A pictorial key to differentiate the recently detected exotic Neumann, 1901 (Acari, Ixodidae) from native congeners in North America.

Until recently, only two haemaphysaline species, (Packard, 1869) and (Packard, 1869), were known to occur in the United States, and neither was considered to be of significant medical or veterinary importance. In 2017-2018 established populations of the Asian longhorned tick, Neumann, 1901, were detected in the eastern US for the first time. has the potential to be a significant threat to human and animal health, and the urgent need to determine the full extent of its distribution and host range requires availability of a straightforward and practical guide to differentiate it from native species. We created a pictorial dichotomous key to all stages of spp. known to occur in North America with scanning electron photomicrographs of all life stages, including rarely seen males, to aid researchers in differentiating these species. The largely Neotropical species Cooley, 1946, with established populations in Mexico and sporadic detections in the US on migrating birds is also included.