Original descriptions of taxa. For coccolithophores, and many calcispheres, these are pages from the Farinacci & Howe Catalog of Calcareous Nannofossils. In other cases (e.g. non-calcifying haptophytes) the data is directly compiled on this site. The "Catalogue of Calcareous Nannofossils" was originally compiled by Prof A. Farinacci 1969-1989, since 2000 it has been updated and extended by Richard Howe - see The Farinacci and Howe Catalog - an Introduction.
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Citation: Chrysochromulina scutellum Eikrem and Moestrup 1998Rank: SpeciesFarinacci catalog page (& compiler): n/a Current citation: Chrysochromulina scutellum Eikrem and Moestrup 1998
Original Description Cells slightly saddle-shaped, 4-9 µm long, 4-8 µm wide, and 4-5 µm deep. Appendages inserted on the concave side of the cell, the flagella equal and homodynamic, 12-20 µm long, the coiling haptonema 1 3-80 µm long, typically two to three times the length of the flagella. Three scale types present on the cell, two bearing a central spine supported by four struts, the third type spineless, the spined scales constituting the outer layer. Scales sometimes slightly elongated and one scale face of the spined scales showing a radiating pattern, the other a concentric fibrillar pattern. One of the spined scale types, measuring 0.25-0.35 X 0.25-0.35 µm, bearing an up right rim, the spine usually shorter than or equal to the radius of the scale. The other spined type very similar, measuring 0.30-0.45 X 0.30-0.45 µm but possessing a flat, narrow, thickened rim, the spine usually a little longer than the radius of the scale. Scales of the inner scale layer larger than the spine scales, flat and slightly elongated, measuring 0.5-0.6 X 0.6-0.7 µm, the distal scale facing a radiating pattern, the ribs proceeding from the rim and extending two-thirds of the dis tance to the center of the scale, the central area patternless proximal scale face with a central fibrillar pattern and an in flexed, broad rim. Extra details from original publication General cell structure Three views of live swimmig clls are shown in Figs 1-3. Cells of the larger size ranges generally appear to be more dorsoventrally compressed than small cells, which may be spherical to ovoid. The flagella are equal and homodynamic and the coiling haptonema is usually at least twice the length of the flagella. One of the flagella shows autofluorescence in blue light (not shown). The haptonema belongs to the seven microtubule variety (Fig. 5). The flagella and haptonema are inserted into the cell close to one of the chloroplasts (Fig. 4) and are attached to both the chloroplasts and the nearby mitochondrion by the microtubular root system described in de tail below. Cells contain a posterior nucleus (Fig. 6), a reticulated mitochondrion (Figs 4, 6-9), a Golgi body, and two chloroplasts with immersed pyrenoids (Figs 4, 6-9). Each py renoid is penetrated by branching tubes (Figs 9, 10). A central component is often visible in the tube lumen (Fig. 10). A large vacuole is commonly seen in the thin sections (Fig. 8) and contains some well-defined material. On one occasion a bac terium was seen in the vacuole, indicating its nature as a food vacuole.
Scale structure: The three different scale types are illustrated in detail in Figs 11-17 (see also Diagnosis). Although there is no doubt re garding the distribution of the large underlayer scales, which uniformly cover the cell and are topped by spined scales with upright rims, the distribution of the spine scales with narrow, apparently inflexed rims remains somewhat uncertain. These scales are seen to overlap (Fig. 17), in contrast to those having upright rims (compare Figs 16 and 17) that seem to prevent overlapping. The spine scales with narrow rims are sometimes seen near the flagellar pit, but not exclusively so. They appear to occur in patches, but we have failed to detect any regularity in the distribution of these patches on the cell surface. Although the rim of the large underlayer scales was easily seen in shadowcast mounts (e.g. Fig. 14), details of the rim were difficult to see in thin sections (e.g. Fig. 16). However, in scales overlying strongly curved parts of the cell surface, the base of the scale was commonly curved and in these cases the inflexed nature of the rim was clearly visible (Fig. 15 , inset). In the more typical flat condition of the scale the rims are apparently closely appressed to the base.
Eikrem, W. & Moestrup, Ø. (1998). Structural analysis of the flagellar apparatus and the scaly periplast in Chrysochromulina scutellum sp. nov. (Prymnesiophyceae, Haptophyta) from the Skagerrak and the Baltic. Phycologia. 37: 132-153. gs
Chrysochromulina scutellum: Catalog entry compiled by Jeremy Young. Viewed: 1-6-2023