Georgella koenikei Maglio, 1906

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 : 9-10

Georgella koenikei Maglio, 1906

Hydryphantes koenikei auct.

Georgella intermedia Walter, 1927 , nov. syn.

Hydryphantes intermedius auct. (praeocc. Daday, 1901: K.O. Viets 1987) Hydryphantes dauphinensis K.O. Viets, 1987

Material examined: " Georgella koenikei " SMF, K. Viets 43651, Spain (1/1/0).

Discussion: The type series of this species is lost. Maglio (1906) compared G. koenikei first with G. apsteini , considering the presence of a pair of Ac in the gonopore membrane as a common character distinguishing both species from G. helvetica . Two of the character states he elaborated are hardly significant because they are based on the partly incorrect or incomplete description of Koenike's species: In both species, (1) setae are located all over the coxal surfaces and not restricted to the lateral edge, (2) setae on genital flaps are not restricted to the posterior edge, but arranged in multiple rows ending posterior to the anterior flap margin. Furthermore, Maglio's (1906) Fig. 10 contradicts his statement concerning the lateral indentation of the genital flaps: It is slightly posterior to the centre at left, but on the right side dividing the flaps into two equal parts. The asymmetry of this character in Maglio's specimen and observations in other Georgella - populations show that it is unsuitable for species distinction. Instead, a high acetabula number (about 90 per flap) is documented in Maglio's Fig. 10 as a probably characteristic feature of G. koenikei . A few measurements are given in the original description: Male: Idiosoma L 2000, genital flap L/W 480/190 (setated area L 315). Female: Idiosoma L 3000, frontal shield total L 750, genital flap L 500, gnathsoma L/H 450/360, chelicera L 550, claw 190.

Since G. koenikei was first described, it was the combination of the presence of a gonopore acetabulum (considered a character in common with G. a p s t e i n i) and the anterior position of the frontal eye (considered a character in common with G. h e l v e t i c a), that induced later authors to record this species from various parts of Europe. As the presence of acetabula in the gonopore is probably a character state typical for all Georgella species, with occasional reductions due to intraspecific variability, all these records are questionable and need reconsideration. The specimen described by Láska (1956) under this name has a lower acetabula number and probably belongs to G. helvetica . The same could be true for the populations recorded from Russia, while those from Spain possibly represent an undescribed species (see below).

Also the type material of Georgella intermedia , a species described from Dauphiné (SE France) and from deutonymphs only ( Walter & Motaş 1927), is lost. Walter named it for the shape of the frontal shield, similar to G. helvetica in the relatively long posterior extensions, but to G. apsteini in the central position of the frontal eye. No attempt was made to discuss differences with G. koenikei , neither by Walter, nor by C. Angelier (1953) who, based on a population from the same area in SE France, gave the first description of adults. Also the latter material is not available, but all details in Angelier's description agree with the data given for G. koenikei , as far as available. With regard to the frontal shield, Angelier documented a considerable, but plausible variability: The antero- and posterolateral projections may be slender or stout (probably in older specimens with secondary sclerotization), and the anterolateral projections may be directed laterally or slightly bent anteriorly.

At the present state of our knowledge, the best option is to consider all populations with high numbers of acetabula as conspecific and therefore we propose the synonymization of G. intermedia with G. koenikei , a species in this definition known from the French Alps and Italian prealpine lowlands only. In the following, we summarize briefly the most important characters of this species based on the details given by C. Angelier: Frontal shield anterolateral extensions perpendicular to the longitudinal body axis or slightly bent anteriorly, but their tips not reaching the level of the tip of the anteromedial projection, frontal eye near the base of this projection; anteromedial projection triangular, forming a right or obtuse angle; ratio total L/ W 1.1. Shape of Cx-IV and swimming setae as given for G. helvetica . Genital flaps laterally indented at the centre, on each side with more than 80 acetabula (sexual dimorphism in number). Chelicera L/H 3.0, basal segment/claw 2.5. Palp L ratio P-2/4 0.87, L/H P-4 3.0. Male: Idiosoma L/W 2760/1900, Frontal shield total L/W 610/630; genital flap L 530 with ca. 90 acetabula per flap. Females: Idiosoma L/W 3700/2850, frontal shield total L/ medial L/W 780/700. Genital flap L 600, with ca. 140 acetabula per plate; chelicera L 473, palp segments L/H 92/11, 185/120, 115/126, 212/70, 46/-.

The attribution of these adults to the deutonymphs described by Walter (in Walter & Motaş 1927) may appear problematic as they disagree in the more anterior position of the frontal eye, but this character may probably change between developmental stages. Also Özkan (1981) found deutonymphs with a central medial eye in populations of G. helvetica showing in adults the typical anterior position of this organ. A strong argument for the conspecifity of all the named populations is the high number of acetabula. Each of the paired genital plates in deutonymphs of the type series bear 24 anterior acetabula plus one large posterior acetabulum. In all other Georgella deutonymphs so far described (G. h e l v e t i c a: Özkan 1981, Tuzovskij 1990; " G. koenikei ": K. Viets 1930 , E. Angelier 1954; G. samaraensis: Tuzovskij 2007 ) the anterior acetabula number is <20. The additional pair of acetabula in the future gonopore area reported by Walter (1927) was possibly confused with a sclerotized structure regularly found in the provisional genital organ of most hydryphantid deutonymphs (e.g. Tuzovskij 2007b). The record of G. koenikei from Corsica ( E. Angelier 1954), based only on deutonymphs, in view of the low acetabula number most probably refers to another, still unclear species.