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Lejeunecysta applanata
Lejeunecysta applanata (Bradford, 1977) Artzner and Dörhöfer, 1978
NOW Trinovantedinium. Originally Lejeunia (generic name illegitimate), subsequently Lejeunecysta, thirdly (and now) Trinovantedinium, fourthly Capillicysta.
Taxonomic junior synonym: Trinovantedinium capitatum Reid, 1977 (November), by implication in Matsuoka (1984b, p.6), who did not specify priority, and de Verteuil and Norris (1992, p.408).
Holotype: Bradford, 1977, figs.2:1-4
Age: Recent
Original description, Bradford, 1977: Lejeunia applanata sp. nov. (Fig. 2: 1-8)
1908 Peridinoid cyst; Paulsen: 11, Fig. 8.
1968 Resting spore of Peridinium sp. cf. P. pentagonum Gran: Wall & Dale; 274, Pl. 2; 11, 12.
Derivation of name: Latin applanata-flat; referring to the dorsoventral compression of the cyst.
DIAGNOSIS
Shape: Pericyst. Ambitus shows considerable variation in length-breadth ratio, but always retains its pentagonal shape; cysts are always flattened dorsoventrally. The epipericyst, similar in size to the hypopericyst, has convex flanks, converging apically into a short horn or apical boss. The hypopericyst has straight-to-concave sides; it tapers posteriorly into two distinct antapical horns. These borns are separated by a shallow-to-moderately deep antapical depression. Each horn may be either rounded or pointed distally; on rare occasions, the horns may be very slightly asymmetrical. Endocyst. Not always observable; usually ap"' pressed to pericyst throughout. Fig. 2: 1-4 illustrate the separated nature of the endocyst and the presence of a complete pericoel. The endocyst, when observed separated from the pericyst, displays the typical pentagonal ambital outline. Pericoel. When present, may be complete or as individual cavities at the tips of the apical and antapical horns.
Phragma: Both layers usually of constant thickness and inseparable. Occasional thickening towards the distal regions of the apical and antapical horns. Endophragm, when observed, smooth and lacking in ornamentation. Periphragm thin and usually colourless. Short spines, both parasutural and intratabular, are a diagnostic feature ; however, some intratabular areas possess very few spines, and consequently leave large bald areas on the tract surface. Some spines have capitate distal tips, but most have simple terminations.
Paratabulation: Pericyst. Paratabulation indeterminate. Pericingulum. A row of short spines outlines the pericingulum zone. The pericingulum is narrow, excavated and shows little or no displacement: it is gently inclined posteriorly from the dorsal to the ventral surface. Perisulcus. Not seen in all specimens: when observed, it is wide and shallow, extending in part onto the epipericyst: widens posteriorly. Endocyst. Paratabulation indeterminate.
Archeopyle: Standard hexa resulting from the detachment of the 2a anterior intercalary paraplate. This paraplate may extend almost down to the pericingulum. Since the endophragm and periphragm are generally appressed in this area of the tract, there appear to be one archeopyle and one operculum. Archeopyle Formula I/I (2a/2a).
DIMENSIONS
Holotype-length 78 μm, breadth 74 μm, distance between antapical horns (distally) 25 ,m, maximum height of processes 2.5 μm; other specimens -length 53-87 μm, breadth 47-74 μm, distance between antapical horns (distally) 25-31 μm, maximum height of processes 5 μm. Number of specimens measured 25.
HOLOTYPE
302(8) 99.0x 18.9; slide number, G.M.U.S. Pd. 23, housed in the Palynology Collection of the Geological Museum, University of Saskatchewan. Locality: Recent sediments, water depth 50 metres, Ghubbat Ash Shabus, east coast of the Musandam Peninsula, Oman. Sample collected by the Royal Geographical Society of London Musandam Expedition, January 1972, and obtained from Dr C. Vita-Finzi, Department of Geography, University College, London. (Royal Geographical Society sample number 0/63.)
REMARKS
Lejeunia applanata corresponds to the forms described by Reid (1972, unpublished thesis) from the surface sediments around the British Isles. The Persian Gulf specimens are comparable in size with the British forms; however, the range of variation in forms of similar character as described by Wall & Dale (1968) includes much larger specimens (72-100 μm x 72-84 μm). L. applanata differs from Ginginodinium spinulosum Cookson and Eisenack 1960, by its less prominent apical horn and less squat hypocyst. The latter species also has a denser spinulose ornamentation and was recently described as having a large archeopyle (Formula 3I+3Pa) (Lentin & Williams 1975).
THECAL AFFINITY
These cysts are similar to those incubated by Wall & Dale (1968) to produce Peridinium pentagonum Gran, 1902. The cysts of P. pentagonum and P. cf. pentagonum of Wall & Dale (1968) show very slight differences, the latter having a distinctive ornamentation and marked apical and antapical projections. Wall & Dale (1968) considered that both these cyst types give rise to P. pentagonum; however, the reported distribution of P. pentagonum around the British Isles (Lebour 1925) does not agree with the distribution of the cyst (P. cf. pentagonum) as described by Reid (1972). Wood (1968) described the thecate stage as an estuarine and neritic form, which is widely distributed around the coasts of most oceans.
OCCURRENCE
Rare-to-common, becoming abundant in a few samples from the Musandam Peninsula and the northern Straits of Hormuz. Present in all the Eastern Musandam coastal sediments except for the two southernmost samples, while the odd specimen has been found in several localities in the Gulf of Oman and Northern Arabian Sea. The species has also been found in some areas within the Gulf, although greater numbers are observed towards the north coast and the front of the delta system in the north-west (Fig. 3).
PREVIOUSLY KNOWN DISTRIBUTION
Recent. Common in all samples off the coast of Britain which adjoin the open North Atlantic Ocean (Reid 1972); Harland (1973) recognized this species from recent sediments off south-western Scotland. Other reports of this cyst come from Jamaica, the Arabian Sea (Wall & Dale 1968), and the coast of Japan (Harada 1974).
NOW Trinovantedinium. Originally Lejeunia (generic name illegitimate), subsequently Lejeunecysta, thirdly (and now) Trinovantedinium, fourthly Capillicysta.
Taxonomic junior synonym: Trinovantedinium capitatum Reid, 1977 (November), by implication in Matsuoka (1984b, p.6), who did not specify priority, and de Verteuil and Norris (1992, p.408).
Holotype: Bradford, 1977, figs.2:1-4
Age: Recent
Original description, Bradford, 1977: Lejeunia applanata sp. nov. (Fig. 2: 1-8)
1908 Peridinoid cyst; Paulsen: 11, Fig. 8.
1968 Resting spore of Peridinium sp. cf. P. pentagonum Gran: Wall & Dale; 274, Pl. 2; 11, 12.
Derivation of name: Latin applanata-flat; referring to the dorsoventral compression of the cyst.
DIAGNOSIS
Shape: Pericyst. Ambitus shows considerable variation in length-breadth ratio, but always retains its pentagonal shape; cysts are always flattened dorsoventrally. The epipericyst, similar in size to the hypopericyst, has convex flanks, converging apically into a short horn or apical boss. The hypopericyst has straight-to-concave sides; it tapers posteriorly into two distinct antapical horns. These borns are separated by a shallow-to-moderately deep antapical depression. Each horn may be either rounded or pointed distally; on rare occasions, the horns may be very slightly asymmetrical. Endocyst. Not always observable; usually ap"' pressed to pericyst throughout. Fig. 2: 1-4 illustrate the separated nature of the endocyst and the presence of a complete pericoel. The endocyst, when observed separated from the pericyst, displays the typical pentagonal ambital outline. Pericoel. When present, may be complete or as individual cavities at the tips of the apical and antapical horns.
Phragma: Both layers usually of constant thickness and inseparable. Occasional thickening towards the distal regions of the apical and antapical horns. Endophragm, when observed, smooth and lacking in ornamentation. Periphragm thin and usually colourless. Short spines, both parasutural and intratabular, are a diagnostic feature ; however, some intratabular areas possess very few spines, and consequently leave large bald areas on the tract surface. Some spines have capitate distal tips, but most have simple terminations.
Paratabulation: Pericyst. Paratabulation indeterminate. Pericingulum. A row of short spines outlines the pericingulum zone. The pericingulum is narrow, excavated and shows little or no displacement: it is gently inclined posteriorly from the dorsal to the ventral surface. Perisulcus. Not seen in all specimens: when observed, it is wide and shallow, extending in part onto the epipericyst: widens posteriorly. Endocyst. Paratabulation indeterminate.
Archeopyle: Standard hexa resulting from the detachment of the 2a anterior intercalary paraplate. This paraplate may extend almost down to the pericingulum. Since the endophragm and periphragm are generally appressed in this area of the tract, there appear to be one archeopyle and one operculum. Archeopyle Formula I/I (2a/2a).
DIMENSIONS
Holotype-length 78 μm, breadth 74 μm, distance between antapical horns (distally) 25 ,m, maximum height of processes 2.5 μm; other specimens -length 53-87 μm, breadth 47-74 μm, distance between antapical horns (distally) 25-31 μm, maximum height of processes 5 μm. Number of specimens measured 25.
HOLOTYPE
302(8) 99.0x 18.9; slide number, G.M.U.S. Pd. 23, housed in the Palynology Collection of the Geological Museum, University of Saskatchewan. Locality: Recent sediments, water depth 50 metres, Ghubbat Ash Shabus, east coast of the Musandam Peninsula, Oman. Sample collected by the Royal Geographical Society of London Musandam Expedition, January 1972, and obtained from Dr C. Vita-Finzi, Department of Geography, University College, London. (Royal Geographical Society sample number 0/63.)
REMARKS
Lejeunia applanata corresponds to the forms described by Reid (1972, unpublished thesis) from the surface sediments around the British Isles. The Persian Gulf specimens are comparable in size with the British forms; however, the range of variation in forms of similar character as described by Wall & Dale (1968) includes much larger specimens (72-100 μm x 72-84 μm). L. applanata differs from Ginginodinium spinulosum Cookson and Eisenack 1960, by its less prominent apical horn and less squat hypocyst. The latter species also has a denser spinulose ornamentation and was recently described as having a large archeopyle (Formula 3I+3Pa) (Lentin & Williams 1975).
THECAL AFFINITY
These cysts are similar to those incubated by Wall & Dale (1968) to produce Peridinium pentagonum Gran, 1902. The cysts of P. pentagonum and P. cf. pentagonum of Wall & Dale (1968) show very slight differences, the latter having a distinctive ornamentation and marked apical and antapical projections. Wall & Dale (1968) considered that both these cyst types give rise to P. pentagonum; however, the reported distribution of P. pentagonum around the British Isles (Lebour 1925) does not agree with the distribution of the cyst (P. cf. pentagonum) as described by Reid (1972). Wood (1968) described the thecate stage as an estuarine and neritic form, which is widely distributed around the coasts of most oceans.
OCCURRENCE
Rare-to-common, becoming abundant in a few samples from the Musandam Peninsula and the northern Straits of Hormuz. Present in all the Eastern Musandam coastal sediments except for the two southernmost samples, while the odd specimen has been found in several localities in the Gulf of Oman and Northern Arabian Sea. The species has also been found in some areas within the Gulf, although greater numbers are observed towards the north coast and the front of the delta system in the north-west (Fig. 3).
PREVIOUSLY KNOWN DISTRIBUTION
Recent. Common in all samples off the coast of Britain which adjoin the open North Atlantic Ocean (Reid 1972); Harland (1973) recognized this species from recent sediments off south-western Scotland. Other reports of this cyst come from Jamaica, the Arabian Sea (Wall & Dale 1968), and the coast of Japan (Harada 1974).