Key to adult Bdella (Figs. 41–44).

Species of Bdella have been continuously described since the 18th century. Many older descriptions contain few characters useful for identification and type material has subsequently been lost or species have not been redescribed. An initial attempt to create a key to world species excluded nearly half of the described species because of this problem. We have therefore elected to include regional keys where species are relatively well described.

Key to adult Bdella of North America (Modified from Atyeo 1960a).

Bdella robusta and B. tlascalana are not included in the key as the original descriptions lack sufficient characters. Bdella tlascalana is known only from the type series collected in Tlaxcala, Mexico and may not be present north of Mexico.

1 Hysterosomal setae branched distally (Figs. 41 b, 44b)................................................. B. distincta

- Hysterosomal setae setiform, not branched distally (Figs. 41 a, 44a).............................................. 2

2 (1) Prodorsal striae between pt convex posteriorly (Figs. 42 a, b)...................................................3

- Prodorsal striae between pt longitudinal (Figs. 42 c, d).........................................................5

3 (2) Pedipalpal basifemur with 8–11 setae; pedipalpal tibiotarsus with 6 setae (including two long terminal setae).... B. muscorum

- Pedipalpal basifemur with 13 or more setae; pedipalpal tibiotarsus with 7 setae (including two long terminal setae)........4

4 (3) Prodorsal striae continuous, prodorsal apodeme simple (Fig. 42 a)...................................... B. cardinalis

- Prodorsal striae coarsely broken, prodorsal apodeme reticulated (Fig. 42 b).............................. B. longicornis

5 (2) Prodorsal apodeme simple (Fig. 42 c); leg I telofemur, genu, and tibia approximately of equal length; genu I without duplex setae......................................................................................... B. tropica

- Prodorsal apodeme reticulated (Fig. 42 d); tibia I twice the length of genu I or telofemur I; genu I with duplex setae present............................................................................................. B. longistriata

Key to Bdella of South Africa (Modified from van der Schyff et al. 2005).

1 Prodorsal striae between at and pt longitudinal (Figs. 43 a, b)................................................... 2

- Prodorsal striae between at and pt transverse (Fig. 43 c).................................................. B. aloios

2 (1) Tibia II with 1 solenidion................................................................... B. nylsvleyensis

- Tibia II with 2 solenidia................................................................................ 3

- Tibia II with 3 solenidia................................................................................ 6

3 (2) Tibia I with 2 solenidia; genu I with 1 solenidion; tarsus III without solenidia...................................... 4

- Tibia I with 3 solenidia; genu I with 3 solenidia; tarsus III with 1 solenidion............................ B. boskopensis

4 (3) Tarsus II with 2 solenidia, microseta absent; pedipalpal basifemur with 8 setae..................................... 5

- Tarsus II with 2 solenidia and 1 microseta; pedipalpal basifemur with 9 setae............................... B. carolae

5 (4) Dorsal hysterosomal striae mainly finely broken, striae between eyes vague or absent (Fig. 43 a).................. B. vates

- Dorsal hysterosomal striae continuous to sparsely broken, striae between eyes distinct and transverse (Fig. 43 b)..................................................................................................... B. consobrinae

6 (2) Dorsal hysterosomal setae slightly serrated but pointed distally (Fig. 44 a)............................ B. neograndjeani

- Dorsal hysterosomal setae slightly serrated but branched distally (Fig. 44 b)............................. B. malawiensis

Key to Bdella of Iran (Modified from Ueckermann et al. 2007)

1 Prodorsal striae between pt convex posteriorly (as in Figs.42 a, b)................................................ 2

- Prodorsal striae between pt longitudinal (as in Figs. 42 c,d, 43a,b)................................................ 4

2 (1) Pedipalpal basifemur with 8–11 setae; pedipalpal tibiotarsus with 6 setae (including 2 terminal setae)................... 3

- Pedipalpal basifemur with 13 or more setae; pedipalpal tibiotarsus with 7 setae (including 2 terminal setae).... B. longicornis

3 (2) Prodorsal striae sparsely broken; genu II with duplex setae present..................................... B. muscorum

- Prodorsal striae continuous; genu II with duplex setae absent............................................ B. lattakia

4 (1) Pedipalpal basifemora with 6 or 7 setae.................................................................... 5

- Pedipalpal basifemora with 15 setae............................................................. B. karajiensis

5 (4) Genua I–IV each with a pair of duplex setae present......................................................... 6

- Genua I–IV without duplex setae................................................................. B. captiosa

6 (5) Prodorsal striae longitudinal between at; seta mps long, surpassing bases of at .............................. B. humida

- Prodorsal striae transverse between at; seta mps shorter, reaching only about halfway to at .................... .. B. farabii