Lesquereusia spiralis, with dark mucus surrounding the collar

 

 

Genus Lesquereusia Schlumberger (1845)

 

Diagnosis: test with asymmetrical neck, more or less attached to the body, composed of endogenous siliceous rods or in other species with collected mineral particles, bound together with organic cement. Nucleus ovular.

 

Type species: Lesquereusia spiralis (Ehrenberg 1840).

 

Ecology: in mosses like sphagnum and in detritus. Species feeding on diatoms and green algae.

 

Remarks: Species differ mainly in shape of the siliceous rods, the amount of mineral particles and the orientation of the neck.
This genus was erected by Schlumberger (1845) and obviously named after the swiss naturalist Lesquereux. By lapsus it was first published as Lecqereusia. The currently used spelling was introduced by Hopkinson (in Cash & Hopkinson, 1909)!
16 species have been described, the type species is Lesquereusia spiralis (Ehrenberg, 1840). Three well known species are L. spiralis, L. modesta and L. epistomium.  However, D. modesta and D. spiralis are sometimes hard to distinguish from each other, because they can have a mixture of endogenous rods and mineral particles. I am not sure if both species are  really different species.

 

Lesquereusia spiralis
Lesquereusia modesta
Lesquereusia spiralis and L. modesta, typical forms