Ichthydium Ehrenberg 1830

Genus Ichthydium Ehrenberg, 1830

Ehrenberg, C.G. (1830) Beiträge zur kenntnis der Organization der Infusorien und ihrer geographischen Verbreitung besonders in Sibirien. Abhandlung Akademie der Wissenschaften, Berlin. Jahrgang, 44.

Typus generis: Ichthydium podura (Müller, 1773); designation by Ehrenberg, 1830

Subgenus Ichthydium (Ichthydium sensu stricto) Ehrenberg, 1830 [Hummon, 2008b] [syn. Euichthydium Schwank, 1990]

Type species: Ichthydium podura (Müller, 1773); original designation by Schwank, 1990

Subgenus Ichthydium (Forficulichthys) Schwank, 1990

Type species: Ichthydium (Forficulichthys) forficula (Remane, 1927); original designation by Schwank, 1990

Subgenus Ichthydium (Pseudichthydium) Rudescu, 1967

Type species: Ichthydium (Pseudichthydium) balatonicum (Varga, 1950); original designation by Schwank, 1990: 102

The genus Ichthydium is clearly considered as polyphyletic and thus it is an artificial taxon (Kisielewski,1991). It needs a careful taxonomic revision rather than a division into subgenera based on very few morphological criteria, like the different shape of the furcal tubes and the possible presence of thin dorsal scales on the bare body cuticle. The latter feature is not peculiar of the subgenus I. (Forficulichthys), since cuticular microsculptures and thin scales are occasionally present also in species of the subgenus I.

(Ichthydium s. s.), i.e. I. podura, I. squamigerum. The diagnostic characters of the rare monotypic subgenus Ichthydium (Pseudichthydium) appear so different from the other Ichthydium species that they would require a closer examination of the only species known. For all this reasons the subgenera introduced by Schwank (1990) have not been introduced in the present list.