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 ...
of
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
Sphaeropleaceae
Sphaeropleaceae is a family of green algae in the order Sphaeropleales.
The Sphaeropleaceae consists of solitary cells or filaments of cells. They are coenocytic, and reproduce asexually via zoospores or sexually via anisogamy or oogamy.
The ...
. It was first
circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle.
* Circum ...
by the Swedish botanist
Carl Adolph Agardh
Carl Adolph Agardh (23 January 1785 in Båstad, Sweden – 28 January 1859 in Karlstad) was a Swedish botanist specializing in algae, who was eventually appointed bishop of Karlstad.
Biography
In 1807 he was appointed teacher of mathematics ...
in 1824.
Description
''Sphaeroplea'' consists of unbranched filaments of cells, one cell thick. Cells are usually 10–50 μm in diameter, but one variety can reach up to 170 μm in diameter. Cells are cylindrical, several times longer than wide, with a linear series of alternating vacuoles and cytoplasmic zones containing nuclei and
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 ...
s. The chloroplasts are band-shaped, and contain several
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 ...
s. Nuclei are typically in pairs.
Reproduction
''Sphaeroplea'' reproduces asexually and sexually. In asexual reproduction, the filaments break apart, although one species has been observed to produce
zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion in aqueous or moist environments. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Certain zoospores are ...
s that are biflagellate (i.e. with two
flagella
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...
). Sexual reproduction is typically
oogamous
Oogamy is a form of anisogamy where the gametes differ in both size and form.
In oogamy the large female gamete (also known as ovum) is immotile, while the small male gamete (also known as spermatozoon) is mobile. Oogamy is a common form of anis ...
, where vegetative cells become reproductive cells without changing their shape. Female gametes are large, spherical and green, and are borne in one to several rows within the cell. Male gametes are typically produced on the same filament as female gametes, and are small and biflagellate.
After the gametes fuse, a zygote (termed an
oospore
An oospore is a thick-walled sexual spore that develops from a fertilized oosphere in some algae, fungi, and oomycetes. They are believed to have evolved either through the fusion of two species or the chemically induced stimulation of mycelia ...
) is formed. Zygotes develop a thick
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, ...
with ornamentation, and eventually turn reddish-orange before being released. The zygotes may last for an extended period of time in a desiccated state. During germination, the zygote becomes four biflagellate cells that attach to a substrate, lose their flagella, and develop into a new filament.
Habitat and distribution
''Sphaeroplea'' occurs in temporary
freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...
habitats such as roadside ditches, margins of ponds, and
vlei
A vlei (; ) is a shallow minor lake, mostly of a seasonal or intermittent lake, intermittent nature. It even might refer to seasonal ponds or marshy patches where frogs and similar marsh dwellers breed. Commonly, vleis vary in their extent, or e ...
s. It tends to prefer
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines.
In zoology
''Calcare ...
habitats. It has been recorded from all continents except
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
, but not very frequently. Its occurrence is ephemeral; it tends to appear abundantly in one spot, then disappear for many years. When abundant, it can impart a reddish discoloration to the water with its abundant reddish-orange oospores.
Species
According to
AlgaeBase
AlgaeBase is a global species database of information on all groups of algae, both seaweed, marine and freshwater algae, freshwater, as well as sea-grass.
History
AlgaeBase began in March 1996, founded by Michael D. Guiry, Michael Guiry. Text ...
Sphaeroplea annulina
''Sphaeroplea'' is a genus of green algae in the family Sphaeropleaceae. It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.
Description
''Sphaeroplea'' consists of unbranched filaments of cells, one cell thick. Cells ...
''
* ''
Sphaeroplea chapmanii
''Sphaeroplea'' is a genus of green algae in the family Sphaeropleaceae. It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.
Description
''Sphaeroplea'' consists of unbranched filaments of cells, one cell thick. Cells ...
''
* ''
Sphaeroplea fragilis
''Sphaeroplea'' is a genus of green algae in the family Sphaeropleaceae. It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.
Description
''Sphaeroplea'' consists of unbranched filaments of cells, one cell thick. Cells ...
Sphaeroplea tricarinata
''Sphaeroplea'' is a genus of green algae in the family Sphaeropleaceae. It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.
Description
''Sphaeroplea'' consists of unbranched filaments of cells, one cell thick. Cells ...
''
* ''
Sphaeroplea willmanii
''Sphaeroplea'' is a genus of green algae in the family Sphaeropleaceae. It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.
Description
''Sphaeroplea'' consists of unbranched filaments of cells, one cell thick. Cells ...
''
One
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
species is known:
* †''
Sphaeroplea miocenica
''Sphaeroplea'' is a genus of green algae in the family Sphaeropleaceae. It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.
Description
''Sphaeroplea'' consists of unbranched filaments of cells, one cell thick. Cells ...
''
Species are distinguished from each other by characteristics of the oospores, such as their shape and ornamentation.