4. Ixodes affinis Neumann, 1899 .

A Nearctic and Neotropical species whose adults and immature stages have been found on Artiodactyla: Cervidae, Carnivora: Procyonidae, and Didelphimorphia: Didelphidae; adults alone have been collected from Artiodactyla: Bovidae, Carnivora: Felidae, Canidae and Ursidae, Perissodactyla: Equidae, and rarely from Cathartiformes: Cathartidae; immature stages have been recovered from Lagomorpha: Leporidae, Rodentia: Cricetidae, Muridae and Sciuridae, Soricomorpha: Soricidae, Squamata: Teiidae, and Passeriformes (several families) (Guglielmone et al. 2014, Esser et al. 2016 a, b, Heller et al. 2016, Rodríguez-Vivas et al. 2016, Nadolny & Gaff 2018, Scott et al. 2018, Saracho-Bottero et al. 2020). There are no bona fide records of Ixodes affinis causing human parasitism.

M: Cooley and Kohls (1945), but see note below

F: Neumann (1899)

N: Oliver et al. (1987)

L: Oliver et al. (1987)

Redescriptions

M: Keirans and Clifford (1978), Keirans and Litwak (1989), Guzmán-Cornejo and Robbins (2010), Bermúdez et al. (2018)

F: Cooley and Kohls (1945), Keirans and Clifford (1978), Keirans and Litwak (1989), Guzmán-Cornejo and Robbins (2010), Bermúdez et al. (2018)

N: Durden and Keirans (1996)

L: none

Note: Keirans and Clifford (1978) state that the description of the male of this species is in Fonseca (1935a) under the name Ixodes ricinus aragaoi, but this is in error because that description corresponds to Ixodes aragaoi, currently a synonym of Ixodes fuscipes, treated as a synonym of Ixodes affinis in Cooley and Kohls (1945) and Keirans and Clifford (1978), among others. Clifford et al. (1973) consider Ixodes affinis a Nearctic species, but this is erroneous since its description is based on material obtained in Costa Rica. Ixodes affinis is closely related to Ixodes fuscipes and Ixodes pararicinus, making it difficult to identify with certainty. Rodríguez-Vivas et al. (2016) in Mexico and Polsomboom et al. (2017) in Belize found Ixodes near affinis, suggesting that more than one species may be represented under this name. More recently, Saracho-Bottero et al. (2020) identified as Ixodes cf. I. affinis specimens from northeastern Argentina previously classified as Ixodes pararicinus . Those authors found three populations of Ixodes cf. I. affinis, one in Argentina, another in Colombia-Ecuador, and a third population in Belize-USA that differ at the molecular level from one another and probably from bona fide Ixodes affinis, but found no morphologically significant differences to separate the populations investigated. Most probably the name Ixodes affinis represents a species complex. See also Ixodes pararicinus .