Petalomonas

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Petalomonas
Scientific classification
Domain:
Eukaryota
Phylum:
Euglenozoa
Class:
Euglenophyceae
Order:
Petalomonadida
Family:
Scytomonadidae
Genus:
Petalomonas

F. Stein, 1859

Petalomonas is a genus of phagotrophic, flagellated euglenoids. [1] Phagotrophic euglenoids are one of the most important forms of flagellates in benthic aquatic systems, playing an important role in microbial food webs. [2] The traits that distinguish this particular genus are highly variable, especially at higher taxa. [2] However, general characteristics such as a rigid cell shape and single emergent flagellum can describe the species among this genus.

Contents

History of knowledge

Petalomonas was first described by Dr. Friedrich Stein, a zoologist at the University of Prague, in 1859. [3]

Habitat and ecology

Petalomonas is a cosmopolitan genus, most abundant in fresh water with a few species observed in marine environments. [1] [4] These euglenoids mainly reside in muddy sediments as benthic organisms. [5] The cells are phagotrophic, feeding on bacteria, and/or osmotophic, assimilating nutrients from its surroundings. [1] [6]

Description

These non-metabolic, colourless cells range in size from 8–45 um, with a general flattened, leaf-like shape. [1] The posterior end is rounded or truncate and the anterior end is narrowed; however, cells can span from ovoid, to fusiform or triangular, to elongately oval. [1] [4] A distinguishing feature of the euglenoids is the presence of proteinaceous pellicle strips that are underlined with microtubules. [7] In Petalomonas, cells are covered with approximately a dozen thickly, fused pellicle strips making the cell very rigid and possibly resistant to surface ice crystal formation that can disrupt the cell. [7] These pellicle strips, unlike most euglenoids, are lacking grooves or troughs; however, species specific pellicle features, such as pleat-like thickenings at the joints of pellicle strips, that characterize P. cantuscygni, can distinguish certain species. [5] Strong ribs or keels are also evident in these cells, which can be arranged spirally or relatively straight, ranging in width. [1] [4] Some species may contain furrows that vary in size and depth, and can be located dorsally and/or ventrally on the body of the cell. [4] The cells also have an abundance of paramylon bodies, typically used for the storage of starch, that are observed in all species. [1] [4]

The feeding structure, not visible under light microscopy, is relatively simple consisting of a pocket-like cavity ending with a cytostome, lined with microtubules for phagocytosis. [8] [5] The cells within this genus are also defined by one emergent flagellum extending from a sub-apical opening, directed anteriorly when swimming. [1] [7] [4] The movement of this flagellum is very minimal with some vibration at the tip; however, some species are observed to have vigorously, whipping flagellum that result in rapid rotation and oscillation of the cell body. [4] These euglenoids have also been observed to glide forward using the body, while the flagellum is used to contact the substrate. [7] [4] The nucleus is located centrally to the left side of the cell. [4]

Life history

In euglenoids, sexual reproduction is unknown; however, asexual reproduction has been observed to occur in this genus through longitudinal fission, where the division occurs very quickly, starting at the anterior end of the cell. [6]

List of species

Related Research Articles

<span class="mw-page-title-main">Euglenozoa</span> Phylum of protozoans

Euglenozoa are a large group of flagellate Discoba. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. Euglenozoa are represented by four major groups, i.e., Kinetoplastea, Diplonemea, Euglenida, and Symbiontida. Euglenozoa are unicellular, mostly around 15–40 μm (0.00059–0.00157 in) in size, although some euglenids get up to 500 μm (0.020 in) long.

<i>Euglena</i> Genus of unicellular flagellate eukaryotes

Euglena is a genus of single cell flagellate eukaryotes. It is the best known and most widely studied member of the class Euglenoidea, a diverse group containing some 54 genera and at least 200 species. Species of Euglena are found in fresh water and salt water. They are often abundant in quiet inland waters where they may bloom in numbers sufficient to color the surface of ponds and ditches green (E. viridis) or red (E. sanguinea).

<span class="mw-page-title-main">Euglenid</span> Class of protozoans

Euglenids or euglenoids are one of the best-known groups of flagellates. They are excavate eukaryotes of the phylum Euglenophyta, classified as class Euglenida or Euglenoidea. Euglenids are commonly found in freshwater, especially when it is rich in organic materials, with a few marine and endosymbiotic members. Many euglenids feed by phagocytosis, or strictly by diffusion. A monophyletic group known as Euglenophyceae have chloroplasts and produce their own food through photosynthesis. This group is known to contain the carbohydrate paramylon.

<i>Trachelomonas</i> Genus of euglenoids

Trachelomonas is a genus of swimming, free-living euglenoids characterized by the presence of a shell-like covering called a lorica. Details of lorica structure determine the classification of distinct species in the genus. The lorica can exist in spherical, elliptical, cylindrical, and pyriform (pear-shaped) forms. The lorica surface can be smooth, punctuate or striate and range from hyaline, to yellow, or brown. These colors are due to the accumulation of ferric hydroxide and manganic oxide deposited with the mucilage and minerals that comprise the lorica. In Trachelomonas, the presence of a lorica obscures cytoplasmic details of the underlying cell. In each Trachelomonas cell, there is a gap at the apex of the lorica from which the flagellum protrudes. Thickening around this gap results in a rim-like or collar-like appearance. During asexual reproduction, the nucleus divides yielding two daughter cells one of which exits through the opening in the lorica. This new cell then synthesizes its own new lorica.

<span class="mw-page-title-main">Euglenaceae</span> Family of flagellate eukaryotes

Euglenaceae is a family of flagellates in the phylum Euglenozoa. The family includes the most well-known euglenoid genus, Euglena.

<i>Colpodella</i> Genus of single-celled organisms

Colpodella is a genus of alveolates comprising 5 species, and two further possible species: They share all the synapomorphies of apicomplexans, but are free-living, rather than parasitic. Many members of this genus were previously assigned to a different genus - Spiromonas.

<i>Phacus</i> Genus of algae

Phacus is a genus of unicellular excavates, of the phylum Euglenozoa, characterized by its flat, leaf-shaped structure, and rigid 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.

<i>Peranema</i> Genus of protozoans

Peranema is a genus of free-living phagotrophic euglenids. There are more than 20 nominal species, varying in size between 8 and 200 micrometers. Peranema cells are gliding flagellates found in freshwater lakes, ponds and ditches, and are often abundant at the bottom of stagnant pools rich in decaying organic material. Although they belong to the class Euglenoidea, and are morphologically similar to the green Euglena, Peranema have no chloroplasts, and do not conduct autotrophy. Instead, they capture live prey, such as yeast, bacteria and other flagellates, consuming them with the help of a rigid feeding apparatus called a "rod-organ." Unlike the green euglenids, they lack both an eyespot (stigma), and the paraflagellar body (photoreceptor) that is normally coupled with that organelle. However, while Peranema lack a localized photoreceptor, they do possess the light-sensitive protein rhodopsin, and respond to changes in light with a characteristic "curling behaviour."

<span class="mw-page-title-main">Diplonemidae</span> Family of protozoans

Diplonemidae is a family of biflagellated unicellular protists that may be among the more diverse and common groups of planktonic organisms in the ocean. Although this family is currently made up of three named genera; Diplonema, Rhynchopus, and Hemistasia, there likely exist thousands of still unnamed genera. Organisms are generally colourless and oblong in shape, with two flagella emerging from a subapical pocket. They possess a large mitochondrial genome composed of fragmented linear DNA. These non-coding sequences must be massively trans-spliced, making it one of the most complicated post-transcriptional editing process known to eukaryotes.

Heteronema is a genus of phagotrophic, flagellated euglenoids that are most widely distributed in fresh water environments. This genus consists of two very distinguishable morphogroups that are phylogenetically closely related. These morphogroups are deciphered based on shape, locomotion and other ultrastructural traits. However, this genus does impose taxonomic problems due to the varying historical descriptions of Heteronema species and its similarity to the genus Paranema. The species H. exaratum, was the first heteronemid with a skidding motion to be sequenced, which led to the discovery that it was not closely related to H. scaphrum, contrary to what was previously assumed, but instead to a sister group of primary osmotrophs. This suggests that skidding heteronemids can also be distinguished phylogenetically, being more closely related to Anisoma, Dinema and Aphageae, than to other species within Heteronema.

Colponema is a genus of single-celled flagellates that feed on eukaryotes in aquatic environments and soil. The genus contains 6 known species and has not been thoroughly studied. Colponema has two flagella which originate just below the anterior end of the cell. One extends forwards and the other runs through a deep groove in the surface and extends backwards. Colponema is a predator that feeds on smaller flagellates using its ventral groove. Like many other alveolates, they possess trichocysts, tubular mitochondrial cristae, and alveoli. It has been recently proposed that Colponema may be the sister group to all other alveolates. The genus could help us understand the origin of alveolates and shed light on features that are ancestral to all eukaryotes.

Postgaardia is a proposed basal clade of flagellate Euglenozoa, following Thomas Cavalier-Smith. As of April 2023, the Interim Register of Marine and Nonmarine Genera treats the group as a subphylum. A 2021 review of Euglenozoa places Cavalier-Smith's proposed members of Postgaardia in the class Symbiontida. As Euglenozoans may be basal eukaryotes, the Postgaardia may be key to studying the evolution of Eukaryotes, including the incorporation of eukaryotic traits such as the incorporation of alphaproteobacterial mitochondrial endosymbionts.

Dinema, synonym Dinematomonas, is a genus of flagellated algae in the phylum Euglenozoa.

<i>Urceolus</i> Genus of flagellates

Urceolus is a genus of heterotrophic flagellates belonging to the Euglenozoa, a phylum of single-celled eukaryotes or protists. Described by Russian biologist Konstantin Mereschkowsky in 1877, its type species is Urceolus alenizini. Species of this genus are characterized by deformable flask-shaped cells that exhibit at least one flagellum that is active at the tip, arising from a neck-like structure that also hosts the feeding apparatus. They are found in a variety of water body sediments across the globe. According to evolutionary studies, Urceolus belongs to a group of Euglenozoa known as peranemids, closely related to the euglenophyte algae.

<i>Urceolus cyclostomus</i> Species of flagellate

Urceolus cyclostomus is a species of heterotrophic flagellates. It was initially described by Friedrich Stein in 1878 as Phialonema cyclostomum, from an unknown location. Due to its morphological similarities to Urceolus alenizini, the author of the latter, Konstantin Mereschkowsky, transferred it to the genus Urceolus in 1881. Like other species of the genus, its cells have a neck and a wide aperture to a canal that hosts a single flagellum and its feeding apparatus. It is distinguished from other species by a significantly more rigid cell shape, among other traits. It can be found in the bottom sediment of freshwater and brackish water bodies, as a consumer of algae.

<span class="mw-page-title-main">Peranemid</span> Group of flagellates

The peranemids are a group of phagotrophic flagellates, single-celled eukaryotes or protists. They belong to the Euglenida, a diverse lineage of flagellates that contains the closely related euglenophyte algae. Like these algae, peranemids have flexible cells capable of deformation or metaboly, and have one or two flagella in the anterior region of the cell. They are classified as family Peranemidae (ICZN) or Peranemataceae (ICBN) within the monotypic order Peranemida (ICZN) or Peranematales (ICBN).

<span class="mw-page-title-main">Anisonemia</span> Group of flagellates

Anisonemia is a clade of single-celled protists belonging to the phylum Euglenozoa, relatives of the Euglenophyceae algae. They are flagellates, with two flagella for locomotion. Anisonemia includes various phagotrophic species and a group of primary osmotrophic protists known as Aphagea.

Urceolus cornutus is a species of heterotrophic flagellates present in marine environments. Described in 1990 by Jacob Larsen and David Patterson from sediment samples off the coast of Fiji, it is distinguished from other species by very fine and compact pellicle stripes that follow an S-helix shape, and a collar with a regular or symmetrical outline.

<i>Rapaza</i> Monospecific genus of predatory algae

Rapaza viridis is a species of single-celled flagellate within the Euglenophyceae, a group of algae. It is the only species within the genus Rapaza, family Rapazidae and order Rapazida. It was discovered in a tide pool in British Columbia and described in 2012.

Neometanema is a genus of phagotrophic flagellates belonging to the Euglenida, a diverse group of flagellates in the phylum Euglenozoa. It is the sole genus within the monotypic family Neometanemidae and suborder Metanemina. It composes the order Natomonadida together with a closely related clade of osmotrophs known as Aphagea.

References

  1. 1 2 3 4 5 6 7 8 Guiry, M. D.; Guiry, G. M. (2002). “Petalomonas F.Stein 1859”. Retrieved February 10, 2019, from
  2. 1 2 Lax, G.; Simpson, A. G. (2013). “Combining Molecular Data with Classical Morphology for Uncultured Phagotrophic Euglenids (Excavata): A Single-Cell Approach”. Journal of Eukaryotic Microbiology. 60 (6): 615-625. doi:10.1111/jeu.12068
  3. ↑ Stein, F. (1859). Der Organismus der Infusionsthiere nach eigenen Forschungen in systematischer Reihenfolge bearb. von Friedrich Stein. doi:10.5962/bhl.title.3933
  4. 1 2 3 4 5 6 7 8 9 Shawhan, F. M.; Jahn, T. L. (1947). “A Survey of the Genus Petalomonas Stein (Protozoa: Euglenida)”. Transactions of the American Microscopical Society. 66 (2): 182. doi:10.2307/3223249
  5. 1 2 3 Cavalier-Smith, Thomas; Chao, Ema E.; Vickerman, Keith (2016). “New phagotrophic euglenoid species (new genus Decastava; Scytomonas saepesedens; Entosiphon oblongum), Hsp90 introns, and putative euglenoid Hsp90 pre-mRNA insertional editing”. European Journal of Protistology. 56: 147-170. doi:10.1016/j.ejop.2016.08.002
  6. 1 2 Esson, H. J.; Leander, B. S. (2006). “A model for the morphogenesis of strip reduction patterns in phototrophic euglenids: Evidence for heterochrony in pellicle evolution”. Evolution Development, 8 (4): 378-388. doi:10.1111/j.1525-142x.2006.00110.x
  7. 1 2 3 4 Larsen, Jacob; Patterson, David J. (1990). "Some flagellates (Protista) from tropical marine sediments”. Journal of Natural History, 24 (4): 801-937. doi:10.1080/00222939000770571
  8. ↑ Breglia, Susana A.; Yubuki, N.; Leander, Brian S. (2013). “Ultrastructure and Molecular Phylogenetic Position of Heteronema scaphurum: A Eukaryovorous Euglenid with a Cytoproct”. Journal of Eukaryotic Microbiology. 2: 107-120. doi: 10.1111/jeu.12014
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