Favoritos de roman_romanov

Magnification of all photos: 1000× (oil immersion)
Habitat: planktonic algae collected from the edge of an artificial pond.
Using stage micrometer for calibration, estimated to be about 38 µm long and 11 µm wide when extended.
Video available: https://youtu.be/rAbzrIdgVtA

Composite Plate (duplicate of observations in same location) showing

A. Habitat on silty trail
B. Detail of habitat
C. Habit showing sporophytes and gametophytes
D. Habit showing sporophytes, leaves and protonema
E. Leaf
F. Laminal cells
G. Detail of protonema and rhizoids.

Phacus acuminatus Stockes 1885 from a sample fed with boiled wheat seed from the edge benthos of freshwater glacial kettle hole Kellis Pond. Imaged in Nomarski DIC on Olympus BH2S using SPlan 100 1.25 oil objective plus variable phone camera cropping on Samsung Galaxy S24. The cell measures 29.6 um.

Phacus acuminatus A. Stokes 1885 Species: Cell body flat, anterior narrowed, posterior broadly rounded, with short blunt cauda, 30-40 μm long, 20-30 μm wide, cauda usually straight, but rarely slightly curved, dorsal furrow short and shallow, lateral margins broadly rounded or nearly straight, periplast longitudinally striated, usually a single large paramylon body but sometimes accompanied with a second smaller one.

Cell body 23-40 μm long, 20-30 μm wide, dorsal view nearly spherical; cauda short V-shaped and slightly curved or straight, striae also straight; a locomotive flagellum nearly the same as the cell body in length; paramylon bodies disc-shaped with a hole at the center, 1-2 in number; (An Illustrated Guide to Freshwater Zooplankton in
Japan, 2000).

Phacus acuminatus A.Stokes 1885a: 183, fig. 1 (Fig. 3a and b) Emended diagnosis: Cells oval, wide-oval or almost spherical (20–40 x 13–27 µm), leaf–like and flat (with very low crest); cells terminate with a short, sharp, wedge-shaped, straight or bent sideways tail (on average 2–3 µm long).
"Comments: Following the nomenclatural priority rule, this morphological form (cells small, almost spherical, flat, and terminate with a short, sharp, straight or bent sideways, and wedge-shaped tail) has been assigned the name Phacus acuminatus. The individual seen in Stokes’ drawing (1885a, fig. 1) corresponds with the aforementioned characteristic, similarly to the cells from the UTEX 1317 strain (chosen as the representative strain), from which the epitype originates. However, due to the high morphological similarity to P. minutus, only molecular identification allows the differentiation of the two species. In this situation, designation of epitypes for both species seems justified (see Comments for P. minutus). The taxa that constitute P. acuminatus synonyms are those whose cells have a morphology similar to P. acuminatus and without proper diagnostic traits in their original descriptions" (1).
"Phacus acuminatus. Over 30 intraspecific taxa (subspecies, forms, and varieties) have been described for Phacus acuminatus mainly based on cell shape and size, tail length and shape as well as the number and morphology of the large paramylon grains. Many authors view such differences as intraspecific variability arising from either ontogenesis or environmental conditions (Huber-Pestalozzi 1955, Popova and Safonova 1976 among others). This is further confirmed by our research. In regard to the shape and size of the cells, the obtained results (on average 30 9 20 µm) were compatible with the rich literature (e.g., Popova and Safonova 1976: 25–33 9 19– 22 µm; short tail, no fold; Table 1) and the observed differences in each strain were the result of ontogenesis – the individuals tended to enlarge (particularly their width) right before cell division. Some dissimilarities were also found between strains, but they had no DNA sequence support – all strains occurred in a subclade of clade B (Fig. 2) with nSSU rDNA diversity below 3%. The UTEX 1317 strain (in the collection as P. brachykentron; Fig. 3a) was located among them. This morphological form, described by Pochmann (1942) as P. brachykentron, had been distinguished due to its slight cell asymmetry. For the aforementioned reasons, many taxa described in the literature as having a morphology similar to P. acuminatus and without proper diagnostic traits in their original descriptions, have been placed in synonymy" (1).

1. TAXON-RICH PHYLOGENY AND TAXONOMY OF THE GENUS PHACUS (EUGLENIDA) BASED ON MORPHOLOGICAL AND MOLECULAR DATA. Maja Łukomska-Kowalczyk , Alicja Fells , Katarzyna Chaber , Rafał Milanowski , and Bozena Zakry. J. Phycol. 56, 1135–1156 (2020)

Found in pond water. Rested on the substrate in small balls no bigger than 1cm. Microscope photos at 120x, 300x, 600x.

Not sure if it is a type of algae, however, it is the only thing I could think of it potentially being.