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Nematosphaeropsis snuneymuxwensis
Etymology. From the Hul’q’umi’num’ Snuneymuxw (Snoo-nay- mowck) in the language of the Snuneymuxw First Nation from which the names of the Nanaimo River and the Nanaimo Group of rocks are derived.
Holotype. Plate 7A–D, Sample 6 (GSC C-675003), slide P5405-7 D, EF F34/4.
Paratypes. Plate 7E, F, Sample 8, slide E6-19 B, EF N43/3; Plate 7G–I, Sample 6, slide P5405-7 D, EF V43/0; Plate 8A–H, Sample 6, stub 24D03, specimen 8 (CEDiT2024P191); Plate 9A–F, Sample 6, stub 24D03, specimen 11 (CEDiT2024P192); Plate 9G–I, Sample 6, stub 24D04, specimen 2 (CEDiT2024P193)
Type locality. Nanaimo River, ~350 m downstream from the Elkhorn Creek confluence (49.0723◦-123.9814◦), eastern Vancouver Island, British Columbia, Canada (Fig. 1B, locality 6).
Type stratum. Upper Haslam Formation, lower Campanian.
Repository. Geological Survey of Canada.
Diagnosis. A species of Nematosphaeropsis characterized by subspherical to elliptical autophragm ambitus with microfoveolate surface ornamentation. Apical boss may be present. Ectophragm characterized by proximally to distally fenestrate processes with broad, open or form terminations. Frequency, distribution, and presentation of trabeculae often irregular.
Description. The inner body ambitus ranges from subspherical to elliptical with length exceeding width in 93 % of specimens by an average of 19.6 %. Autophragm wall ranging from ~0.5 to 1.5 μm in total thickness. Some specimens, as in the holotype (Plate 7A–D), possess a prominent apical boss. The autophragm surface is microfoveolate with pores and perforate foveolations occurring infrequently. Septal ridges may be somewhat subdued or prominently raised reflecting a gonyaulacoid tabulation with the inferred formula 3′, 6′′, as, 6c, s, sp, 1p, 6′′′, 1′′′′. Cingular displacement is minimal if present. Sulcal plates are not expressed. Processes typically gonal, but rare intergonal projections occur (Plate 8B); stems robust, hollow, triangular in cross- section with flat to concave sides (Plate 8C; Plate 9F). Processes are wide, proximally to distally fenestrate, often with longitudinal fenestrae along the length of the process. Distal process terminations range from broad, open trifurcations with secondary bifurcations to fenestrate multifurcate or lamellar trifurcations forming a petaloid platform with numerous perforations and fenestrae (e.g., Plate 8C, E, H; see septentrionalis- and pseudofurcatus-type processes in Londeix et al., 2018). The frequency, distribution, and presentation of trabeculae is often irregular. Adjacent processes are typically joined by two trabeculae (Plate 8E, H; Plate 9C, F, H), which may occasionally fuse at their midpoint. In rare instances, a single trabeculum may join two processes (Plate 9H). Trabeculae may also be absent between the furcations of some processes (e.g., Plate 8C; Plate 9I), while other processes may be entirely isolated with their terminations free of trabecular connections (e.g., Plate 7G–I).
Dimensions. Holotype: ectocyst length =93.7 μm; ectocyst width =88.9 μm; autocyst length =56.2 μm; autocyst width =52.0 μm; autocyst length-to-width ratio =1.1. Range: ectocyst length =62.9 (81.1) 95.9 μm; ectocyst width =53.2 (72.4) 94.4 μm; autocyst length =39.4 (49.9) 58.6 μm; autocyst width =33.2 (42.7) 55.4 μm; autocyst length-to- width ratio =1.0 (1.2) 1.5. Specimens measured: 30. Values presented in Appendix B, Table B.3.
Comparison. Although generally larger, Nematosphaeropsis snuneymuxwensis sp. nov. is most similar to the type species Nematosphaeropsis balcombiana from the middle Miocene Gellibrand Clay of southern Australia (Deflandre and Cookson, 1955), which also bears irregularity of trabecular connections and the presence of fenestrae. However, no observation was made by either Deflandre and Cookson(1955) or Wrenn(1988) in his subsequent emendation of N. balcombiana with respect to surface features beyond well-developed septal ridges. While not noted in the original description of N. balcombiana, fenestrae are apparent from the image of the holotype figured by Deflandre and Cookson(1955) as well as from the sketch subsequently produced by Wrenn(1988, pl. 7, fig. 3) based on said specimen. Head and Wrenn(1992) recommended that the name N. balcombiana be restricted to the holotype. The only other species to exhibit fenestrations is Nematosphaeropsis lativittatus reported from the upper Miocene–lower Pliocene offshore deposits within the northeastern Gulf of Mexico, which are occasionally expressed along its broad, ribbon-like trabeculae (Wrenn, 1988, pl. 5, figs. 2, 4; pl. 6, fig. 5). Also comparable is Nematosphaeropsis scala from the Lower Cretaceous strata of England (Duxbury, 1977) and Denmark (Davey, 1982) which bears distally fenestrate process terminations. No comment was made with regard to surface ornamentation for the species, although the holotype of Duxbury(1977, pl. 9, fig. 2) bears a smooth autophragm as re-illustrated images available through the open-access database PALSYS confirm a laevigate surface (Bijl and Brinkhuis, 2023). Additionally, underdeveloped trabeculae may be common beyond the holotype of N. scala given other figured specimens (Duxbury, 2018, pl. 11, figs. 5, 6, 2024, pl. 2, figs. 2, 3). Duxbury(1977, p. 43) originally attributed the absence of complete trabecular networks in his material to loss due to damage stating that trabeculae are often “partially broken and sometimes . . . completely destroyed leaving the nevertheless distinctive widely flared and fenestrate processes”. However, Duxbury(2018, p. 188) would later characterize the trabecular network of the species as “less-regular” and “often fragmented”. Aside from a smooth autophragm, the species also differs from N. snuneymuxwensis sp. nov. by the presence of a thinner wall and a lack of an apical boss. Nematosphaeropsis snuneymuxwensis sp. nov. differs significantly from the two species known from similarly- aged upper Campanian strata in the Northern Hemisphere—Nematosphaeropsis philippotii (Deflandre, 1947) De Coninck, 1968of France and Belgium, and Nematosphaeropsis lilaensis Slimani et al., 2021of northwestern Morocco—with its microfoveolate autophragm and robust processes with fenestrae occurring throughout. The defining traits of accepted species have been concisely summarized for comparative purposes in the studies carried out by Wrenn(1988, table 1) and Slimani et al.(2021, table 1). Trabeculidium quinquetrum, described by Duxbury(1980) from the middle Barremian of the Speeton Clay, England, is superficially analogous to N. snuneymuxwensis sp. nov. with dual trabeculae stemming from trifurcate process terminations, but members of the genus Trabeculidium lack sutural crests or any tabular definition.
Stratigraphic range. Upper Santonian–lower upper Campanian.
Occurrence. Within the Comox OA, Nematosphaeropsis snuneymuxwensis sp. nov. has been found in the lower Trent River Formation on the Trent River (Sample 1) and the upper section of the formation at the Northwest Bay Quarry (Sample 8) as well as from an exposure of the upper Trent River Formation on the Puntledge River (Sample 9) also outcropping along the Trent River (samples 10, 11, 13) and upper Cedar District Formation along the coast of western Denman Island (samples 15, 16, 19, 20), British Columbia, Canada. Within the Nanaimo OA, the species has been recovered from outcrops of the upper Haslamtion along the Nanaimo River (samples 3–6) and in the Lower Nanaimo Quarry (Sample 7).
Holotype. Plate 7A–D, Sample 6 (GSC C-675003), slide P5405-7 D, EF F34/4.
Paratypes. Plate 7E, F, Sample 8, slide E6-19 B, EF N43/3; Plate 7G–I, Sample 6, slide P5405-7 D, EF V43/0; Plate 8A–H, Sample 6, stub 24D03, specimen 8 (CEDiT2024P191); Plate 9A–F, Sample 6, stub 24D03, specimen 11 (CEDiT2024P192); Plate 9G–I, Sample 6, stub 24D04, specimen 2 (CEDiT2024P193)
Type locality. Nanaimo River, ~350 m downstream from the Elkhorn Creek confluence (49.0723◦-123.9814◦), eastern Vancouver Island, British Columbia, Canada (Fig. 1B, locality 6).
Type stratum. Upper Haslam Formation, lower Campanian.
Repository. Geological Survey of Canada.
Diagnosis. A species of Nematosphaeropsis characterized by subspherical to elliptical autophragm ambitus with microfoveolate surface ornamentation. Apical boss may be present. Ectophragm characterized by proximally to distally fenestrate processes with broad, open or form terminations. Frequency, distribution, and presentation of trabeculae often irregular.
Description. The inner body ambitus ranges from subspherical to elliptical with length exceeding width in 93 % of specimens by an average of 19.6 %. Autophragm wall ranging from ~0.5 to 1.5 μm in total thickness. Some specimens, as in the holotype (Plate 7A–D), possess a prominent apical boss. The autophragm surface is microfoveolate with pores and perforate foveolations occurring infrequently. Septal ridges may be somewhat subdued or prominently raised reflecting a gonyaulacoid tabulation with the inferred formula 3′, 6′′, as, 6c, s, sp, 1p, 6′′′, 1′′′′. Cingular displacement is minimal if present. Sulcal plates are not expressed. Processes typically gonal, but rare intergonal projections occur (Plate 8B); stems robust, hollow, triangular in cross- section with flat to concave sides (Plate 8C; Plate 9F). Processes are wide, proximally to distally fenestrate, often with longitudinal fenestrae along the length of the process. Distal process terminations range from broad, open trifurcations with secondary bifurcations to fenestrate multifurcate or lamellar trifurcations forming a petaloid platform with numerous perforations and fenestrae (e.g., Plate 8C, E, H; see septentrionalis- and pseudofurcatus-type processes in Londeix et al., 2018). The frequency, distribution, and presentation of trabeculae is often irregular. Adjacent processes are typically joined by two trabeculae (Plate 8E, H; Plate 9C, F, H), which may occasionally fuse at their midpoint. In rare instances, a single trabeculum may join two processes (Plate 9H). Trabeculae may also be absent between the furcations of some processes (e.g., Plate 8C; Plate 9I), while other processes may be entirely isolated with their terminations free of trabecular connections (e.g., Plate 7G–I).
Dimensions. Holotype: ectocyst length =93.7 μm; ectocyst width =88.9 μm; autocyst length =56.2 μm; autocyst width =52.0 μm; autocyst length-to-width ratio =1.1. Range: ectocyst length =62.9 (81.1) 95.9 μm; ectocyst width =53.2 (72.4) 94.4 μm; autocyst length =39.4 (49.9) 58.6 μm; autocyst width =33.2 (42.7) 55.4 μm; autocyst length-to- width ratio =1.0 (1.2) 1.5. Specimens measured: 30. Values presented in Appendix B, Table B.3.
Comparison. Although generally larger, Nematosphaeropsis snuneymuxwensis sp. nov. is most similar to the type species Nematosphaeropsis balcombiana from the middle Miocene Gellibrand Clay of southern Australia (Deflandre and Cookson, 1955), which also bears irregularity of trabecular connections and the presence of fenestrae. However, no observation was made by either Deflandre and Cookson(1955) or Wrenn(1988) in his subsequent emendation of N. balcombiana with respect to surface features beyond well-developed septal ridges. While not noted in the original description of N. balcombiana, fenestrae are apparent from the image of the holotype figured by Deflandre and Cookson(1955) as well as from the sketch subsequently produced by Wrenn(1988, pl. 7, fig. 3) based on said specimen. Head and Wrenn(1992) recommended that the name N. balcombiana be restricted to the holotype. The only other species to exhibit fenestrations is Nematosphaeropsis lativittatus reported from the upper Miocene–lower Pliocene offshore deposits within the northeastern Gulf of Mexico, which are occasionally expressed along its broad, ribbon-like trabeculae (Wrenn, 1988, pl. 5, figs. 2, 4; pl. 6, fig. 5). Also comparable is Nematosphaeropsis scala from the Lower Cretaceous strata of England (Duxbury, 1977) and Denmark (Davey, 1982) which bears distally fenestrate process terminations. No comment was made with regard to surface ornamentation for the species, although the holotype of Duxbury(1977, pl. 9, fig. 2) bears a smooth autophragm as re-illustrated images available through the open-access database PALSYS confirm a laevigate surface (Bijl and Brinkhuis, 2023). Additionally, underdeveloped trabeculae may be common beyond the holotype of N. scala given other figured specimens (Duxbury, 2018, pl. 11, figs. 5, 6, 2024, pl. 2, figs. 2, 3). Duxbury(1977, p. 43) originally attributed the absence of complete trabecular networks in his material to loss due to damage stating that trabeculae are often “partially broken and sometimes . . . completely destroyed leaving the nevertheless distinctive widely flared and fenestrate processes”. However, Duxbury(2018, p. 188) would later characterize the trabecular network of the species as “less-regular” and “often fragmented”. Aside from a smooth autophragm, the species also differs from N. snuneymuxwensis sp. nov. by the presence of a thinner wall and a lack of an apical boss. Nematosphaeropsis snuneymuxwensis sp. nov. differs significantly from the two species known from similarly- aged upper Campanian strata in the Northern Hemisphere—Nematosphaeropsis philippotii (Deflandre, 1947) De Coninck, 1968of France and Belgium, and Nematosphaeropsis lilaensis Slimani et al., 2021of northwestern Morocco—with its microfoveolate autophragm and robust processes with fenestrae occurring throughout. The defining traits of accepted species have been concisely summarized for comparative purposes in the studies carried out by Wrenn(1988, table 1) and Slimani et al.(2021, table 1). Trabeculidium quinquetrum, described by Duxbury(1980) from the middle Barremian of the Speeton Clay, England, is superficially analogous to N. snuneymuxwensis sp. nov. with dual trabeculae stemming from trifurcate process terminations, but members of the genus Trabeculidium lack sutural crests or any tabular definition.
Stratigraphic range. Upper Santonian–lower upper Campanian.
Occurrence. Within the Comox OA, Nematosphaeropsis snuneymuxwensis sp. nov. has been found in the lower Trent River Formation on the Trent River (Sample 1) and the upper section of the formation at the Northwest Bay Quarry (Sample 8) as well as from an exposure of the upper Trent River Formation on the Puntledge River (Sample 9) also outcropping along the Trent River (samples 10, 11, 13) and upper Cedar District Formation along the coast of western Denman Island (samples 15, 16, 19, 20), British Columbia, Canada. Within the Nanaimo OA, the species has been recovered from outcrops of the upper Haslamtion along the Nanaimo River (samples 3–6) and in the Lower Nanaimo Quarry (Sample 7).