Aturus rotundus Romijn, 1921

Gerecke, Reinhard, 2014, Studies on European species of the water mite family Aturidae Thor (Acari: Hydrachnidia), Zootaxa 3841 (1), pp. 1-46 : 19-20

Aturus rotundus Romijn, 1921

Fig. 13 A–B

Aturus scaber rotundus auct.

Material examined. Italy: Lazio, I 1287 (1/0/0).

First record from Italy.

Remark. This taxon has been considered for a long time a subspecies of Aturus scaber Kramer, 1875 . Clear differences in males (anterior surface of IV-L-5 without the proximal extension; IV-L-6 without the seta-bearing tubercle typical for A. scaber and with a higher number of ventral setae) and females (idiosoma oval, posterior margin equally rounded, not projecting as in A. scaber ) indicate that A. rotundus is a separate species. These two species represent a very distinct species group, characterized in males by insertions of IV-L at lateral idiosoma margin, the extremely shortened segment IV-L-4, and the strongly enlarged IV-L claws. Exceptionally in the genus, also females in this group are easily recognized due to the presence of paired triangular, hyaline terminal platelets flanking the gonopore.

Habitat. Shaded medium order streams. Habitat preference in Europe still little documented due to frequent confusion with A. scaber .

Figures

FIGURE 13. A. – B. Aturus rotundus, male. A. posterior venter; B. IV-L- 4 – 6 anterior. C. – H. Aturus scaber; C. – E. male; C. IV- L anterior; D. palp; E. dorsum; F. – G. female; F. IV-L- 4 – 6; G. dorsum; H. venter. Scale bars = 100 µm.