Hexaxonopsis Viets, 1926

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), Zootaxa 3919 (1), pp. 111-156 : 142

Genus Hexaxonopsis Viets, 1926 stat. nov.

Axonopsis (Hexaxonopsis) : Cook, 1974a, pp. 335–336, figs. 1413–1417. Axonopsis (Plesiobrachypoda) : Cook, 1974a, p. 336, fig. 1420.

Axonopsis (Hexaxonopsis) : K.O. Viets, 1987, pp. 190–192.

Axonopsis (Hexaxonopsis) : Smit & Pešić, 2010, pp. 45–48, figs. 32–35.

Diagnosis. Larva: Unknown.

Adults (modified from Cook 1974a, 1974b): Character states of Axonopsis -like mites. Dorsal and ventral shields separate or incompletely fused anteriorly; lacking caudal development posteriorly. Dorsal furrow lacking glandularia. Dorsal shield with or without paired rows of spinose projections anterolaterally; bearing six pairs of glandularia none of which flank excretory pore. Ventral shield on each side with ridge originating at lateral end of suture line between third and fourth coxal plates extending anterolaterally to lateral edge of shield; first and second coxal plates produced anteriorly into recurved, pointed, hook-like projections; fourth coxal plate usually bearing two pairs (rarely three pairs) of glandularia in region between genital field and opening for insertion of fourth leg. Genital field bearing three pairs of acetabula. Suture lines between genital field and ventral shield clearly delineated. Gnathosoma with mouth opening subterminal in position; gnathosomal apodemes moderately long. Pedipalp tibia moderately long and slender, bearing a long, thick seta on a prominent projection and a sessile slender seta ventrally; tarsus shorter than tibia. Fourth leg with segments not flattened and telofemur not reduced in size.

Type species. Hexaxonopsis violacea Viets.

Species included. Numerous species listed by K.O. Viets (1987) and Pešić, Smit & Saboori (2012) under Axonopsis (Hexaxonopsis) and by K.O. Viets (1987) under Axonopsis (Plesiobrachypoda) , and see below under subgenera.

Distribution. Holarctic (Europe, Southeast Asia, China, Japan, Iran, North America) and Africa.

Discussion. Cook (1974a, 1974b) treated Hexaxonopsis as a subgenus of Axonopsis . Here we propose elevation of this taxon to full generic rank based on the unique combination of character states listed above. We also propose that the taxon Plesiobrachypoda Viets, 1942 , previously regarded as a subgenus of Axonopsis , should now be considered as a subgenus of Hexaxonopsis .