Identificaciones de bdstaylor

Spirostomum ambiguum Ehrenberg, 1834. from the superficial river edge benthos of the freshwater segment of the estuarine Peconic River. Imaged in Nomarsdki DIC on Olympus BH2S using Splanapo 20 0.70 and SPlanapo 40 0.95 objectives plus variable phone camera cropping on Samsung Galaxy S9+. The cell measures 920 um in length. The peristome is 2/3 the length of the body with the cytostome at the posterior 2/3 location. There is a large terminal contractive vacuole with a long collecting canal reaching almost the anterior end of the cell. The macronucleus is moniliform forming a chain of connected elongate spindle shaped macronuclear nodules beginning at the anterior 40% of the cell length and extending almost to the posterior end.

"Spirostomum ambiguum Ehrenberg, 1834. [syn: Trichoda ambiguum Müller, 1786; S. ambiguum var. major Roux, 1901] 900 m several mm long. Length: width ratio about 9-17. 15-25 kineties on each side; heterogeneous, numerous (4-5) CG rows per stripe. Peristome always longer than 1/2 of the body length, often reaching 2/3. CV much shorter than body length, rarely exceeding 1/10. The color depends on cytoplasmic granules. Moniliform MAC with 12-50 (avg. 15-25) nodules not exceeding 35 45 m in length when stained by Feulgen reaction. Numerous (up to 100) MICs 1-2 m long. Mono phyletic. Only found in freshwater. Reported in central and northern Europe, England, Russia, central Africa, USA, Jamaica, India and Japan. It sometimes harbors prokaryotic symbionts in the MAC. Spirostomum ambiguum is a well-defined, easily recognizable morphospecies whose monophyly is also strongly supported by molecular sequences" (1).

"Differential diagnosis
1) Size in vivo 1-000-4000 x 48-100 um, mostly 1200-2000 um. Visible with the naked eye as a white thread. Very flexible and contractile, shortens to approximately 390-430 x200-220 um. Contracted cells cigar-shaped.
2) Shape slender to moderately broad worm-shaped, more or less parallel-sided, 10-17 times longer than wide. Front end rounded, rear end truncated. Slightly flattened laterally. Ventral side in area of ​​the mouth entrance slightly bulging.
3) Macronucleus moniliform or rosary-shaped, consists of 10-50, mostly 15-20 ellipsoids, about 18-53 x 12-24 um large nodes that form a long band that approaches the dorsal side. The number of nodes correlates positively with the age of the cell (REPAK & ISQUITH L974).
4) Contractile vacuole at the posterior end, with a long collecting duct extending forward along the dorsal side which sometimes shows ampullary extensions.
5) Close under the pellicle there are many spherical, spherical, yellowish granules arranged in elongated bands of 4-5 rows each which give the cell a yellowish to brownish color.
6) About 70-90 slightly spiraling rows of cilia, consisting of basal bodies arranged in pairs are constructed, but only the front one has a cilium.t
When the cells contract (startle reaction), the rows of eyelashes spiral around the body.
7) The adoral membrane zone extends from the anterior end to the posterior third (about 65-70 % of the body length) and turns to the right at the lower end. Parallel to the adoral membranelle zone a non-ciliated oral groove, which is bordered on the right by an undulating membrane.
8} Movement hatching, worm-like crawling and writhing. Fluidity with longitudinal rotation axis, with the front end describing a cone-shaped body of revolution. In the plankton falling floating with inclined longitudinal axis" (2).

"Spirostomum ambiguum is easy to recognize because of its size and shape, but the differentiation with S. minus causes considerable difficulties. There are many shape variations which occur, size and shape are not reliable distinguishing features. Usually S. minus is significantly slimmer and almost never reaches a length of 1 mm, while S. ambiguum is more compact, stockier and over 1 m long. Only the length of the adoral membrane zone in relation for body length (S. ambiguum: 65-70 %; S. minus: 35-50%) remains reasonably reliable distinguishing feature, but here too the differences do not seem to be too pronounced. Furthermore, the ciliates S. semivirescens have a similar size and shape (up to 2 mm, very slender, adoral membrane zone up to 50 % of body length, green through symbiontic algae) and Homalozoon vermiculare (up to 1.5 mm, 5-21 contractile vacuoles along the dorsal side, mouth small and only at the front end) as well as microturbellaria and nematodes. The characteristics 1,3 and 7 are particularly important for identification" (2).

1. Focusing on Genera to Improve Species Identification: Revised Systematics of the Ciliate Spirostomum Vittorio Boscaroa,1, Daniela Carducci, Giovanna Barbieri, Marcus V.X. Senra, Ilaria Andreoli, Fabrizio Erra, Giulio Petroni, Franco Verni, and Sergei I. Fokin. Protist, Vol. 165, 527–541, August 2014
2. FOISSNER W., BERGER H. & KOHMANN F. (1992): Taxonomische und ökologische Revision der Ciliaten des Saprobiensystems - Band II: Peritrichia, Heterotrichida, Odontostomatida. – Informationsberichte des Bayer. Landesamtes für Wasserwirtschaft, 5/92: pp 317-25.

Video (x4 speed): https://youtu.be/3sFKqLA1sBQ
Video (x1 speed): https://youtu.be/1SEFARLR6c0

Photos depict snapshots of the same individual featured in the video.

Size: see scale bar (photos no.2 and no.3)

Site of collection: Pavilion, Takamori Higashi Park (a freshwater habitat), Sendai, Japan

Date of collection: Aug. 8th 2021

Weather: Rainy

Water temp.: 29.0°C

pH 6.6

Date of observation: August 28th 2021 (the collected sample in a plastic container was left near a window out of direct sunlight at room temperature until observation).

Bright field observation using a Wraymer microscope (model BX-3500TL, Osaka, Japan) equipped with a Floyd-2 HDMI ethernet digital camera (Wraymer, Osaka, Japan). The accuracy of the scale bar was confirmed by using a stage micrometer glass slide (1 div. = 10 µm; Wraymer, Osaka, Japan) at each magnification.

Caenomorpha medusula PERTY, 1852 from the superficial river edge benthos of the freshwater segment of the estuarine Peconic River. Imaged in Nomarsdki DIC on Olympus BH2S using Splanapo 40 0.95 and Splan 100 1.25 oil objectives plus variable phone camera cropping on Samsung Galaxy S9+.

This metopid ciliate is a fast swimmer and often difficult to track, but also holds on to the substrate thigmotactically with the dorsally located long cirri. It is an inhabitant of saprobic anoxic decaying benthic organic debris. My population averages 100 um in total length including the single long caudal spine. There are three macronuclear nodules with two sometimes incompletely separated and a single micronucleus. There is an anterior refractile granular agggregate. The cytoplasm contains diverse rod-shaped bacterial symbionts. The contractile vacuole was rather large in diastole in some individuals. All of these features are in agreement with the most recent redescription by Li et al 2017 (1).

Li et al 2017 provide the most recent and detailed redescription of the species. In describing the most important characters, they write: "Although this species has been studied for more than 150 years, species identification remains problematic because many descriptions are based only on live materials without redescription of the ciliature. Furthermore, some features, e.g. body shape, appear to vary among individuals in different environments, but, nonetheless, have traditionally been used as key characters in the taxonomy of Caenomorpha. The original description of Caenomorpha medusula by Perty (1852) was rather superficial and failed to note some important features (e.g. the numbers of adoral membranelles, bell kineties and spines, etc.), which renders the identification of this organism difficult. However, according to the original and subsequent investigations, this species can be recognized by a combination of the following characters: (i) multiple macronuclear nodules; (ii) two unequal-length bell kineties; (iii) one conspicuous posterior spine" (1).

"Description: Body medusoid, covered with a transparent rigid pellicle, 112–125 × 50–65 um in vivo with a ratio of length to width about 2:1. Posterior spine slender, about 45–55 um long in vivo; ratio of spine length to body length about 0.4. Plump rod-shaped epibiotic bacteria often found in US population but not found in China population. Cytoplasm clear and colourless, with some dark globules (1–2 m across) and an aggregate of transparent granules in anterior body part, rod-like bacteria exist in cytoplasm in China population, very likely endosymbionts. Edges of preoral bell never adjoin closely to posterior body; peristome narrow, deep funnel-shaped. Cytostome near base of spine; undulating membrane recognizable after staining, length of membrane about 50 m long. Contractile vacuole located near base of spine, about 15–20 m in diameter, pulsates at intervals of 3–5 min. Three (41 of 60 cells [Chinese population], 36 of 45 cells [US population]), four (19 of 60 cells [Chinese population], 8 of 45 cells [US population]) or five (1 of 45 cells [US population]) macronuclear nodules, usually ovoid or ellipsoidal, arranged in line, located in center of cell, sometimes incompletely separated; one micronucleus, ellipsoidal, near macronuclear nodules. Movement leisurely, spiraling while rotating around the long axis of the body" (1).

"Two strongly thigmotactic bell kineties about 68 um and 35 um long, respectively, located in anterior part of dorsal side of cell, consist of about 94 and 56 cirri (Chinese population), and 108 and 59 cirri (US population) respectively (n = 21); cirri in each kinety arranged in indistinct zig-zag pattern. Perizonal stripe beginning near anterior end of cell, about 6.4 um wide at middle part, composed of 114–180 kineties (114–169 in China population, 123–180 in US population), spiraling 450 degrees around axis; each kinety inclined about 60 degrees to edge of shield; longest kinety (at middle of stripe) composed of about 15 pairs of kinetosomes in both populations, whereas ones near oral region with only two pairs of kinetosomes. Adoral zone composed of 41-67 membranelles (Chinese population), each with three or four rows of kinetosomes, spiraling 360 degrees around body axis from near the distal perizonal stripe, terminates near cytostome. Undulating membrane on undersurface of preoral bell (i.e. roof of peristomial region), about 50 m long. Cilia on base of spine, invariably arranged in two short kineties, each 10–15 m long, composed of about 25 kinetosomes each. The two spine kineties inclined about 20 degrees to each other, converge posteriorly" (1).

Jankowski provided an older but elegant description: "Body medusoid, covered with a clear transparent rigid pellicle that looks like an armour; body length, without a spine, is 70-90 x 65-70 ul, spine 30-35 um long. The shield bears no ciliary meridians except for those of a perizonal ciliary stripe. Instead. it bears two groups of long thick flexible cirri, with 8-10 cirri in each group: they are perfectly seen from the left side. These cirri are highly thigmotactic- one can frequently observe a prolonged adhesion of the animals to sapropelic particles by the aid of these cirri, while both perizonal cilia and adoral membranelles continue their activity. The edges of the shield never adjoin closely to the body surface; instead, a narrow deep funnel may be observed between them. The perizonal ciliary stripe occupy the margin of the shield; it is composed of 5 ciliary rows not separated into two groups, unlike that of Metopidae (where it includes 2 upper and 3 lower kinetics). The PCS of Caenomorpha looks like a wide densely ciliated field composed by a number of short oblique ciliary rows with 5 kinetosomes each. It serves for both feeding and movement in this genus. The synchronous beating of the perizonal cilia and adoral membranelles produces a rotation of the swimming animal and, in addition, creates the intense water current along the buccal groove. driving the food-particles into the intrastomium. The cytostome in C. medusula occupies a typical for all the caenomorphids posterior position with a thin tubular cytopharynx raising right up into the anterior body part, where colourless food vacuoles are concentrated" (2).

1. Description of two species of caenomorphid ciliates (Ciliophora, Armophorea): Morphology and molecular phylogeny. Song Li, William A. Bourland, Saleh A. Al-Farraj, Lifang Li and Xiaozhong Hu. European Journal of Protistology 61 (2017) 29–40.
2. Morphology and Evolution of Ciliophora. III. Diagnoses and Phylogenesis of 53 Sapropelebionts, Mainly of the order Heterotrichida. ANATOL W. JANKOWSKI. Arch. Protistenk. Bd. 107, S. 185-294 (1964)