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Lejeunia diversiforma
Lejeunia diversiforma Bradford, 1977, p.49,52,55-56
NOW Lejeunecysta. Originally Lejeunia (generic name illegitimate), subsequently (and now) Lejeunecysta.
Following I.C.N. Article 55.1, the species name Lejeunia diversiforma is validly published even though the generic name Lejeunia is illegitimate.
Holotype: Bradford, 1977, fig.4:1
Age: Holocene
Original description, Bradford, 1977: Lejeunia diversiforma sp. nov. (Fig. 4: 1--4, 6, 7)
1964 Peridinium leonis cyst Pavillard; Evitt and Davidson: 5, Pl. l; 9, Text-fig. 1.
1968 Resting spore of Peridinium leonis Pavillard; Wall & Dale: 276, Pl. 2: 18-20.
1969 Peridinium leonis cyst Pavillard; Evitt, Text-fig. 18-3a.
1971 Resting spore of Peridinium leonis Pavillard; Wall; Pl. 2: 13.
Derivation of name: Latin diversus - different; Latin forma - shape; refers to the wide morphologic variation observed in this species.
DIAGNOSIS
Shape: Pericyst. Considerable variation in overall length-to-breadth ratio is exhibited by this species; however, the ambitus is always pentagonal. The epipericyst, usually of a smaller size than the hypopericyst, has straight-to-convex flanks forming a rounded-to-pointed apex. A high degree of variation occurs in the protrusion of the apical horn and in the thickening of the apical phragma (examples shown in Fig. 4). In some specimens considerable apical flattening can be observed (Fig. 4: 4). The hypopericyst has straight-to-concave flanks which taper posteriorly, usually into two antapical horns; however, these horns may be reduced so much that they are only represented by two small wall thickenings . In consequence, the antapical depression can vary from prominent to nonexistent; the distance between the antapical tips is likewise variable. However, the antapical phragma thickening appears to be a characteristic feature in this species. Endocyst: Not always observable; usually appressed to pericyst throughout. (Fig. 4: 2 and 7 illustrate the separated nature of the phragmas and the presence of an incomplete pericoel, which is usually more pronounced in the antapical region. Pericoel: When present, may be complete (Fig. 4: 7?) or as individual cavities at the tips of apical and antapical horns.
Phragma: Both layers usually of constant thickness, although pericingular, antapical and to a lesser extent apical phragma thickening are distinctive features of this species. Endophragm, when observed, is smooth and lacks ornamentation. Periphragm, usually thicker than endophragm, is often yellowish brown in colour with laevigate, striate or microgranular ornamentation. Longitudinal striations are observed in some forms on the antapical horns. The periphragm is susceptible to folding, although no regula patterns were recognized.
Paratabulation: Pericyst. Paratabulation indeterminate. Pericingulum zone is very narrow and occurs at the broadest portion of the tract. Pericingulum is represented by a narrow line composed of thickened phragma material. It is circular and nonexcavated, with no relative displacement of its ends. Perisulcus: when observed, is generally wide with a moderate depth and can extend into the epipericyst. In some specimens, folds in the phragma outline the perisulcal region. Endocyst: Paratabulation indeterminate.
Archeopyle: Standard hexa resulting from the detachment of the 2a anterior intercalary paraplate. Since the periphragm and endophragm are generally appressed in this area of the tract, there appear to be one archeopyle and one operculum. Archeopyle Formula l/I(2a/2a).
DIMENSIONS
Holotype-length 75 μm, breadth 77 μm, distance between antapical horns (distally) 23.5 μ.m, archeopyle height 18.6 μm, archeopyle width 25.0 μm. Other specimens-length 56-91 μm, breadth 61-87 μm, distance between antapical horns (distally) 16-30 μm, archeopyle height 7-20 μm, archeopyle width 23-33 μm. Number of specimens measured: 15.
HOLOTYPE
6(10) 103.1 x 22.0 Slide number, G.M.U.S. Pd 26, housed in the Palynology Collection of the Geology Museum, University of Saskatchewan. Locality: Recent sediments, water depth 22 metres, Straits of Hormuz, North of the Musandam Peninsula, Oman, 26.62° N, 56.43° E. Sample collected by Dr G. Evans, Imperial College, London. (Imperial College sample number PG/1/6263).
REMARKS
Lejeunia diversiforma shows a high degree of morphologic variation in most regions of the tract. This, however, is more obvious in the antapical area, as the height of the antapical depression, the length of the horns, and the distance between their tips are particularly variable. This form is comparable in many features with L. hyalina Gerlach, 1961; however, the latter differs in having a wider and more deeply excavated pericingulum, a constantly prominent apical horn and a thinner, more granular phragma. L. diversif orma may be compared with cysts described by Reid ( 1972, unpublished thesis) from around the British Isles.
THECAL AFFINITY
Cysts similar to these forms have been shown (Wall & Dale 1968) to give rise toPeridinium leonis Pavillard, 1916. However, the wide variation in some of the morphologic characters observed in L. diversiforma may suggest that these cysts could possibly produce several different motile species of dinoflagellates. In fact, Wall & Dale (1968) commented that the relationship of P. leonis with other similar dinoflagellates is unclear, and that species such as P. marielebourae and P. obtusum may be synonymous.
OCCURRENCE
Rare to common. Found in the majority of samples located along the Iranian coastline, from the northwestern end of the Persian Gulf to the Straits of Hormuz; also present in three samples from the south and west of the Northern Arabian Sea, in one sample from the Gulf of Oman and in the majority of the samples from around the east coast of the Musandam Peninsula (Fig. 5).
PREVIOUSLY KNOWN DISTRIBUTION
Recent. Reid (1972, unpublished thesis) describes a scattered distribution around the coast of the British Isles. Wall & Dale (1968) observed their forms from waters and sediments off Wood's Hole, Massachusetts, while Evitt & Davidson (1964) found these cysts in tidal pools on the Californian coast. Harada (1974, unpublished thesis) illustrated several forms with L. diversiforma characters from the Japanese continental shelf.
NOW Lejeunecysta. Originally Lejeunia (generic name illegitimate), subsequently (and now) Lejeunecysta.
Following I.C.N. Article 55.1, the species name Lejeunia diversiforma is validly published even though the generic name Lejeunia is illegitimate.
Holotype: Bradford, 1977, fig.4:1
Age: Holocene
Original description, Bradford, 1977: Lejeunia diversiforma sp. nov. (Fig. 4: 1--4, 6, 7)
1964 Peridinium leonis cyst Pavillard; Evitt and Davidson: 5, Pl. l; 9, Text-fig. 1.
1968 Resting spore of Peridinium leonis Pavillard; Wall & Dale: 276, Pl. 2: 18-20.
1969 Peridinium leonis cyst Pavillard; Evitt, Text-fig. 18-3a.
1971 Resting spore of Peridinium leonis Pavillard; Wall; Pl. 2: 13.
Derivation of name: Latin diversus - different; Latin forma - shape; refers to the wide morphologic variation observed in this species.
DIAGNOSIS
Shape: Pericyst. Considerable variation in overall length-to-breadth ratio is exhibited by this species; however, the ambitus is always pentagonal. The epipericyst, usually of a smaller size than the hypopericyst, has straight-to-convex flanks forming a rounded-to-pointed apex. A high degree of variation occurs in the protrusion of the apical horn and in the thickening of the apical phragma (examples shown in Fig. 4). In some specimens considerable apical flattening can be observed (Fig. 4: 4). The hypopericyst has straight-to-concave flanks which taper posteriorly, usually into two antapical horns; however, these horns may be reduced so much that they are only represented by two small wall thickenings . In consequence, the antapical depression can vary from prominent to nonexistent; the distance between the antapical tips is likewise variable. However, the antapical phragma thickening appears to be a characteristic feature in this species. Endocyst: Not always observable; usually appressed to pericyst throughout. (Fig. 4: 2 and 7 illustrate the separated nature of the phragmas and the presence of an incomplete pericoel, which is usually more pronounced in the antapical region. Pericoel: When present, may be complete (Fig. 4: 7?) or as individual cavities at the tips of apical and antapical horns.
Phragma: Both layers usually of constant thickness, although pericingular, antapical and to a lesser extent apical phragma thickening are distinctive features of this species. Endophragm, when observed, is smooth and lacks ornamentation. Periphragm, usually thicker than endophragm, is often yellowish brown in colour with laevigate, striate or microgranular ornamentation. Longitudinal striations are observed in some forms on the antapical horns. The periphragm is susceptible to folding, although no regula patterns were recognized.
Paratabulation: Pericyst. Paratabulation indeterminate. Pericingulum zone is very narrow and occurs at the broadest portion of the tract. Pericingulum is represented by a narrow line composed of thickened phragma material. It is circular and nonexcavated, with no relative displacement of its ends. Perisulcus: when observed, is generally wide with a moderate depth and can extend into the epipericyst. In some specimens, folds in the phragma outline the perisulcal region. Endocyst: Paratabulation indeterminate.
Archeopyle: Standard hexa resulting from the detachment of the 2a anterior intercalary paraplate. Since the periphragm and endophragm are generally appressed in this area of the tract, there appear to be one archeopyle and one operculum. Archeopyle Formula l/I(2a/2a).
DIMENSIONS
Holotype-length 75 μm, breadth 77 μm, distance between antapical horns (distally) 23.5 μ.m, archeopyle height 18.6 μm, archeopyle width 25.0 μm. Other specimens-length 56-91 μm, breadth 61-87 μm, distance between antapical horns (distally) 16-30 μm, archeopyle height 7-20 μm, archeopyle width 23-33 μm. Number of specimens measured: 15.
HOLOTYPE
6(10) 103.1 x 22.0 Slide number, G.M.U.S. Pd 26, housed in the Palynology Collection of the Geology Museum, University of Saskatchewan. Locality: Recent sediments, water depth 22 metres, Straits of Hormuz, North of the Musandam Peninsula, Oman, 26.62° N, 56.43° E. Sample collected by Dr G. Evans, Imperial College, London. (Imperial College sample number PG/1/6263).
REMARKS
Lejeunia diversiforma shows a high degree of morphologic variation in most regions of the tract. This, however, is more obvious in the antapical area, as the height of the antapical depression, the length of the horns, and the distance between their tips are particularly variable. This form is comparable in many features with L. hyalina Gerlach, 1961; however, the latter differs in having a wider and more deeply excavated pericingulum, a constantly prominent apical horn and a thinner, more granular phragma. L. diversif orma may be compared with cysts described by Reid ( 1972, unpublished thesis) from around the British Isles.
THECAL AFFINITY
Cysts similar to these forms have been shown (Wall & Dale 1968) to give rise toPeridinium leonis Pavillard, 1916. However, the wide variation in some of the morphologic characters observed in L. diversiforma may suggest that these cysts could possibly produce several different motile species of dinoflagellates. In fact, Wall & Dale (1968) commented that the relationship of P. leonis with other similar dinoflagellates is unclear, and that species such as P. marielebourae and P. obtusum may be synonymous.
OCCURRENCE
Rare to common. Found in the majority of samples located along the Iranian coastline, from the northwestern end of the Persian Gulf to the Straits of Hormuz; also present in three samples from the south and west of the Northern Arabian Sea, in one sample from the Gulf of Oman and in the majority of the samples from around the east coast of the Musandam Peninsula (Fig. 5).
PREVIOUSLY KNOWN DISTRIBUTION
Recent. Reid (1972, unpublished thesis) describes a scattered distribution around the coast of the British Isles. Wall & Dale (1968) observed their forms from waters and sediments off Wood's Hole, Massachusetts, while Evitt & Davidson (1964) found these cysts in tidal pools on the Californian coast. Harada (1974, unpublished thesis) illustrated several forms with L. diversiforma characters from the Japanese continental shelf.