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Ynezidinium tazaense
Ynezidinium tazaense, Slimani et al., 2008, p.334, 336
Holotype: Slimani et al., 2008, figs.5A–D,6A–B.
Age: early Danian.
Type locality: Ouled Haddou section, north of Taza, northern Morocco
Original description: Slimani et al., 2008:
Diagnosis: A species of Ynezidinium with an ovoidal to spherical microreticulate autocyst and a small apical protrusion. Gonyaulacoid tabulation with a characteristic epicystal plate arrangement, expressed by low and narrow sutural crests. Precingular, pentagonal archeopyle formed by loss of the precingular plate 300. Operculum detached.
Description:
Acavate, proximate autocyst, oval to round. Cyst wall 1-1.5 µm thick, microreticulate (Fig. 5L). An apical boss c. 3 µm in height and 10 µm in diameter is often present. Crests very low (0.5-1 µm high), solid and narrow (c. 0.5 µm wide).
Reflected tabulation is 4', 6'', 6c, 6''', 1p, 1'''', as, ps, 2s. The precingular (6'') plate is subpentagonal to subhexagonal. In many specimens the three anterior sides are almost equal in length and contact apical (1', 4') plates and sulcus (Figs. 5D and 6B). Plates 1' and 4' are rectangular to subrectangular, longitudinally parallel and of about equal length. Contacts 1'/6'' and 1'/sulcal area are almost equal in length. Plate 1' is separated from a large, straight, undifferentiated sulcal area (5-8 µm wide) by a small, narrow (1-2 µm wide), subrectangular sulcal field, limited posteriorly by a crest and located between precingular 1'' and 6'' plates (Figs. 5D and 6B).
Cingulum 4-7µm wide.
Anterior sulcal plate narrows anteriorly and widens posteriorly to meet posterior sulcal plate (ps), which is partially separated from sulcus by a short extension of a low crest (Fig. 6B). Postcingular plate 1''' is not visible. Antapical plate 1'''' is generally pentagonal and borders 3''', 4''', 5''', 1p and ps (Figs. 5C and 6B), but rarely subpentagonal to subhexagonal with a narrower contact with 6'''.
Dimensions (in µm):
Holotype, paratype and range for 12 specimens measured: length 48, 49, 38(45)50; width 45, 45, 35(41)50.
Affinities/Comparison: Ynezidinium tazaensis sp. nov. is easily recognized by the combination of a microreticulate wall surface, low, narrow sutural crests and the subpentagonal to subhexagonal shape of the precingular 6'' plate. It differs from Y. brevisulcatum (Michoux, 1985) Lucas-Clark and Helenes, 2000 and Y. pentahedrias (Damassa, 1979b) Lucas-Clark and Helenes, 2000 and other species in being rounded in outline and in having a thinner and microreticulate wall, lower and narrower sutural crests, subpentagonal to subhexagonal 6'', a narrower anterior sulcal area and an apical boss. Ynezidinium pentahedrias also has a preapical tabulation, and Y. waipaense (Wilson, 1988) Lucas-Clark and Helenes, 2000 and Y. malloyi Lucas-Clark and Helenes, 2000 have a prominent apical horn rather than an apical boss.
Holotype: Slimani et al., 2008, figs.5A–D,6A–B.
Age: early Danian.
Type locality: Ouled Haddou section, north of Taza, northern Morocco
Original description: Slimani et al., 2008:
Diagnosis: A species of Ynezidinium with an ovoidal to spherical microreticulate autocyst and a small apical protrusion. Gonyaulacoid tabulation with a characteristic epicystal plate arrangement, expressed by low and narrow sutural crests. Precingular, pentagonal archeopyle formed by loss of the precingular plate 300. Operculum detached.
Description:
Acavate, proximate autocyst, oval to round. Cyst wall 1-1.5 µm thick, microreticulate (Fig. 5L). An apical boss c. 3 µm in height and 10 µm in diameter is often present. Crests very low (0.5-1 µm high), solid and narrow (c. 0.5 µm wide).
Reflected tabulation is 4', 6'', 6c, 6''', 1p, 1'''', as, ps, 2s. The precingular (6'') plate is subpentagonal to subhexagonal. In many specimens the three anterior sides are almost equal in length and contact apical (1', 4') plates and sulcus (Figs. 5D and 6B). Plates 1' and 4' are rectangular to subrectangular, longitudinally parallel and of about equal length. Contacts 1'/6'' and 1'/sulcal area are almost equal in length. Plate 1' is separated from a large, straight, undifferentiated sulcal area (5-8 µm wide) by a small, narrow (1-2 µm wide), subrectangular sulcal field, limited posteriorly by a crest and located between precingular 1'' and 6'' plates (Figs. 5D and 6B).
Cingulum 4-7µm wide.
Anterior sulcal plate narrows anteriorly and widens posteriorly to meet posterior sulcal plate (ps), which is partially separated from sulcus by a short extension of a low crest (Fig. 6B). Postcingular plate 1''' is not visible. Antapical plate 1'''' is generally pentagonal and borders 3''', 4''', 5''', 1p and ps (Figs. 5C and 6B), but rarely subpentagonal to subhexagonal with a narrower contact with 6'''.
Dimensions (in µm):
Holotype, paratype and range for 12 specimens measured: length 48, 49, 38(45)50; width 45, 45, 35(41)50.
Affinities/Comparison: Ynezidinium tazaensis sp. nov. is easily recognized by the combination of a microreticulate wall surface, low, narrow sutural crests and the subpentagonal to subhexagonal shape of the precingular 6'' plate. It differs from Y. brevisulcatum (Michoux, 1985) Lucas-Clark and Helenes, 2000 and Y. pentahedrias (Damassa, 1979b) Lucas-Clark and Helenes, 2000 and other species in being rounded in outline and in having a thinner and microreticulate wall, lower and narrower sutural crests, subpentagonal to subhexagonal 6'', a narrower anterior sulcal area and an apical boss. Ynezidinium pentahedrias also has a preapical tabulation, and Y. waipaense (Wilson, 1988) Lucas-Clark and Helenes, 2000 and Y. malloyi Lucas-Clark and Helenes, 2000 have a prominent apical horn rather than an apical boss.