Back
Lithodinia bejui
Lithodinia "bejui" (Zotto et al., 1987, p.199-202, pl.1, figs.1a-b,2a-c,3; text-figs.5a-c) Williams et al., 1993, p.55.
NOW Meiourogonyaulax. Originally(and now) Meiourogonyaulax, subsequently Lithodinia. This combination was not validly published in Dodekova (1992, p.46), since that author did not fully reference the basionym.
Holotype: Zotto et al., 1987, pl.1, figs.1a-b.
Age: Kimmeridgian.
Locus typicus: SW North-Atlantic
Original description: Zotto et al., 1987, p. 199-202: Meiourogonyaulax bejui
Description: Barrel-shaped, proximochorate-septate, leptodinioid cysts. Compressed specimens have a subspherical polyhedral outline; they tend to be flattened dorso-ventrally or laterally, but there are also oblique apical-antapical compressions; compression folds are rare or absent. Cyst wall consists of two appressed layers; pericoels absent. Apical and antapical horns lacking. Cingulum is well-developed; it is offset at the sulcus approximately one cingulum-width. Sulcus is well-developed and more-or-less straight. Tabulation is well-developed over the entire cyst, and is expressed by even, low-lying but erect, septa defining plate boundaries. Septa are completely alveolate, with alveolae crowded to produce a circularly reticulate pattern. Alveolae also occur in the intratabular areas of plate, where they are typically few and scattered and of uneven size; in only very few specimens are they sufficiently numerous to produce an intratabular alveolate reticulate pattern. Alveolare restricted to periphragm. Tabulation pattern sexiform gonyaulacoid with L- type ventral organization. Tabulation formula is gonyaulacacean, 2pr, (P.Q.), 4", Xa, 6"", 6c, 6""", p, 1"""", with the sulcus constructed of ps, rs, ls, ras, as and a flagellar scar plate (fs). The apical series consists of an elongated, slender, first apical (1") plate, the second (2") apical plate which is hexagonal and third (3") apical plate which is pentagonal, and a fourth apical (4") which is elongatedly pentagonal ("arrowhead"). The long axis of plate 4" is subparallel to that of plate 1", but is shorter. Plates 1", 2" and 4" have a common juncture at the apex. A small, oval, pre-apical plate (P) is situated at this juncture and may be elongated for a short distance along the 2"/4" plate boundary or may be almost circular. Plate 3" is offset from the apex along the length of this boundary. At the juncture of plates 2", 3", and 4", there is a second, smaller and typically circular, pre-apical plate (Q). Small anterior intercalary plates may occur near the base of the second and third apical plates, but could not be clearly distinguished because of the obscuring alveolate plate boundaries. The precingular series consists of a large mid-dorsal third precingular (3"") which is pentagonal, second (2"") and fourth (4"") precingular plates which are quadrate, and first (1""), fifth (5"") and sixth (6"") precingular plates which are pentagonal. Precingular plate 6"" is almost equidimensionally pentagoanl. All six plates of the cingulm are transversely rectangular to transversely elongated hexagonal; the boundaries between plates within this series are in about the same positions as those of the paltes within the precingular series. The postcingular series is characterized by a very small rectangular or quadrate first postcingular (1""") plate which is typically inserted into the sulcus against paltes ls, fs, and as. It is situated close to, but does not contact, the cinguulum. The second postcingular (2""") is larger and is about the same size as the posterior intercalary (lp) plate, which it contacts at its posterior boundary. The third postcingular (3""") plate is still larger and contacts plates 2""", lp and the single antapical (1""") plate without contacting the sulcus. The sulcus consists of sic plates. The posterior sulcal (ps) is relatively large and is rounded at its posterior end; it is only slightly intended into antapical plate 1""". The anterior sulcal (as) plate is also larger, but is more rectangular in outline. In contrast, the right sulcal (rs), left sulcal (ls), right anterior sulcal (ras) and flagellar scar (fs) plates form a quadrate cluster of very small plates that is largely restricted in position to the area of the sulcus immediately posterior to its intersection with the cingulum. The rs, ls, and ras plates are pentagonal, and the fs plate is hexagonal. Evidence of flagellar pore scars in the flagellar scar plate, or of any splitting of the sulcus, is absent. The archeopyle is apical and involves all plates of the apical series and the pre-apicals P and Q. The operculum is ismple and free, although in some specimens remains close to the archeople. size of cysts ranges from 51 to Ám high, and 56 to 73 Ám wide. Ten specimens were measured.
Afinities:
Zotto et al., 1987, p. 200-202: Meiourogonyaulax bejui
Meiourogonyaulax bejuii, new species is characterized by the L-type organization of its ventral surface, sexiform hypocystal tabulation, presence of pre-apical P and Q, apical plate 3" offset form the apex, mid-dorsal position of both precingular plate 3"" and postcingular plate 4""", the very small sulcal plates ras, fs, rs and ls relative to as and ps, and the well-developed alveolation of its septa. In detailsl of sulcal tabulation, it is very close to that of Leptodinium mirabile Klement (text-fig. 8). Klement (1960, p. 49, figs. 25-26) shows the same quadrate cluster of very small sulcal plates and the inserted rectangular plate which we interpret as postcingular 1""", after the tabulation illustrated by Dodekova (1966) [as Gonyaulacysta mirabile (Klement)].
Meiourogonyaulaux valensii Sarjeantis similar to M. bejuii in overall form and expression of tabulation by septa defining plate boundaries. M. valensii differs by its higher septa which are even higher at plate junctures, by the offset position of postcingular plate 4""" relative to precingular plate 3"", and by details of sulcal tabulation. In M. valensii (Sarjeant, in Davey et al. 1966 p. 145, fig 37), sulcal plates ls and rs are relatively large. Also, although the outline of the archeopyle in M. valensii suggests that the apical series in both species may be the same, it is not known if apical plate 3" is offset from the apex or if pre-apical plates P and Q are present. Further, in the holotype of M. valensii illustrated in Davey et al. (1966, pl. 15, fig. 7) the intratabular areas appear to be densely perforate but not alveolate, and the septa appear to be striatoreticulate and not alveolate. Also, the anterior sulcal plate (as) is attenuated, giving the appearance of as wedge-shaped sulcus.
Fenton et al. (1980, pl. 15 figs 1 and 3) illustrated a specimen as Lithodinia valensii (Sarjeant) Lentin and Williams 1977, which shows the same quadrate cluster of small sulcal plates as in M. bejuii. However, in their specimen the septa are striatoreticulate and not alveolate. Also, the intratabular areas do not appear to be perofrate or alveolate.
Meiourogonyaulax bejuii is similar in gross morphology to M. caytonensis (Sarjeant) Sarjeant 1969 and to Meiourogonyaulax sp. cf. M. caytonensis of Erkmen and Sarjeant 1980. These forms are distinguished by their irregularly perforate septa and by the apparent lack of sulcal tabulation.
NOW Meiourogonyaulax. Originally(and now) Meiourogonyaulax, subsequently Lithodinia. This combination was not validly published in Dodekova (1992, p.46), since that author did not fully reference the basionym.
Holotype: Zotto et al., 1987, pl.1, figs.1a-b.
Age: Kimmeridgian.
Locus typicus: SW North-Atlantic
Original description: Zotto et al., 1987, p. 199-202: Meiourogonyaulax bejui
Description: Barrel-shaped, proximochorate-septate, leptodinioid cysts. Compressed specimens have a subspherical polyhedral outline; they tend to be flattened dorso-ventrally or laterally, but there are also oblique apical-antapical compressions; compression folds are rare or absent. Cyst wall consists of two appressed layers; pericoels absent. Apical and antapical horns lacking. Cingulum is well-developed; it is offset at the sulcus approximately one cingulum-width. Sulcus is well-developed and more-or-less straight. Tabulation is well-developed over the entire cyst, and is expressed by even, low-lying but erect, septa defining plate boundaries. Septa are completely alveolate, with alveolae crowded to produce a circularly reticulate pattern. Alveolae also occur in the intratabular areas of plate, where they are typically few and scattered and of uneven size; in only very few specimens are they sufficiently numerous to produce an intratabular alveolate reticulate pattern. Alveolare restricted to periphragm. Tabulation pattern sexiform gonyaulacoid with L- type ventral organization. Tabulation formula is gonyaulacacean, 2pr, (P.Q.), 4", Xa, 6"", 6c, 6""", p, 1"""", with the sulcus constructed of ps, rs, ls, ras, as and a flagellar scar plate (fs). The apical series consists of an elongated, slender, first apical (1") plate, the second (2") apical plate which is hexagonal and third (3") apical plate which is pentagonal, and a fourth apical (4") which is elongatedly pentagonal ("arrowhead"). The long axis of plate 4" is subparallel to that of plate 1", but is shorter. Plates 1", 2" and 4" have a common juncture at the apex. A small, oval, pre-apical plate (P) is situated at this juncture and may be elongated for a short distance along the 2"/4" plate boundary or may be almost circular. Plate 3" is offset from the apex along the length of this boundary. At the juncture of plates 2", 3", and 4", there is a second, smaller and typically circular, pre-apical plate (Q). Small anterior intercalary plates may occur near the base of the second and third apical plates, but could not be clearly distinguished because of the obscuring alveolate plate boundaries. The precingular series consists of a large mid-dorsal third precingular (3"") which is pentagonal, second (2"") and fourth (4"") precingular plates which are quadrate, and first (1""), fifth (5"") and sixth (6"") precingular plates which are pentagonal. Precingular plate 6"" is almost equidimensionally pentagoanl. All six plates of the cingulm are transversely rectangular to transversely elongated hexagonal; the boundaries between plates within this series are in about the same positions as those of the paltes within the precingular series. The postcingular series is characterized by a very small rectangular or quadrate first postcingular (1""") plate which is typically inserted into the sulcus against paltes ls, fs, and as. It is situated close to, but does not contact, the cinguulum. The second postcingular (2""") is larger and is about the same size as the posterior intercalary (lp) plate, which it contacts at its posterior boundary. The third postcingular (3""") plate is still larger and contacts plates 2""", lp and the single antapical (1""") plate without contacting the sulcus. The sulcus consists of sic plates. The posterior sulcal (ps) is relatively large and is rounded at its posterior end; it is only slightly intended into antapical plate 1""". The anterior sulcal (as) plate is also larger, but is more rectangular in outline. In contrast, the right sulcal (rs), left sulcal (ls), right anterior sulcal (ras) and flagellar scar (fs) plates form a quadrate cluster of very small plates that is largely restricted in position to the area of the sulcus immediately posterior to its intersection with the cingulum. The rs, ls, and ras plates are pentagonal, and the fs plate is hexagonal. Evidence of flagellar pore scars in the flagellar scar plate, or of any splitting of the sulcus, is absent. The archeopyle is apical and involves all plates of the apical series and the pre-apicals P and Q. The operculum is ismple and free, although in some specimens remains close to the archeople. size of cysts ranges from 51 to Ám high, and 56 to 73 Ám wide. Ten specimens were measured.
Afinities:
Zotto et al., 1987, p. 200-202: Meiourogonyaulax bejui
Meiourogonyaulax bejuii, new species is characterized by the L-type organization of its ventral surface, sexiform hypocystal tabulation, presence of pre-apical P and Q, apical plate 3" offset form the apex, mid-dorsal position of both precingular plate 3"" and postcingular plate 4""", the very small sulcal plates ras, fs, rs and ls relative to as and ps, and the well-developed alveolation of its septa. In detailsl of sulcal tabulation, it is very close to that of Leptodinium mirabile Klement (text-fig. 8). Klement (1960, p. 49, figs. 25-26) shows the same quadrate cluster of very small sulcal plates and the inserted rectangular plate which we interpret as postcingular 1""", after the tabulation illustrated by Dodekova (1966) [as Gonyaulacysta mirabile (Klement)].
Meiourogonyaulaux valensii Sarjeantis similar to M. bejuii in overall form and expression of tabulation by septa defining plate boundaries. M. valensii differs by its higher septa which are even higher at plate junctures, by the offset position of postcingular plate 4""" relative to precingular plate 3"", and by details of sulcal tabulation. In M. valensii (Sarjeant, in Davey et al. 1966 p. 145, fig 37), sulcal plates ls and rs are relatively large. Also, although the outline of the archeopyle in M. valensii suggests that the apical series in both species may be the same, it is not known if apical plate 3" is offset from the apex or if pre-apical plates P and Q are present. Further, in the holotype of M. valensii illustrated in Davey et al. (1966, pl. 15, fig. 7) the intratabular areas appear to be densely perforate but not alveolate, and the septa appear to be striatoreticulate and not alveolate. Also, the anterior sulcal plate (as) is attenuated, giving the appearance of as wedge-shaped sulcus.
Fenton et al. (1980, pl. 15 figs 1 and 3) illustrated a specimen as Lithodinia valensii (Sarjeant) Lentin and Williams 1977, which shows the same quadrate cluster of small sulcal plates as in M. bejuii. However, in their specimen the septa are striatoreticulate and not alveolate. Also, the intratabular areas do not appear to be perofrate or alveolate.
Meiourogonyaulax bejuii is similar in gross morphology to M. caytonensis (Sarjeant) Sarjeant 1969 and to Meiourogonyaulax sp. cf. M. caytonensis of Erkmen and Sarjeant 1980. These forms are distinguished by their irregularly perforate septa and by the apparent lack of sulcal tabulation.