# Phacus

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Genus of flagellate algae

Phacus Phacus sp. Scientific classification Domain: Eukaryota Clade: Discoba Phylum: Euglenozoa Class: Euglenida Clade: Euglenophyceae Order: Euglenales Family: Phacaceae Genus: Phacus Dujardin, 1841 Type species Phacus longicauda (Ehrenberg) Dujardin[1]

***Phacus*** is a [genus](/source/Genus) of [unicellular](/source/Unicellular) [euglenoids](/source/Euglenoid), of the [phylum](/source/Phylum) [Euglenozoa](/source/Euglenozoa) (also known as Euglenophyta), characterized by its flat, leaf-shaped structure, and rigid [cytoskeleton](/source/Cytoskeleton) known as a pellicle. These eukaryotes are mostly green in colour, and have a single flagellum that extends the length of their body. They are morphologically very flat, rigid, leaf-shaped, and contain many small discoid chloroplasts.

*Phacus* are commonly found in [freshwater](/source/Fresh_water) habitats around the globe and include several hundred species that continue to be discovered to this day.[2] There are 564 [species](/source/Species) of *Phacus* in the database, but only 171 have been accepted taxonomically.[1] It is a large and complex genus, with ongoing species revisions continuing to the present.[3]

## Etymology

The genus name is believed to have originated from the [Greek](/source/Greece) word φακός (*phakós*), meaning lentil or lens.[4] This may be due to the general round or oval shape of the many species that are part of this genus. Its origins date back to the nineteenth century, in [Germany](/source/Germany), where it was first coined by Nitzsch and later formally established by Dujardin.[5] The genus name is treated in literature as masculine.[1]

## History of knowledge

Drawings of *Cercaria pleuronectes* in the *Iconographia Zoologica*

[Otto Friedrich Müller](/source/Otto_Friedrich_M%C3%BCller) is credited to have first seen organisms matching *Phacus*, in 1773; he named his organism *Cercaria pleuronectes* and placed it in the genus *Cercaria*. However, [Christian Ludwig Nitzsch](/source/Christian_Ludwig_Nitzsch) in 1817 noted that his genus *Cercaria* was an artificial grouping of different organisms, and later in 1827 transferred the genus *Cercaria pleuronectes* to the genus *Phacus*. Earlier in 1823, [Jean-Baptiste Bory de Saint-Vincent](/source/Jean-Baptiste_Bory_de_Saint-Vincent) proposed the name *Virgulina* which technically had priority over the name *Phacus*. The name *Virgulina* was later [rejected](/source/Rejected_name) in favor of *Phacus*.[5]

The genus in its modern sense was established by the French biologist [Félix Dujardin](/source/F%C3%A9lix_Dujardin) in 1841, using Nitzsch's name.[5] Dujardin first published collective findings of the genus in the scientific journal *Histoire naturelle des Zoophytes, Infusoires* in 1841, separating them from the genus *Euglena*. The reason behind the separation was in order to create a group that correctly organizes their established morphological characteristics such as their rigid, flat, leaf-shape and small discoid [chloroplasts](/source/Chloroplast) with absent pyrenoids.[6]

[Christian Ehrenberg](/source/Christian_Gottfried_Ehrenberg) was one of the first scientists to discover and classify members of the genus; his discovery of *Phacus longicauda* (Ehrenberg) was one of the first species of the genus to be discovered (1830) and was later used as the [lectotype](/source/Lectotype) species for the genus.[1] Later workers such as [Lemmermann](/source/Ernst_Lemmermann) (1930), Pochmann (1942) and Huber-Pestalozzi (1955) added additional species. They also attempted to subdivide *Phacus* into a number of subgenera and sections, mostly based on the morphology of the spiral pellicle surrounding the cells.[5]

Since the establishment of the genus, classification of taxa has been difficult because many species display enormous morphological variability in characters such as cell shape and size. Many taxa of different ranks (species, [varieties](/source/Variety_(taxonomy)) and [forms](/source/Form_(botany))) have been described, but the criteria for distinguishing them are often vague. With the advent of [molecular phylogenetic](/source/Molecular_phylogenetic) methods, *Phacus* has undergone significant reclassification and some species are now distinguished by more reliable morphological differences, such as the presence of perpendicular "struts" in the periplast.[7] Some species have been found to be [cryptic](/source/Cryptic_species), and are difficult or impossible to distinguish from each other using morphology alone.[2] Two species, *Euglena limnophila* and *Lepocinclis salinus*, were found to be nested within the clade of *Phacus*. The genus *Phacus* was therefore redefined to include these species, preserving its [monophyly](/source/Monophyly), but these two species (now classified as *[Phacus limnophilus](https://en.wikipedia.org/w/index.php?title=Phacus_limnophilus&action=edit&redlink=1)* and *[Phacus salinus](https://en.wikipedia.org/w/index.php?title=Phacus_salinus&action=edit&redlink=1)*) differ from other *Phacus* in not having flattened cells.[3]

## Habitat and ecology

*Phacus* are commonly found in freshwater habitats all over the world. Many species of this genus have been discovered in several countries, including Japan, the United States, Portugal, Brazil, Korea and the Philippines.[2][8][9] Different members of the genus have been found in temperatures ranging from 11.4 to 21.6 °C, and a [pH](/source/PH) between 6.2 and 7.5. *Phacus* organisms are found in a range of freshwater environments (some more acidic or alkaline than others), prefer cooler temperatures, and on average exist in more neutral pH aquatic habitats.[8] Many species of *Phacus* are considered to be euplanktonic (free-floating organisms or open water plankton) because they are commonly found together with other genera of *[euglenids](/source/Euglenid)* such as *[Lepocinclis](/source/Lepocinclis), [Trachelomonas](/source/Trachelomonas), [Euglena](/source/Euglena)*. Although very common, they rarely become numerous enough to form [blooms](/source/Algal_bloom), unlike *Euglena* and *Trachelomonas*.[5]

Being in an organically enriched freshwater environment is essential for the development of these species. Different studies have shown that the addition or removal of certain organic elements can have profound effects on cell development.[10] In studies using beef extract to increase organic content of certain cultures, some species of *Phacus* were observed to have clear morphological changes different from the controls.[10] These changes include: increasing thickness of the cell, increase in [paramylon](/source/Paramylon) bodies (both in size and number in *Phacus curvicauda*), and the overall structure of the cells. Regardless of a large or small change in organic enrichment, studies show a consistency to these morphological changes. However, the amount of change that occurs varies between species and is dependent on the specific organic nutrients present.[10] If the amount of organic nutrients in the genus' habitat is insufficient, occasionally they form resting [cysts](/source/Cyst). If this occurs, the cells would expand (swell) and become more rounded, and also lose their flagella. This increase in size forces the cell to increase the number of paramylon storage granules and develop a [polysaccharide](/source/Polysaccharide) mucilaginous wall for protection until it enters a more habitable environment. In addition, cell division continues to take place even as a reproductive cyst.[4]

### Feeding

Almost all *Phacus* are [photosynthetic](/source/Photosynthesis) unicellular organisms, meaning that they are capable of producing their own food. Although the cells obtain nutrients through photosynthesis, they also have what appears to be a vestigial feeding apparatus located on their underside, similar to those of their [phagotrophic](/source/Phagotrophic) relatives.[11] One species, *[Phacus ocellatus](https://en.wikipedia.org/w/index.php?title=Phacus_ocellatus&action=edit&redlink=1)*, is secondarily non-photosynthetic and obtains its nutrients via [osmotrophy](/source/Osmotrophy).[12]

## Description

### Morphology

*Phacus* consists of single-celled, microscopic organisms. Generally these species are small, free-swimming and exhibit a vibrant green colour. *Phacus* is distinguished from other photosynthetic genera, such as *Euglena*, from the presence of its rigid cytoskeleton (although some species have semi-rigid or plastic cytoskeleton) made up of pellicular strips and its predominantly flat, leaf-shaped structure.[8] Many different species express secondary fusion of these pellicular strips and many of the strips have a variety of shapes including S-shaped, A-shaped, M-shaped or plateau.[13] The pellicle forms a shell around the cytoskeleton covering the whole cell and fuses together around the [microtubule](/source/Microtubule) reinforced-pocket (MTR).[11] This pocket acts as a sort of [cytostome](/source/Cytostome) or ingestion organelle, allowing the organism to feed when bacteria enter inside. The microtubules are arranged in a peculiar doublet and triplet pattern in the upper canal. In certain species of *Phacus*, the MTR is a microtubule organizing center and is connected to a reservoir membrane by a striated fiber.[11] Many species also possess an elongated caudal process (tail) with extended pellicle strips. Throughout the cytoplasm of the cell, there are numerous small, discoid [chloroplasts](/source/Chloroplast).[9] Chloroplasts that are present in large numbers are typically smaller, are without [pyrenoids](/source/Pyrenoid) and species containing fewer chloroplasts tend to have much larger ones. *Phacus*, like all photosynthetic euglenoids, obtained their plastids through secondary [endosymbiosis](/source/Endosymbiosis), where the ancestral phagocytic euglenoid engulfed a [green alga](/source/Green_algae), and the resulting organism became the [plastid](/source/Plastid).[14]

Cells of *Phacus* possess a reddish [eyespot](/source/Eyespot_apparatus) (stigma), located in the anterior of the cell, and two [flagella](/source/Flagella) which are inserted in a small reservoir (opening). One flagellum is long and emerges from the reservoir (the emergent flagellum), while the second flagellum is a short stump and vibrates within the reservoir.[15] The emergent flagellum is responsible for cell movement by gyrating in the direction of travel allowing the cell to glide and swim in the water. Aside from the flagella, the flagellar apparatus also contains two basal bodies connected by a striated fiber, three asymmetric microtubular roots, and other connective fibers.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

*Phacus* stores energy in the form of [paramylon](/source/Paramylon), a carbohydrate similar to starch; it has small paramylon grains distributed throughout the entire cell. In addition to the small paramylon grains, one or two larger paramylon grains occur and have a characteristic shape (globose, ring-shaped, rod-shaped, or semilunate) and are located at a characteristic part of the cell.[15] The nucleus of the cell is generally positioned towards the middle of the cell and is adjacent to the paramylon reserve. Within the nucleus are permanently condensed chromosomes, which can easily be viewed under a light microscope.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

### Differences in morphology

Although the general morphology of the genus is considered to be well established, given the large number of species there are critical morphological differences observed worth noting.[8] The [sulcus](/source/Sulcus_(morphology)) for example, in many species is shallow (*Phacus viridioryza*), and in others it is deep and longitudinal (*Phacus hordeiformis*). As well, the shape of the cell in some species are completely flat, while many have also been described as helically twisted, straight or curved. *Phacus helikoides* is actually helical in shape throughout the entire cell as opposed to flat and leaf-shaped like most *Phacus* organisms.

Metaboly, which is the ability of some organisms to alter their shape, is not possible in *Phacus* due to the fusion of the genus' pellicular strips. These varied morphological shapes make defining the genus as [symmetrical](/source/Symmetry) or asymmetrical rather difficult. Scientists who study the genus *Phacus* Dujardin, have also observed the presence of ellipsoid, tiny disk-shaped or flat-shaped paramylon grains. In some species of *Phacus,* a single plate dominates the interiors of the [cell](/source/Cell_(biology)) (*Phacus orbicularis*), and in others there are multiple plates with different morphologies that exist (*Phacus curvicauda*).[16]

Other differences among species include: the presence or lack of haplopyrenoids within the chloroplasts, position of the nucleus, a large or small endosome, shape of the cytoskeleton, few to several paramylon discoid grains, the presence of lateral caps and presence of oblique truncated poles. In addition, the morphology of the caudal process in many species of *Phacus* is extremely varied. *Phacus parvullis* and *Phacus pusillus* have very a blunt caudal process while *Phacus segretti* and *Phacus stokesii* actually lack a caudal process entirely. Those species are described as having rounded posteriors in place of the caudal process. Studies show that morphological changes observed in the genus are possibly due to the level of organic enrichment in their freshwater [habitats](/source/Habitat).[10] These morphological differences, given the massive size of the genus, have led to certain confusion in *Phacus* taxonomy.

### Life cycle

*Phacus* and other euglenids reproduce [asexually](/source/Asexual_reproduction). They do so by dividing their cells longitudinally, from the apex of the cell to the base. The process may occur while motile, or in a nonmotile, "palmelloid" stage. Until [cytokinesis](/source/Cytokinesis) is fully complete, the cells remain attached to one another, forming what looks like a "two-headed" organism.[5] Prior to cytokinesis, the amount of pellicle strips each cell has is doubled in order to have an equal number between each [daughter cell](/source/Cell_division). In addition, each daughter cell will contain half the number of the newly formed strips and half the number of the old strips present prior to cell division.

### Genetics

A major genetic change in the genus occurred in its chloroplast genome throughout its evolution. This resulted in a [genome reduction](/source/Genome_reduction) - possibly due to gene loss or transfer to the [nucleus](/source/Cell_nucleus), an increase in the number of [introns](/source/Intron), and large genomic rearrangements.

## Evolution

The literature mentioned above have also looked into the evolutionary history of the genus' morphology. It is believed that the rigidity of the cells has [evolved](/source/Evolution) numerous times, and that was determined by comparing the semi-rigid [pellicles](/source/Pellicle_(biology)) of ancestral species with the rigid pellicles of their descendants.[17] Another feature believed to have evolved, are the longitudinal strips that appear on most species. It appears that the number of those strips has either increased or decreased over time depending on certain species and that their arrangement (either helical or longitudinal) has also changed throughout evolution.[17] Furthermore, it has been argued that certain behavioral and locomotor traits which previously existed for predatory feeding have no longer been selected. This seemed to have had an effect on the number of strips species of *Phacus* generally have. The changing numbers of strips and the clustered patterns associated are not actually adaptive themselves, but may have evolved due to the cell becoming more flat and more rigid over time. Those traits are believed to have evolved in order to adapt to a more planktonic lifestyle.[17]

### Phylogeny

*Phacus* is a member of the family [Phacaceae](https://en.wikipedia.org/w/index.php?title=Phacaceae&action=edit&redlink=1),[18] the order Euglenales, class Euglenoidea, and finally the phylum Euglenozoa. Many studies have attempted to determine is reconstruct the [phylogenetic tree](/source/Phylogenetic_tree) of *Phacus* based on molecular sequence data.[19] Although the genus *Phacus* is recovered as [monophyletic](/source/Monophyletic),[20] this has required some adjustments to retain its monophyly, such as including the species *Lepocinclis salinus* which has non-flattened cells.[3] It is sister to *[Lepocinclis](/source/Lepocinclis)*, a similarly rigid genus.[20] A current hypothesis is as follows (not all accepted species are included):[3]

Phacus Clade K P. anomalus P. anacoelus P. curvicauda P. alatus P. stokesii Clade J P. orbicularis P. paraorbicularis Clade I P. lismorensis Clade H P. ankylonoton P. tenuis P. applanatus P. hamelii P. segretii Clade G P. salinus Clade F P. gigas P. sp. P. hamatus Clade E P. caudatus P. manginii P. raciborskii P. mariae P. sp. Clade D P. oscillans group Clade C P. longicauda group P. helikoides group P. elegans Clade B P. pleuronectes P. minutus P. acuminatus P. triqueter Clade A P. limnophilus P. arnoldii Lepocinclis (outgroup)

## Fossil history

The [fossil record](/source/Fossil_record) for *Phacus*, like most euglenoids, is very scarce, and little information is actually known of their geographical origins. However, there have been reports that *Phacus*-like microfossils have been discovered from pyriform cells, which seem to closely resemble that of *Phacus* or another closely related genus, *Lepocinclis*. These fossils, although not certain to belong to the genus, are estimated to be over 60 million years old.[21]

## Practical importance

The presence of *Phacus* in certain bodies of water can actually indicate the level of organic [pollution](/source/Pollution) of the water. It has been observed that if a large number of *Phacus* organisms are present, that is indicative of high organic pollution. This particular trait allows scientists to determine the health of different bodies of water.[22]

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1. **[^](#cite_ref-13)** Leander, Brian S.; Farmer, Mark A. (2001-02-06). "Evolution of *Phacus* (Euglenophyceae) as Inferred From Pellicle Morphology and SSU rDNA". *Journal of Phycology*. **37** (1): 143–159. [Bibcode](/source/Bibcode_(identifier)):[2001JPcgy..37..143L](https://ui.adsabs.harvard.edu/abs/2001JPcgy..37..143L). [doi](/source/Doi_(identifier)):[10.1046/j.1529-8817.2001.037001143.x](https://doi.org/10.1046%2Fj.1529-8817.2001.037001143.x). [ISSN](/source/ISSN_(identifier)) [1529-8817](https://search.worldcat.org/issn/1529-8817). [S2CID](/source/S2CID_(identifier)) [14334118](https://api.semanticscholar.org/CorpusID:14334118).

1. **[^](#cite_ref-14)** Kasiborski, Beth A.; Bennett, Matthew S.; Linton, Eric W. (2016-06-01). "The chloroplast genome of *Phacus orbicularis* (Euglenophyceae): an initial datum point for the phacaceae". *Journal of Phycology*. **52** (3): 404–411. [Bibcode](/source/Bibcode_(identifier)):[2016JPcgy..52..404K](https://ui.adsabs.harvard.edu/abs/2016JPcgy..52..404K). [doi](/source/Doi_(identifier)):[10.1111/jpy.12403](https://doi.org/10.1111%2Fjpy.12403). [ISSN](/source/ISSN_(identifier)) [1529-8817](https://search.worldcat.org/issn/1529-8817). [PMID](/source/PMID_(identifier)) [27273533](https://pubmed.ncbi.nlm.nih.gov/27273533). [S2CID](/source/S2CID_(identifier)) [30363801](https://api.semanticscholar.org/CorpusID:30363801).

1. ^ [***a***](#cite_ref-Bicudo_and_Menezes2006_15-0) [***b***](#cite_ref-Bicudo_and_Menezes2006_15-1) Bicudo, Carlos E. M.; Menezes, Mariângela (2006). *Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições* (2 ed.). RiMa Editora. p. 508. [ISBN](/source/ISBN_(identifier)) [85-7656-064-X](https://en.wikipedia.org/wiki/Special:BookSources/85-7656-064-X).

1. **[^](#cite_ref-16)** Monfils, Anna K; Triemer, Richard E; Bellairs, Emily F (2011-02-28). "Characterization of paramylon morphological diversity in photosynthetic euglenoids (Euglenales, Euglenophyta)". *Phycologia*. **50** (2): 156–169. [Bibcode](/source/Bibcode_(identifier)):[2011Phyco..50..156M](https://ui.adsabs.harvard.edu/abs/2011Phyco..50..156M). [doi](/source/Doi_(identifier)):[10.2216/09-112.1](https://doi.org/10.2216%2F09-112.1). [S2CID](/source/S2CID_(identifier)) [85569364](https://api.semanticscholar.org/CorpusID:85569364).

1. ^ [***a***](#cite_ref-:8_17-0) [***b***](#cite_ref-:8_17-1) [***c***](#cite_ref-:8_17-2) Esson, Heather J.; Leander, Brian S. (2010-01-01). "Evolution of Distorted Pellicle Patterns in Rigid Photosynthetic Euglenids (Phacus Dujardin)". *Journal of Eukaryotic Microbiology*. **57** (1): 19–32. [doi](/source/Doi_(identifier)):[10.1111/j.1550-7408.2009.00447.x](https://doi.org/10.1111%2Fj.1550-7408.2009.00447.x). [ISSN](/source/ISSN_(identifier)) [1550-7408](https://search.worldcat.org/issn/1550-7408). [PMID](/source/PMID_(identifier)) [19878404](https://pubmed.ncbi.nlm.nih.gov/19878404). [S2CID](/source/S2CID_(identifier)) [2010902](https://api.semanticscholar.org/CorpusID:2010902).

1. **[^](#cite_ref-Kim_18-0)** Kim, Jong Im; Shin, Woongghi; Triemer, Richard E. (2010). "Multigene Analyses of Photosynthetic Euglenoids and New Family, Phacaceae (Euglenales)". *Journal of Phycology*. **46** (6): 1278–1287. [Bibcode](/source/Bibcode_(identifier)):[2010JPcgy..46.1278K](https://ui.adsabs.harvard.edu/abs/2010JPcgy..46.1278K). [doi](/source/Doi_(identifier)):[10.1111/j.1529-8817.2010.00910.x](https://doi.org/10.1111%2Fj.1529-8817.2010.00910.x). [S2CID](/source/S2CID_(identifier)) [86347770](https://api.semanticscholar.org/CorpusID:86347770).

1. **[^](#cite_ref-:7_19-0)** Milanowski, Rafał; Kosmala, Sylwia; Zakryś, Bozżena; Kwiatowski, Jan (2006-06-01). "Phylogeny of Photosynthetic Euglenophytes Based on Combined Chloroplast and Cytoplasmic SSU rDNA Sequence Analysis". *Journal of Phycology*. **42** (3): 721–730. [Bibcode](/source/Bibcode_(identifier)):[2006JPcgy..42..721M](https://ui.adsabs.harvard.edu/abs/2006JPcgy..42..721M). [doi](/source/Doi_(identifier)):[10.1111/j.1529-8817.2006.00216.x](https://doi.org/10.1111%2Fj.1529-8817.2006.00216.x). [ISSN](/source/ISSN_(identifier)) [1529-8817](https://search.worldcat.org/issn/1529-8817). [S2CID](/source/S2CID_(identifier)) [86618135](https://api.semanticscholar.org/CorpusID:86618135).

1. ^ [***a***](#cite_ref-Kim2015_20-0) [***b***](#cite_ref-Kim2015_20-1) Kim, Jong Im; Linton, Eric W.; Shin, Woongghi (2015). ["Taxon-rich multigene phylogeny of the photosynthetic euglenoids (Euglenophyceae)"](https://doi.org/10.3389%2Ffevo.2015.00098). *Frontiers in Ecology and Evolution*. **3**: 98. [Bibcode](/source/Bibcode_(identifier)):[2015FrEEv...3...98K](https://ui.adsabs.harvard.edu/abs/2015FrEEv...3...98K). [doi](/source/Doi_(identifier)):[10.3389/fevo.2015.00098](https://doi.org/10.3389%2Ffevo.2015.00098).

1. **[^](#cite_ref-21)** Bradley, W. H. (1929). "Fresh water algae from the Green River Formation of Colorado". *Bulletin of the Torrey Botanical Club*. **56** (8): 421–428. [doi](/source/Doi_(identifier)):[10.2307/2480453](https://doi.org/10.2307%2F2480453). [JSTOR](/source/JSTOR_(identifier)) [2480453](https://www.jstor.org/stable/2480453).

1. **[^](#cite_ref-22)** Brunn, K (2012). ["Algae can function as indicators of water pollution | WALPA"](http://www.walpa.org/waterline/june-2012/algae-can-function-as-indicators-of-water-pollution). *Nostoca Algae Laboratory*. Retrieved 2017-07-25.

## Further reading

- Nannavecchia, Paula; Tolivia, Analia; Conforti, Visitacion (March 2014). "Ultrastructural alterations in Phacus brachykentron (Euglenophyta) due to excess of organic matter in the culture medium". *Ecotoxicology and Environmental Safety*. **101**: 36–41. [Bibcode](/source/Bibcode_(identifier)):[2014EcoES.101...36N](https://ui.adsabs.harvard.edu/abs/2014EcoES.101...36N). [doi](/source/Doi_(identifier)):[10.1016/j.ecoenv.2013.12.007](https://doi.org/10.1016%2Fj.ecoenv.2013.12.007). [hdl](/source/Hdl_(identifier)):[11336/19526](https://hdl.handle.net/11336%2F19526). [PMID](/source/PMID_(identifier)) [24507124](https://pubmed.ncbi.nlm.nih.gov/24507124).

- Su, H M; Won, L J; Ho, G Y (27 September 2013). "Bacterial mixture useful for controlling proliferation of harmful algae including Microcystis, Anabaena, Aphanizomenon, Phacus, Euglena, Peridinium, Cyclotella, Chlamydomonas and Rhodomonas, comprises Lactobacillus and Lactococcus". *Kr2013009902-A; Kr1311837-B1*.

- Phacus. (n.d.). Retrieved from [http://eol.org/pages/11710/overview](http://eol.org/pages/11710/overview)

- Pritchard, A., et al. 1861: [A history of Infusoria, including the Desmidiaceae and Diatomaceae, British and foreign](https://archive.org/stream/historyofinfusor00prit#page/n6/mode/1up). London: Whitaker and co.

v t e Discoba classification Domain Archaea Bacteria Eukaryota (major groups Metamonada Discoba Diaphoretickes Hacrobia Cryptista Rhizaria Alveolata Stramenopiles Plants Amorphea Amoebozoa Opisthokonta Animalia Fungi Mesomycetozoea) Eolouka* Tsukubea Tsukubamonadidae Tsukubamonas Jakobea Ophirinina Agogonidae Agogonia Ophirinidae Ophirina Andalucina Andaluciidae Andalucia Stygiellidae Stygiella Velundella Histionina Histionidae Histiona Reclinomonas Jakobidae Jakoba Moramonadidae Moramonas Seculamonas Discicristata Euglenozoa Euglenida Petalomonadida Scytomonadidae Atraktomonas Biundula Calycimonas Dolium Dylakosoma Notosolenus Pentamonas Petalomonas Scytomonas Tropidoscyphus Sphenomonadidae Sphenomonas Ploeotiida* Entosiphonidae Entosiphon Gaulosia Chelandium Olkasia Alistosa Ploeotiidae Ploeotia Serpenomonas Decastava Keelungia Lentomonas Karavia Hemiolia Liburna Spirocuta Anisonemia Anisonemida Anisonemidae Anisonema Dinema Heteronema Natomonadida Metanemina Neometanemidae Neometanema Aphagea Astasiidae Astasia Rhabdomonas Gyropaigne Menoidium Parmidium Distigma Peranemida Peranemidae Chasmostoma Jenningsia Peranema Teloprocta Urceolus Euglenophyceae Rapazida Rapazidae Rapaza Eutreptiales Eutreptiaceae Eutreptia Eutreptiella Euglenales Euglenaceae Colacium Cryptoglena Euglena Euglenaformis Euglenaria Monomorphina Strombomonas Trachelomonas Phacaceae Discoplastis Flexiglena Lepocinclis Phacus incertae sedis Ascoglena Euglenamorpha Euglenopsis Glenoclosterium Hegneria Klebsina Euglenocapsa incertae sedis Peranemopsis Tropidoscyphus Michajlowastasia Parastasiella Dinemula Paradinemula Mononema Ovicola Naupliicola Embryocola Copromonas Symbiontida Bihospites Calkinsia Postgaardi Glycomonada Diplonemea Diplonemidae Diplonema Rhynchopus Lacrimia Sulcionema Flectonema Hemistasiidae Hemistasia Eupelagonemidae Eupelagonema Kinetoplastea Prokinetoplastina Ichthyobodonidae Ichthyobodo Perkinsela Metakinetoplastina Allobodonidae Allobodo Novijibodo Neobodonida Neobodonidae Actuariola Avlakibodo Azumiobodo Cruzella Cryptaulaxella Klosteria Neobodo Phanerobia Rhynchobodo Rhynchomonadidae Rhynchomonas Dimastigella Parabodonida Cryptobiidae Cryptobia Jarrellia Procryptobia Trypanoplasma Parabodonidae Parabodo Eubodonida Bodonidae Bodo Trypanosomatida Trypanosomatinae Trypanosoma Leishmaniinae Borovskyia Crithidia Leptomonas Lotmaria Novymonas Porcisia Zelonia Endotrypanum Leishmania Herpetomonadinae Herpetomonas Lafontella Phytomonas Strigomonadinae Angomonas Kentomonas Strigomonas Blastocrithidiinae Blastocrithidia Obscuromonas Blechomonadinae Blechomonas Paratrypanosomatinae Paratrypanosoma Jaenimonas Vickermania Sergeia Wallacemonas Cercoplasma Malacozoomonas Nematodomonas Rhynchoidomonas incertae sedis Bordnamonas Cephalothamnium Rhynchoidomonas Heterolobosea Pharyngomonada Pharyngomonadea Pharyngomonadida Pharyngomonadidae Pharyngomonas Tetramitia Orodruinidae? Orodruina Gruberella Stachyamoeba Selenaionea Selenaionida Selenaionidae Selenaion Neovahlkampfiida Neovahlkampfiidae Neovahlkampfia Eutetramitea Euplaesiobystra Fumarolamoeba Heteramoeba Parafumarolamoeba Paravahlkampfia Oramoeba Vrihiamoeba Naegleriida Aurem Marinamoeba Acrasidae Acrasis Allovahlkampfia Pocheina Naegleriidae Naegleria Willaertia Trimastigamoeba? Tulamoebidae Pleurostomum Tulamoeba Vahlkampfiidae Tetramitus Vahlkampfia Pseudovahlkampfia? Tetramastigamoeba? Percolomonadida Barbeliidae Barbelia Nonamonas Lulaidae Lula Percolomonadidae Percolomonas Pseudociliatida Stephanopogonidae Stephanopogon Creneida Creneidae Creneis Lyromonadida Psalteriomonadidae Harpagon Psalteriomonas Monopylocystis Pseudoharpagon Sawyeria Lyromonas *paraphyletic or polyphyletic groups ?uncertain position

Taxon identifiers Phacus Wikidata: Q144584 Wikispecies: Phacus AlgaeBase: 43655 CoL: 6MBX EoL: 11710 EPPO: 1PHCUG GBIF: 5424921 iNaturalist: 200867 ITIS: 9766 NBN: NHMSYS0000605213 NCBI: 96783 NZOR: 7a09319b-6cbc-4990-aa0d-7fe30bb30601 WoRMS: 163339

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Adapted from the Wikipedia article [Phacus](https://en.wikipedia.org/wiki/Phacus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Phacus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.