Petalomonas is a genus of phagotrophic, flagellated euglenoids.Guiry, M. D.; Guiry, G. M. (2002). "Petalomonas F.Stein 1859". Retrieved February 10, 2019, from Phagotrophic euglenoids are one of the most important forms of flagellates in benthic aquatic systems, playing an important role in microbial food webs.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 The traits that distinguish this particular genus are highly variable, especially at higher taxa. However, general characteristics such as a rigid cell shape and single emergent flagellum can describe the species among this genus. This genus belongs to the Scytomonadidae family and the Petalomonadida order.
History of knowledge Petalomonas was first described by Dr. Friedrich Stein, a zoologist at the University of Prague, in 1859.Stein, F. (1859). Der Organismus der Infusionsthiere nach eigenen Forschungen in systematischer Reihenfolge bearb. von Friedrich Stein. doi:10.5962/bhl.title.3933
Habitat and ecology Petalomonas is a cosmopolitan genus, most abundant in fresh water with a few species observed in marine environments.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 These euglenoids mainly reside in muddy sediments as benthic organisms.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 The cells are phagotrophic, feeding on bacteria, and/or osmotophic, assimilating nutrients from its surroundings.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
Description These non-metabolic, colourless cells range in size from 8–45 um, with a general flattened, leaf-like shape. 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. A distinguishing feature of the euglenoids is the presence of proteinaceous pellicle strips that are underlined with microtubules.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 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. 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. Strong ribs or keels are also evident in these cells, which can be arranged spirally or relatively straight, ranging in width. 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. The cells also have an abundance of paramylon bodies, typically used for the storage of carbohydrates, that are observed in all species.
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.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 The cells within this genus are also defined by one emergent flagellum extending from a sub-apical opening, directed anteriorly when swimming. 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. These euglenoids have also been observed to glide forward using the body, while the flagellum is used to contact the substrate. The nucleus is located centrally to the left side of the cell.
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.
List of species
Petalomonas abscissa (Dujardin) Stein Petalomonas acuminata Hollande Petalomonas africana Bourrelly Petalomonas alata (A.C. Stokes) A.C. Stokes Petalomonas applanata Skuja Petalomonas arcuata Hollande Petalomonas asymmetrica Schawhan & Jahn Petalomonas bicarinata Shawhan & Jahn Petalomonas calycimonadoides Christen Petalomonas calycimonoides W.J.Lee & D.J.Patterson Petalomonas cantuscygni J.Cann & N.Pennick Petalomonas carinata A.C.Stokes Petalomonas christenii W.J.Lee & D.J.Patterson Petalomonas conchata Christen Petalomonas curvata Skuja Petalomonas dentata Christen Petalomonas dilatata Hollande Petalomonas dorsalis Stokes Petalomonas dubosqui Hollande Petalomonas excavata Skuja Petalomonas gibbera Christen Petalomonas gigas Skuja Petalomonas hyalina Christen Petalomonas inflexa G.A.Klebs Petalomonas intorta W.J.Lee & D.J.Patterson Petalomonas involuta Skuja Petalomonas irregularis Skuja Petalomonas iugosa W.J.Lee & D.J.Patterson Petalomonas kkongi Lee Petalomonas klebsii Christen Petalomonas klinostoma Skuja Petalomonas labrum W.J.Lee & D.J.Patterson Petalomonas larseni Lee & Lax Petalomonas lata Christen Petalomonas masanensis Lee Petalomonas mediocanellata F. Stein Petalomonas messikommeri Christen Petalomonas micra R.E.Norris Petalomonas minor Larson & D.J. Patterson Petalomonas minuta Hollande Petalomonas minutula Christen Petalomonas mira Awerinzew Petalomonas ornata Skvortzov Petalomonas ovata Skvortzov Petalomonas ovum Matvienko Petalomonas paludosa Christen Petalomonas pentacarinata Péterfi Petalomonas phacoides Skuja Petalomonas plana W.J.Lee & D.J.Patterson Petalomonas platyrhyncha Skuja Petalomonas pluteus Christen Petalomonas praegnans Skuja Petalomonas pringsheimii Christen Petalomonas prototheca Skuja Petalomonas punctato-striata Skuja Petalomonas pusilla Skuja Petalomonas quadrilineata Penard Petalomonas quinquecarinata Hollande Petalomonas quinquemarginata Shawhan & Jahn Petalomonas robusta Christen Petalomonas sampali Lee Petalomonas septemcarinata Shawhan & Jahn Petalomonas sexlobata Klebs Petalomonas simplex Christen Petalomonas sinica Skvortzov Petalomonas sinuata F.Stein Petalomonas sphagnicola Tschermak-Woess Petalomonas sphagnophila Christen Petalomonas spinifera (Lackey) W.J.Lee & D.J.Patterson Petalomonas splendens Hollande Petalomonas steinii Klebs Petalomonas stellata Skvortzov Petalomonas sulcata A.C.Stokes Petalomonas tenuis Christen Petalomonas triangula Z.X.Shi Petalomonas tricarinata Skuja Petalomonas triquetra Skvortzov Petalomonas variabilis Christen Petalomonas ventritracta Skuja Petalomonas virgata W.J.Lee & D.J.Patterson Petalomonas vulgaris Skuja Petalomonas wuhanica Z.Shi
References