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Hystrichosphaeridium echinatum
Hystrichosphaeridium echinatum Menéndez, 1965, p.12–13, pl.2, fig.9. Emendation: Guerstein et al., 2008, p.79, as Lingulodinium echinatum.
NOW Lingulodinium. Originally Hystrichosphaeridium, subsequently Hystrichosphaeridium?, thirdly (and now) Lingulodinium. Questionable assignment: Stover and Evitt (1978, p.56) as a problematic species.
Holotype: Menéndez, 1965, pl.2, fig.9, lost according to Guerstein et al. (2008, p.79).
Neotype: Guerstein et al., 2008, pl.1, figs.11–12, designated by Guerstein et al. (2008, p.79).
Locus typicus: Tierra del Fuego, Argentinia
Stratum typicum: Late Cretaceous
Original diagnosis: Menéndez, 1965, p.12
Ellipsoidal body, membrane irregular granulate; numerous radial, spiney appendages; apex sharp, truncated, or having a small, apparently bifurcate expansion.
Dimensions: Total diameter 48 by 62.4 µm; central body 30 µm.
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Emendation (Guerstein et al., 2008):
Lingulodinium echinatum Menéndez, 1965 n. comb., emend. (Pl. 1, figs 10–12)
Basionym. Hystrichosphaeridium? echinatum Menéndez, 1965: 12–13; pl. 2, fig. 9.
Neotype. Plate 1, figs 10–11. Río Candelaria section, 11 m above the base. UNS RC 59/99- 48/97 EF: T 49/3. Designated here.
Emended description. Chorate cysts with a subspherical central body, covered with numerous nontabular processes. Processes relatively thin, flexuous, flattened, with acuminate tips and with a length about one quarter of the cyst diameter. The wall is two-layered, with a thick endophragm and a thin, densely granular periphragm. Granules are distributed evenly along the processes. Archaeopyle precingular, type P or 2P.
Dimensions. Range of five specimens-central body 54–68 µm; length of processes 14–17 µm.
Occurrence. Río de la Turba section, RT7, RT9; Río Candelaria section, RC1–RC3, RC5–RC6.
Remarks. In the protologue, Menéndez (1965) described this species as having processes that are acuminate or truncate, or that have tips with a small expansion that appears bifurcate. However, the specimens here have processes with thin, flexuous and strongly acuminate tips; bifurcate or capitate tips were not observed. The apparently truncate ends and small bifurcations described by Menéndez (1965) possibly reflect the flexuous structure of the processes. His specimens are smaller than those described from the Cabo Peña Formation. Because of poor preservation of the slides, the holotype or any topotype material could not be located. Thus, a neotype is designated. Lingulodinium echinatum closely resembles Lingulodinium pycnospinosum but is considerably larger and has granulate processes that are not perforated by pores.
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NOW Lingulodinium. Originally Hystrichosphaeridium, subsequently Hystrichosphaeridium?, thirdly (and now) Lingulodinium. Questionable assignment: Stover and Evitt (1978, p.56) as a problematic species.
Holotype: Menéndez, 1965, pl.2, fig.9, lost according to Guerstein et al. (2008, p.79).
Neotype: Guerstein et al., 2008, pl.1, figs.11–12, designated by Guerstein et al. (2008, p.79).
Locus typicus: Tierra del Fuego, Argentinia
Stratum typicum: Late Cretaceous
Original diagnosis: Menéndez, 1965, p.12
Ellipsoidal body, membrane irregular granulate; numerous radial, spiney appendages; apex sharp, truncated, or having a small, apparently bifurcate expansion.
Dimensions: Total diameter 48 by 62.4 µm; central body 30 µm.
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Emendation (Guerstein et al., 2008):
Lingulodinium echinatum Menéndez, 1965 n. comb., emend. (Pl. 1, figs 10–12)
Basionym. Hystrichosphaeridium? echinatum Menéndez, 1965: 12–13; pl. 2, fig. 9.
Neotype. Plate 1, figs 10–11. Río Candelaria section, 11 m above the base. UNS RC 59/99- 48/97 EF: T 49/3. Designated here.
Emended description. Chorate cysts with a subspherical central body, covered with numerous nontabular processes. Processes relatively thin, flexuous, flattened, with acuminate tips and with a length about one quarter of the cyst diameter. The wall is two-layered, with a thick endophragm and a thin, densely granular periphragm. Granules are distributed evenly along the processes. Archaeopyle precingular, type P or 2P.
Dimensions. Range of five specimens-central body 54–68 µm; length of processes 14–17 µm.
Occurrence. Río de la Turba section, RT7, RT9; Río Candelaria section, RC1–RC3, RC5–RC6.
Remarks. In the protologue, Menéndez (1965) described this species as having processes that are acuminate or truncate, or that have tips with a small expansion that appears bifurcate. However, the specimens here have processes with thin, flexuous and strongly acuminate tips; bifurcate or capitate tips were not observed. The apparently truncate ends and small bifurcations described by Menéndez (1965) possibly reflect the flexuous structure of the processes. His specimens are smaller than those described from the Cabo Peña Formation. Because of poor preservation of the slides, the holotype or any topotype material could not be located. Thus, a neotype is designated. Lingulodinium echinatum closely resembles Lingulodinium pycnospinosum but is considerably larger and has granulate processes that are not perforated by pores.
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