''Echinosphaeridium'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

, in the family

Neochloridaceae Neochloridaceae is a family of green algae in the order Sphaeropleales. Neochloridaceae consists of aquatic, coccoid algae. The cells are spherical or with complex polyhedral shapes. Chloroplasts have pyrenoids that are surrounded by continuous ...

. It is found in freshwater habitats, but it is very rare. It has only been recorded a few times since its original discovery in Sweden.

Description

''Echinosphaeridium'' consists of solitary, spherical cells surrounded by thin spines. The spines are surrounded by a triangular structure at the base, which consist of three "wings" similar in form to the

fletching Fletching is the fin-shaped aerodynamic stabilization device attached on arrows, crossbow bolts, Dart (missile), darts, and javelins, typically made from light semi-flexible materials such as feathers or Bark (botany), bark. Each piece of such a ...

s on arrows. Unlike the related genus '' Golenkinia'', cells are not surrounded by a layer of mucilage. One

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

is present per cell, containing a pyrenoid. ''Echinosphaeridium'' is similar to the genus ''Golenkinia'', and several authors have considered it to be an anomalous form of the latter. However, ''Echinosphaeridium'' is distinguished by the structure of the spines (particularly at their bases), and the lack of mucilage surrounding the cells. Occasionally, the mucilage layer in ''Golenkinia'' may be draped around the spines, giving it a superficially similar appearance.

References

Sphaeropleales genera Sphaeropleales Freshwater algae {{Chlorophyceae-stub