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Protoperidinium tricingulatum
Protoperidinium tricingulatum Kawami et al., 2009, p.262–264, figs.2a–l,3a–p,4.
Originally (and now) Protoperidinium, subsequently Islandinium (combination not validly published). This species is based on an motile cell.
Holotype: Kawami et al., 2009, figs.3a–p.
Age: extant.
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Original description (Kawami et al., 2009):
Protoperidinium tricingulatum Kawami, van Wezel, Koeman et Matsuoka sp. nov. (Fig. 3).
Diagnosis : Motile cell is subspherical without spine or horn, 25.0–35.0 µm long and 30.0–36.0 µm wide. Plate formula: Po, X, 4′, 2a, 7″, 3c, 6s?, 5′″, 2″″ (Figs 3E–P and 4A–C). The first apical plate is a meta type. The first antapical plate is extremely small, and does not connect with the third postcingular plate. The cingulum consists of three plates. Cyst is round and brown. Cyst is smooth on the surface and bears many solid and slender spines with capitate distal tips randomly distributed on the surface. Archeopyle theropylic. Parasutures are formed at the plate boundaries of 2′/1a (complete), 2′/2a (complete), 3′/2a (complete), 4′/2a (complete), 4′/6″ (incomplete) and 4′/7″ (incomplete?).
Type locality: Huibertsplaat, Wadden Sea, the Netherlands (53°36′N, 06°35′E)
Etymology: The species epithet depicts its most distinguishing motile cell morphological feature, which is the characteristic three cingular plates.
Morphology of motile cell
Theca: 25–35 µm (mean 30.7 µm) in length, 30–36 µm (mean 34 µm) in width and approximately 20 µm in thickness (n = 12) (Fig. 3A,B). The motile cell of P. tricingulatum is subspherical and slightly compressed dorso-ventrally without spines or horns. Chloroplast is lacking. Epitheca is roundly conical and hypotheca is trapezoidal in shape. The cingulum circles at the equator of the cell, and is concave without lists on the edge. The sulcus is flat, slightly deflected towards the right, and reaches the antapical end (Fig. 3C). Vesicles are visible in light microscopy observation (Fig. 3B). The large spherical nucleus is located in the center of the cell. The thecal plate is thin, fragile, and smooth with trichocyst pores scattered on the surface (Fig. 3O).
Plate formula is Po, X, 4′, 2a, 7″, 3c, 6s?, 5′″, 2″″. The apical pore plate (Po) and canal plate (X) are square without the collar (Fig. 3E,H). The first apical plate (1′) is of the meta type (five-sided) (Fig. 3F). The second apical plate (2′) is elongatedly pentagonal in dorso-ventral direction (Fig. 3E). The third apical plate (3′) is quadrant and the sutures between the 3′ plate and the second intercalary plate (2a) form a quadrant arch (Fig. 3G). The fourth apical plate (4′) is hexagonal (Fig. 3H). The first anterior intercalary plate (1a) is an elongated pentagon in shape, located at the left side of the cell, and touches the 1′ plate directly (Fig. 3I). The second anterior intercalary plate (2a) is large and laterally wide, and bordered with the 2′, 3′, 4′, 1a, 2″, 3″, 4″, 5″ and 6″ plates (Fig. 3G,J,L). The first and seventh precingular plates (1″ and 7″) are asymmetrically trapezoidal and located on the ventral side (Fig. 3I,M). The second and sixth precingular plates (2″ and 6″) are pentagonal and located on the lateral side of the cell. The third, fourth and fifth precingular plates (3″, 4″, 5″) are rectangular with longitudinal compression. The cingulum consists of three plates and lacks the transitional plate (Fig. 3I–N). The length of the first cingular plate (1c) is equal to the width of the first postcingular plate (1′″) (Fig. 3I). The second cingular plate (2c) occupies mostly two-thirds of the cingulum at the dorsal side (Fig. 3K,L). The length of the third cingular plate (3c) is equal to the width of the fifth postcingular plate (5′″) (Fig. 3M). The sulcal plates are composed of four main large plates and two additional small plates. The anterior sulcal plate (Sa) is large, flat, seven-sided, and slightly invades into the epitheca (Fig. 3N). The flagellar pore is covered with a small fin rising from the left side of the right sulcal plate (Sd) (Fig. 3N). The left sulcal plate (Ss) is the largest among the sulcal plates and curved along the flagellar pore (Fig. 3N). The posterior sulcal plate (Sp) is large, V-shaped and located at the antapical end of the cell (Fig. 3N). The postcingular series consists of five plates (Fig. 3K,N,O,P). The first and fifth postcingular plates (1′″ and 5′″) are trapezoidal shape asymmetrically-inverted (Fig. 3N), and the posterior end of these plates touches the Sp plate. (Fig. 3N,O). The third and fourth postcingular plates (3′″ and 4′″) are rectangular. The 3′″ plate does not touch the first antapical (1″″) plate directly (Fig. 3P). The antapical series is composed of two plates. The 1″″ plate is remarkably smaller than the 2″″ plate and located on the ventral side (Fig. 3O). The 2″″ plate occupies almost the whole posterior part of the hypotheca (Fig. 3P).
Morphology of cysts:
Cyst: 27–34 µm (mean 31 µm) in diameter, the length of the spine is 5–7 µm (n = 10). Cysts are spherical and covered with numerous slender spines randomly distributed on the surface. The cyst wall is approximately 0.8 µm in thickness; light brown in color and its surface is smooth to slightly granulate (Fig. 2A,B). The spines are mostly solid except for a hollow proximal base (Fig. 2A,B) and capitate or cauliforate without branching at the distal extremities (Fig. 2A,K). The cross-section of the proximal bases of spines is circular (Fig. 2B). Approximately 15 spines are distributed per 100 µm2. The archeopyle is theropylic (slit-like) and these parasutures probably correspond to thecal plate boundaries of 2′/1a (complete: for definition, see Matsuoka 1988), 2′/2a (complete), 3′/2a (complete), 4′/2a (complete), 4′/6″ (incomplete) and 4′/7″ (incomplete?) (Figs 2C–I and 4d), because the parasutures that make the characteristic quadrant on the surface of some specimens show the same shape of the third apical plate (Fig. 2D,E).
Cyst-theca relationship of Protoperidinium tricingulatum:
The thecate cells of P. tricingulatum and round, brown, spiny cysts were found in the water column at Huibertsplaat, Wadden Sea. Some of the thecate cells in the water sample contained the round, brown and spiny cysts (Fig. 2J). Microscope observation on the thecae stained with Fluorescence Brightener 28 proved these cells to be identical to P. tricingulatum. To confirm the cyst-theca relationship of P. tricingulatum, DNA sequences were compared between the vegetative thecate cell and the cyst. DNA sequences of 5.8S rDNA, ITS1 and ITS2 region (approximately 600 bp) of a thecate cell and two cysts were determined (Figs 2K,L and 3C,D) and were found to be concordant (Fig. 5, GenBank/EMBL/DDBJ accession numbers AB474273–AB474275).
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Emendation (Potvin et al., 2013):
Islandinium tricingulatum (Kawami, van Wezel, Koeman et Matsuoka) comb. nov.
Basionym: Protoperidinium tricingulatum Kawami et al. 2009
Motile cell
Motile cell is subspherical without spine or horn, 25.0–35.0 μm long and 30.0–36.0 μm wide. Plate formula: Po, X, 4′, 2a, 7″, 3C, 6S?, 5′″, 2″″ (Figs. 3, e–p; 4, a–c, Kawami et al. 2009). The first apical plate is a meta type. The first antapical plate is extremely small, and does not connect with the third postcingular plate. The cingulum consists of three plates.
Cyst
Cyst is round and brown. Cyst is smooth on the surface and bears many solid and slender spines with capitate distal tips randomly distributed on the surface. Archeopyle theropylic. Parasutures are formed at the plate boundaries of 2′/1a (complete), 2′/2a (complete), 3′/2a (complete), 4′/2a (complete), 4′/6″ (incomplete) and 4′/7″ (incomplete?).
-----------------------------------
Originally (and now) Protoperidinium, subsequently Islandinium (combination not validly published). This species is based on an motile cell.
Holotype: Kawami et al., 2009, figs.3a–p.
Age: extant.
-----------------------------------
Original description (Kawami et al., 2009):
Protoperidinium tricingulatum Kawami, van Wezel, Koeman et Matsuoka sp. nov. (Fig. 3).
Diagnosis : Motile cell is subspherical without spine or horn, 25.0–35.0 µm long and 30.0–36.0 µm wide. Plate formula: Po, X, 4′, 2a, 7″, 3c, 6s?, 5′″, 2″″ (Figs 3E–P and 4A–C). The first apical plate is a meta type. The first antapical plate is extremely small, and does not connect with the third postcingular plate. The cingulum consists of three plates. Cyst is round and brown. Cyst is smooth on the surface and bears many solid and slender spines with capitate distal tips randomly distributed on the surface. Archeopyle theropylic. Parasutures are formed at the plate boundaries of 2′/1a (complete), 2′/2a (complete), 3′/2a (complete), 4′/2a (complete), 4′/6″ (incomplete) and 4′/7″ (incomplete?).
Type locality: Huibertsplaat, Wadden Sea, the Netherlands (53°36′N, 06°35′E)
Etymology: The species epithet depicts its most distinguishing motile cell morphological feature, which is the characteristic three cingular plates.
Morphology of motile cell
Theca: 25–35 µm (mean 30.7 µm) in length, 30–36 µm (mean 34 µm) in width and approximately 20 µm in thickness (n = 12) (Fig. 3A,B). The motile cell of P. tricingulatum is subspherical and slightly compressed dorso-ventrally without spines or horns. Chloroplast is lacking. Epitheca is roundly conical and hypotheca is trapezoidal in shape. The cingulum circles at the equator of the cell, and is concave without lists on the edge. The sulcus is flat, slightly deflected towards the right, and reaches the antapical end (Fig. 3C). Vesicles are visible in light microscopy observation (Fig. 3B). The large spherical nucleus is located in the center of the cell. The thecal plate is thin, fragile, and smooth with trichocyst pores scattered on the surface (Fig. 3O).
Plate formula is Po, X, 4′, 2a, 7″, 3c, 6s?, 5′″, 2″″. The apical pore plate (Po) and canal plate (X) are square without the collar (Fig. 3E,H). The first apical plate (1′) is of the meta type (five-sided) (Fig. 3F). The second apical plate (2′) is elongatedly pentagonal in dorso-ventral direction (Fig. 3E). The third apical plate (3′) is quadrant and the sutures between the 3′ plate and the second intercalary plate (2a) form a quadrant arch (Fig. 3G). The fourth apical plate (4′) is hexagonal (Fig. 3H). The first anterior intercalary plate (1a) is an elongated pentagon in shape, located at the left side of the cell, and touches the 1′ plate directly (Fig. 3I). The second anterior intercalary plate (2a) is large and laterally wide, and bordered with the 2′, 3′, 4′, 1a, 2″, 3″, 4″, 5″ and 6″ plates (Fig. 3G,J,L). The first and seventh precingular plates (1″ and 7″) are asymmetrically trapezoidal and located on the ventral side (Fig. 3I,M). The second and sixth precingular plates (2″ and 6″) are pentagonal and located on the lateral side of the cell. The third, fourth and fifth precingular plates (3″, 4″, 5″) are rectangular with longitudinal compression. The cingulum consists of three plates and lacks the transitional plate (Fig. 3I–N). The length of the first cingular plate (1c) is equal to the width of the first postcingular plate (1′″) (Fig. 3I). The second cingular plate (2c) occupies mostly two-thirds of the cingulum at the dorsal side (Fig. 3K,L). The length of the third cingular plate (3c) is equal to the width of the fifth postcingular plate (5′″) (Fig. 3M). The sulcal plates are composed of four main large plates and two additional small plates. The anterior sulcal plate (Sa) is large, flat, seven-sided, and slightly invades into the epitheca (Fig. 3N). The flagellar pore is covered with a small fin rising from the left side of the right sulcal plate (Sd) (Fig. 3N). The left sulcal plate (Ss) is the largest among the sulcal plates and curved along the flagellar pore (Fig. 3N). The posterior sulcal plate (Sp) is large, V-shaped and located at the antapical end of the cell (Fig. 3N). The postcingular series consists of five plates (Fig. 3K,N,O,P). The first and fifth postcingular plates (1′″ and 5′″) are trapezoidal shape asymmetrically-inverted (Fig. 3N), and the posterior end of these plates touches the Sp plate. (Fig. 3N,O). The third and fourth postcingular plates (3′″ and 4′″) are rectangular. The 3′″ plate does not touch the first antapical (1″″) plate directly (Fig. 3P). The antapical series is composed of two plates. The 1″″ plate is remarkably smaller than the 2″″ plate and located on the ventral side (Fig. 3O). The 2″″ plate occupies almost the whole posterior part of the hypotheca (Fig. 3P).
Morphology of cysts:
Cyst: 27–34 µm (mean 31 µm) in diameter, the length of the spine is 5–7 µm (n = 10). Cysts are spherical and covered with numerous slender spines randomly distributed on the surface. The cyst wall is approximately 0.8 µm in thickness; light brown in color and its surface is smooth to slightly granulate (Fig. 2A,B). The spines are mostly solid except for a hollow proximal base (Fig. 2A,B) and capitate or cauliforate without branching at the distal extremities (Fig. 2A,K). The cross-section of the proximal bases of spines is circular (Fig. 2B). Approximately 15 spines are distributed per 100 µm2. The archeopyle is theropylic (slit-like) and these parasutures probably correspond to thecal plate boundaries of 2′/1a (complete: for definition, see Matsuoka 1988), 2′/2a (complete), 3′/2a (complete), 4′/2a (complete), 4′/6″ (incomplete) and 4′/7″ (incomplete?) (Figs 2C–I and 4d), because the parasutures that make the characteristic quadrant on the surface of some specimens show the same shape of the third apical plate (Fig. 2D,E).
Cyst-theca relationship of Protoperidinium tricingulatum:
The thecate cells of P. tricingulatum and round, brown, spiny cysts were found in the water column at Huibertsplaat, Wadden Sea. Some of the thecate cells in the water sample contained the round, brown and spiny cysts (Fig. 2J). Microscope observation on the thecae stained with Fluorescence Brightener 28 proved these cells to be identical to P. tricingulatum. To confirm the cyst-theca relationship of P. tricingulatum, DNA sequences were compared between the vegetative thecate cell and the cyst. DNA sequences of 5.8S rDNA, ITS1 and ITS2 region (approximately 600 bp) of a thecate cell and two cysts were determined (Figs 2K,L and 3C,D) and were found to be concordant (Fig. 5, GenBank/EMBL/DDBJ accession numbers AB474273–AB474275).
-----------------------------------
Emendation (Potvin et al., 2013):
Islandinium tricingulatum (Kawami, van Wezel, Koeman et Matsuoka) comb. nov.
Basionym: Protoperidinium tricingulatum Kawami et al. 2009
Motile cell
Motile cell is subspherical without spine or horn, 25.0–35.0 μm long and 30.0–36.0 μm wide. Plate formula: Po, X, 4′, 2a, 7″, 3C, 6S?, 5′″, 2″″ (Figs. 3, e–p; 4, a–c, Kawami et al. 2009). The first apical plate is a meta type. The first antapical plate is extremely small, and does not connect with the third postcingular plate. The cingulum consists of three plates.
Cyst
Cyst is round and brown. Cyst is smooth on the surface and bears many solid and slender spines with capitate distal tips randomly distributed on the surface. Archeopyle theropylic. Parasutures are formed at the plate boundaries of 2′/1a (complete), 2′/2a (complete), 3′/2a (complete), 4′/2a (complete), 4′/6″ (incomplete) and 4′/7″ (incomplete?).
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