Key to males and females of North American Haemaphysalis species*

1. Palpal segment III with posterodorsal spur............................... H. longicornis Neumann, 1901 (introduced)

Palpal segment III without dorsal spur..................................................................... 2

2. Palpal segment III with very long and narrow ventral spur........................................... H. juxtakochi

Palpal segment III with short ventral spur.................................................................. 3

3. Hypostome with dentition 5/5, coxa I with internal spur only......................................... H. chordeilis

Hypostome with dentition 3/3, coxa I with internal and external spurs............................................ 4

4. Palpal segment II with longer and more acute lateral salience, palpal segment III with short and broad ventral spur, coxa I with short and broad internal spur.............................................................. H. leporispalustris

Palpal segment II with shorter and more obtuse lateral salience, palpal segment III with longer and narrower ventral spur, coxa I with longer and narrow internal spur......................................................... H. mariae n. sp.

*Another Haemaphysalis species introduced to the US, H. punctata Canestrini & Fanzago, 1878, is excluded from the key since no morphological evidence has ever been published supporting its identity in the country.