Hygrobates, Koch, 1837

Gerecke, Reinhard, 2021, The water mites of the family Hygrobatidae (Acari, Hydrachnidia) in Italy, Zootaxa 5009 (1), pp. 1-85 : 49

Hygrobates (s. str.) cf. turcicus Pešić, Esen & Dabert, 2017

(Figs 21 C; 23 D)

Material examined: Basilicata: I 441, 0/2/0 slide; Calabria: I 101, 0/1/0; I 428, 3/4/0; I 438, 1/2/1 slide; I 1083, 0/0/1; I 1101, 2/1/0; I 1105, 1/1/0; I 1129, 17/16/10; I sa 9, 0/0/1; I sa 13, 0/1/0; Campania: I sa 8, 0/3/0; Sicilia: I 61, 2/1/6 (1/1/2 slide); I 68, 1/0/0; I 181, 43/ 6/4 (17/3/4 slide). 14 sites, 131 specimens .

Remarks: A revision of the material published under the name of H. fluviatilis from Sicily and Southern Italy reveals that the species s.str. is probably absent from the area in question. Representatives of most populations have an integument structure as described by Pešić et al. (2017) for H. persicus Pešić & Asadi, 2017 and H turcicus , with a fine internal striation inside the meshes of the reticulation. A further species with this character state, H. mediterraneus Pešić, 2020 , is now known from small Mediterranean streams in Montenegro (Pešić et al. 2020)

The presence of denticles on P-2 covering more than half of the proximoventral margin, not restricted to the distal projection, would separate the S Italian specimens from all three taxa named above. Until molecular data is available, the material is provisionally listed here as H. cf. turcicus . The character states of some further H. fluviatilis - like populations from this area, mostly collected in larger springs, agree with the description of H. arenarius (see above).

Habitat: Rhithrobiont. In middle order streams.

Distribution: Turkey-South Italy? Hygrobates turcicus represents a species group with a Mediterranean – Middle Eastern distribution (see Pešić et al. 2020 for a discussion). First record from Italy.

Subgenus Rivobates Thor, 1897

Diagnosis: Genital field with more than three, often numerous pairs of acetabula.

Discussion: A little defined taxon, at present difficult to separate from extra-European polyacetabulate genera, see also discussion of the subgenus Hygrobates . Interestingly, all species share a preference for spring habitats and/ or cold-water streams.