal filaments present to filament apices | ||
| d. Gills simple, or with a dorsal flap at least on Ab1 | ||
| 4a(3a) | a. Hindwingpads present | Anafroptilum Kluge, in part |
| 4b | a. Hindwingpads absent | 5 |
| 5a(4b) | a. Abdominal segments with very few lateral spinules, usually restricted to posterolateral terga of Ab8-9 (rarely absent) | Anafroptilum minor (McDunnough) |
| b. Thoracic nota usually with variously developed dorsally projected bumps or spines | ||
| c. Caudal filaments with subdistal band of darkened segments | ||
| d. Middle sterna heavily darkened on anterior margin and with paried submedial dark dashes adjacent to the posterior margin | ||
| e. Patella-tibial suture absent on foreleg | ||
| 5b | a. Ab3-9 or Ab4-9 with many long, lateral spines | Neocloeon Traver |
| b. Thoracic nota lack dorsal armature as above | ||
| c. Caudal filaments with no subdistal band | ||
| d. Middle sterna not marked as above | ||
| e. Patella-tibial suture present on forewing | ||
| 6a(1b) | Gills on one or more segments compound, with distinct large flaps |
7 |
| 6b | Gills simple | 8 |
| 7a(6a) | a. Labial palpi apparently 2-segmented, blunt apically |
Callibaetis Eaton |
| b. Hind wing pads present | ||
| c. Gills with recurved flaps folded ventrally | ||
| 7b | a. Labial palpi 3-segmented, obliquely truncate apically | Cloeon dipterum (Linnaeus) |
| b. Hind wing pads absent | ||
| c. Gills with recurved flaps folded dorsally | ||
| 8a(6b) | Claws about one-half as long as the resepctive tarsi |
Paracloeodes minutus (Daggy) |
| 8b | Claws clearly less than one-half as long as the respective tarsi | 9 |
| 9a(8b) | a. Villopore present on all or some legs | 10 |
| b. Terminal filament subequal or reduced to the cerci | ||
| c. Mandibles without setae between the prostheca and molars | ||
| 9b | a. Villopore absent on all legs | 16 |
| b. Terminal filament subequal to the cerci | ||
| c. Mandibles with setae on the surface between the prostheca and the molars or, if mandibles lack setae in this area, the prostheca of the right mandible is reduced to a single simple setae | ||
| 10a(9a) | a. Antennal scape with a distal lobe | Pseudocloeon Klapálek |
| b. Maxillary palps with a subapical excavation | ||
| c. Segment 2 of labial palps greatly expanded medially | ||
| d. Villopore often reduced or absent on the forefemora | ||
| 10b | a. Antennal scape without a distal lobe | 11 |
| b. Maxillary palps without a subapical excavation | ||
| c. Segment 2 of labial palps variable, but not greatly expanded as above | ||
| d. Villopore usually well-developed on forefemora | ||
| 11a(10b) | a. Terminal filament well-developed |
Baetis Leach (in part) |
| b. Hind wing pads present | ||
| 11b | a. Terminal filament reduced | 12 |
| b. Hind wing pads absent or present | ||
| 12a(11b) | a. Tarsal claws with two rows of denticles, or a row of denticles and a secondary ridge that may be serrate or not (these claw characters require viewing at 400x) |
Heterocloeon curiosum (McDunnough) |
| b. Terminal filament minute to a visible stub not longer than Ab10 tergite | ||
| c. Procoxae with or without gills | ||
| 12b | a. Tarsal claws with a single row of denticles | 13 |
| b. Terminal filament reduced, but longer than Ab10 tergite | ||
| c. Procoxae without gills | ||
| 13a(12b) | Hind wing pads present (although sometimes reduced to a small thread-like flap) |
14 |
| 13b | Hind wing pads absent | 15 |
| 14a(13a) | a. Segment 2 of labial palp with a well-developed medially-projecting corner |
Baetis Leach (in part) |
| b. Abdominal tergal scale-like setae present | ||
| 14b | a. Segment 2 of labial palps without a well-developed medially-projecting corner | Acentrella Bengtsson (in part) |
| b. Abdominal tergal scale-like setae absent | ||
| 15a(13b) | a. Femora, tibiae, and tarsi without a row of long setae on the outer margin |
Plauditus Lugo-Ortiz and McCafferty |
| b. Labial palps as in picture, with the inner apical edge of segment 3 more or less straight (i.e., not forming a smooth curve to the apex) | ||
| 15b | a. Femora, tibiae, and tarsi with a row of long setae on the outer margins, or the femora and tibiae with a few long setae but none on the tarsi | Acentrella Bengtsson (in part) |
| b. Labial palps as in picture, with the inner apical edge of segment 3 smoothly curved | ||
| 16a(9b) | Gills present on Ab2-7 |
Diphetor hageni (Eaton) |
| also: Segment 2 of labial palps without a well-developed medial digitate-lobe; paraglossae not rectangular, but more broadly rounded apically; prostheca of right mandible slender, bifid, and minutely pectinate | ||
| 16b | Gills present on Ab1-7, gill 7 slender to apically pointed | Acerpenna Waltz and McCafferty |
| also: Segment 2 of labial palp with a well-developed anteriorly projecting digitate-lobe; Claws with one row of denticles, and without unparied subapical setae; no tuffs of setae on abdominal sterna | ||
References
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Jacobus LM, Wiersema NA. 2014. The genera Anafroptilum Kluge, 2011 and Neocloeon Traver, 1932, reinstated status, in North America, with remarks about the global composition of Centroptilum Eaton, 1869 (Ephemeroptera: Baetidae). Zootaxa 3814(3): 385-391.
Waltz RD, Burian SK. 2008. Ephemeroptera, pp. 181-236 in Merritt RW, Cummins KW, Berg MB (eds.), An Introduction to the Aquatic Insects of North America, Fourth Edition. Kendall/Hunt Publishing Company, Dubuque, Iowa, USA.
Page created: November 10, 2003; Last edited: January 20, 2015 (EB)