Volvulina

{{Automatic taxobox

| image = Volvulina steinii.jpg

| image_caption = Volvulina steinii

| taxon = Volvulina

| authority = Playfair

| type_species = Volvulina steinii

| type_species_authority = Playfair{{AlgaeBase genus | id=43498 | title=Volvulina Playfair, 1915 | access-date=2025-04-04 }}

| subdivision_ranks = Species

| subdivision =

}}

Volvulina is a genus of colonial green algae in the family Volvocaceae.See the NCBI [https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=47792 webpage on Volvulina]. Data extracted from the {{cite web | url=http://ftp.ncbi.nih.gov/pub/taxonomy/ | title=NCBI taxonomy resources | publisher=National Center for Biotechnology Information | accessdate=2007-03-19}} It is cosmopolitan, but rare.

Description

Volvulina is a multicellular organism. The colony, termed a coenobium, is broadly ellipsoidal or spherical and consists of a fixed number of cells, usually 16 in mature individuals (rarely 4, 8 or 32). The cells are located at periphery of the coenobium and separated from each other by being embedded in a gelatinous matrix. The cell body is lens-shaped or hemispherical when mature, with two equal flagella. The chloroplast is dish- or bowl-shaped. Pyrenoids may be absent or present (located at the base of the chloroplast); eyespots are present, with eyespots in anterior cells larger than those in posterior cells. The nucleus is centrally located[http://protist.i.hosei.ac.jp/PDB/images/Chlorophyta/Volvulina/index.html Protist Images: Volvulina.] and there may be two contractile vacuoles at the base of each flagella, or several scattered contractile vacuoles.

Volvulina reproduces both asexually and sexually. In asexual reproduction, each cell of the colony develops into a daughter colony through successive cell divisions, and then subsequent colony inversion. Sexual reproduction is isogamous.

Species

Three species of Volvulina are well-characterized: Volvulina steinii, Volvulina pringsheimii, and Volvulina compacta. The three species differ from each other in morphology, namely: the shape of the cells and whether they are contiguous, and the presence or location of pyrenoids.{{cite journal|doi=10.2216/i0031-8884-29-4-410.1 |title=Volvulina compacta sp. nov. (Volvocaceae, Chlorophyta) from Nepal |date=1990 |last1=Nozaki |first1=H. |last2=Kuroiwa |first2=T. |journal=Phycologia |volume=29 |issue=4 |pages=410–417 |bibcode=1990Phyco..29..410N }} In addition to these three species, there is also Volvulina playferiana which is poorly described and may be an immature form of V. steinii, and Volvulina boldii which is a nomen nudum.{{cite journal|doi= 10.51033/jjapbot.85_6_10256|date= 2010|volume= 85|last1= Nakada|first1=T.|last2=Tomita|first2=M.|last3=Nozaki|first3=H.|title= Volvulina compacta (Volvocaceae, Chlorophyceae), new to Japan, and its phylogenetic position |journal= Journal of Japanese Botany}}

Phylogeny

Molecular phylogenetic studies show that Volvulina is paraphyletic with respect to Pandorina:{{cite journal|doi=10.1186/s12915-021-01087-0|doi-access=free |title=Phylotranscriptomics points to multiple independent origins of multicellularity and cellular differentiation in the volvocine algae |date=2021 |last1=Lindsey |first1=Charles Ross |last2=Rosenzweig |first2=Frank |last3=Herron |first3=Matthew D. |journal=BMC Biology |volume=19 |issue=1 |page=182 |pmid=34465312 |pmc=8408923 |bibcode=2021BMCB...19..182L }}{{cite journal|doi=10.1093/gbe/evad142 |title=A Reinvestigation of Multiple Independent Evolution and Triassic–Jurassic Origins of Multicellular Volvocine Algae |date=2023 |last1=Ma |first1=Xiaoya |last2=Shi |first2=Xuan |last3=Wang |first3=Qiuping |last4=Zhao |first4=Mengru |last5=Zhang |first5=Zhenhua |last6=Zhong |first6=Bojian |journal=Genome Biology and Evolution |volume=15 |issue=8 |pmid=37498572 |pmc=10410301 }}{{Cite journal |last1=Lindsey |first1=Charles Ross |last2=Knoll |first2=Andrew H. |last3=Herron |first3=Matthew D. |last4=Rosenzweig |first4=Frank |date=2024-04-10 |title=Fossil-calibrated molecular clock data enable reconstruction of steps leading to differentiated multicellularity and anisogamy in the Volvocine algae |journal=BMC Biology |volume=22 |issue=1 |pages=79 |doi=10.1186/s12915-024-01878-1 |issn=1741-7007 |pmid=38600528 |doi-access=free|pmc=11007952 |bibcode=2024BMCB...22...79L }}

{{clade

|1=

{{clade

|1=Platydorina + Colemanosphaera (outgroup)

|2={{clade

|1=Volvulina steinii

|2={{clade

|1=

{{clade

|1="Volvulina boldii"

|2=Pandorina colemaniae

}}