Revision of the status of some genus-level water mite taxa in the families Pionidae Thor, 1900, Aturidae Thor, 1900, and Nudomideopsidae Smith, 1990 (Acari: Hydrachnidiae) Author Smith, Ian M. Author Cook, David R. Author Gerecke, Reinhard text Zootaxa 2015 3919 1 111 156 journal article 10.11646/zootaxa.3919.1.6 4c40552e-e778-4d8e-a6b7-9662436cadc2 1175-5326 244587 F711CA99-1B2C-4E18-9F4B-7521D38D2303 Subgenus Hexaxonopsis Axonopsis ( Hexaxonopsis ) : Cook, 1974a , pp. 335–336, figs. 1413–1417 . Diagnosis of adults. Character states of genus Hexaxonopsis . Fourth leg of males with segments unmodified. Species included. Numerous species listed by K.O. Viets (1987) under Axonopsis ( Hexaxonopsis ) . There are several undescribed species of Hexaxonopsis (s. s.) from North America in the Canadian National Collection of Insects and Arachnids. Distribution. Holarctic (Europe, Southeast Asia, China , Japan , North America ) and Africa. Discussion. See above.