Genus Nudomideopsis Szalay, 1945 Mideopsis (Nudomideopsis): Cook, 1974a, p. 379, figs. 1671, 1672, 1674, 1676, 1688. Mideopsis (Nudomideopsis): Smith, 1977a, pp. 533–535, figs. 1–5. Nudomideopsis: Smith, 1983c, pp. 913–919, figs. 1–8. Nudomideopsis: Cook, 1983, pp. 119–120, figs. 534–537. Nudomideopsis: K.O. Viets, 1987, p. 580. Nudomideopsis (in part): Smith, 1990, pp. 234–241, figs. 1–12. Nudomideopsis (in part): Smith & Cook, 1991, pp. 551, 577, figs. 16.86–16.88. Nudomideopsis: Cook, 1992, pp. 52–56, figs. 37–51. Nudomideopsis (in part): Smith et al., 2001, pp. 579, 611, figs. 176, 178, 179, 385. Nudomideopsis (in part): Smith et al., 2010, pp. 522, 553, figs. 15.176, 15.178, 15.179, 15.385. Diagnosis. Larva (modified from Smith 1983c, 1990): Character states of family Nudomideopsidae. First coxal plate with setae 1a short, third coxal plate with transverse muscle attachment scar relatively short. Adults (modified from Smith 1990): Character states of family Nudomideopsidae. Idiosoma nearly round in shape; convex dorsally. First coxal plate extending to or just beyond anterior edge of shield; suture line between third and fourth coxal plate ending medially on posterior coxal group so that fourth plate has an extensive medial edge; fourth coxal plate bearing small projection that completely covers opening for insertion of fourth leg, with suture line at posterior edge distinct. Genital field bearing three pairs of acetabula that are free in gonopore in both sexes. Pedipalp tibia stocky and slightly expanded ventrally; bearing two slender setae ventrally in proximal half of segment. Type species. Mideopsis (Nudomideopsis) longipalpis Szalay. Species included. Many species as listed by K.O. Viets (1987) and supplemented by Cook (1992). Distribution. Holarctic (Eurasia, eastern North America) and New Zealand. The genus is especially well represented in Japan with more than 20 described species. Discussion: Cook (1974a) considered Nudomideopsis to be a subgenus of Mideopsis. Smith (1983c) elevated Nudomideopsis to full generic status and this treatment was followed by Smith (1990), Cook (1992), Smith & Cook (1991, 1999), and Smith et al. (2001, 2010), and is followed by us here. There is considerable variation in the morphology of the pedipalp among described species, suggesting that further revision of the genus may be necessary in the future.

Published as part of Smith, Ian M., Cook, David R. & Gerecke, Reinhard, 2015, 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), pp. 111-156 in Zootaxa 3919 (1) on page 153, DOI: 10.11646/zootaxa.3919.1.6, http://zenodo.org/record/244587