Water mite from Brittany – identification unknown

fig 10 dorsal

This water mite was caught the 4th July in the stream of the river of Kerescars in Brittany.

My description

  • Length : 950µm
  • Width : 870µm
  • Colour : yellow creamy with dark patches on the back. Legs yellow. Eyes red.
  • Coxae almost transparent.
  • Reg patch at the base of the gnathosoma.
  • Coxae hard to discern but probably fused altogether.
  • The coxae are covering roughly the half of the body.
  • Genital area away from the posterior margin of the coxae.
  • Acetabulae very hard to discern also. It seams that they are in 2 groups.
  • Gonopore (opening of the reproductive system) in the shape of a spearhead (fig 50).

Log of my identification process.

  • At the beginning, I have strictly no idea about the genus of this water mite. I can only eliminate some genus I have already encountered (Atractides : no the particular first legs, Arrenurus : not the same shape, Limnesia : no 2 eyes…)
  • I begin, as usually in this case for an European water mite, with the key of Hopkins.
  • My first look in the Hopkins key doesn’t give any result except maybe some similarity with some Unionicola female for the disposition of the acetabulae.
  • I’ve also tried to find some idea in all the 3 volumes of Soar & Williamson but with no more result.
  • And finally a check in the « Water mites Genera and subgenera » from cook 1974 didn’t produce any more tracks.
  • Now I give up for this identification. The next time I go to Britanny, I will put the water mites in Koenike’s fluid for a better inspection.



  • Hopkins, C.L. (1961). Key to the Water Mites (Hydracarina) of the Flatford Area. Field Studies Council.


Some more pictures.

fig 20 ventral

fig 30 eyes and palpi

fig 40 acetabulae

fig 50 genital from the back

fig 60 genital

fig 70 genital

fig 80 genital and coxae



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