Structure of Haller’s Organ and Taxonomy of Hard Ticks of the Subfamily Ixodinae (Family Ixodidae)

Abstract

The structure of Haller’s organ, the main sensory organ of hard ticks, studied by methods of scanning electron microscopy, was analyzed in 43 species of the genus Ixodes Latreille, 1795, the solitary genus of the subfamily Ixodinae, on the basis of own and literary data. The structure of Haller’s organ was described in representatives of 13 subgenera: Ixodes s. str. (14 species), Pholeoixodes Schulze, 1942 (3 species), Ixodiopsis Filippova, 1957 (4 species), Ceratixodes Neumann, 1902 (1 species), Scaphixodes Schulze 1941 (2 species), Trichotoixodes Reznik, 1961 (2 species), Partipalpiger Hoogstraal, Clifford, Saito and Keirans 1973 (1 species), Pomerantzevella Feider, 1965 (1 species), Eschatocephalus Frauenfeld, 1851 (2 species), Afrixodes Morel, 1966 (1 species), Sternalixodes Schulze, 1938 (8 species), Multidentatus Clifford, Sonenshine, Keirans and Kohls, 1973 (3 species), Endopalpiger Schulze (1935) (1 species). The main taxonomic characters were distinguished, including the number and topography of sensilla in different parts of the organ; the presence and shape of the capsular orifice; the shape of the anterior trough, etc. It was shown that the structure of Haller’s organ is specific of separate subgenera, whereas differences between species (within each subgenus) are virtually absent. The data obtained were compared with the existing views on the taxonomy of the genus Ixodes.