1. Gills relatively large with one or more recurved ventral (posterior) flaps or lobes on at least gills 1-6 (those with large flaps appearing as double or triple gills); branching tracheation always apparent in gills and consisting of mid-longitudinal main trunk in at least basal half of gill with bilateral and apical branching; main lamella of at least gills 4-7 longer than broad; claws somewhat long and slender and only slightly curved, ventrally with two rows of well-developed denticles, with more-distal denticles spinelike. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Callibaetis sp.[Note: Callibaetis is commonly found in lentic habitats but also can be found in lotic habitats.]
Gills variable, but never as above, often simple, without flaps or lobes, of if flap present, then single and dorsal (anterior) on one or more pairs of gills; gills either without branching tracheation, or with variable types of branching such as with mid-longitudinal trunks with bilateral branching, or with mid-longitudinal trunk with asymmetrical branching mostly toward inner expanded area of gill, or with several main trunks emerging form central base of gill; gills varying in shape, sometimes broader than long; claws variable, often short and moderately to strongly curved, sometimes long or very long and lanceolate, rarely rakelike, and with or without denticles, claws elongate and with two rows of denticles, then denticles not developed as above. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Median caudal filament (middle tail) developed, at least half as long as cerci (lateral pair of tails) . 3
Median caudal filament reduced, ranging from minute to not much longer than abdominal tergum 10, usually with 10 or fewer segments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3. Terminal segment of labial palps simple, without lobes, and usually with more or less straight apical margin (truncate), often slightly concave or slightly rounded, distal margin often perpendicular to mid-longitudinal line of terminal segment or sometimes oblique (diagonal to mid-longitudinal line of terminal segment), and labial palps rarely falcate (hooked) distally (appearing oblique principally because oute aspect produced somewhat distally; gills simple or with wingle dorsal flap (or combination of both on individuals), gills sometimes broad and when tracheated, then with asymmetrical branching to inner expanded side or commonly palmate with trunks radiation form central base. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12[Note: These are referred to as the long clawed baetids, but other taxa may have long claws. These tend to be very slender and fusiform and are among the most minnowlike of the small minnow mayflies]
Terminal segment of labial palps variable, but not as above, gills simple (without dorsal flap), generally longer than broad and, when tracheated, with at least mid-longitudinal trunk for some distance and often with bilateral branching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Labial palps with triangular pointed projection; hindwings absent . . . . . . . . . . . Paracloeodes
Labial palps variable, but not as above; hindwingpads present. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Gills present on abdominal segment 1; coloration and general appearance of specimens variable. . 6
[Note: At least gill sockets should be present in cases where gills 1 were dislodged.]
Gills and associated gill sockets absent on abdominal segment 1; dorsal color pattern of abdomen sometimes with one pair of submedian pale dots and anteriorly converging pale streaks; posterior terga often paler than anterior terga; fluid-preserved specimens often with hunched-backed appearance not usuallly seen in other taxa. . . . . . . . . . . . . . . . . . . . . . . . . . . . Diphetor hageni
6. Labial palps mittenlike, with large thumblike lobe distomedially oriented (at approximately 50-60 degree angle with palp; gills 7 relatively sharply pointed. . . . . . . . . . . . . . . . . . . . . . . Acerpenna
Labial palps variable, never as above, if labial palp with large lobe, then lobe very broad and mesially oriented (at nearly right angle with palp); gills 7 more or less rounded apically or at most bluntly pointed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Basal segment (scape) of antennae with small notch at distal margin producing small outer distal lobe; maxillary palps with inner subapical excavation; labial palps usually with broad medially directed lobe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Labiobaetis
Basal segment of antennae without notch or lobe as above; maxillary palps not excavated; labial palps variable, but not exactly as above, with poorly developed or less developed medial lobe. . . . . . . . . . 8
8. Antennae 2-3 times length of head capsule; forecoxal gill filaments not present . . . . . . . . Baetis
9. Claws usually with two rows of denticles, with one row having more distinctive denticles and secondary row having less developed (sometimes poorly developed) denticles or secondary row represented only by weak ridge with no denticles; if secondary ridge of claws without denticles, then such individuals relatively large, with mature body length about 7-9 mm, and with femora lacking marginal femoral row of long fine setae, and with tibiae having deeply forked, short spatulate setae on anterior face; otherwise mature body length 3-9 mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Claws with one row of denticles and no secondary ridge; mature body length about 3-6 mm. . . . . 11
10. Primary row of claw denticles becoming progressively longer toward apex of claws; mature body length 4-9 mm; gill filament often present near base of forelegs; small hindwingpads often present; tibae not expanded. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heterocloeon
Primary row of claw denticles of equal length except for shorter basal denticles; mature body length 3-4 mm; gill filaments never present near base of forelegs; hindwingpads not present (represented by microscopic scale at most); tibbiae with expanded appearance. . . . . . . . . . . . . . . . Iswaeon anoka
11. Femora with marginal row of fine, often somewhat long setae*; labium with short palps with segments 2 and 3 sometimes appearing fused with outer and apical margins rounded, segment 3 usually somewhat boxing-glove-fist shaped, and segment 2 usually strongly curved nearaly 90 degrees to medial, resulting in palp ovrlapping paraglossa, and with compact gossae and paraglossae (tightly fitted with paraglossae tending inword over apices of glossae); hindwingpads present, absent or vestigial.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Acentrella
[*Note: these pale setae may be difficult to detect without proper illumination.]
Femora without marginal row of fine setae (if row of marginal setae presaent, then somewhaat short and bristlelike); labium with terminal segment 3 of palp distinct, subquadrate or subfalcate apically, and with segment 2 not as curickved inwardly as above, and paraglossae and glossae not compacted as above; hindwingpads absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Plauditus
12. Labrum with broad V-shaped distal margin; labium with glossae broad apically blunt, and distinctly shorter than paraglossae; claws somewhat longer than respective tarsi; hindwingspads present; larval habitant usually gravel or sand . . . . . . . . . . . . . . . . . . . Pseudocentroptiloides usa
Labrum not as above; glossae width variable, but pointed and subequal to, or not much shorter than, paraglossae; claws usually at least somewhat shorter than respective tarsi; hindwingpads present or absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
13. Labial palps falcate (curved like a sickle, hooked) distally; gills 1-6 with well-developed dorsal flaps, with dorsal flap on gill 6 subequal to flap on gil 5; hindwingpads absent; lentic habitats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cloeon dipterum
Not with exact combination of characterists given above; hindwingpads present or absent; generally lotic habitats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
14. Both mandibles with incisors fused for half length or more; planate mandible with inner incisor curving inward so apices of denticles rowed more ventrically than horizontally, and with prostheca broadened; usually one or more pairs of gills with dorsal flap, or sometimes all gills simple; well-developted lateral spines always present on at least abdominal segment 8 and 9; hindwingpads present of absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Procloeon sp. (ID as Procloeon sp. with hindwingpads, or Procloeon sp. without hindwingpads.)
Angulate mandible with incisors somewhat fused (slightly less than half length); planate mandible with incisors separate to base, with inner incisor often narrowing distally and not curved inward, and with prostheca appearing as simple bristle with some lateral hairlike branches; all gilis simple without dorsal flap; lateral spines on abdomen variable (absent, poorly developed, or well developed); hindwings present or absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
15. Maxillary palps three segmented, with segment 3 subequal to, or longer than, segment 2; robust setae appressed along outer margin of cerci not changing in essential form or relative size in distal third of cerci compaired to more proximal setae; abdominal sternal color patttern without large transverse band anteriorly on sterna 7-9 or 8-9; hindwingpads present or absent. . . . . . . . . . . 16
Maxillary palps apparently two or three segmented, with segment 3 when detectable less than half length of segment 2; robust setae appressed along out margiins of distal third of cerci becoming spindle shaped and longer than respective cercal segments compared so setae in more proximal regioon of cerci; abdomiinal sterna with marginal transverse band between sterna 7-8 and 8-9 (and sometimes between other sterna); hindwingpads present. . . . . . . . . . . . . Procloeon viridoculare *
*Note: Possesses a highly recognizable unique color pattern among long-clawed baetids. The presence of the marginal transverse bands in the posterior region of the ventral abdomen shoud ensure identification.
16. Hind wingpads present. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anafroptilum
Hind wingpads absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
17. Body with dorsal projections; mature body length less than 5 mm, usually 3.0-4.4 mm; legs with only sparse stout setae and only in ventral aspect (on side of direction of claw curvature); middle abdominal sterna each darkened at anterior margin and with pair of submedian dark dashes adjacent to posterior margin; lateral abdominal spines absent or limited to small spines only in posterior forth of segment 8 and 9; caudal filaments with dark subdistal band. . . . . . . . . . Anafloptilum minor sp.
Body without dorsal projections; mature body length at least 5 mm; legs heavily armored dorsally and ventrally with numerous stout setae; middle abdomiinal sterna not marked as above; many relatively long lateral spines on abdominal segments 3-9 or 4-9; caudal filaments witihout subdistal band. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Neocloeon
Key to Ohio Baetidae Nymph Genera