Atractides spinipes (Piersig, 1894)

Gerecke, Reinhard, 2003, Water mites of the genus Atractides Koch, 1837 (Acari: Parasitengona: Hygrobatidae) in the western Palaearctic region: a revision, Zoological Journal of the Linnean Society 138, pp. 141-378 : 143

ATRACTIDES SPINIPES KOCH, 1837: THE UNRESOLVED

PROBLEM OF THE TYPUS GENERIS

The first described species is not documented by a deposited type specimen, and the only information that can be gleaned from Koch’s drawing published in 1842 is the character of the first leg with two long distoventral sword setae and a curved terminal segment.

As mentioned above, the second species of the genus, ovalis , owes its origin to Neuman’s error, who regarded the ventral morphology of a deutonymph depicted by Kramer (1875) as a diagnostic adult feature. The specimen depicted by Neuman as Megapus spinipes , and baptized by Koenike in 1883 as A. ovalis , is lost. Further complicating the situation, Koenike based his first description on specimens from Canada, which he recognized in 1908 as representing ‘ crassipalpis ’, a different species. The same year he published figures of a well-defined, clearly recognizable A. ovalis . All authors who had used this name in the previous 25 years could therefore not have known its morphological details, and in many cases probably based their identifications on the misunderstood character of number of acetabula.

During this period, researchers discovered the main lines of morphological diversification in the genus and described ten additional species (nine from Europe and one from Madagascar). Apart from gabretae Thon (1901) (probably a malformation) they are all clearly defined by important peculiarities, such as presence of dorsal idiosomal sclerites, shape of palps and first legs, and morphology of the genital area.

It seems likely that for many years the name of the type species spinipes has been used as a dumping ground for a variety of not easily determinable specimens often listed in faunistic surveys as single finds. Evidence for this is provided by the numerous specimens given this name in the main European collections, which represent either unidentifiable juveniles and females, or aberrant, homoiomorphic males of different species. Koch’s description probably referred to one of the more widely distributed species. A dubious benefit of the unavailability of his type specimen is that it helps avoid further taxonomic changes and confusion. In this paper, Atractides spinipes is redescribed on the basis of a neotype from a large population collected in southern Germany.

The taxonomic history of this species is unfortunately not atypical, with an initial published name used as a wastepaper bin for all poorly identified specimens. Consequently, early descriptions of the larval stages of A. spinipes ( Piersig, 1894) and A. ovalis ( Piersig, 1896) cannot be included in the taxonomic discussion.