Atractides (s. str.) fluviatilis

Gerecke, Reinhard, 2021, The water mites of the family Hygrobatidae (Acari, Hydrachnidia) in Italy, Zootaxa 5009 (1), pp. 1-85 : 21-22

Atractides (s. str.) fluviatilis species group

Diagnosis: Both sexes: Integument lineated; muscle insertions unsclerotized; glandularia small (diameter <30). Genital field with relatively small Ac in a weakly curved line, genital setae in males specifically varying in number and arrangement; excretory pore smooth, Vgl-1/-2 separate. Segment I-L-5 moderately thickened, S-1/-2 away from each other, S-1 distally not strongly enlarged, bluntly pointed, distinctly longer and slenderer than S-2; I-L-6 curved, central part slightly slenderer than proximally and distally. Palp with or without sexual dimorphism in shape of P-2 (ventral margin straight in females, from straight over slightly bowed to bluntly protruding in males).

Remarks: In my keys for Atractides males and females, based on type material, original descriptions, and/or small populations analysed for comparison ( Gerecke 2003), two species pairs Atractides valencianus (K. Viets, 1930) / A. inflatipalpis K. Viets, 1950 vs. A. fluviatilis ( Szalay, 1929) / A. algeriensis ( Lundblad, 1942) were placed on distant branches. Males of the former pair should have in common the presence of a ventral projection of P-2 (not found in A. fluviatilis / algeriensis ), both sexes have a finely striated integument (held to be lineated in A. fluviatilis / algeriensis ). Since Pešić et al. (2010) discovered that the attribution of a striated integument to A. fluviatilis was erroneous, and introduced the name A. stankovici Pešić & Gerecke, 2010 for A. fluviatilis sensu K. Viets (1936) , things became more complicated. In the new scenario, A. algeriensis and A. stankovici (both not recorded from the Italian territory) are similar in a finely striated integument. The attribution “ fluviatilis species group” is introduced here for the remaining three species for practical reasons: their phylogenetic relationships among each other and with other, similar, species cannot be understood without additional studies relying on additional character sets such as larval morphology or molecular analysis. The treatment of Italian populations of these three species shows that their diagnostic characters are weakly defined. In view of the wide variability of characters and proportions, presence of further, still undiscovered species is probable. As no diagnostic characters could be found for distinguishing females in this group (but see also discussion under A. valencianus ), representatives of this sex are treated as follows: (1) females found accompanied by males of only one of the species are listed with these males under the corresponding name; (2) females recorded together with males of several species, or found without accompanying males of the fluviatilis group, are listed here in the following.

Material examined (undetermined females, some damaged males, deutonymphs with typical integument): Calabria: I 437, 0/4/0 slide; I 1083, 0/1/0 slide; I sa 11, 0/1/1 slide; I sa 13, 0/1/0 slide; I sa 14, 0/1/0 slide; Emilia- Romagna: I 1332, 0/1/0 slide; Sicilia: All parts. I 49, 0/1/0 slide; I 55, 0/1/0 slide; I 70, 0/1/0 slide; I 74, 0/1/0 slide; I 109, 3/12/0 (0/6/0 slide); I 134, 0/2/0 slide; I 178, 0/6/0 slide; I 181, 0/1/0 slide; I 298, 0/1/0 slide; I 303, 0/1/0 slide; I 404, 0/4/1 slide; I 480, 0/1/0 slide; I 481, 0/5/0 slide; I 575, 0/1/0 slide; I 592 Int 1, 0/1/0 slide; I 662, 0/1/0 slide; I dp 7, 0/6/0 (lost); I dp 15, 0/1/1 slide (lost); I dp 19, 0/2/0 slide; I dp 22, 0/2/0 slide; I dp 29, 0/1/0 slide; I dp 35, 0/2/0 slide; I dp 38, 0/1/0 slide; I dp 44, 0/1/2 slide; I dp 45, 1/0/0 slide (damaged specimen); I dp 53, 0/1/0 slide; I dp 57, 0/4/0 slide; I dp 61, 0/1/0 slide; I dp 65, 0/2/0 slide; I dp 68, 0/1/0 (lost); I dp 69, 0/1/0 slide; I dp 83, 0/9/0 slide; I dp 85, 1/16/0 (lost); I dp 86, 0/1/0 (lost); I dp 88, 0/1/3 (lost); I dp 96, 0/1/0 slide; I dp 102, 0/1/0 slide I dp 128, 0/2/0 slide; I dp 137, 0/1/0 slide (lost); I dp 138, 1/8/0 slide (lost). 43 sites, 102 specimens .

Fig. 11: Atractides fluviatilis (I 109). A-D, ♂. A, palp medial; B, I-L-5/6 (specimen with misshapen I-L-6 - inlet: normallyshaped other leg of same specimen); C, venter, partial view, genital setae omitted; D, genital field; E, ♀ venter, partial view. Scale bars: 100 µm.