Key to the known species of Tridactylidae found in Florida (modified from Woo 2021)

1. Larger, body length 3.8–10 mm; integument smooth; hind tarsus present (Fig. 1A)................... 2 ( Neotridactylus)

1’. Smaller, length 3–5 mm; integument usually somewhat hairy; hind tarsus reduced to a tiny flap concealed between the hind tibial spurs (Fig. 1B).......................................................................... 4 ( Ellipes)

2. Larger, length 5.5–10 mm; fully winged (occasionally with reduced hind wings but hind wings always present); swimming plates on hind tibia present (Figs. 2A, 2B); color variable; usually found in sandy or muddy areas along water.. N. apicialis

2’. Smaller, length 3.8–4.9 mm; tegmina abbreviated, hind wings absent; swimming plates absent (Fig. 2C); uniformly dark colored; always found in xeric scrub habitats............................................................... 3

3. Jet black overall and integument shiny; male epiproct more shallowly incised at base and with lateral lobes less sclerotized (Figs. 3A, 3C); found in scrub habitats of the Florida peninsula....................................... N. archboldi

3’. More brownish and integument matte; male epiproct deeply incised at base and with lateral lobes heavily sclerotized (Figs. 3B, 3D); restricted to coastal dune scrub of the Florida panhandle.................................. N. insularis sp. nov.

4. Fully winged (occasionally hind wings shortened); color variable but never uniformly pale (Fig. 4A); usually found in sandy or muddy areas along water............................................................................... 5

4’. Tegmina abbreviated, hind wings absent; coloration pale white with brown/red markings (Figs. 4B, 4C); always found in xeric scrub or sandhill habitats............................................................................... 6

5. Antennae in both sexes 10–segmented (Fig. 5A). White markings on head not as below...................... E. minuta

5’. Antennae in the male 11-segmented, in the female 12-segmented (Fig. 5B). White rim of the eyes continuing forward to almost the anterior border of the forehead (Florida populations only).......................................... E. gurneyi

6. Head and pronotum brick red and unmarked; paraproct processes orange (Fig. 6A); restricted to scrub in Manatee County......................................................................................... E. ignis sp. nov.

6’. Head and pronotum creamy white, often with black markings or even completely dark; paraproct processes white (Figs. 6B, 6C, 6D)................................................................................................ 7

7. Pronotum creamy and unmarked (Fig. 6B); found in yellow sand scrub habitat in Polk county................ E. deyrupi

7’. Pronotum clearly marked with black or brown (Figs. 6C, 6D).................................................. 8

8. Head dark brown with pale Y-shaped marking (Fig. 6C)............................................... E. eisneri

8’. Head mostly creamy, with dark brown base and two dark spurs extending towards antennal bases (Fig. 6D)................................................................................................. E. ceratiola sp. nov.