Back
Pterodinium ayachense
Pterodinium ayachense Guédé and Slimani in Guédé et al., 2014, p.298, figs.6A–P.
Holotype: Guédé et al., 2014, figs.6A–D.
Age: Maastrichtian–Selandian.
Original description (Guédé et al., 2014):
Pterodinium ayachensis Guédé and Slimani nov. sp. Fig. 6
1993. Pterodinium? sp. C - Schiøler and Wilson, figs. pp. 3–10, pl. 4, fig. 7.
1998. Pterodinium sp. C in Schiøler and Wilson, 1993 - Cavagnetto and Tambareau, fig. 9A.
2010. Pterodinium? sp. C of Schiøler and Wilson, 1993 - Slimani, Table S1.
Etymology: Named after the village Arba Ayacha nearby the outcrop.
Holotype: Sample Th4, slide 1, EF coordinates B54/1 (Fig. 6(A– D)). Specimen dimensions: total length 43 µm, total width 42 mm, central body length 35 µm, central body width 33 µm.
Repository: Botanical collection of the National Herbarium (RAB), Scientific Institute, Mohammed V-Agdal University, Rabat, Morocco.
Type locality and horizon: Tahar section (Jbel Tahar, Arba Ayacha, Larache Province, northwestern Morocco), Upper Maastrichtian; sample Th4, about 64 m below the K–Pg boundary.
Occurrence: Upper Maastrichtian (samples Th1 to Th7b, Tahar section; this study); Maastrichtian of the Danish North Sea (Schiøler and Wilson, 1993); Selandian of Oraas, French Atlantic Pyrenees (Cavagnetto and Tambareau, 1998); Upper Maastrichtian–lower Danian at Ouled Haddou, northeastern Morocco (Slimani et al., 2010).
Measurements (min-[mean]-max; 10 specimens measured): total length 43-[48]-53 µm, total width 40-[42]-46 µm, central body length 25-[31]-35 µm, central body width 23-[29]-35 µm, septa height 6-15 µm.
Diagnosis: Small, spherical to ovoidal, smooth and thin-walled Pterodinium characterized by high parasutural septa with slightly convex distal margin, but generally unindented in the gonal areas; a continuous and regular overall cyst outline reflecting the central body shape. The paratabulation is expressed by the precingular archeopyle type P, the paracingulum and the parasulcus. Other indications of the paratabulation are often indiscernible.
Description: This small-sized murochorate dinoflagellate cyst has a spherical to ovoidal central body. An apical horn is lacking. The wall of the central body consists of a smooth, hyaline and thin autophragm with a maximum thickness of 1 mm. Smooth and high parasutural septa (about half the central body diameter) arise from the central body. The distal margins of the septa are simple, slightly convex and enlarged, but generally unindented in the gonal areas. The overall cyst outline is continuous and regular and often has the same silhouette as the central body. The reflected gonyaulacoid paratabulation is 4’, 6’’, 6c, 5’’’, 1’’’’, Xs. The paracingulum, the parasulcus and the precingular archeopyle are often the sole expression of the paratabulation. The paracingulum is slightly laevorotatory. The parasulcus is sigmoidal and untabulated. The archeopyle is formed by the release of the precingular paraplate 300. The operculum is free or in place.
Remarks: The features of this new species are identical to the specimens figured as Pterodinium? sp. C by Schiøler and Wilson (1993: pl. 4, fig. 7), Pterodinium sp. C in Schiøler and Wilson (1993) by Cavagnetto and Tambareau (1998: fig. 9A), and Pterodinium sp? C of Schiøler and Wilson (1993) by Slimani et al. (2010: table S1). It differs from all other Pterodinium species by its smaller size, the absence of an apical horn, the high parasutural septa (half of the central body diameter) with slightly convex distal margins that are simple and generally unindented in the gonal areas, and a continuous and regular overall cyst outline reflecting the central body shape. Pterodinium agadirense resembles the new species in its septa arrangement, but differs in being larger and having an apical horn.
Holotype: Guédé et al., 2014, figs.6A–D.
Age: Maastrichtian–Selandian.
Original description (Guédé et al., 2014):
Pterodinium ayachensis Guédé and Slimani nov. sp. Fig. 6
1993. Pterodinium? sp. C - Schiøler and Wilson, figs. pp. 3–10, pl. 4, fig. 7.
1998. Pterodinium sp. C in Schiøler and Wilson, 1993 - Cavagnetto and Tambareau, fig. 9A.
2010. Pterodinium? sp. C of Schiøler and Wilson, 1993 - Slimani, Table S1.
Etymology: Named after the village Arba Ayacha nearby the outcrop.
Holotype: Sample Th4, slide 1, EF coordinates B54/1 (Fig. 6(A– D)). Specimen dimensions: total length 43 µm, total width 42 mm, central body length 35 µm, central body width 33 µm.
Repository: Botanical collection of the National Herbarium (RAB), Scientific Institute, Mohammed V-Agdal University, Rabat, Morocco.
Type locality and horizon: Tahar section (Jbel Tahar, Arba Ayacha, Larache Province, northwestern Morocco), Upper Maastrichtian; sample Th4, about 64 m below the K–Pg boundary.
Occurrence: Upper Maastrichtian (samples Th1 to Th7b, Tahar section; this study); Maastrichtian of the Danish North Sea (Schiøler and Wilson, 1993); Selandian of Oraas, French Atlantic Pyrenees (Cavagnetto and Tambareau, 1998); Upper Maastrichtian–lower Danian at Ouled Haddou, northeastern Morocco (Slimani et al., 2010).
Measurements (min-[mean]-max; 10 specimens measured): total length 43-[48]-53 µm, total width 40-[42]-46 µm, central body length 25-[31]-35 µm, central body width 23-[29]-35 µm, septa height 6-15 µm.
Diagnosis: Small, spherical to ovoidal, smooth and thin-walled Pterodinium characterized by high parasutural septa with slightly convex distal margin, but generally unindented in the gonal areas; a continuous and regular overall cyst outline reflecting the central body shape. The paratabulation is expressed by the precingular archeopyle type P, the paracingulum and the parasulcus. Other indications of the paratabulation are often indiscernible.
Description: This small-sized murochorate dinoflagellate cyst has a spherical to ovoidal central body. An apical horn is lacking. The wall of the central body consists of a smooth, hyaline and thin autophragm with a maximum thickness of 1 mm. Smooth and high parasutural septa (about half the central body diameter) arise from the central body. The distal margins of the septa are simple, slightly convex and enlarged, but generally unindented in the gonal areas. The overall cyst outline is continuous and regular and often has the same silhouette as the central body. The reflected gonyaulacoid paratabulation is 4’, 6’’, 6c, 5’’’, 1’’’’, Xs. The paracingulum, the parasulcus and the precingular archeopyle are often the sole expression of the paratabulation. The paracingulum is slightly laevorotatory. The parasulcus is sigmoidal and untabulated. The archeopyle is formed by the release of the precingular paraplate 300. The operculum is free or in place.
Remarks: The features of this new species are identical to the specimens figured as Pterodinium? sp. C by Schiøler and Wilson (1993: pl. 4, fig. 7), Pterodinium sp. C in Schiøler and Wilson (1993) by Cavagnetto and Tambareau (1998: fig. 9A), and Pterodinium sp? C of Schiøler and Wilson (1993) by Slimani et al. (2010: table S1). It differs from all other Pterodinium species by its smaller size, the absence of an apical horn, the high parasutural septa (half of the central body diameter) with slightly convex distal margins that are simple and generally unindented in the gonal areas, and a continuous and regular overall cyst outline reflecting the central body shape. Pterodinium agadirense resembles the new species in its septa arrangement, but differs in being larger and having an apical horn.