Georgella Koenike, 1907

Sabatino, Antonio Di, Gerecke, Reinhard, Gledhill, Terence & Smit, Harry, 2009, On the taxonomy of water mites (Acari: Hydrachnidia) described from the Palaearctic, part 2: Hydryphantoidea and Lebertioidea, Zootaxa 2266, pp. 1-34 : 7

Genus Georgella Koenike, 1907

Remark: With his study on larval morphology Tuzovskij (2007b) provided convincing arguments for considering Georgella and Hydryphantes as separate genera. As far as it is known, Georgella species parasitize imagines of Odonata however, notwithstanding the high dispersal capacity of their hosts, they are only rarely found. Several species have been described from Europe, but no attempt has been made to elaborate clearcut diagnostic features and/or to discuss their taxonomic justification. The key published by Özkan (1981) was based exclusively on data and figures from the literature.

During revisional work presented here, the following observations were made which are probably valid for all representatives of the genus:

Coxae bear numerous fine, long setae on Cx-I-III in lines away from the anterior/posterior plate margins but in dense groups at the anterior/posterior corners, on Cx-IV they are scattered all over the plate surface, but near the posterior margin are concentrated in a small group posterior to the leg insertion. Swimming setae numbers of legs are rather homogeneous in all species. In contrast to Hydryphantes species, where swimming setae are restricted to the posterior segment surfaces, such setae may be arranged also on the anterior surface of IV-L-3 and IV-L-4. Except for individual aberrations, all species bear a free acetabulum in the membranous gonopore area, probably homologous to Ac-2 of Hydryphantes . All other acetabula are located on the genital flaps, sorted to an anterior and a posterior group (obviously deriving from multiplication of Ac-1 resp. Ac-3). Mouth parts are stout, gnathosoma with a short rostrum, palp with rich setation.