Arrenurus

Smit, Harry, Gerecke, Reinhard, Pešić, Vladimir & Gledhill, Terence, 2015, On the taxonomic state of water mite taxa (Acari: Hydrachnidia) described from the Palaearctic, part 3, Hygrobatoidea and Arrenuroidea with new faunistic data, Zootaxa 3981 (4), pp. 542-552 : 550

Arrenurus (s.str.) denticulatus Motaş, 1927

Arrenurus furciger K. VIETS, 1935 — nov. syn.

Tyahun (1970) was the only author who noted and discussed the similarity of A. denticulatus and A. furciger . According to Tyahun, differences between the two species are found in the length of the setae on the dorsum (long in furciger , short in denticulatus ), the shape of the dorsal margin of the petiole (rounded in furciger , triangular in denticulatus ), the shape of the setae associated with the petiole (bifurcated in furciger ) and the number of setae on P-2 (six in furciger , five in denticulatus ). The number of teeth on the ventral side of the petiole shows much variation, and cannot be used to separate the two species. The only important difference between A. furciger and A. denticulatus is found in the setae associated with the petiole: bifurcated in furciger , and simple in denticulatus . However, the bifurcated setae are difficult to observe and may therefore have been overlooked by previous authors. All other differences are either not important (setae on P-2), or probably the result of inadequate illustrations (setae on the dorsum) or are variable characters (shape of the posterior margin of the petiole). Consequently, we propose to synonymize the two species.