Acercella Lundblad, 1941

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 : 124

Genus Acercella Lundblad, 1941

Acercella: Cook, 1974a , pp. 282–283, figs. 1175, 1176, 1190. Acercella: Harvey, 1996 , pp. 372–378, figs. 32–51.

Acercella: Harvey, 1998 , p. 91, figs. 9E, 11F, 15F, 28A, 28E.

Diagnosis. Larva: Unknown.

Adults (modified from Cook 1974a): Character states of subfamily Tiphyinae. Fourth coxal plates with large, anteriorly concave projections covering insertions of fourth legs. Pedipalp with segments relatively long and slender and with tibia bearing a long, blade-like seta distomedially on a prominent projection. Genital field bearing three pairs of acetabula. Males with genital acetabula relatively widely separated from one another and borne on slender acetabular plates that completely encircle gonopore and extend laterally to but not beyond posteromedial angles of fourth coxal plates; second leg with tibia lacking two spatulate setae distoventrally; fourth leg with genu expanded and bearing a row of blade-like setae and a few long swimming hairs on ventral edge, and tibia expanded and greatly modified with a long distodorsal projection extending well beyond insertion of tarsus. Females with genital acetabula relatively widely separated from one another and borne on acetabular plates that are either slender and curved or nearly triangular and about as wide as long, and with second and third acetabula on each side not forming a row near posterior edge of plate that is nearly at right angles to long axis of idiosoma.

Type species. Acercella falcipes Lundblad.

Species Included. Acercella falcipes Lundblad , A. poorginup Harvey , both from Australia.

Distribution. Australia.

Discussion. Cook (1974a) and Harvey (1996, 1998) considered Acercella to be a distinct genus, and we follow that treatment here.