Petalomonas

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Petalomonas
Petalomonas mediocannellata var disomata BSJ-2022.png
Petalomonas mediocannellata var. disomata. Scale bar: 10 μm.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Discoba
Phylum: Euglenozoa
Class: Euglenida
Order: Petalomonadida
Genus: Petalomonas
Stein, 1859
Type species
Petalomonas abcissa
(Dujardin, 1841) Stein, 1859 [1]

Petalomonas is a genus of phagotrophic, flagellated euglenoids. [2] Phagotrophic euglenoids are one of the most important forms of flagellates in benthic aquatic systems, playing an important role in microbial food webs. [3] The traits that distinguish this particular genus are highly variable, especially at higher taxa. [3] 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. [4]

Habitat and ecology

Petalomonas is a cosmopolitan genus, most abundant in fresh water with a few species observed in marine environments. [2] [5] These euglenoids mainly reside in muddy sediments as benthic organisms. [6] The cells are phagotrophic, feeding on bacteria, and/or osmotophic, assimilating nutrients from its surroundings. [2] [7]

Description

These non-metabolic, colourless cells range in size from 8–45 um, with a general flattened, leaf-like shape. [2] 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. [2] [5] A distinguishing feature of the euglenoids is the presence of proteinaceous pellicle strips that are underlined with microtubules. [8] 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. [8] 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. [6] Strong ribs or keels are also evident in these cells, which can be arranged spirally or relatively straight, ranging in width. [2] [5] 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. [5] The cells also have an abundance of paramylon bodies, typically used for the storage of carbohydrates, that are observed in all species. [2] [5]

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. [9] [6] The cells within this genus are also defined by one emergent flagellum extending from a sub-apical opening, directed anteriorly when swimming. [2] [8] [5] 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. [5] These euglenoids have also been observed to glide forward using the body, while the flagellum is used to contact the substrate. [8] [5] The nucleus is located centrally to the left side of the cell. [5]

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. [7]

List of species

References

  1. ↑ Kostygov, Alexei Y.; Karnkowska, Anna; Votýpka, Jan; Tashyreva, Daria; Maciszewski, Kacper; et al. (2021). "Euglenozoa: taxonomy, diversity and ecology, symbioses and viruses". Open Biology. 11 (3) 200407. doi:10.1098/rsob.200407. PMC   8061765 . PMID   33715388.
  2. 1 2 3 4 5 6 7 8 Guiry, M. D.; Guiry, G. M. (2002). "Petalomonas F.Stein 1859". Retrieved February 10, 2019, from
  3. 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
  4. ↑ Stein, F. (1859). Der Organismus der Infusionsthiere nach eigenen Forschungen in systematischer Reihenfolge bearb. von Friedrich Stein. doi:10.5962/bhl.title.3933
  5. 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
  6. 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
  7. 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
  8. 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
  9. ↑ 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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