CATALOG - Phaeocystis cordata


Folder trail: Farinacci -> Haptophytes -> Phaeocystis -> Phaeocystis cordata
Folders this level: P. amoeboidea, P. antarctica, P. brucei, P. cordata, P. globosa, P. jahnii, P. scrobiculata, P. sphaeroides,

Original descriptions of taxa. For coccolithophores, and many calcispheres, these are pages from the 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 compiled by Prof A. Farinacci 1969-1989 and updated by Richard Howe 2000-2016 - see also this page.
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Current identification/main database link: Phaeocystis cordata Zingone and Chrétiennot-Dinet in Zingone et al. 1999

Compiled data

Citation: Phaeocystis cordata Zingone and Chrétiennot-Dinet in Zingone et al. 1999
Rank: Species
Type locality: Tyrrhenian Sea, station MC, 2 miles offshore Naples (40
Standardised type level: 160_HOLOCENE
Type specimens: Holotype: Figure 3. Isotypes: Figures 1–2, 5–9, 11–13, 15, 16, 18, 20. Authentic strain: Phaeonap1, deposited at the Stazione Zoologica ‘Anton Dohrn,’ Naples, Italy.
Farinacci catalog page (& compiler): n/a


Original Description
Cellulae (3.2 x 3.8 µm) cum flagellis cordiformes vel triangulares, dorso-ventraliter compressae, cum satis profunda et ephippiomorpha depressione, circum insertionem flagellorum. Flagella duo subequalia (5.5-7.5 and 4.5-6 µm) et breve haptonema (2.2-2.5 µm). Chloroplasti duo, aureo-brunnei, lateraliter dispositi. Cellulae stratis dimorphorum squamarum obductae: squamae strati interni et continui ovales et parviores (0.18 x 0.13 µm), margine inflexo, squamae strati externi et continui majores (0.25 x 0.18 µm), cum centrata papula, margine erecto. Cellulae extrudens quinque fila delineantes pentagonas stellas in centro. Coloniarius habitus ignotus.

Size: Cells 3.2-3.8 µm

Etymology: The species name cordata (‘‘heart-shaped’’) refers to the shape of heart shown by many cells.

Extra details from original publication
Species description: Light microscopy. Flagellate cells are triangular to heart-shaped, 3 to 3.5 µm long and 3 to 4 µm wide, with two flagella and a short, non-coiling haptonema emerging from a deep depression (Figs. 1, 2). In lateral view, the cell outline appears oval and thinner (ca 2.5 µm). Two parietal chloroplasts are light golden-brown in color. One flagellum is slightly longer than the other, their respective lengths being 5.5 to 7.5 µm and 4.5 to 6 µm. The haptonema (Fig. 2), 2.2 to 2.5 µm long, is not easily seen, especially during swimming. In the anterior part of the cell, one to three disklike bodies are at times present that, in lateral view, appear as short bars. Each disklike body discharges five filaments radiating from a common center (not shown). Small bodies and filaments are commonly seen only in recently established cultures, but filaments were occasionally observed 7 years after isolation.

Cells typically swim with the flagella straight, close one to another, obscuring the haptonema, and pushing the cell. The flagella cause the cells to rotate about their longitudinal axis as they move. Some cells are seen to move differently, with the flagellar pole directed forward. In other cases, cells rotate around one of the flagella for some time. Colonial and nonmotile stages have not been observed.

Electron microscopy. With SEM (Figs. 3-8), cells exhibit a characteristic shape of a heart, more or less pointed at the pole opposite the flagella insertion. The two flagella and the haptonema emerge from a deep, saddle-shaped invagination as seen with LM. This invagination is flanked by the raised shoulders of the cell body (Figs. 3-5, 7). At their insertion point, the flagella are aligned along the dorsoventral axis of the invagination (Fig. 4). The cell surface consists of a continuous layer of nonoverlapping, oval scales with raised rims, showing a smooth central knob (Fig. 8) and giving the cell surface a rough appearance. Scales are shed without any apparent order.

The TEM whole mounts (Fig. 9) show the heart-shaped body (2.3 µm long and 3.3 µm wide), the flagella (5.6 and 4.9 µm long, respectively), and the haptonema (2.2 µm long). Cells joined at the pole opposite to the flagellar insertion were found (Fig. 10) that probably were division stages. Oval scales of two different sizes are visible around the cells (Figs. 9, 11) or attached to the cell surface in ultrathin sections (Figs. 12, 13). A faint pattern of radiating ribs can be seen on both kinds of scales (Fig. 11). The larger scales (0.25 x 0.18 µm), which form the external investment of the cells (Fig. 13), are the same ones visible with SEM. They have an upraised rim (Fig. 13). The central knob is visible with shadow casting (Fig. 11) and appears as a faint marking in glancing sections (Fig. 12). The inner-layer scales are smaller (0.18 x 0.13 µm) and have an inflexed rim (Fig. 13). As in P. globosa, P. antarctica, and P. pouchetii, the five-filament structure ejected by the cells exhibits a five-pointed star at its center (Fig. 14). Scale size and filament pattern did not show significant variability in specimens occasionally observed in whole mounts of natural samples or dilution cultures from the Gulf of Naples. Specimens from cultures MEDNS2 and MEDNS3 showed smaller scales (0.22 x 0.17 µm and 0.17 x 0.14 µm for larger and smaller scales, respectively).

The TEM sections (Figs. 15-22) show a similar organelle arrangement as described for P. globosa (as P. pouchetii in Parke et al. 1971). The two chloroplasts (Figs. 15, 17, 18, 20) are sausage to kidney-shaped, with a pyrenoid of the immersed type, pointed and having transversing thylakoids (Figs. 17, 18). The nucleus, with a single nucleolus (Fig. 16), is located at the end of the cell opposite the flagella (Figs. 15, 16) and is surrounded by a continuous membrane that includes the two chloroplasts (Fig. 18). Round or elongated sections of mitochondrial profiles are seen at different levels in the cell, from the nuclear to the flagellar pole (Figs. 15, 16, 20), where they occupy part of the two shoulders flanking the flagellar invagination. The Golgi body (Fig. 19) is composed of several stacked cisternae that are situated between the two chloroplasts. Scales are seen forming in the distal cisternae (Fig. 19, arrow).

As also seen with SEM, the two flagella and the haptonema emerge from the cell along a line that is transversal to the plane crossing the two chloroplasts (Fig. 20). This is also illustrated in Figure 16 because this section cuts the three appendages but does not cross the chloroplasts. In more proximal transversal sections, the flagellar bases are aligned along a line crossing both chloroplasts (not shown), indicating that torsion of the two basal bodies takes place proceeding from their proximal ends toward the point where the flagella emerge from the cell. The flagellar bases and transition zone (Fig. 21) show the same features illustrated for other members of the Prymnesiophyceae (Birkhead and Pienaar 1994), including a distal and a proximal plate and an electron-dense core in the lumen of the bases. The haptonema has a distal swelling (Fig. 22) similar to that previously described for Phaeocystis globosa (Parke et al. 1971).

References:

Zingone, A., Chrétiennot-Dinet, M. -J., Lange, M. & Medlin, L. (1999). Morphological and genetic characterization of Phaeocystis cordata and P. jahnii (Prymnesiophyceae), two new species from the Mediterranean Sea. Journal of Phycology. 35: 1322-1337. gs


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Phaeocystis cordata: Catalog entry compiled by Jeremy Young. Viewed: 25-9-2020

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