Favoritos de mnold1

A muranotrich anaerobe, Murathrix cf felix, from the medium coarse sand of the superficial intertidal benthos of estuary Acabonac Harbor at Louse Point launching ramp. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+. I previously showed Muranthrix gubernata, the type species of the genus (https://www.inaturalist.org/observations/142244375). The cells of the current observation measure 103 um in length. Without silver staining I cannot count adoral membranelles however the number of macronuclear nodules in the Louse Point launching ramp population is 8 which is the second major character and is consistent with M. cf felix (Daniel Méndez-Sánchez, personal communication). "Muranothrix felix sp. nov. can be easily distinguished from M. gubernata by having fewer adoral membranelles (26–33 vs. 40–56) and macronuclear nodules (6–14 vs. 15–33; Rotterová et al., 2020" (1). However it must be said that "Muranotrichean diversity in brackish and marine anoxic habitats is likely much greater than current reports would suggest" (1).

"The recently erected class Muranotrichea currently comprises two monotypic genera of anaerobic ciliates (respective type species Muranothrix gubernata and Thigmothrix strigosa), inhabiting anoxic marine or brackish environments, characterized by slender cells with a rightward-spiraling anterior neck region, and invariably coated with prokaryotic ectosymbionts (Rotterová et al., 2020)"(1,2).

Méndez-Sánchez et al 2023 describe the new species as follows: "Cells 80–140×14–21 μm in vivo. Cells elongated, narrowly the postoral body part broadly ellipsoidal, “pin-shape”. Slender anterior neck region spiralized rightward approximately 360°. Cortex flexible, with longitudinal furrows. Surface of the cortex coated with rod-shaped bacteria (ca. 2 μm long) oriented transversely between ciliary rows. Cytoplasm with sparse globular inclusions up to 5 μm in diameter, food vacuoles contain prokaryotes, diatom frustules. Contractile vacuole terminal. Macronuclei comprise 6–14 spherical to ellipsoidal nodules (about 10 μm), each with several nucleoli, clustered in mid-body region, one single spherical micronucleus (ca. 2.7 μm in diameter) among macronuclear nodules. Swims rapidly, intermittently reverses course. Somatic ciliature composed of ordinarily spaced dikinetids, only anterior basal body ciliated, cilia about 10 μm long, arranged in 10–12 narrowly spaced somatic kineties, lying on more or less straight longitudinal furrows. Bristle-like somatic cilia (ca. 10μm long) interspersed at regular intervals along kineties and perpendicularly oriented to body margin. Caudal cilia intermittently converge in an inverted cone arrangement surrounding stiffened much longer (34–65μm) coherent caudal cilia. Peristome elongated, inverted keyhole shaped, spiralizes around anterior neck region. Buccal cavity more or less equatorial. Buccal ciliature comprises long paroral membrane parallel to adoral zone of membranelles, both spiralize rightward about 360° extending almost to anterior end of cell. Adoral zone extends from buccal cavity to terminate subapically, comprises 26–33 membranelles, all of similar size (ca. 5 μm long). Paroral membrane long reverse J-shape, originates on left posterior wall of buccal cavity, borders its posterior margin, and extends anteriorly in peristome, occupies about 90% of adoral zone length, bears long cilia (about 15 μm) resembling a “velum” or “sail” (1).

1. Morphology and phylogenetic position of three anaerobic ciliates from the classes Odontostomatea and Muranotrichea (Ciliophora). Daniel Méndez-Sánchez, Ondřej Pomahač, Johana Rotterová, William A. Bourland and Ivan Čepička. J. Eukaryot. Microbiol. 2023;00:e12965. https://doi.org/10.1111/jeu.12965
2. Rotterová, J., Salomaki, E., Pánek, T., Bourland, W.A., Žihala, D., Táborský, P. et al. (2020) Genomics of new ciliate lineages provides insight into the evolution of obligate anaerobiosis. Current Biology, 30, 1–14.

Metromonas simplex (Griessmann, 1913) Larsen & Patterson, 1990 thriving in a six week old sample of medium coarse sand from the superficial intertidal benthos of marine estuary Acabonac Harbor at Louse Point launching ramp. The swinging spermatozooa-like flagellates which measure about 4 um and attach to the slide by a single flagellum. Some are yellow while others are not. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone cropping on Samsung Galaxy S9+.Thanks to Kristina Prokina for identifying as Metromonas.

From: J. Ekebom, David J. Patterson, and N. Vors; Heterotrophic Flagellates from Coral Reef Sediments (Great Barrier Reef, Australia). Arch.Protistenkd. 146:251-272, 1995/96

Metromonas Larsen & Patterson, 1990 Free-living heterotrophic flagellates.
Metromonas simplex (Griessmann, 1913) Larsen & Patterson, 1990 (ref. ID; 4872 Protista Incertae sedis)
Cell obovate or tapering markedly to posterior (flagellated) end. Dorso-ventrally flattened, pellicle smooth or with small infrequent pustules (protrusions). Usually with open flagellum but occasionally with two flagella of unequal length arising from the posterior part. The dominant flagellum is twice as long as the cell or longer, and ends in a hook that is attached to substrate. The second flagellum when present emerges next to the first but can be difficult to see. The behaviour of the cell resembles a pendulum swinging with an arc of up to 110 degrees. Inflexion point at the attaching flagellum immediately above the hook. Cells normally attach to the substrate but may detach and glide with the cell body held up from the surface in an angle and the longer flagellum trailing along the surface. Gliding cell shake lightly from side to side. (ref. ID; 4872)
Food ingestion takes place at the margins of cell (Patterson unpubl.) or through the anterior part of the cell (Griessmann 1913) but no mouth is visible. This species usually appears in large numbers after sediments have been kept for several days. This is consistent with their predatory nature. They may ingest other flagellates (Patterson, unpubl. obs).
Measurements
Cell length 6.1 um, range 4-8.2 um. Size range 4-8 um reported by Larsen & Patterson (1990), Vors (1922).

David Patterson remarks on my observation: That little flagellate is Metromonas (named after a metronome). I am very fond of the attached photo of it. It is a predator. Not part of any familiar group of flagellates, related to many others with tubular mitochondrial cristae. Myl’nikov, A.A., Prokina, K.I. & Myl’nikov, A.P. Cell Structure of Predatory Flagellate Metromonas grandis Larsen et Patterson (Cercozoa). Inland Water Biol 13, 163–169 (2020). https://doi.org/10.1134/S1995082920020091

From :
Small Free-Living Heterotrophic Flagellates from Marine Sediments
of Gippsland Basin, South-Eastern Australia. Won Je LEE. Acta Protozool. (2015) 54: 53–76

Metromonas simplex (Griessmann 1913) Larsen and Patterson 1990
Cell outline is obovate. Cells are 3.5 -7 µm long and dorsoventrally flattened, and have smooth pellicle. Two flagella of very unequal length arise from the posterior part of the cell. The major flagellum is 1.5 to 3.0 times the cell length, the shorter flagellum is inactive and about 1 µm long, and inserts to the right of the major flagellum. It may be difficult to see. The cells normally attach to the substratum with the long flagellum and swing from side to side like a pendulum and the cells may also glide with the cell body in front of the flagellum.

This species was found in various marine sites in the world and cell lengths from 3 to 9 µm were reported (Griessmann 1913; Larsen and Patterson 1990; Vørs 1992a, b, 1993a; Ekebom et al. 1996; Patterson and Simpson 1996; Tong 1997b; Tong et al.1997, 1998; Lee and Patterson 2000; Al-Qassab et al.2002; Lee 2006b; Aydin and Lee 2012).

Metromonas grandis was reported from marine sites in Australia, Brazil, Fiji, Hawaii and Turkey
(Aegean Sea), cell length reported was 5 to 12 µm (Larsen and Patterson 1990; Tong et al. 1998; Lee and Patterson 2000; Al-Qassab et al. 2002; Lee 2002b,
2006b; Aydin and Lee 2012). M. grandis is distinguished from M. simplex by its cell shape, slightly larger size and folded margin. The cell shape and folded margin may
be good diagnostic characters for this species. This species usually co-occurs with M. simplex. According to Lee (2002b), Skvortzov (1957) reported 9 new Ancyromonas species with one long flagellum, but these species may be gliding stages of Metromonas. The short flagellum in Metromonas is easy to overlook.

Euastrum affine Ralfs 103 um. From the acidic spring-fed freshwater pond Chatfield's Hole situated in a white pine forest. Imaged in Nomarski DIC on Olympus BH2 using SPlan 20x objective plus variable phone camera cropping on Samsung Galaxy S9+.

EUASTAUM AFFINE Ralfs, SemiceIls 3.lobed, but with a small lateral intermediate lobule; the polar lobe swollen and anvil-shaped, the lateral angles broadly rounded, the apical margin convex and with a deep median notch; lateral margins of the polar lobe converging and then extended laterally to form the shoulder-like intermediate lobule, then deeply emarginate to the lower basal lobes which are slightly bilobed, the lower angles broadly rounded; the sinus narrowly linear, slightly dilated at the extremities; vertical view elliptic, the poles broadly rounded and slightly extended, with four swollen undulations on either side; side view of the semicell rectangular, the pole truncate and the angles broadly rounded, lateral margins sub-parallel and forming a "neck," the lower part of the semi-cell enlarged with two low swellings on either side; the face of the semicell showing a swelling within the basal lateral lobes and with four in the mid. region, two just above the isthmus and two larger ones just above these; the wall coarsely punctate and with a central mucilage pore; L. 114 um, W. 63 um isthmus 19 um, thickness 29 um.

The Fresh-Water Algae of Southern United States III, The Desmid Genus Euastrum, with Descriptions of Some New Varieties
Gerald W. Prescott and Arthur M. Scott
The American Midland Naturalist
Vol. 34, No. 1 (Jul., 1945), pp. 231-257

Closterium species from the acidic freshwater spring-fed pond Chatfield's Hole. 356 um

Discussion adapted from: https://fmp.conncoll.edu/Silicasecchidisk/LucidKeys3.5/Keys_v3.5/Carolina35_Key/Media/Html/Closterium_Main.html

Closterium is a genus of unicellular charophyte green algae in the family Closteriaceae. Closterium cells are crescent-shaped or elongate and lack spines. Some are quite straight and needle-like, while others are much broader with curved ends. The ends of the cell are usually tapered and may be pointed or rounded. Each semicell has a single axial, ridged chloroplast with at least one pyrenoid. Occasionally there are two chloroplasts per semicell. The nucleus is located in the center of the cell between the chloroplasts.

Terminal vacuoles at the cell tips hold vibrating crystals of barium or calcium sulfate, the function of which are unknown. Brownian motion causes these microscopic particles to move erratically due to the impacts of collisions with the surrounding liquid molecules in which they are suspended.

Approximately 140 species of Closterium have been described, with 88 found in North America. Closterium is most common in the benthic or periphytic communities of acidic, oligotropic lakes and ponds. However, some species also inhabit alkaline, eutrophic environments. Closterium aciculare and Closterium acutum are often found among cyanobacterial blooms. They sometimes form bloom conditions themselves and indicate eutrophic waters.

At low light concentrations, Closterium may utilize glucose through mitochondrial respiration. At high irradiance levels, glucose is utilized via chlororespiration, a form of respiration within the chloroplast.

Conjugation may occur between both morphologically mature cells and recently-divided immature cells. A conjugation tube is not usually present. Both cells split open at the middle to allow the gametes to move and fuse inside the empty walls. Some species may form spores.

Imaged in Nomarski DIC on Olympus BH2 using SPlan 20x and 40 x objectives plus variable phone cropping on Samsung Galaxy S9+.

Water sample (freshwater) was taken on 2023-04-29 using a turkey baster.

Extended Length: 750µm.
Extended Width: 40µm.
Extended L/W: 19.

Peristome about 45% of the body length.
CV about 28% of body length.
Macronucleus does appear to be moniliform (I think).

The strombidiid species Omegastrombidium elegans (Florentin, 1901) Agatha, 2004 from the superficial intertidal benthos of marine estuary Acabonac Harbor at Louse Point launching ramp. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone cropping on Samsung Galaxy S9+. The cell measures 65 um in length. The cell shape and size, macronucleus, and particularly the ridge-like pad on the right side are characteristic of S. elegans.

Strombidium elegans Florentin, 1899 or 1901
Descriptions
The yellow coloured body is obovoid in form with a projected apical collar. A cytoplasmic pad-like protuberance and a transparent thin plate are attached at the left and right side, respectively. Membranelles of adoral zone are pinnate at their anterior extremities. Trichites in a band are present on the dorsal side which runs from the right side, transversely to the left side and extends laterally to the posterior extremity. The macronucleus is round according to Florentin (1901), but Kahl (1932) described it as ellipsoid. It is very active and feeds on diatoms and green algae. A marine species. Size, 40-60 um.

From Song et al 2021:
Genus Omegastrombidium (Agatha, 2004)

Diagnosis: Girdle kinety horizontally oriented on dorsal side, extending to posterior end of body on ventral side (Agatha, 2004).

Type species: Omegastrombidium elegans (Florentin, 1901; Agatha, 2004)

Florentin (1901) described this species under the name Strombidium elegans. Song et al. (2000) provided a redescription and revealed its ciliary pattern for the first time. Based on the girdle kinety performing a “Ω” shape, Agatha (2004) established the genus Omegastrombidium and designated O. elegans the type species.

1. Overview of the Diversity, Phylogeny and Biogeography of Strombidiid Oligotrich Ciliates (Protista, Ciliophora), With a Brief Revision and a Key to the Known Genera. Wen Song, Dapeng Xu, Xiao Chen, Alan Warren, Mann Kyoon Shin, Weibo Song and Lifang Li1. Front. Microbiol., 16 September 2021. Sec. Aquatic Microbiology Volume 12 - 2021 https://doi.org/10.3389/fmicb.2021.700940

Acineta compressa Claparede and Lachmann, 1859 found attached to filamentous algae from the shoreline of marine estuary Gardiner's Bay. Average width in 95 um. Imaged in Nomarski DIC on Olympus BH2 using mainly SPlan 20x sometimes 40x objectives plus variable phone camera cropping on Samsung Galaxy S9+.

"Acineta compressa Claparede and Lachmann, 1859 syn Cothurnia havniensis Ehrenberg, 1838 Paracinetapatula Wailes, 1943 Medium (60-130 um long), marine, loricate species that is oval to conical in outline, usually as broad or broader than deep, strongly flattened laterally. There are two anterior-lateral actinophores each bearing a fascicle of capitate tentacles. Stalk long, 100-250 um, which joins the lorica via a definite collar-like region; collar widens to at least twice stalk width. Found attached to marine algae. Spherical macronucleus and a single contractile vacuole. NOTE. Collin (1912) considered Acineta papillifera Keppen, 1888 to be a synonym of this species. Kahl (1934) disagreed and reinstated A. papillifera whose stalk collar has a more complicated structure than A. compressa" (1).

"The papilla is located between the stem and the shell. Euryhaline view. Shell length 100- 120 microns, width 60-76, length of stalk 150-215, diameter 4-6, diameter of basodisk 8-12, macronucleus 18-22, length of tentacles 60-120, diameter of contractile vacuole 10-20... Acineta compressa " (2)

FAMILY ACINETIDAE EHRENBERG, 1838 = Cryptophryidae Jankowski, 1978 syn. n. Suctorians with a laterally flattened, trapezium-like, triangular or (rarely) disc-like body. Tentacles are arranged in two, rarely three fascicles or rows. As a rule actinophores are present. The macronucleus is ovoid or ribbon-like, never ramified. The presence of the stalk and all types of the lorica is characteristic of the family. Swarmers ovoid with longitudinal kineties. Habitat. Commensals of marine and freshwater invertebrates and plants, as well as periphytic forms.

1. A revision of the Suctoria (Ciliophora, Kinetofragminophora) 1. Acineta and its morphological relatives. Colin R. Curds. Bull. Br. Mus Nat. Hist. (Zool.) 1985 48(2): 75-129
2. Keys for identification of tentaculous infusoria (Ciliophora, Suctoria) of the Ukrainian fauna. January 1996Vestnik Zoologii 2:1-42. Igor Dovgal

Diophrys scutum Dujardin 1841 from the superficial intertidal benthos of marine estuary Acabonac Harbor at Louse Point launching ramp. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective4 plus variable camera phone cropping on Samsung Galaxy S9+. The cell measures 130 um in length. The size and the conspicuous concavity at posterior right edge of the cell point to D. scutum.

Diophrys-like spirotrich ciliates are commonly found worldwide in marine and estuarine biotopes, especially sandy beaches and salt marshes. Members of the genus Diophrys are characterized by having a prominent right posterior-lateral concavity where the sickle-shaped caudal cirri are located. This genus is important of benthic communities in estuarine and tidal marshes. Both benthic and planktonic Diophrys populations are found in marine and estuarine habitats. There are no freshwater representatives. The Diophrys cell is more or less the shape of a bar of soap. Its elongated oval body has relatively parallel sides, has a flattened, circular appearance in cross-section and has a smooth arched dorsal surface with little sculpturing.

"The Diophrys-complex is a common group of order Euplotida and belongs to the most morphologically complex class in Spirotrichea. These species have dominant oral field and strong cirri on ventral side, and generally exist in marine and estuarine biotopes (Song et al., 2007, 2009a; Lynn, 2008; Hu et al., 2019). In the past 40 years, this complex group was clarified many times and include six genera now. For example, Jankowski (1979) divided it into Diophrys and Paradiophrys; Hill and Borror (1992) established the third genus, Diophryopsis; Jankowski (2007) reassigned these three genera in Diophryinae. Hereafter, three more genera, Apodiophrys, Heterodiophrys and Pseudodiophrys, have been reported and added to this subfa mily (Jiang and Song, 2010; Jiang et al., 2011). Subsequently, Huang et al. (2012) and Fan et al. (2013) revealed some opinions based on molecular and morphogenetic characters, and some of them did not completely support the classification of the subfamily, i.e., Paradiophrys and Apodiophrys were not included in this group. After several revisions and divestitures, several species have been removed from the genus Diophrys. The remaining species are mainly characterized by the combined fea tures, namely three caudal cirri located in a prominent pos terior concave area, oral area with prominent adoral zone of membranelles and distinct paroral and endoral membranes, ventral side arranged with five frontal, two ventral, five transverse, and one or two left marginal cirri. So far, only ten species still remain in genus Diophrys" (2).

Ciliary components of the ventral surface are the AZM, frontoventral cirri, endoral and paroral membranes, transverse and caudal cirri. The AZM extends from the cytostome along two-thirds of the left side, arching at the anterior end to the dorsal surface and back toward the ventral surface extending one-fourth of the way down the right side of the cell. The AZM is composed of both anterior and buccal membranelles. Two undulating membranes lie to the right of the AZM. The one topographically nearest to the AZM is the endoral membrane; the other is the paroral membrane. The membranes extend anteriorly from the cytostome along the edge of the right buccal overture.

"General morphology: size in vivo 125-225 x 75 -140 pm, mostly 180 x 120 pm. Length/width ratio about 1.5/1. The largest species of Diophrys. Body slenderly ovoid form with a collar, cell conspicuously rigid. Concavity at posterior right edge conspicuous. Thick and wide longitudinal ridge along lower buccal cavity on ventral side. Cytoplasm colourless, dark gray coloured cytoplasmic inclusion at low magnification. CV located near CC. Frontal and buccal field: FVC seven in number and about 25 pm long in vivo, arranged in two distinct cirral groups; five cirri at anterior part, and rest two cirri situated at mid-ventral surface and upper TC. Buccal field large and prominent, extending over about 44-76% of body length. AZM extending to middle of right border of body. AZM wide with membrane up to 102 pm and with 58-75 (average 66) AMs; about 20-26 membranelles in distal part of AZM, arching at anterior end to dorsal surface and back toward ventral surface, proximal part of AZM on ventral side composed of approximately 32-40 membranelles along left margin of buccal cavity. Undulating membrane composed of endoraal membrane and paroral membrane. PM long, prominently curved around mid-portion, extending to anterior end of buccal area. EM about 2/3 of PM length, originated from proximal end of AZM. PM and EM divergent from 1/3 portion of PM" (1).

"Somatic infraciliature: ventral side ciliary pattern aligned in typical Diophrys. Five TC, about 5011m long and prominent. Usually two relatively weak LMC positioned posterior to the level of TC, aligned transversely, two LMC conspicuously well separated. Three CC on dorsal surface of right posterior margin, prominent and about 30-40 pm long. Dorsal surface bearing 5-6 DKs and about 7 gm long in marginal DB. Nuclear appearance: two irregular, slender and long Ma nodules, about 60-85 x 10 um. Small nucleoli scattered within Ma. Mi small, 2.5 um in diameter, located close to each Ma nodule, repectively. Locomotion: Behavior and movement gliding on substrate and benthic. Crawling on substrate with jumps. Distribution. America, Antarctic, Europe. Middle Asia, China, Japan and Korea" (1).

1. Redescriptions of Diophrys appendiculata and D. scutum (Ciliophora: Spirotrichea: Uronychiidae) New to Korea. Choon-Bong Kwon, Eun-Sun Lee, Mann Kyoon Shin.
   Kor. J. Syst. Zool. Animal Systematics Evolution and Diversity July 2008 24(2). DOI: 10.5635/KJSZ.2008.24.2.191. https://www.researchgate.net/publication/264176803

2. The Morphology and Phylogeny of Three Diophrys Ciliates Collected from the Subtropical Waters of China, Including a New Species (Ciliophora; Euplotia).
   ZHANG Chaojian, HUANG Jie, YE Tingting, LU Borong, and CHEN Xiangrui. Journal of Ocean University of China 2020, Vol. 19 Issue (4): 975-987. http://qdhb.cbpt.cnki.net/WKD/WebPublication/index.aspx?mid=qdhy

My sample from the shoreline benthos of marine estuary Shinnecock Bay included some broad leafed algae that were attatched to rocks and the bottom sand. This rotted after four or five days giving rise to a dense fetid smelling bacterial biofilm that supported thriving but ephemeral populations of several organisms: flagellates of the type Carpediemonas-like organisms (CLO), philasterine scuticociliates which I suspect are a species of Metanophrys, and a medium sized hypotrich. The first two are waning while the hypotrich is now quite abundant and predominant. Also appearing at this stage is an interesting suctorian. The body measures 75 um across and is variably acinetoform having a short bell-shaped to inverted triangular configuration with two actinophores present, often well developed but may be reduced in some specimens, each bearing a fascicle of capitate tentacles. No lorica is present giving the impression of a recently begun disseminating swarm of the organism. In fact, single swarmer embryos were noted taking the form of oval buds with 5 oblique ciliary rows. The buds were sometimes observed swimming within the partially hollowed out body of its parent, seemingly consuming its contents.

Given that this is from a marine habitat, from shallow shoreline waters with included alga, and the size and shape of the suctorian forms, I believe this is a developing community of immature swarming and settling Acineta tuberosa or perhaps more appropriately the synonym Acineta foetida (given the foul-smelling character of the biofilm) which is well known to be attached to alga and inanimate surfaces. The oval buds with 5 oblique ciliary rows is also quite characteristic of A. tuberosa (A. foetida). You can see sometimes early maturing buds that have lost their cilia and have developed a few tentacles in two clusters as yet without development of the actinophores.

Imaged in Nomarski DIC on Olympus BH2 using SPlan 100x oil immersion objective plus variable camera phone cropping on Samsung Galaxy S9+.

Curds 1885 considers A. foetidus to be a junior synonym of A. tuberosa (1) while Dovgal 1996 (2) treats A. foetidus as a separate species. Bruce Taylor writes: "Dovgal's scheme supercedes that of Curds, in work published in the last two decades. Some online databases, like CoL and GBIF, still have A. foetida as a synonym of A. tuberosa, but WoRMS accepts the species".

From Curds 1885:
Acineta tuberosa Ehrenberg, 1833
syn.

Brachionus tuberosus Pallas, 1766
Vorticella tuberosa Miller, 1786
Volverella astoma Bory, 1825
Podophrya poculum Allman, 1875 nomen nudum
Acineta poculum Hertwig, 1875
Acineta foetida Maupas, 1881
Acineta aequalis Stokes, 1891
Acineta corrugata Stokes, 1894
Acineta sp. Prowasek, 1900
Acineta tuberosa var.fraiponti Sand, 1901
Acineta tuberosa var. foetida Collin, 1912
Acineta tuberosa f. brevipes Collin, 1912
Acineta laomedeae Precht, 1935
Tokophrya species Precht, 1935
Acineta brevicaulis Rieder, 1936
Acineta limnetis Goodrich and Jahn, 1943
Tokophrya microcerberi Delamare Deboutteville and Chappuis, 1956
Acineta tuberosa var. bipartita Lopez-Ochoterena, 1963

Ubiquitous marine and fresh- and brackish-water species, observed on inanimate substrates, algae, but often found on representatives of crustaceans. This the type species small to medium (25-120 um long), freshwater, brackish or marine loricate suctorian that varies from bell to Y-shape in outline, laterally flattened. Two actinophores present, often well developed but may be reduced in some specimens, each bearing a fascicle of capitate tentacles. Apical aperture dumb-bell shape. Cytoplasm does not always completely fill the lorica which is sometimes smooth but is often transversely striated or ribbed. Stalk variable in length (5-90 um long) joining lorica without an intervening collar or other structure, usually with basal disc. Attached to a variety of substrata including inanimate objects, aquatic plants, Crustacea, isopods and amphipods, and a freshwater turtle. Reproduction by endogenous budding. Oval buds with 5 oblique ciliary rows, incorrectly redrawn with only 4 rows in Kent (1882) see Fig. 3m, n. Spherical macronucleus centrally located, single contractile vacuole situated apically. Often reported from organically polluted environments. NOTE. It will be noted from the synonymy list that this species has had a long and rich nomenclatural history. Because it is so variable in almost all of its attributes it has been given many different specific names. It is probably the most commonly reported of all the species in the genus. Distribution: Widespread.

1. A revision of the Suctoria (Ciliophora, Kinetofragminophora). 1. Acineta and its morphological relatives. Colin R. Curds. Bull. Br. Mm. nat. Hist. (Zool.) 48(2): 75-129.
2. Keys for identification of tentaculous infusoria (Ciliophora, Suctoria) of the Ukrainian fauna. Igor Dovgal. Vestnik Zoologii 2:1-42 Jan. 1996.

Marine Chaetonotid gastrotrich of genus Heterolepidoderma , probably H. ocellatum, from the superficial intertidal benthos of marine estuary Accabonac Harbor at Louse Point launching ramp. The biotope is clean medium grain sand. Imaged in Nomarski DIC on Olympus BH2 using SPlan 40x objective plus variable phone camera cropping on Samsung Galaxy S9+.

Gastrotricha are microscopic (0.06-3.0 mm in body length) free-living, acoelomate, aquatic worms, characterised by a meiobenthic life style. In marine habitats they are mainly interstitial, whereas in fresh waters they are ubiquitous as a component of periphyton and benthos and to a more limited extend also of the plankton. In marine sediments, gastrotrich density may reach 364 individuals/10 cm2 ; typically they rank third in abundance following the Nematoda and the harpacticoid Copepoda, although in several instances they have been found to be first or the second most abundant meiofaunal taxon" (1). "Gastrotricha are considered to have originated in the sea (Kieneke et al. 2008). However, our understanding of how they adapted from marine to freshwater ecosystems is still incomplete" (2).

"In aquatic environments the ecological role of the gastrotrichs is realised within the microphagous,detritivorous, benthic community. Like free-living nematodes, gastrotrichs swallow their food, which is made up of microalgae, bacteria and small protozoans, by means of the powerful sucking action of the triradiate muscular pharynx, and in turn they are preyed upon by turbellarians and small macrofauna. The phylum is cosmopolitan with about 820 described species grouped into two orders: Macrodasyida, with some 250 strap-shaped species, all but two of which are marine or estuarine, and Chaetonotida with some 450 tenpin-shaped species, two thirds of which live in freshwater. Macrodasyida include 7 families and 32 genera, whereas Chaetonotida counts 8 families and 30 genera. However due to the numerous species, and at least three new genera that wait to be described, these statistics should be considered as very conservative, particularly for the Chaetonotida" (1).

"Currently, approximately 820 Gastrotricha species have been described, divided into two orders: Chaetonotida Remane, 1925 [Rao & Clausen, 1970] and Macrodasyida Remane, 1925 Rao & Clausen, 1970. The representatives of Chaetonotida inhabit fresh, brackish and marine waters, while the Macrodasyida species almost exclusively inhabit marine waters. Only five taxa (including two fully described and named species) among all known Macrodasyida have been found in fresh waters (Rutner-Kolisko 1955; Kisielewski 1987a; Garraffoni et al. 2010; Todaro et al. 2012; Araújo et al. 2013; Kånneby et Wicksten 2014)" (2).

"In marine environments, the majority of gastrotrich species are interstitial dwellers, preferring especially fine- to medium-grained, clean sand. Only a small number of known species have adapted to other marine habitats, such as sediments rich in organic matter, rocky bottom, macrophytes or even hydrothermal vent zones (Hummon 1982; Kisielewski 1990; Kieneke et Zekely 2007; Kolicka et al. 2014)" (2).
"Heterolepidoderma is undoubtedly a genus of systematic and biogeographic interest, being one of few gastrotrich genera that include both marine and freshwater species" (3). Genus: Heterolepidoderma Remane, 1927 Typus generis: Heterolepidoderma ocellatum (Mečnikow, 1865) Terra typica: Russia. Scales with a keel. Common; freshwater, brackish-water, marine: epibenthic, periphytic, interstitial.

Heterolepidoderma is a genus of gastrotrichs belonging to the family Chaetonotidae. Heterolepidoderma Remane, 1927 is considered a polyphyletic genus (Kieneke et al. 2008, Kånneby et al. 2012, 2013) (2). "The genus Heterolepidoderma Remane, 1927 contains 36 valid species, 22 of which are freshwater1 (Balsamo et al. 2009; Kånneby 2011; Kånneby et al. 2012) and 14 marine or brackish (Hummon & Todaro 2010; Kånneby 2011; Kolicka et al. 2015). Heterolepidoderma is characterized by having keeled scales, i.e., scales equipped with strong median longitudinal keels (Schwank 1990; Kisielewski 1991), although keeled scales have also been reported in freshwater species for the genera Aspidiophorus, Chaetonotus and Ichthydium (e.g. Kisielewski 1991; Kånneby et al. 2009)"(3). Thus, "the main character which allows classification of a taxon as a member of genus Heterolepidoderma Remane, 1927 is body covering by elongated and keeled scales without posterior notches (e.g. Remane 1927; Schwank 1990; Kisielewski 1997; Todaro et Hummon 2008)" (1,2).

I found a pair of ocellar granules in my specimens which measured 90 um in length when fully extended. There was also a cuticular pharyngeal reinforcement. I suspect that my observation is Heterolepidoderma ocellatum Metschnikoff,1865, a relatively small sized species, with five-lobed head and a pair of ocellar granules. This species is widely distributed in Europe (see e. g. Greuter 1917; Mola 1932; Remane 1935–36; Valkanov 1937; Rudescu 1967; Martin 1981; Schwank 1990; Kisielewski 1998) and is also reported from Canada (Schwank 1990), United States (Schwank 1990), Japan (Saito 1937) and Brazil (Kisielewski 1991) (4). The species is reported in freshwater as well as marine biotopes and listed in the World Register of Marine Species (5). H. ocellatus is "a relatively small sized species, with five-lobed head and a pair of ocellar granules. Sporadic absence of ocellar granules have been reported in some populations (Schwank 1990; Fregni et al. 1998). Two pairs of sensory bristles present, each of the posterior pair anchored by a double-keeled scale. Dorsal body surface covered by elongated elliptical keeled scales, smaller in size in head and neck regions. Interciliary area naked except for a pair of keeled terminal scales and 1–2 transverse rows of 3–4 keeled scales. Pharynx with small swellings at both ends" (4).

1. An overview and a dichotomous key to genera of the phylum Gastrotricha M. Antonio Todaro* and William D. Hummon. Meiofauna Marina, Vol. 16, pp. 3-20, https://www.researchgate.net/publication/236021984

The flagellate Mallomonas.

Mallomonas from the leaf litter and superficial benthos at the edge of a freshwater woodland pond. The images are a compendium of several different individuals possibly representing more than one species as one is much more elongated than the others.

Imaged in phase contrast using Zeiss Photomicroscope III under Neofluar PH2 16x and PH2 40x objectives plus variable phone cropping on Samsung Galaxy S9+.

The following is adapted from: https://en.m.wikipedia.org/wiki/Mallomonas

Mallomonas is a genus comprising unicellular algal eukaryotes and characterized by their intricate cell coverings made of silica scales and bristles.[1] The group was first named and classified by Dr. Maximilian Perty in 1852.[2] These organisms live in freshwater and are widely distributed around the world.[3] Some well known species include Mallomonas caudata and Mallomonas splendens.

The organisms in this genus have streamlined morphology in spherical, oval, or elliptical forms, and they have a wide range of sizes that vary from the smallest being 10 µm to the largest being 100 µm. Two flagella emerge from the anterior apical flagellar pocket; one can be easily seen in the light microscope as it is longer and covered in hairs (called mastigonemes) while the other is much shorter, with no hairs, and is not as easily seen.[1]

Pigments such as chlorophyll c1 and fucoxanthin within the chloroplasts cause the cells to have a distinct, golden or yellow-brown colour. The chloroplasts themselves are bi-lobed, but some cells have two single-lobed chloroplasts. Cells have a girdle lamella, grouped thylakoids stacked in three, and additional membranes around the chloroplast called the chloroplast endoplasmic reticulum (CER).[1]
The large nucleus is located between the chloroplast and the Golgi complex. Vacuoles full of the storage product known as chrysolaminarin are found near the posterior end of the cell.[1]

The genus Mallomonas is based on the organization of its scales, which are silica plates that are intricately designed, species-specific, and cover the cell. There are many parts to the entire structure; it’s made up of anterior spine scales, posterior spine scales, body scales, and some specialized scales. An example of a specialized scale is one that can fit around a flagellar pocket. The scales are accompanied by bristles, which are long, elongated structures that are tucked under the scales with the use of a small bend in the end, which is called a ‘foot’.[5]

Bristles are composed of two parts, the foot and the shaft. The foot is at the proximal end, in regards to the bristle, and it is the part of the structure that is tucked under the distal end of the scale, under the dome. The foot is flat and bends at a 30° to 90° angle relative to the shaft. The shaft could be smooth, curved, ribbed, or serrated, and in some species, instead of being a solid bar, it appears rolled up so that the slit running along the shaft length is the point of convergence where both sides meet.[1] Each region of the bristle (whether it is the proximal end, the middle, or the distal end) has varying degrees of differences and flexibility in morphology. This variation in characteristics differentiates species.

Mastigamoeba species from the intertidal benthos of marine estuary Acabonac Harbopr at Louse Point imaged in Nomarski DIC on Olympus BH2 under SPlan 40x objective plus variable phone cropping on Samsung Galaxy S9+. Folllowing discussion is from: https://de.wikipedia.org/wiki/Mastigamoeba
Mastigamoeba is characterized as a genus of unicellular organisms characterized by an amoeboid (polymorphic) body with hyaline (transparent) cytoplasm and a flagella (amoeboid flagellates). Currently, the World Register of Marine Species lists only two marine species: M. pachyderma Skuja, 1948 and M. schizophrenia Simpson, Bernard, Fenchel & Patterson, 1997.

Due to its similarity to genera such as Mastigella and Mastigina, the genus Mastigamoeba was specified in 1891 to include only organisms with the following characteristics: amoeboid flagellates with hyaline cytoplasm, a direct connection between flagella and nucleus, lateral pseudopodia (pseudopods) and an elongated nucleus. However, the members of the genus change between different morphologies during their life cycle and can exist not only as amoeboid flagellates but also as unflagellated (aflagellate) amoebae, as multinucleated amoebas and as cysts.

During the 20th century, hundreds of species were described under the genus Mastigamoeba solely on the basis of external morphological features. However, recent research on their life cycle has shown that one and the same organism takes on many different morphologies (forms) over the course of its life, calling into question this large number of species described. Currently, there are about nine confirmed and distinguished species of Mastigamoeba, with many more being questioned (see below). Cavalier-Smith described the class Archamoebea in 1983 and included the order Mastigamoebida with the genus Mastigamoeba. Historically, amoeboid flagellates were included in the Pelobionta, with the Mastigamoebidae and the Pelomyxidae (genera Pelomyxa and Mastigella). The naming of the genus is controversial. The genera Mastigamoeba and Phreatamoeba are now considered synonymous by many researchers, although this is questioned by others.

The representatives of the Mastigamoeba are microoxic, i.e. they thrive in environments with low oxygen content (10–20%), e.g. in upper layers of mud or sand or on the sediment surface of shallow ponds. Some have also been found in sewage treatment plants. Such pelobionts are usually found worldwide, studies have confirmed their widespread occurrence in the temperate regions of Europe and North America. Typical habitats include habitats rich in organic matter. Among freshwater rivers and lakes, these organisms are most abundant in stagnant waters where oxygen-poor environments are common. Pelobionts are also found in marine environments. Although most pelobionts are free-living, some representatives are considered endobiotic, i.e. they survive only in the intestines of their hosts. These representatives are completely anoxic and thrive at low pH. They have been found in various vertebrates and invertebrate hosts, especially primates and dogs.

The length of the flagella ranges from 10 μm to 60 μm. In amoeboid locomotion with the help of the pseudopods, the species of clade A have a so-called uroid (also uropodium,typically mulberry-like structure at the rear end, which can appear rounded, rotten and hairy), while the types of clade B instead have a trailing pseudopodium. There is only a single flagellum (flagellum). This consists of the 9+ microtubule structure typical of eukaryotes. The flagellum apparatus consists of a single basal body from which the scourge originates. There is a microtubularcone, a cone-shaped structure that connects the flagellum apparatus directly to the cell nucleus. In the types of clade A, this cone is wide and originates at the base and lateral ends of the basal body. In the species of clade B, however, it is narrow and originates only at the base of this structure. The flagellum apparatus is arranged anteriorly and supports locomotion.

The outside of the cell is covered with a thin, unevenly distributed layer of organic, filamentous (threadlike) material. These threads run parallel to the cell and are 1 μm thick at their thickest point. The chemical composition of this extracellular shell is unknown. Some Mastigamoeba species have spines that are irregularly distributed around the cell. These spines are hollow, and their composition is also unknown. The organic layer sometimes contains prokaryotic symbionts of unknown identity; the exact relationship between the Mastigamoeba sp. and this symbiont is unknown (as of 2011). Another feature of the genus Mastigamoeba is the lack of a Golgi apparatus (dictyosome). However, its central functions are taken over by related elements in the endomembrane system – the endoplasmic reticulum contains some bundled structures and various vesicles that perform the core functions of a Golgi dictyosome. Not all Archamoebae have peroxisomes present. However, studies have shown that some Mastigamoeba species contain at least peroxisomal proteins.

The Archamoebae are all amitochondria, i.e. they have no typical, true mitochondria. The mitochondria in the mastigamoeba have been reduced (in the course of evolution) or transformed into forms that still retain some mitochondrial functions or have altered functions. These are commonly referred to as mitochondria-related organelles (MROs). For example, species like M. balamuthi have MROs called hydrogenosomes. Hydrogenosomes have arisen from mitochondria due to the loss of aerobic life stages. The hydrogenosomes have lost their former genome and the electron transport chain in the course of evolution. However, they continue to be used for ATP production by partial anaerobic oxidation of pyruvate and produce hydrogen gas as a by-product. The biosynthesis of iron-sulfur clusters has passed into a cytosolic function through lateral gene transfer (from the MRO genome to the nuclear genome) and is no longer carried out in the MROs. Other species have reduced mitochondrial organelles called mitosomes. These MROs have been reduced to such an extent that their only function is the biosynthesis of iron-sulfur clusters. They no longer have a function in energy metabolism, so these organisms must obtain their energy in other ways. To compensate for the loss of their own ATP production, these amitochondrial organisms have acquired the ability to import ATP from a host or symbiotic partner.

Several cellular phenotypes are known from many members of the Archamoebae, e.g. (mononucleated) amoeba, multinucleated amoeba, cyst and flagellate. The cyst stage has a single nucleus and is filled with granules and surrounded by a wall of unknown composition (as of 1986). The most important trophic form (growth form, as opposed to resting form) of Mastigamoeba is a mononuclear amoeboid flagellate. However, some species show (at least in some phases of life) a multinucleated morphology: M. schizophrenia has up to 10 nuclei in the multinucleated stage. In M. balamuthi, the predominant trophic form is that of a multinucleated organism that can have up to 46 nuclei. Propagation occurs by mitosis and subsequent budding. In the multinucleated form, this usually results in an unequal number of nuclei in the daughter cells.

Oxyrrhis marina Dujardin, 1841. This interesting flagellate with two flagella is from the intertidal benthos of marine estuary Acabonac Harbor at Louse Point but I often see it in my estuarine samples.. Measures 25 um in length. Several mating or fissioning pairs were present. Imaged in Nomarski DIC using Olympus BH2 under SPlan 40x and 100x objectives plus variable phone cropping on Samsung Galaxy S9+ . Following discussion excerpted from: https://en.m.wikipedia.org/wiki/Oxyrrhis_marina.

It has a global distribution except for polar seas. It is most common in the intertidal zone and other coastal regions, where it is a member of the plankton. Habitat types include tide pools and estuaries. It was first described from a salt marsh.It tolerates wide ranges in salinity, temperature, and pH.

It is heterotrophic, obtaining nutrients externally instead of synthesizing them by an internal process such as photosynthesis. It is an omnivorous grazer, consuming various types of tiny organisms from its environment. It eats phytoplankton such as minute algaes.Some of these food items are relatively large, as large as the O. marina cell itself. It is selective in its grazing, showing clear preferences for certain food taxa. It can also pick certain individuals over others, as evidenced by its preference for virus-infected Emiliana huxleyi cells over healthy cells. It is cannibalistic, as well. It feeds by phagocytosis, totally engulfing its prey. It has been observed spinning one of its flagella in such a way that it creates a current, pulling the item closer so it can seize it. It is also raptorial, approaching and pouncing on the prey item, especially when the item is a protist. O. marina can sense and respond to certain chemicals that are exuded by algal prey.

Several mating pairs are present. In terms of reproduction, O. marina is isogamous, with reproductive cells smaller than the body cell, but very little is known about these.Isogamy is a form of sexual reproduction that involves gametes of the same morphology (indistinguishable in shape and size), found in most unicellular eukaryotes.] Because both gametes look alike, they generally cannot be classified as male or female.Instead, organisms undergoing isogamy are said to have different mating types, most commonly noted as "+" and "−" strains.

This protozoan species has an asymmetrical oval shape to its single-celled body. It has been likened to a rugby ball. The cell usually measures between 20 and 30 micrometers, but it is known to reach 60. It has two flagella with a protruding, tentacle-like bulge between them. The flagella are covered in scales. Most individuals have scales on the body surface, as well. The two flagella have separate functions. One undulates in waves and the other is coiled, producing a corkscrew-like propulsion to move the cell. The individual appears colorless, but a concentrated culture of cells may have a pink tinge.

The oblong form without chromatophores is somewhat compressed dorso-ventrally and composed of a larger epicone and a smaller conical hypocone, which are divided by a sulcus developing on the ventral side. In that side a part of the epicone hangs to make a plasmic lobe, and a backward longitudinal and transversal flagella arise at the base of the lobe.

Another sighting of Stichotricha marina Stein, 1867 - a tube dwelling marine hypotrich from the intertidal benthos of marine estuary Acabonac Harbor at Louse Pont. Imaged in Nomarski DIC using Olympus BH2 under SPlan 40x objective plus variable phone cropping on Samsung Galaxy S9+. This individual measures 225 um in length, larger than the first individual I found at another beach of the same estuary where it measured only 112 um (https://www.inaturalist.org/observations/149148857). So thus far Acabonac Harbor has individuals that both exceed and are smaller than the size range stated by Hu and Song 2001 (1). In this individual, we can clearly see the spiralization of the cirral rows and watch as the animal leaves its lorica to become pelagic.

Stichotricha marina Stein, 1867. Family Spirofilidae von Gelei, 1929 Genus Stichotricha Perty, 1849 . "Marine flexible Stichotricha with twisted body shape; in vivo about 160–200 µm with elongated body shape; peristomial field narrowed and neck-like, about half of body length; ca. 70 adoral membranelles, two clearly differentiated frontal cirri; 27–41 buccal cirri, arranged in one long row along with buccal field; transverse cirri absent; three complete dorsal kineties and three caudal cirri. Consistently two macronuclear nodules, and gelatinous lorica tube-like" (1).

Stichotricha are elongate, spindle shaped organisms which have an inflexible body and a narrow flexible neck region. The ventral surface is equipped with spiralling rows of cirri. Transverse cirri absent. The peristome is long, thin, and narrow. The first few membranelles of the AZM are stout. Contractile vacuole situated anteriorly at the base of the neck region. Members of this genus are often found inhabiting a detritus covered lorica or tube, sometimes in colonies.

I originally classified this as the freshwater species S. aculeata as the size is closer to that species and illustations of this species are quite similar (2,3). It is puzzling that Carey (4) lists S. aculeata as being marine as does World Register of Marine Species, but Bourland 2005 (2) mentions only freshwater biotopes and Hu and Song also emphasize the freshwater biotope of S. aculeata in comparing it to S. marina (1). Most notably, S. aculeata has quite long and conspicuous dorsal ciliary bristles (see Bourland 2015 (2)- fig 8A and Kahl 1932 fig. 96) while my observation has small and rather inconspicuous (but still visualized) dorsal bristles. Size is an oftenunreliable character so this is best classified as S. marina.

1. Redescription of the little-known marine ciliate, Stichotricha marina Stein, 1867 (Ciliophora, Hypotrichida) from the mantle cavity of cultured scallops
   Xiaozhong Hu & Weibo Song. Hydrobiologia 464: 71–77, 2001.

2. Morphology, ontogenesis and molecular characterization of Atractos contortus Vörösváry, 1950 and Stichotricha aculeata Wrzesniowskiego, 1866 (Ciliophora, Stichotrichida) with consideration of their systematic positions. William A. Bourland. European Journal of Protistology 51 (2015) 351–373
3. New record of 21 ciliate species (Protozoa, Ciliophora) from South Korea. Atef Omar and Jae-Ho Jung. Journal of Species Research 10(3):301-320, 2021
4. Philip G. Carey. Marine Interstitial Ciliates. Chapman & Hall. 1992. p 174.

Strombidium sulcatum Claparade and Lachmann, 1858 from the intertidal benthos of marine estuary Acabonac Harbor at Louse Point. The cell measures 40 um in length. Notable features are the prominent anterior protuberance, round posterior macronucleus, posterior polysaccharide cortical platelets, and bundles of trichites in a funnel-like configuation. The conforms to several descriptions. Notably, Carey 1991 writes: "The aterior is bluntly pointed due to the peristomial collar. The AZM extends only 1/3 the length of the body. The posterior is rounded, the region of cortical platelets commencing at the equatorial cleft, There is a band of trichites in a funnel-like configuration in this region. A ventral cleft and perilemma are present" (1). In several descriptions, the bundling of trichites seems to be an important character (1,2,4).

MONTAGNES, TAYLOR and LYNN, in describing their new species Strombidium inclinatum and comparing it with the similar S. sulcatum, provided the description of Strombidium sulcatum from the work of Faure-Fremiet 1911 and Fauri-Fremiet & Ganier 1970:

"Description. Length 40-50 prn. Width maximum 25-30 pm. Prominent anterior rostrum. Portion of cell anterior to the girdle is cylindrical; c 25 um. Portion of cell posterior to girdle is hemispherical; c 18 um. Cytostome ventral at bottom of short oral cavity. Anterior polykinetid zone perpendicular to cell axis. Open circle of polykinetids: 12 anterior polykinetids; each 6-7 um wide (anterior polykinetids composed of 7-8 ventral polykinetids. Paroral kinety present. Contractile vacuole present. Macronucleus, subequatorial, in center of cell; nearly spherical about 10 pm across. Girdle of dikinetids in transverse groove. Polygonal polysaccharide cortical platelets present. Ventral kinety composed of dikinetids, extends as argentophilic stripe from girdle to posterior pole and onto dorsal surface a short distance. Girdle of trichites in posterior; insert anterior to transverse groove. Habitat: euryhaline, marine, intertidal" (2).

"Strombidium sulcatum is a heterotrophic oligotrich, about 40 μm in length, and in the laboratory feeds on bacteria, small algae and heterotrophic nanoflagellates. In common with many free-living protists, it generally reproduces asexually via binary fission or cell division. Cyst production has not been reported but cannot be excluded. Among oligotrich ciliates, the dividing cell develops a new mouth for the daughter cell and the original mouth does not degrade or become dis-organized thus the dividing cell continues to swim and possibly ingest prey while dividing. Swimming in Strombidium sulcatum is characterized by movement in a helical pattern interrupted by occasional ‘tumbles’ resulting in a change of direction (Fenchel and Jonsson 1988)" (3).

"The oligotrich ciliate Strombidium sulcatum has been the subject of many studies. The species was described by Claparède and Lachmann from the Fjord of Bergen (Norway) in 1858 as the type species for the genus (Claparède and Lachmann 1858); it is then one of the longest-known oligotrich ciliates and is apparently cosmopolitan (Agatha 2011). It was subsequently found in the Bay of Kiel (Bütschli 1873). In the Mediterranean, it was found first in the Gulf of Naples by Entz (1884) and then in the port of Bastia in Corsica (Gourret and Roeser 1888). The first detailed observations made on S. sulcatum were by Fauré-Fremiet who examined cells from the marshes of Croisic, on the Atlantic coast of France (Fauré-Fremiet, 1911, Fauré-Fremiet, 1912). However, S. sulcatum was not brought into culture until 1983 when Dave Brownlee, established cultures in Villefranche-sur-Mer. From 1983 to 2003, S. sulcatum was maintained in wheat grain culture providing the raw material for the 22 laboratory studies" (3).

Strombidium parasulcatum Tsai, Ling, and Chiang 2022 is very similar in morphological characters to Strombidium sulcatum Claparède and Lachmann, 1859 (sensu Song et al., 2000). "Strombidium parasulcatum n. sp. can be separated from S. sulcatum (Granda and Montagnes, 2003) by its larger cell width (30–40 vs. 23 µm in vivo), the disappearance of apical protrusion after protargol staining (vs. appearance with different staining methods), its larger buccal cavity width (15 vs. 7 µm), the shape of macronucleus (variable vs. bilobed), the arrangement of extrusomes (no-grouped vs. several in bundle), its shorter ventral kinety (4–8 µm vs. 10 µm), the position of the ventral kinety (occupying posterior 1/4 of cell length vs. posterior 1/3 of cell length), and different numbers of dikinetids in the girdle and ventral kineties (48–64 vs. 37–50 and 4–8 vs. 9– 11, respectively). With reference to the general appearance and even the morphology characters commonly used for species distinguishing of genus Strombidium, it is difficult to separate the new species from S. sulcatum sensu Song et al. (2000) and Zhang et al. (2010). For example, they are similar in cell size, the appearance of anterior protrusion in vivo and after stained, number of collar and buccal membranelles, number of dikinetids of girdle and ventral kinety, and length of ventral kinety. However, the low similarity of the 18S rRNA gene sequences between them demonstrates that they cannot be conspecific. Moreover, their dissimilarities in terms of the position of the largest cell width (equatorial area vs. posterior of mid-body), the width and depth of buccal cavity (15 vs. 7 µm and 25 vs. 33% of cell length), arrangement of extrusomes (no-grouped vs. several in bundle), the position of girdle kinety (posterior one-third vs. mid-body), and the length of cilia in collar membranelles (25 vs. 20 µm) justify naming our organism as a separate species" (4).

1. Marine Interstitial Ciliates: An illustrated key. Philip G. Carey. p 169.