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Spiniferites pseudorhomboideus
Derivation of name. From the Latin pseudo meaning pretended, in reference to the similarity in shape and size of Spiniferites rhomboideus.
Holotype. Plate 5, figure 1; from a cuttings sample at 2552m, well 25/4-13S. Cyst size with processes, length ¼40.5mm, width ¼39mm.
Type locality. Norwegian North Sea Quad 25 – Alvheim Field, Lista Formation.
Diagnosis. Cyst sub-rounded to pentagonal/polygonal in shape. Processes are numerous, very short, and truncate, proximally united by well-developed, low sutural crests. Gonal processes are robust, while intergonal processes are thinner and variable in number across plates. Processes lack the typical bi- or trifurcate terminations characteristic of most Spiniferites species, including the closely related species Spiniferites rhomboideus.
Description. Intermediate-sized, proximochorate dinoflagellate cyst exhibiting marked dorso-ventral compression. Central body shape ranges from sub-rounded to polygonal or pentagonal. The wall is relatively thin, ranging from smooth to scabrate in texture. Gonal and intergonal processes are uniformly short and truncate, with gonal processes more robust than the intergonal processes. The processes are interconnected by a continuous, low sutural crest, occasionally exhibiting small perforations (see arrows in Plate 5, fig 1, 4). Intergonal processes are numerous (c. 4–8 per boundary between adjacent plates) and often aligned along the crests, with variation in number and size depending on plate dimensions. Processes are non-furcate, distinguishing this species from most congeners. Tabulation is not clearly discernible, often obscured by folding. The archeopyle is precingular, formed by the loss of plate 300, with a free operculum.
Dimensions. Overall length of the cyst body 35 (43) 49um, width 30 (37) 46um, processes length 2 (3.5) 5.5um. Number of specimens measured =18.
Comparison. This short-ranging new species closely resembles Spiniferites rhomboideus (Vieira and Mahdi 2019), but differs primarily in possessing uniformly truncate, non-furcate processes, lacking the bi- and trifurcate terminations observed in S. rhomboideus. Spiniferites pseudorhomboideus also shares similarities with S. truncatus (Vieira and Mahdi 2019), as both taxa exhibit truncate, non-furcate processes. However, whereas S. truncatus displays only gonal processes, S. pseudorhomboideus is distinguished by numerous gonal processes distributed along the sutural crests. In addition, S. pseudorhomboideus shows small perforations along the sutural crests, a feature recently documented in Spiniferites magnificus and S. rhomboideus (Vieira et al. 2025).
Holotype. Plate 5, figure 1; from a cuttings sample at 2552m, well 25/4-13S. Cyst size with processes, length ¼40.5mm, width ¼39mm.
Type locality. Norwegian North Sea Quad 25 – Alvheim Field, Lista Formation.
Diagnosis. Cyst sub-rounded to pentagonal/polygonal in shape. Processes are numerous, very short, and truncate, proximally united by well-developed, low sutural crests. Gonal processes are robust, while intergonal processes are thinner and variable in number across plates. Processes lack the typical bi- or trifurcate terminations characteristic of most Spiniferites species, including the closely related species Spiniferites rhomboideus.
Description. Intermediate-sized, proximochorate dinoflagellate cyst exhibiting marked dorso-ventral compression. Central body shape ranges from sub-rounded to polygonal or pentagonal. The wall is relatively thin, ranging from smooth to scabrate in texture. Gonal and intergonal processes are uniformly short and truncate, with gonal processes more robust than the intergonal processes. The processes are interconnected by a continuous, low sutural crest, occasionally exhibiting small perforations (see arrows in Plate 5, fig 1, 4). Intergonal processes are numerous (c. 4–8 per boundary between adjacent plates) and often aligned along the crests, with variation in number and size depending on plate dimensions. Processes are non-furcate, distinguishing this species from most congeners. Tabulation is not clearly discernible, often obscured by folding. The archeopyle is precingular, formed by the loss of plate 300, with a free operculum.
Dimensions. Overall length of the cyst body 35 (43) 49um, width 30 (37) 46um, processes length 2 (3.5) 5.5um. Number of specimens measured =18.
Comparison. This short-ranging new species closely resembles Spiniferites rhomboideus (Vieira and Mahdi 2019), but differs primarily in possessing uniformly truncate, non-furcate processes, lacking the bi- and trifurcate terminations observed in S. rhomboideus. Spiniferites pseudorhomboideus also shares similarities with S. truncatus (Vieira and Mahdi 2019), as both taxa exhibit truncate, non-furcate processes. However, whereas S. truncatus displays only gonal processes, S. pseudorhomboideus is distinguished by numerous gonal processes distributed along the sutural crests. In addition, S. pseudorhomboideus shows small perforations along the sutural crests, a feature recently documented in Spiniferites magnificus and S. rhomboideus (Vieira et al. 2025).