Redescription of the male and description of the female of Ixodes abrocomae Lahille, 1916 (Acari: Ixodidae).

The male of Ixodes abrocomae Lahille, 1916 (Acari: Ixodidae) is redescribed and the female described for the first time from specimens collected on the rodents Abrothrix longipilis (Waterhouse), A. olivaceous (Waterhouse) and Phyllotis xanthopygus (Waterhouse) at Coquimbo, Chile. The males of I. abrocomae are peculiar in having the combination of the following features: length and width less than 2 mm and 1 mm, respectively; hypostome notched with two rows of stout denticles and several small internal denticles; article II of the palpi with two conspicuous dorsal setae; coxa I with two subequal spurs; coxae II-IV with a single spur plus an indication of a second spur; and a scutum with long, scattered hairs except for the glabrous postero-median field which reaches to the marginal fold. The females of I. abrocomae are peculiar in possessing a combination of: a pointed hypostome, with a 3/3 dentition of flared denticles; a long, narrow scutum with few 'hairs' and with punctations which are especially numerous in the posterior region; a triangular basis capituli, with oval porose areas lacking definitive borders and separated by the width of one area, and a sinuous posterior margin with small cornuae; one spur on coxae I-IV; and conspicuous setae on the interno-dorsal face of palpal article II and the ventral face of article I. Sequences of 16S rDNA were identical for male and female I. abrocomae, but differ by 3.8% and 5.5% from sequences of their closest relatives, I. stilesi Neumann, 1911 and I. sigelos Keirans, Clifford & Corwin, 1976, respectively. Characters enabling the separation of I. abrocomae from Ixodes spp. distributed in the southwestern Neotropics are presented. Records of I. abrocomae in different climatic areas and on different, widely distributed rodent hosts indicate that this species may be present beyond its known Chilean territorial range (Regions III and IV).