The Small World of Freshwater Gastrotrichs
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Setopus tongiorgii

  • Order: CHAETONOTIDA Remane, 1925
    • Suborder: PAUCITUBULATINA d'Hondt, 1971
      • Family: DASYDYTIDAE Daday, 1905
        • Subfamily:
          • Genus: Setopus Grünspan, 1908
            • Species: tongiorgii Balsamo, 1982
(after (Balsamo, 1982))
Length ( bottle ):
84 µm - 140 µm

26 µm - 40 µm

Width of the head ( five-lobed ):
25 µm - 38 µm


Length of the furca:

Adhessive tubes (none):

Pharyx ( cylindrical ):
25 µm - 29 µm

Diameter of the mouth ( around ):

Dorsal scales:
Terminal spines with secondary apices on triangular scale rudiments; unequal in length (27-30 µm; 43-55 µm); numerous dorsolateral spines with secondary apices on scale rudiments; 21 per side.

rare; bog lake

Similar species:
S. chatticus : no scales and fewer shorter spines

scaled ventral interciliate field


Setopus tongiorgii has been found so far only in Italy and some locations in Germany and is - like all Setopus species - relatively rare.

Overview with focus on the ring of eyelashes on the head (©️ Dr. Stephan Krall).

cross section
Transverse section; Rs: trunk spines; Cs: caudal spines (©️ Dr. Ole Riemann).

In the cross section the lateral spines with their secondary spike are well visible. Terminal are two caudal spines of unequal length, which also carry a secondary tip.

Scaling of the ventral intermediate field (©️ Dr. Ole Riemann).

Ventrally, the small, roundish scales and the keeled terminal plates of the ventral interciliar field can be seen. So far only in S. tongiorgii scales were found in this area. This feature is therefore of special importance for the diagnosis of the species.


(Balsamo, 1982)
(Kieneke und Riemann 2008)
(Kieneke, Martínez Arbizu, und Riemann 2008)