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Odontochitina kwutlkwuensis
Etymology. From the Pentl’atch Kwutl’kwu (Kwo-tl-kwo), in reference to the local region of the Salish Sea in the language of the K’´omoks and Qualicum First Peoples, the original inhabitants of central Vancouver and Denman islands, British Columbia, Canada.
Holotype. Plate 10A–C. Sample 18 (GSC 77455), slide E6-20 E, EF Y37/3.
Paratypes. Plate 10D–F, Sample 18, slide E6-20 D, EF B36/4; Plate 10G–I, Sample 18, slide E6-20 D, EF L23/2; Plate 11A–C, Sample 18, slide E6-20 D, EF B30/3; Plate 11D–F, Sample 18, slide E6-20 D, EF R30/ 4; Plate 11G–I, Sample 18, slide E6-20 D, EF D31/0; Plate 12A–C, Sample 18, slide E6-20 D, EF H46/4; Plate 12D–G, Sample 20, slide E6- 20 D, EF F18/3; Plate 12H, I, Sample 18, slide E6-20 D, EF B25/0; Plate 12J, K, Sample 18, slide E6-20 D, EF Z35/3; Plate 13A–C, Sample 20 (GSC C-677475), slide P5408-4 A, EF S8/1; 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; Plate 15A–C, stub 24D06, specimen 1 (CEDiT2024P194); Plate 15D–H, stub 24D02, specimen 28 (CEDiT2024P195); Plate 15I, J, stub 24D06, specimen 11 (CEDiT2024P196); Plate 16A–G, stub 24D02, specimen 27 (CEDiT2024P197); Plate 16H–J, stub 24D02, specimen 18 (CEDiT2024P198); Plate 17A, B, stub 24D01, specimen 2 (CEDiT2024P199); Plate 17C, stub 24D01, specimen 6 (CEDiT2024P200); Plate 17D–H, stub 24D02, specimen 15 (CEDiT2024P201).
Type locality. End of point ~365 m north of Chrisman Road terminus (49.5773◦-124.8401◦), 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 broadly circumcavate species of Odontochitina with ceratoid ambitus and three large distally-open horns. Endophragm and periphragm microfoveolate-microcorrugate, irregularly vesiculate, and occasionally denticulate. Gonyaulacoid tabulation expressed predominantly by the archeopyle margin and pericyst cingular ridges with folds reflecting sutures of the pre- and postcingular plate series.
Description. Cyst cornucavate to more commonly broadly circumcavate with ceratoid ambitus. Endocyst ellipsoidal with length exceeding width in 90 % of specimens by 19 % on average, and typically asymmetrical due to lateral distention toward—or development of bulge protruding into—the lateral horn. In a minority of specimens, a pronounced node-like boss is developed from the endocyst projecting into the apical horn (Plate 12H, I). Horns broad-based proximally, tapering distally with terminations generally open, ragged, or splayed into ribbon-like bands of periphragm. The lateral horn develops an elbow at its midpoint and undergoes an abrupt recurvature toward the antapex. Under SEM, the endophragm is seen to be narrowly punctate, vesiculate, and the periphragm densely microfoveolate-microcorrugate with unevenly distributed vesicles (e.g., Plate 15F; Plate 16G, J). Isolated intratabular vesicles vary greatly in size (from 0.5 to 5 μm in diameter) and can occur scattered throughout either wall layer (Plate 16G; Plate 17F–H). Many vesicles may be burst and calderic, exhibiting a concave bowl-like appearance (Plate 15F, G). In extreme cases, elongate, expansive vacuoles are situated along plate margins (e.g., Plate 12D; Plate 14C; Plate 16B, I). In rare specimens (<7 %), denticles up to 8 μm in length may arise from sutural crests in proximity to plate junctions and along the lateral margins of the perycist giving the appearance of a serrated ambitus (e.g., Plate 13B, E, F; Plate 14D). Tabulation is clearly expressed on the pericyst by the consistent presence of low, sutural ridges demarcating the boundaries of the precingular, cingular, and postcingular plate series as well as along the margins of the ventral sulcus. In some specimens, transverse ridges continue across the equatorial region presenting the cingulum most prominently as a deeply- incised furrow wrapping around the left lateral margin corresponding to the position of plate 1c (e.g., Plate 11C; Plate 16A, C). Inferred reflected tabulation formula 4′, 5′′, 5c, Xs, 6′′′, 2′′′′.
Dimensions. Holotype: endocyst length (without operculum) =57.0 μm; endocyst width =44.8 μm; endocyst length-to-width ratio =1.3; lateral horn base width =24.0 μm; antapical horn base width =35.6 μm; lateral horn length =39.2 μm; antapical horn length =57.1 μm; distance between antapical and lateral horn tips =75.3 μm; angle subtending lateral and antapical horns =88.8◦; distance between lateral and antapical horn bases =20.2 μm. Range: endocyst length (without operculum) =46.7 (54.3) 66.3 μm; endocyst width =34.8 (47.4) 78.0 μm; endocyst length-to-width ratio =0.9 (1.2) 1.5; lateral horn base width =17.9 (24.8) 37.7 μm; antapical horn base width =20.3 (32.1) 51.4 μm; lateral horn length =26.1 (37.9) 61.7 μm; antapical horn length =23.5 (44.8) 64.8 μm; distance between antapical and lateral horn tips =43.2 (70.9) 112.3 μm; angle subtending lateral and antapical horns =72.0 (81.3) 88.8◦; distance between lateral and antapical horn bases =14.0 (22.9) 33.1 μm; operculum length =47.0 (77.0) 101.9 μm; operculum width =21.7 (32.3) 41.1 μm; apical horn length =33.7 (55.7) 83.6 μm; apical horn base width =11.1 (17.1) 21.8 μm. Specimens measured: 30. Values presented in Appendix B, Table B.4.
Comparison. Of the nineteen previously recognized species of Odontochitina, only six express circumcavation, or at least semi- circumcavation to the extent that periphragm separation results in pericoel connectivity between the antapical and lateral horns (see Soliman et al., 2024, table 1). These species are Odontochitina diducta Pearce, 2010, Odontochitina elbeialyi Soliman et al., 2024, Odontochitina imparilis Duxbury, 1980, Odontochitina indigena Marshall, 1988, Odontochitina octopus Nú˜nez-Betelu and Hills, 1998, and Odontochitina ornata Soliman et al., 2024. Of these taxa, Odontochitina kwutlkwuensis sp. nov. is most similar to Odontochitina elbeialyi in being circumcavate with horn terminations that are generally open or ragged, but the horns of the former species are typically longer, with the antapical horn around the length of the central body. Both species share the common expression of node-like endophragm protrusions into the periphragm at the horn bases, the extent of which has otherwise only been observed in Odontochitina costata (Alberti, 1961, pl. 6, fig. 12; as Odontochitina stratoperforata: Cookson and Eisenack, 1962, pl. 3, figs. 16, 17) and possibly Odontochitina tabulata (El-Mehdawi, 1998, pl. 1, fig. 6). Odontochitina kwutlkwuensis sp. nov. and O. tabulata exhibit horns of similar length, although the new species differs from all others in possessing a microfoveolate-microcorrugate periphragm with well-demarcated sutural ridges, unevenly distributed vesicles, and in rare instances, denticulate septae.
Stratigraphic range. Lower upper Campanian.
Occurrence. Odontochitina kwutlkwuensis sp. nov. has been recovered from coastal exposures of the upper Cedar District Formation along western Denman Island (samples 15, 17–20) within the Comox OA, British Columbia, Canada.
Remarks. The presence of five cingular plates in Odontochitina kwutlkwuensis sp. nov. is significant in that it suggests affinity with the modern ceratiacean genus Tripos (G´omez et al., 2010; G´omez, 2013). Of the species of Odontochitina which express tabulation, Odontochitina tabulata (El-Mehdawi, 1998, fig. 2) and Odontochitina ornata (Soliman et al., 2024, p. 10) have been attributed 6c, Odontochitina dilatata has been questionably assigned 6c (Niechwedowicz, 2019, pl. 9, fig. 10), Odontochitina streelii presents 5c (Slimani, 1996, p. 378, fig. 6), and Odontochitina indigena 4c (Marshall, 1988, p. 198, fig. 5). In spite of Marshall(1988) making the inference of four cingular plates in O. indigena, the emended generic diagnosis provided by El-Mehdawi(1998, p. 174) only allows for either 5c or 6c.
Holotype. Plate 10A–C. Sample 18 (GSC 77455), slide E6-20 E, EF Y37/3.
Paratypes. Plate 10D–F, Sample 18, slide E6-20 D, EF B36/4; Plate 10G–I, Sample 18, slide E6-20 D, EF L23/2; Plate 11A–C, Sample 18, slide E6-20 D, EF B30/3; Plate 11D–F, Sample 18, slide E6-20 D, EF R30/ 4; Plate 11G–I, Sample 18, slide E6-20 D, EF D31/0; Plate 12A–C, Sample 18, slide E6-20 D, EF H46/4; Plate 12D–G, Sample 20, slide E6- 20 D, EF F18/3; Plate 12H, I, Sample 18, slide E6-20 D, EF B25/0; Plate 12J, K, Sample 18, slide E6-20 D, EF Z35/3; Plate 13A–C, Sample 20 (GSC C-677475), slide P5408-4 A, EF S8/1; 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; Plate 15A–C, stub 24D06, specimen 1 (CEDiT2024P194); Plate 15D–H, stub 24D02, specimen 28 (CEDiT2024P195); Plate 15I, J, stub 24D06, specimen 11 (CEDiT2024P196); Plate 16A–G, stub 24D02, specimen 27 (CEDiT2024P197); Plate 16H–J, stub 24D02, specimen 18 (CEDiT2024P198); Plate 17A, B, stub 24D01, specimen 2 (CEDiT2024P199); Plate 17C, stub 24D01, specimen 6 (CEDiT2024P200); Plate 17D–H, stub 24D02, specimen 15 (CEDiT2024P201).
Type locality. End of point ~365 m north of Chrisman Road terminus (49.5773◦-124.8401◦), 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 broadly circumcavate species of Odontochitina with ceratoid ambitus and three large distally-open horns. Endophragm and periphragm microfoveolate-microcorrugate, irregularly vesiculate, and occasionally denticulate. Gonyaulacoid tabulation expressed predominantly by the archeopyle margin and pericyst cingular ridges with folds reflecting sutures of the pre- and postcingular plate series.
Description. Cyst cornucavate to more commonly broadly circumcavate with ceratoid ambitus. Endocyst ellipsoidal with length exceeding width in 90 % of specimens by 19 % on average, and typically asymmetrical due to lateral distention toward—or development of bulge protruding into—the lateral horn. In a minority of specimens, a pronounced node-like boss is developed from the endocyst projecting into the apical horn (Plate 12H, I). Horns broad-based proximally, tapering distally with terminations generally open, ragged, or splayed into ribbon-like bands of periphragm. The lateral horn develops an elbow at its midpoint and undergoes an abrupt recurvature toward the antapex. Under SEM, the endophragm is seen to be narrowly punctate, vesiculate, and the periphragm densely microfoveolate-microcorrugate with unevenly distributed vesicles (e.g., Plate 15F; Plate 16G, J). Isolated intratabular vesicles vary greatly in size (from 0.5 to 5 μm in diameter) and can occur scattered throughout either wall layer (Plate 16G; Plate 17F–H). Many vesicles may be burst and calderic, exhibiting a concave bowl-like appearance (Plate 15F, G). In extreme cases, elongate, expansive vacuoles are situated along plate margins (e.g., Plate 12D; Plate 14C; Plate 16B, I). In rare specimens (<7 %), denticles up to 8 μm in length may arise from sutural crests in proximity to plate junctions and along the lateral margins of the perycist giving the appearance of a serrated ambitus (e.g., Plate 13B, E, F; Plate 14D). Tabulation is clearly expressed on the pericyst by the consistent presence of low, sutural ridges demarcating the boundaries of the precingular, cingular, and postcingular plate series as well as along the margins of the ventral sulcus. In some specimens, transverse ridges continue across the equatorial region presenting the cingulum most prominently as a deeply- incised furrow wrapping around the left lateral margin corresponding to the position of plate 1c (e.g., Plate 11C; Plate 16A, C). Inferred reflected tabulation formula 4′, 5′′, 5c, Xs, 6′′′, 2′′′′.
Dimensions. Holotype: endocyst length (without operculum) =57.0 μm; endocyst width =44.8 μm; endocyst length-to-width ratio =1.3; lateral horn base width =24.0 μm; antapical horn base width =35.6 μm; lateral horn length =39.2 μm; antapical horn length =57.1 μm; distance between antapical and lateral horn tips =75.3 μm; angle subtending lateral and antapical horns =88.8◦; distance between lateral and antapical horn bases =20.2 μm. Range: endocyst length (without operculum) =46.7 (54.3) 66.3 μm; endocyst width =34.8 (47.4) 78.0 μm; endocyst length-to-width ratio =0.9 (1.2) 1.5; lateral horn base width =17.9 (24.8) 37.7 μm; antapical horn base width =20.3 (32.1) 51.4 μm; lateral horn length =26.1 (37.9) 61.7 μm; antapical horn length =23.5 (44.8) 64.8 μm; distance between antapical and lateral horn tips =43.2 (70.9) 112.3 μm; angle subtending lateral and antapical horns =72.0 (81.3) 88.8◦; distance between lateral and antapical horn bases =14.0 (22.9) 33.1 μm; operculum length =47.0 (77.0) 101.9 μm; operculum width =21.7 (32.3) 41.1 μm; apical horn length =33.7 (55.7) 83.6 μm; apical horn base width =11.1 (17.1) 21.8 μm. Specimens measured: 30. Values presented in Appendix B, Table B.4.
Comparison. Of the nineteen previously recognized species of Odontochitina, only six express circumcavation, or at least semi- circumcavation to the extent that periphragm separation results in pericoel connectivity between the antapical and lateral horns (see Soliman et al., 2024, table 1). These species are Odontochitina diducta Pearce, 2010, Odontochitina elbeialyi Soliman et al., 2024, Odontochitina imparilis Duxbury, 1980, Odontochitina indigena Marshall, 1988, Odontochitina octopus Nú˜nez-Betelu and Hills, 1998, and Odontochitina ornata Soliman et al., 2024. Of these taxa, Odontochitina kwutlkwuensis sp. nov. is most similar to Odontochitina elbeialyi in being circumcavate with horn terminations that are generally open or ragged, but the horns of the former species are typically longer, with the antapical horn around the length of the central body. Both species share the common expression of node-like endophragm protrusions into the periphragm at the horn bases, the extent of which has otherwise only been observed in Odontochitina costata (Alberti, 1961, pl. 6, fig. 12; as Odontochitina stratoperforata: Cookson and Eisenack, 1962, pl. 3, figs. 16, 17) and possibly Odontochitina tabulata (El-Mehdawi, 1998, pl. 1, fig. 6). Odontochitina kwutlkwuensis sp. nov. and O. tabulata exhibit horns of similar length, although the new species differs from all others in possessing a microfoveolate-microcorrugate periphragm with well-demarcated sutural ridges, unevenly distributed vesicles, and in rare instances, denticulate septae.
Stratigraphic range. Lower upper Campanian.
Occurrence. Odontochitina kwutlkwuensis sp. nov. has been recovered from coastal exposures of the upper Cedar District Formation along western Denman Island (samples 15, 17–20) within the Comox OA, British Columbia, Canada.
Remarks. The presence of five cingular plates in Odontochitina kwutlkwuensis sp. nov. is significant in that it suggests affinity with the modern ceratiacean genus Tripos (G´omez et al., 2010; G´omez, 2013). Of the species of Odontochitina which express tabulation, Odontochitina tabulata (El-Mehdawi, 1998, fig. 2) and Odontochitina ornata (Soliman et al., 2024, p. 10) have been attributed 6c, Odontochitina dilatata has been questionably assigned 6c (Niechwedowicz, 2019, pl. 9, fig. 10), Odontochitina streelii presents 5c (Slimani, 1996, p. 378, fig. 6), and Odontochitina indigena 4c (Marshall, 1988, p. 198, fig. 5). In spite of Marshall(1988) making the inference of four cingular plates in O. indigena, the emended generic diagnosis provided by El-Mehdawi(1998, p. 174) only allows for either 5c or 6c.