Orientilimnesia Yi & Jin

Yi, Tianci, Jin, Daochao, Guo, Jianjun & Zhang, Xu, 2009, Descriptions of a new genus Orientilimnesia (Hydrachnidia: Limnesiidae Thor, 1900) with a new species from China, Zootaxa 2140, pp. 27-32 : 28

Orientilimnesia Yi & Jin , gen. nov.

Diagnosis: Characters of the subfamily Limnesiinae (see Cook 1974). Body soft and papillate. Edges of epimera and genital flaps thickened. Genital flaps fused anteriorly and posterioly in male and the flaps movable in female. Three pairs of elongated acetabula present, the margin of acetabula thickened and irregularly shaped; the second acetabulum parallel, posterior to and somewhat underneath the third acetabulum; the first acetabulum approximately at a right angle with second and third acetabulum in male. E4 located on the third epimera. Peg-like seta on ventral side of P-II. Legs without pronounced sexual dimorphism; swimming hairs present.

Type species: Orientilimnesia sinica Yi & Jin sp. nov.

Etymology: Limnesia -like mite from the oriental. “Orienti-”, from “Orientalis” in latin, means oriental.

Remarks: The number and position of genital acetabula are used as characters for the diagnosis of genera and species of water mites ( Cook 1974, Barr 1982).Within Limnesiidae the number of acetabula is three pairs to many; their shape is round, oval, elongated or lobated; they are usually situated on genital flaps or plates ( Cook 1974) but may also lay under genital flaps beside the gonopore (Goldschmidt 2004).

Within the Limnesiidae two species have elongated acetabula: Limnesia longipora Lundblad, 1953 from Brazil and Limnesides epimeratus Lundblad, 1936 from Colombia. However, all these taxa differ significantly from Orientilimnesia gen. nov. in the arrangement of acetabula. In Limnesides and Limnesia , the second acetabulum is located between the first and the third one or, in some case, at the same level as the third one (e.g., Limnesia papillosa Viets, 1935 , the adults were reported by Lundblad in 1971), whereas in Orientilimnesia the second acetabulum is posterior to and underneath the third one.