Under construction!

0.5mm. No compound eye.
Monospilus dispar

0.35mm
Narrow posterior margin (much less than max height) and spherical or broadly ellipsoid body. Valves with a conspicuous projection at the anteroventral margin. Without a spine at the ventroposterior angle (tail).
Anchistropus minor

to 1.0 mm
Posterior margin not notably less than maximum height. Dorsal crest extending onto the head. Narrow postabdominal claws with a secondary tooth and both lateral and marginal denticles.
Genus Camptocercus
2 Great Lakes species

to 1.0 mm
Posterior margin not notably less than maximum height. Dorsal crest which does not extend onto the head. Narrow postabdominal claws with a secondary tooth and both lateral and marginal denticles.
Kurzia latissima

0.8-0.9mm
Posterior margin not notably less than maximum height. Postabdominal claws with a secondary tooth and only lateral denticles.
Acroperus harpae

0.5-0.7mm
Posterior margin not notably less than maximum height. Rostrum not much longer than 1st antennae (2) and not narrowed abruptly (1) . Postabdominal claws without a secondary tooth. Very short carapace teeth forming an abbreviated tail (3).
Graptoleberis testudinaria

0.8mm
Posterior margin not notably less than maximum height. Broad postabdominal claws with a secondary tooth and both lateral and marginal denticles.
Alonopsis elongata

0.5mm
Posterior margin not notably less than maximum height. Rostrum much longer than 1st antennae. Postabdominal claws without a secondary tooth. Postabdomen with 2-3 marginal denticles and numerous lateral denticles.
Rhynchotalona falcata

0.9-1.0mm
Posterior margin not notably less than maximum height. Rostrum not much longer than 1st antennae and abruptly narrowed at the tip. Postabdominal claws without a secondary tooth but with clusters of large spines. No carapace teeth forming a tail.
Genus Leydigia
2 Great Lakes species

0.4-1.0mm
Posterior margin not notably less than maximum height. Rostrum not much longer than 1st antennae and abruptly narrowed at the tip. Postabdominal claws without a secondary tooth and without clusters of large spines.
Genus Alona
6 Great Lakes species

0.48mm
Valves striated. Rostrum longer than 1st antennae recurved and reaching the ventral margin, but extending only slightly beyond the tips of the terminal olfactory setae. Postabdomen with marginal denticles. Postabdominal claws without a secondary tooth, with one basal spine. Posterior margin without teeth along the entire length but usually with 1 minute tooth at the inferoposterior angle (1).
Genus Disparalona
2 Great Lakes species

0.2-0.5mm
Narrow posterior margin (much less than max height). Posterior margin may be notched or with a spine at the ventroposterior angle or with a small tooth at the inferoposterior angle (tail).
Genus Alonella
2 Great Lakes species

0.5-0.8mm
Narrow posterior margin (much less than max height) (1) and elongate body. Rostrum long, extending well past the tips of the olfactory setae but not curved forward (2) . Postabdominal claw with 2 major basal spines (3). Posterior margin without teeth along the entire length but with 1 or more very short carapace teeth forming an abbreviated tail.
Genus Pleuroxus
5 Great Lakes species

0.3-0.8mm
Narrow posterior margin (much less than max height) (1) and spherical or ovate body. Postabdomen short and broad with a prominent preanal angle (2). Without a spine at the ventroposterior angle (tail)(3).
Genus Chydorus
5 Great Lakes species