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Spiniferites crassus
Derivation of name. From the Latin crassus meaning thick, stout with reference to the wall thickness.
Holotype. Plate 3, figure 1; from a core sample at 2115.55m, well 25/7-5. Cyst size with processes =49um, without
=37 um, process length =12um.
Type locality. Norwegian North Sea Quad 25 – Alvheim Field, Lista Formation.
Diagnosis. Proximochorate cyst, spherical to ovoidal, with a thick wall up to 4 mm. Processes are solid and gonal. Distally, processes are mainly trifurcate with bifid tips; proximally, they are connected to a thick and continuous sutural ridge (Plate 4, Fig. 5). The archeopyle is formed by the loss of a single precingular plate (300), operculum often free.
Description. Intermediate-sized, proximochorate cyst, spherical to ovoidal in shape, with a cyst wall approximately 3–4 um thick. The wall comprises two closely adpressed layers: a thick, minutely granulate to scabrate endophragm and a thinner, smooth periphragm. Under SEM, the central body surface exhibits faint scabrate ornamentation.
Processes are thick, relatively long (c. one-third to two-thirds of central body diameter in length), and gonal, with occasional specimens exhibiting shorter processes (less than one-third of central body diameter). These processes are connected by a thin, low (generally 2um high) continuous sutural ridge and terminate in bifurcate to minutely trifurcate distal ends. Process surfaces are typically smooth. SEM analysis reveals nanno-perforations at the process bases (see Plate 4, Fig. 5), extending towards the distal tips, and similar perforations occur along the sutural ridges. The archeopyle is precingular, formed by the loss of plate 300, with the operculum often free.
Dimensions. Cyst diameter with processes 45 (48) 56um, without processes 30 (35) 40um, processes length 5 (6) 12um. Number of specimens measured ¼25.
Comparison. Spiniferites crassus sp. nov. is distinguished by its unusually thick cyst wall and robust, thick processes. It most closely resembles Achomosphaera calosa Matsuoka 1983(Pliocene to Early Pleistocene, Japan), but differs in having a smoother periphragm that lacks the coarse grana characteristic of A. calosa. It also shows similarities to Spiniferites pachydermus (Rossignol 1964) Reid 1974(Pleistocene–Holocene), which shares a thick, circular central body; however, in S. pachydermus, the processes are notably thinner, and the cyst wall exhibits prominent granulation not observed in S. crassus sp. nov.
Remarks. This species was first recognized and recorded in the 1990s from Thanetian sediments of the Lista Formation in the North Sea Basin by palynologists at Ichron Limited (now Petrostrat Limited), under the informal name Spiniferites ‘pachyderma’. Spiniferites crassus sp. nov. is considered a particularly useful biostratigraphical marker within the Lista Formation due to its relatively high abundance in some areas and its short stratigraphical range (Figure 1).
Holotype. Plate 3, figure 1; from a core sample at 2115.55m, well 25/7-5. Cyst size with processes =49um, without
=37 um, process length =12um.
Type locality. Norwegian North Sea Quad 25 – Alvheim Field, Lista Formation.
Diagnosis. Proximochorate cyst, spherical to ovoidal, with a thick wall up to 4 mm. Processes are solid and gonal. Distally, processes are mainly trifurcate with bifid tips; proximally, they are connected to a thick and continuous sutural ridge (Plate 4, Fig. 5). The archeopyle is formed by the loss of a single precingular plate (300), operculum often free.
Description. Intermediate-sized, proximochorate cyst, spherical to ovoidal in shape, with a cyst wall approximately 3–4 um thick. The wall comprises two closely adpressed layers: a thick, minutely granulate to scabrate endophragm and a thinner, smooth periphragm. Under SEM, the central body surface exhibits faint scabrate ornamentation.
Processes are thick, relatively long (c. one-third to two-thirds of central body diameter in length), and gonal, with occasional specimens exhibiting shorter processes (less than one-third of central body diameter). These processes are connected by a thin, low (generally 2um high) continuous sutural ridge and terminate in bifurcate to minutely trifurcate distal ends. Process surfaces are typically smooth. SEM analysis reveals nanno-perforations at the process bases (see Plate 4, Fig. 5), extending towards the distal tips, and similar perforations occur along the sutural ridges. The archeopyle is precingular, formed by the loss of plate 300, with the operculum often free.
Dimensions. Cyst diameter with processes 45 (48) 56um, without processes 30 (35) 40um, processes length 5 (6) 12um. Number of specimens measured ¼25.
Comparison. Spiniferites crassus sp. nov. is distinguished by its unusually thick cyst wall and robust, thick processes. It most closely resembles Achomosphaera calosa Matsuoka 1983(Pliocene to Early Pleistocene, Japan), but differs in having a smoother periphragm that lacks the coarse grana characteristic of A. calosa. It also shows similarities to Spiniferites pachydermus (Rossignol 1964) Reid 1974(Pleistocene–Holocene), which shares a thick, circular central body; however, in S. pachydermus, the processes are notably thinner, and the cyst wall exhibits prominent granulation not observed in S. crassus sp. nov.
Remarks. This species was first recognized and recorded in the 1990s from Thanetian sediments of the Lista Formation in the North Sea Basin by palynologists at Ichron Limited (now Petrostrat Limited), under the informal name Spiniferites ‘pachyderma’. Spiniferites crassus sp. nov. is considered a particularly useful biostratigraphical marker within the Lista Formation due to its relatively high abundance in some areas and its short stratigraphical range (Figure 1).