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Hiddenocysta matsuokae
Synonymy.
Spiniferites sp. 1 Dobell and Taylor (1981), Pl. 1, Figs. 4, 11.
Spiniferites sp. 2 Dobell and Taylor (1981), Pl. 1, Figs. 9, 10, 12, 13, 16.
Spiniferites sp. Dobell and Taylor (1981), Pl., Figs. 14, 15, 19, 20.
Etymology. In honor of Dr. Kazumi Matsuoka, who made fundamental contributions to the taxonomy of dinoflagellates, mainly from the Pacific domain, specifically about cyst stages.
Holotype. Kyuquot Sound (BC, Canada), core 2012002PGC133, slide UVic 2015-594-2 (870 cm core depth, ~11 ka), EF Q42/1 (label left), Pl. 1, Figs. 1–6; Pl. 2, Fig. 1.
Repository. Royal Belgian Institute of Natural Sciences (RBINS, Brussels), accession n° IRSNB b7162.
Diagnosis. Cysts relatively large, spherical or slightly elongated, skolochorate. Wall granular and ornamented with numerous processes. Generally, gonal processes trifurcate and intergonal processes bifurcate. The distribution of the processes reflects a gonyaulacoid plate pattern. Process bases are hollow and periphragm heavily fenestrated. Neighboring processes can be connected by crests; mostly by a discrete lineation reflecting a septum or by an expanded periphragm that merges between two processes. One type of process is long, slender and trifurcate, with each of the three ends bifurcate and recurved. Other processes are shorter and broader with more expanded bases and also often trifurcate with bifurcate terminations. Distally from the pericoel, the processes are solid, but occasionally with one or more bubblelike structures along the length of the process shaft, above, below or at the trifurcation. Archeopyle compound, operculum involves two precingular plates (3´´ and 4´´) that release separately, and is free.
Dimensions. Holotype: central body 62 × 51 μm; process length 14.8 μm (N = 4). Forma 1 has a smaller central body and longer processes, whereas Forma 2 has a larger central body and shorter processes. The average sum of the central body diameter and process length is ~71.9 μm for Forma 1 and ~71.2 μm for Forma 2. Central body wall is ~1.1 μm thick (N=3). For Forma 1, the height of the trifurcation above the process base is ~7.7 μm (N=16). See Table 1.
Description. The cysts are spherical to ovoidal. The archeopyle margins follow the suture lines, and a projection from the apical margin of the archeopyle suggests 2P (Pl. 3, Fig. 1–3). These plates are of similar size; plates 3´´ is pentagonal and 4´´ is quadrangular (Pl. 3, Fig. 1- Accepted Manuscript 2; see also Dobell and Taylor 1981). The cyst wall is granular on the outside and smooth on the inside (Pl. 2, Fig. 5), and an endophragm and periphragm can be distinguished (cf. Evitt 1985; Fig. 3). Near the processes, the phragma separate, and a pericoel forms the hollow process base. The periphragm lining the pericoel is heavily fenestrated (Pl. 1–3). morphological end-members can be defined within this species, and morphologies ranging between these end members were observed. The first end member (Forma 1; Fig. 3; Pl. 1, Fig. 1–6; Pl. 2, Fig. 1–2) has long and slender trifurcate processes terminating into recurved bifurcations resembling tendrils (cf. a Greek Ionian pillar). A single bubble-like structure is present below, at or above the trifurcation (Pl. 2, Fig. 1). The processes in Forma 1 are never connected by crests but by very low lineations only. The other end member (Forma 2; Fig. 3; Pl. 2, Fig. 2–9) has no clear single bubble-like structures as in Forma 1 but sometimes has numerous distributed small bubble-like structures in the processes (Pl. 2, Fig. 7); process bases are more expanded, more heavily fenestrated and are more often connected by the merging of the expanded periphragm at the respective process bases. There are more intergonal processes in Forma 2. There is no apparent heterogeneity in processes with respect to position on the cyst body. Distally from the pericoel, the process is solid, but in high magnification SEM micrographs of broken processes of Forma 1 (see Pl. 3, Fig. 6, indicated by an arrow), eight holes are visible, spread more or less evenly along the width of the process. It is unclear whether these are small bubble-like structures or canals running along the length of the processes. An apical boss is occasionally observed (Pl. 2, Fig. 2, 8), but appears not to be diagnostic. The cysts are often collapsed, folded and torn in palynologically prepared slides, which can also be observed when manipulating cysts (Pl. 2; Pl. 3, Figs. 4, 9, 10).
Remarks. Two end-members of this species were distinguished based on the process type. Specimens were observed bearing both types of processes, suggesting intraspecific variation. Accepted Manuscript The species described here is identical to the specimens depicted by Dobell and Taylor (1981) based on size, tabulation, wall structure and the structure and organization of the processes.
Comparison. As it is the only species described in the genus Hiddenocysta, the comparison is as for the genus. The processes of H. matsuokae Forma 1 are often more slender than most Spiniferites species (Limoges et al. 2018; Mertens et al. 2018). Spiniferites solidago of de Verteuil and Norris (1996) has a comparable shape and the same characteristic vacuoles in the processes. However, this species differs from Hiddenocysta matsuokae by a 1P archeopyle, its wall ornamentation, its characteristic alveoles in the cyst wall and process terminations that are more simply bifurcate and do not resemble tendrils. Spiniferites lazus has similar perforations at the process base, but has a more elongated central body and a 1P archeopyle (Reid 1974; Gurdebeke et al., 2018b).
Distribution and biostratigraphy. The species is described here from estuarine waters of southwestern British Columbia and Vancouver Island (Canada), specifically from surface sediments of Hidden Basin (~6 m water depth, sea surface temperature (SST) 7–16 °C, sea surface salinity (SSS) 24–32 PSU, e.g., Gurdebeke et al. 2018a)) and as a present to rare species (up to 1.6% of the assemblage; terminology of Pospelova et al. 2004) throughout Holocene sediments of Kyuquot Sound (~150 m water depth; Fig. 2; Supplementary Information Table 1). A specimen with endospore/cell content (Pl. 1, Fig. 1–6) was found in the early Holocene, ~11 ka (UVic 2015-594). This excludes reworking of the cysts, which is also improbable because of the local geology and hydrology of the fjord system (e.g., Muller et al. 1974) and because Dobell and Taylor (1981) successfully hatched similar cysts. The species was also observed in Ise Bay, Central Japan (34°57.24’N, 136°43.84’E, 25 m water depth; SST 10–23 °C and SSS 33–34 PSU, e.g., Narita et al. 2006) (K. Matsuoka, pers. comm.). From these limited observations, H. matsuokae occurs in ice-free estuaries with up to 150 m water depth in the temperate North Pacific. At present it is not clear whether Forma 1 and 2 represent ecotypes, and if so, what is the driving environmental parameter. It is observed, however, that at the majority of the stratigraphic levels at which H. matsuokae is recorded in the Kyuquot Sound core, it is dominated by one Forma (Fig. 2).
Spiniferites sp. 1 Dobell and Taylor (1981), Pl. 1, Figs. 4, 11.
Spiniferites sp. 2 Dobell and Taylor (1981), Pl. 1, Figs. 9, 10, 12, 13, 16.
Spiniferites sp. Dobell and Taylor (1981), Pl., Figs. 14, 15, 19, 20.
Etymology. In honor of Dr. Kazumi Matsuoka, who made fundamental contributions to the taxonomy of dinoflagellates, mainly from the Pacific domain, specifically about cyst stages.
Holotype. Kyuquot Sound (BC, Canada), core 2012002PGC133, slide UVic 2015-594-2 (870 cm core depth, ~11 ka), EF Q42/1 (label left), Pl. 1, Figs. 1–6; Pl. 2, Fig. 1.
Repository. Royal Belgian Institute of Natural Sciences (RBINS, Brussels), accession n° IRSNB b7162.
Diagnosis. Cysts relatively large, spherical or slightly elongated, skolochorate. Wall granular and ornamented with numerous processes. Generally, gonal processes trifurcate and intergonal processes bifurcate. The distribution of the processes reflects a gonyaulacoid plate pattern. Process bases are hollow and periphragm heavily fenestrated. Neighboring processes can be connected by crests; mostly by a discrete lineation reflecting a septum or by an expanded periphragm that merges between two processes. One type of process is long, slender and trifurcate, with each of the three ends bifurcate and recurved. Other processes are shorter and broader with more expanded bases and also often trifurcate with bifurcate terminations. Distally from the pericoel, the processes are solid, but occasionally with one or more bubblelike structures along the length of the process shaft, above, below or at the trifurcation. Archeopyle compound, operculum involves two precingular plates (3´´ and 4´´) that release separately, and is free.
Dimensions. Holotype: central body 62 × 51 μm; process length 14.8 μm (N = 4). Forma 1 has a smaller central body and longer processes, whereas Forma 2 has a larger central body and shorter processes. The average sum of the central body diameter and process length is ~71.9 μm for Forma 1 and ~71.2 μm for Forma 2. Central body wall is ~1.1 μm thick (N=3). For Forma 1, the height of the trifurcation above the process base is ~7.7 μm (N=16). See Table 1.
Description. The cysts are spherical to ovoidal. The archeopyle margins follow the suture lines, and a projection from the apical margin of the archeopyle suggests 2P (Pl. 3, Fig. 1–3). These plates are of similar size; plates 3´´ is pentagonal and 4´´ is quadrangular (Pl. 3, Fig. 1- Accepted Manuscript 2; see also Dobell and Taylor 1981). The cyst wall is granular on the outside and smooth on the inside (Pl. 2, Fig. 5), and an endophragm and periphragm can be distinguished (cf. Evitt 1985; Fig. 3). Near the processes, the phragma separate, and a pericoel forms the hollow process base. The periphragm lining the pericoel is heavily fenestrated (Pl. 1–3). morphological end-members can be defined within this species, and morphologies ranging between these end members were observed. The first end member (Forma 1; Fig. 3; Pl. 1, Fig. 1–6; Pl. 2, Fig. 1–2) has long and slender trifurcate processes terminating into recurved bifurcations resembling tendrils (cf. a Greek Ionian pillar). A single bubble-like structure is present below, at or above the trifurcation (Pl. 2, Fig. 1). The processes in Forma 1 are never connected by crests but by very low lineations only. The other end member (Forma 2; Fig. 3; Pl. 2, Fig. 2–9) has no clear single bubble-like structures as in Forma 1 but sometimes has numerous distributed small bubble-like structures in the processes (Pl. 2, Fig. 7); process bases are more expanded, more heavily fenestrated and are more often connected by the merging of the expanded periphragm at the respective process bases. There are more intergonal processes in Forma 2. There is no apparent heterogeneity in processes with respect to position on the cyst body. Distally from the pericoel, the process is solid, but in high magnification SEM micrographs of broken processes of Forma 1 (see Pl. 3, Fig. 6, indicated by an arrow), eight holes are visible, spread more or less evenly along the width of the process. It is unclear whether these are small bubble-like structures or canals running along the length of the processes. An apical boss is occasionally observed (Pl. 2, Fig. 2, 8), but appears not to be diagnostic. The cysts are often collapsed, folded and torn in palynologically prepared slides, which can also be observed when manipulating cysts (Pl. 2; Pl. 3, Figs. 4, 9, 10).
Remarks. Two end-members of this species were distinguished based on the process type. Specimens were observed bearing both types of processes, suggesting intraspecific variation. Accepted Manuscript The species described here is identical to the specimens depicted by Dobell and Taylor (1981) based on size, tabulation, wall structure and the structure and organization of the processes.
Comparison. As it is the only species described in the genus Hiddenocysta, the comparison is as for the genus. The processes of H. matsuokae Forma 1 are often more slender than most Spiniferites species (Limoges et al. 2018; Mertens et al. 2018). Spiniferites solidago of de Verteuil and Norris (1996) has a comparable shape and the same characteristic vacuoles in the processes. However, this species differs from Hiddenocysta matsuokae by a 1P archeopyle, its wall ornamentation, its characteristic alveoles in the cyst wall and process terminations that are more simply bifurcate and do not resemble tendrils. Spiniferites lazus has similar perforations at the process base, but has a more elongated central body and a 1P archeopyle (Reid 1974; Gurdebeke et al., 2018b).
Distribution and biostratigraphy. The species is described here from estuarine waters of southwestern British Columbia and Vancouver Island (Canada), specifically from surface sediments of Hidden Basin (~6 m water depth, sea surface temperature (SST) 7–16 °C, sea surface salinity (SSS) 24–32 PSU, e.g., Gurdebeke et al. 2018a)) and as a present to rare species (up to 1.6% of the assemblage; terminology of Pospelova et al. 2004) throughout Holocene sediments of Kyuquot Sound (~150 m water depth; Fig. 2; Supplementary Information Table 1). A specimen with endospore/cell content (Pl. 1, Fig. 1–6) was found in the early Holocene, ~11 ka (UVic 2015-594). This excludes reworking of the cysts, which is also improbable because of the local geology and hydrology of the fjord system (e.g., Muller et al. 1974) and because Dobell and Taylor (1981) successfully hatched similar cysts. The species was also observed in Ise Bay, Central Japan (34°57.24’N, 136°43.84’E, 25 m water depth; SST 10–23 °C and SSS 33–34 PSU, e.g., Narita et al. 2006) (K. Matsuoka, pers. comm.). From these limited observations, H. matsuokae occurs in ice-free estuaries with up to 150 m water depth in the temperate North Pacific. At present it is not clear whether Forma 1 and 2 represent ecotypes, and if so, what is the driving environmental parameter. It is observed, however, that at the majority of the stratigraphic levels at which H. matsuokae is recorded in the Kyuquot Sound core, it is dominated by one Forma (Fig. 2).