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Odontochitina kwutlkwuensis ssp. serrata
Etymology. From the Latin serratus with reference to the serrate appearance of the ambital margin due to the presence of denticulation and angular projections of periphragm.
Holotype. Plate 13A–C, Sample 20 (GSC C-677475), slide P5408-4A, EF S8/1.
Paratypes. Plate 13D–F, Sample 20, slide P5408-4 D, EF V42/3; Plate 13G–I, Sample 20, slide P5408-4 E, EF H33/0; Plate 14A–C, Sample 20, slide P5408-4 B, EF W19/0; Plate 14D–F, Sample 20, slide P5408-4 C, EF H23/3; Plate 14G–I, Sample 19, slide P5408-3 C, EF P29/1.
Type locality. Informally-named ‘Gladstone Bay’ intertidal platform (49.5845◦-124.8407◦), northwestern Denman Island, British Columbia, Canada (Fig. 1B, locality 3).
Type stratum. Upper Cedar District Formation, lower upper Campanian.
Repository. Geological Survey of Canada.
Diagnosis. A cornucavate to circumcavate subspecies of Odontochitina kwutlkwuensis with ceratoid ambitus and three large distally-open horns. Endophragm and periphragm microfoveolate-microcorrugate, irregularly vesiculate. Gonyaulacoid tabulation expressed predominantly by the archeopyle margin and pericyst cingular ridges with denticulate folds reflecting sutures of the pre- and postcingular plate series.
Description. Members of Odontochitina kwutlkwuensis sp. nov. exhibiting the development of sutural denticulation and presenting jagged, angular irregularity along the ambital margin. Forms herein assigned to O. kwutlkwuensis subsp. kwutlkwuensis sp. et subsp. nov. are distinguished by lacking denticulation and an angular ambitus.
Stratigraphic range. Lower upper Campanian.
Occurrence. Odontochitina kwutlkwuensis subsp. serrata sp. et subsp. nov. has been recovered from coastal exposures of the upper Cedar District Formation along northwestern Denman Island, British Columbia, Canada (samples 19, 20).
Remarks. The presence of denticles in Odontochitina kwutlkwuensis subsp. serrata sp. et subsp. nov. necessitates comparison with the genus Xenascus distinguished by Fensome et al.(2009, p. 67) from other ceratiacean forms largely on the grounds of a “periphragm with irregularly distributed, variably shaped processes, spines or protrusions” with a tendency toward sutural alignment. Namely, the Albian–Campanian species Xenascus esbeckianus as exemplified by the image figured by Yun(1981, pl. 14, fig. 4), which bears some similarity. However, the species lacks a distinct cingulum, exhibits occasionally interrupted longitudinal ridges that may merge into a row of spines that apparently do not reflect tabulation, and possesses a thin, smooth periphragm from which the processes emerge (Yun, 1981). The presence of all other defining characters associated with O. kwutlkwuensis sp. nov. coupled with shared proportions and cyst geometry suggests that O. kwutlkwuensis subsp. serrata sp. et subsp. nov. is an end member of the new species across its plexus of variation, and that denticulate projections alone do not take priority as to warrant assignment to Xenascus. Indeed, ceratiacean morphotypes have been observed that occupy a transitional space between both Odontochitina and Xenascus (A. Soliman pers. comm., 2025), presenting an intriguing avenue for further research.
Holotype. Plate 13A–C, Sample 20 (GSC C-677475), slide P5408-4A, EF S8/1.
Paratypes. Plate 13D–F, Sample 20, slide P5408-4 D, EF V42/3; Plate 13G–I, Sample 20, slide P5408-4 E, EF H33/0; Plate 14A–C, Sample 20, slide P5408-4 B, EF W19/0; Plate 14D–F, Sample 20, slide P5408-4 C, EF H23/3; Plate 14G–I, Sample 19, slide P5408-3 C, EF P29/1.
Type locality. Informally-named ‘Gladstone Bay’ intertidal platform (49.5845◦-124.8407◦), northwestern Denman Island, British Columbia, Canada (Fig. 1B, locality 3).
Type stratum. Upper Cedar District Formation, lower upper Campanian.
Repository. Geological Survey of Canada.
Diagnosis. A cornucavate to circumcavate subspecies of Odontochitina kwutlkwuensis with ceratoid ambitus and three large distally-open horns. Endophragm and periphragm microfoveolate-microcorrugate, irregularly vesiculate. Gonyaulacoid tabulation expressed predominantly by the archeopyle margin and pericyst cingular ridges with denticulate folds reflecting sutures of the pre- and postcingular plate series.
Description. Members of Odontochitina kwutlkwuensis sp. nov. exhibiting the development of sutural denticulation and presenting jagged, angular irregularity along the ambital margin. Forms herein assigned to O. kwutlkwuensis subsp. kwutlkwuensis sp. et subsp. nov. are distinguished by lacking denticulation and an angular ambitus.
Stratigraphic range. Lower upper Campanian.
Occurrence. Odontochitina kwutlkwuensis subsp. serrata sp. et subsp. nov. has been recovered from coastal exposures of the upper Cedar District Formation along northwestern Denman Island, British Columbia, Canada (samples 19, 20).
Remarks. The presence of denticles in Odontochitina kwutlkwuensis subsp. serrata sp. et subsp. nov. necessitates comparison with the genus Xenascus distinguished by Fensome et al.(2009, p. 67) from other ceratiacean forms largely on the grounds of a “periphragm with irregularly distributed, variably shaped processes, spines or protrusions” with a tendency toward sutural alignment. Namely, the Albian–Campanian species Xenascus esbeckianus as exemplified by the image figured by Yun(1981, pl. 14, fig. 4), which bears some similarity. However, the species lacks a distinct cingulum, exhibits occasionally interrupted longitudinal ridges that may merge into a row of spines that apparently do not reflect tabulation, and possesses a thin, smooth periphragm from which the processes emerge (Yun, 1981). The presence of all other defining characters associated with O. kwutlkwuensis sp. nov. coupled with shared proportions and cyst geometry suggests that O. kwutlkwuensis subsp. serrata sp. et subsp. nov. is an end member of the new species across its plexus of variation, and that denticulate projections alone do not take priority as to warrant assignment to Xenascus. Indeed, ceratiacean morphotypes have been observed that occupy a transitional space between both Odontochitina and Xenascus (A. Soliman pers. comm., 2025), presenting an intriguing avenue for further research.