''Mucidosphaerium pulchellum'', also known by its synonym ''Dictyosphaerium pulchellum'', is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of freshwater

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

Chlorellaceae Chlorellaceae are a family of green algae in the order Chlorellales. About 250 species are currently accepted in the family. Members of the family are distributed worldwide and are common in a variety of freshwater, terrestrial and marine enviro ...

. ''Mucidosphaerium pulchellum'' is widespread, occurring in

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

of freshwater bodies. It appears to be the most common in temperate to subarctic climates. For example, it is present in many lakes in southern

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

and Argentina including Lanalhue, Quillén, Lácar, and

Nahuel Huapi Nahuel Huapi Lake () is an Andean lake in the lake region of northern Patagonia between the provinces of Río Negro and Neuquén, in Argentina. The lake has a northwest-southeast elongated shape and complex geography with several branches, pe ...

. In this last lake it is the dominant algae species in the winter halfyear. It has occasionally been found terrestrially on soil.

Description

''Mucidosphaerium pulchellum'' consists of colonies of cells up to 80 μm wide, with 16 to 32 (rarely 64) cells, or solitary cells. Young cells are obovoid to ellipsoidal or spindle-shaped, while older cells are spherical. The cells are attached on tetrachotomously branched (i.e. 4-branched) threads by their narrow ends. The

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 basal and cup- or saucer-shaped, and contains a

pyrenoid Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...

covered by two

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diet ...

grains. Reproduction occurs by the formation of

autospore Autospores are a type of spores that are produced by algae to enable asexual reproduction and spread. They are non-motile and non-Flagellated cell, flagellated Aplanospore, aplanospores that are generated within a parent cell and have the same sha ...

s (two to four per sporangium), which are released from a tear in the parental

cell wall A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...

Taxonomy

Traditionally, ''Mucidosphaerium pulchellum'' was distinguished from similar species (e.g. '' Dictyosphaerium ehrenbergianum'', ''Dictyosphaerium tetrachotomum''—now '' Hindakia tetrachotoma'') by morphological features, such as the cell size and shape, and attachment of the cell to its stalk. However,

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies have found that algae matching the morphology of ''Dictyosphaerium'' ''

sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...

'' may be genetically distinct and belong to different species or genera, which are more or less cryptic in nature.

References

: Chlorellaceae Chlorophyta species Freshwater algae {{Green algae-stub