Aturus asserculatus Walter, 1906

Gerecke, Reinhard, 2014, Studies on European species of the water mite family Aturidae Thor (Acari: Hydrachnidia), Zootaxa 3841 (1), pp. 1-46 : 6-7

Aturus asserculatus Walter, 1906

Fig. 3

Aturus intermedius serrata K.Viets, 1922 , nov. syn.

Material examined. Type series: Lectotype ♂, here designated: the dissected specimen mounted with dorsum directed upside on slide NHMB 4498 " Aturus asserculatus Walter ♂, Bach b. Arlesheim 17.April 1906 " "Typus" " V/73 ". Paralectotypes: The same slide, 7 ♂♂, one dissected with venter directed upside, the others undissected; NHMB 4501 " Bächlein b. Wyhlen , 25.Nov.1906 " ♂, ♀ on one slide (both heavily squeezed and ♂ lacking most legs); NHMB 4499 " Birszufluss zw. Tavannes u. Fuel , 27.Juni 1905 ", 2 ♀♀ (completely dried, on ♀ only idiosoma), NHMB 4500, as 4499, bearing only two squeezed palps of one ♀ of NHMB 4499.

Further material. Switzerland: NHMB 4506 " Lützel, Lüssel , Grundwasser SCH 29" 2 ♂♂ (slightly squeezed, one of them lacking palps).

Aturus asserculatus serratus K. Viets, 1922 : Type series: Lectotype, here designated: SMF 42818, " Aturus asserculatus serratus ♂ Type, Vogler, Hüttebach in Moos, 20.7.1920, Viets leg. 2762". Paralectotype, SMF 42817, same date and site, ♀, "Viets leg. 2761". Further material: SMF 49791 "Mölle [...] 23.7.1953 1802" ♂, 49792, ditto, ♀.

Refused attribution. France: SMF 42829 "Alp. franc. Doméne 15.9.50 Vaillant coll. 7124" " Aturus asserculatus Walt. ♂"; SMF 49794, ditto "4563" "♂, ♀": All specimens represent A. gallicus (see there).

Remarks. Walter (1906a) did not define a holotype in the original description where he listed the following collecting sites in the surroundings of Basel which are consequently type localities: River Birs and affluents, streams near Wyhlen, Muttenz and Arlesheim. Consequently, all specimens in coll. Walter deriving from these sites and collected in 1906 or earlier are syntypes. Among them, as suggested by a red " Typus " label (overpasted with additional labels by C. Bader), specimens on slide NHMB 4498 were considered as reference specimen by the author himself. The ♂ specimen with important characters of the dorsum well visible is designated as lectotype.

In the original description, an error underwent when Walter considered the setation of IV-L-4: In contrast to his statements and figures, no enlarged, truncated and distally serrated setae are inserted at the distal margin of this segment. Instead, in this position long and pointed, laterally finely denticulate setae are found as they are typical for most other species of the genus. Also all other examined specimens attributed to A. asserculatus do not show truncated and distally serrated setae as depicted by Walter.

Posterior to the transverse dorsal ridge characteristic for males of this species, a pair of weakly sclerotized structures is more or less well visible. These are in oblique position and form together an obtuse, anteriorly directed angle.

Aturus asserculatus serratus was originally described ( K. Viets, 1922d) as subspecies of Aturus intermedius , with a discussion of diagnostic differences to the latter and to A. natangensis only. The author did not define a holotype such that all specimens from the listed collecting sites are syntypes. In addition to the site on the lectotype label, the original description refers to material from: "Ständige Quelle im Kohlhai 65/66 oberhalb des Holenberger Wegs, 350 m ü.M, 20.7.1920 "; "Quelle und Rinne in Breitegrund 60 Fisemke 62, 21.7.1920 ", "Sickerquelle im Kohlhai 65 am Abhange nach dem Hüttebach gegenüber Fuchsloch, Abteilungslinie 68/ 69, 250 m ü.M., 24.7.1920 "; "Quellenloch an der Chaussee Scharfolfendorf-Kapellenhangen zwischen km 3,8 und 3, 9, 250 m ü.M., 23.7.1920 ". The author used, however, to mark selected specimens as " types ", on which his description based in particular. In this case, it is surely in his sense to designate the male from Hüttebach as lectotype.

Only later on, K.Viets (1928f) got aware of the close similarity to A. asserculatus and placed the taxon as subspecies of the latter, considering the shape of the distal setae on IV-L-4 (pointed, laterally serrate) as a diagnostic difference. As it is now obvious that Walters description of this character state in A. asserculatus was erroneous, A. serratus must be considered its junior synonym.

Habitat. Shaded low order streams and rheocrenes.

Figures

FIGURE 3. Aturus asserculatus, male. A. dorsal shield; B. IV-L- 4 – 6 posterior; C. IV-L- 4 – 6 anterior. Scale bars = 100 µm.