Docidium

Docidium is a genus of algae belonging to the family Desmidiaceae. The species of this genus have a cosmopolitan distribution but are rare; they typically occur in acidic, oligotrophic waters.^[1]

Docidium
Docidium baculum
Scientific classification
Kingdom:	Plantae
Class:	Zygnematophyceae
Order:	Desmidiales
Family:	Desmidiaceae
Genus:	Docidium Brébisson ex Ralfs, 1848
Type species
Docidium baculum Brébisson ex Ralfs[1]
Species[2]
Docidium baculum Bréb. ex Ralfs, 1848 Docidium hexagonum (Borge) Willi Krieger Docidium manubrium West & G.S.West Docidium undulatum Bailey

The name Docidium comes from the Greek term δοκίδιον (dokídion, 'small beam'), referring to its shape.^[2]

Description

Docidium consists of elongate, cylindrical cells which are many times longer than broad, and are composed of two identical halves, termed semicells. The apices are truncate and are either smooth or ornamented along the margins. The cell wall is smooth, undulated or annulate and may be covered in pores. At the base of the semicell (near the center of the cell) there is a row of granules/crenations or "teeth". The chloroplast is axile, stellate in cross section, and has a row of several pyrenoids along its length. Sexual reproduction is unknown.^[3]

The genus is very similar to Pleurotaenium and Haplotaenium, from which it differs in having a row of teeth at the base of the semicells.^[3]