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Rhynchodiniopsis downiei
Rhynchidiniopsis downiei (Pocock, 1972) Sarjeant 1982
Originally Gonyaulacysta subsequently Hystrichosphaeropsis, thirdly Rhynchodiniopsis?, fourthly Rhynchodiniopsis. Sarjeant, 1982 considered this to be a "provisionally accepted species" of Rhynchodiniopsis.
Tax. jr. synonym of Gonyaulacysta cladophora (Deflandre, 1938) Dodekova, 1967, according to Fisher and Riley, 1980; this synonymy was accepted by Lentin and Williams, 1981 but was rejected on a later page (p.150) of the same paper. This inconsistency was corrected in Lentin and Williams, 1985 who accepted the views of Fisher and Riley, 1980 rather than the transfer of this species to Rhynchodiniopsis by Sarjeant, 1982. Jansonius, 1986 retained Gonyaulacysta (as Rhynchodiniopsis) downiei as a separate species and did not question the generic assignment, but Kunz, 1990 agreed with Fisher and Riley, 1980.
Holotype: Pocock, 1972, pl.22, figs.1-2; Jan du Chêne et al., 1986, pl.97, figs.7-12
Locus typicus: Imperial Tidewater Carlyle, Western Canada
Stratum typicum: Oxfordian-Kimmeridgian
Original description: Pocock, 1972, p. 87: Gonyaulacysta downiei
Vesicle longer than it is wide; epitheca hemispherical; terminated by a short, blunt process up to 10.0 µm long and 10.0 µm wide; hypotheca more elongate; antapex rounded; no processes developed; transverse furrow well developed; helicoidal, longitudinal furrow more or less parallel-sided; tabulation 4", 6", 6""", 1P, 1""""; archeopyle simple, precingular, with simple free operculum; comprises plate 3"; sutures reflected onto surface of vesicle as low raised ridges about 1 µm wide; bearing rows of pinnate spines 1.5 (3.8) 5.5 µm long, rising from bases about 1 µm wide, spaced 2.0-5.0 µm apart; similar spines flank transverse and longitudinal furrows; vesicle two-layered; capsule thin-walled; smooth, tightly appressed to outer layer; outer layer about 1 µm thick; granulose; color pale yellow; length of vesicle 91.3--99.0 µm (excluding spines); equatorial diameter 72.6 (80.0) 88.0 µm.
Supplemental description: Jansonius, 1986, p.216
(Holotype) 91 x 75 µm, broadly oval, epicyst and hypocyst nearly equal in size; at apex a slight, broad, dome-shaped protrusion, 10 µm wide, 3 µm high. (This is superimposed upon a minute Filisphaeridium which had been taken to form a short but distinct horn in Pocock"s text-fig. 2 and the contouring of his pl. 22, fig. 1,2.)
Paratabulation marked by low ridges (1 µm), all topped by rows of slender spines (1 µm at base, tapering to 1/4 µm at distal tip), 4-5 µm tall, all with a slight broadening and/or bifurcation at the tip. The wall appears single-layered; no evidence of a distinct central body is observed. Wall faintly wavy in outline, in surface view flecked with irregular thickenings that may form a shallow reticulation- foveolation-pitting; the wall of the epicyst is distinctly thinner and smoother. Cingulum 4-5 µm wide, equatorial on dorsal face, somewhat bent antapically near the ventral sulcus. Archeopyle precingular, 3", broad based and triangular in shape but its outline somewhat affected by folding; operculum lost. No ridges or spines at apical pole. Paratabulation of the apicals is difficult to determine (especially 2", 3"). No pre-apicals observed; intercalary plates, if present, indistinct.
Affinities:
Jansonius, 1986, p.216: In the type residue, and in some other samples, specimens belonging to this species are readily identified by the slender parasutural spines and especially by the shallow apical dome. These features differentiate this species from R. cladophora (Defl.) Below; the synonymy of R. canadensis and R. downiei with R. cladophora, as proposed by Fisher and Riley ( 1980, p. 320), is here rejected, as it unnecessarily broadens and distorts the delineation of the latter species.
Originally Gonyaulacysta subsequently Hystrichosphaeropsis, thirdly Rhynchodiniopsis?, fourthly Rhynchodiniopsis. Sarjeant, 1982 considered this to be a "provisionally accepted species" of Rhynchodiniopsis.
Tax. jr. synonym of Gonyaulacysta cladophora (Deflandre, 1938) Dodekova, 1967, according to Fisher and Riley, 1980; this synonymy was accepted by Lentin and Williams, 1981 but was rejected on a later page (p.150) of the same paper. This inconsistency was corrected in Lentin and Williams, 1985 who accepted the views of Fisher and Riley, 1980 rather than the transfer of this species to Rhynchodiniopsis by Sarjeant, 1982. Jansonius, 1986 retained Gonyaulacysta (as Rhynchodiniopsis) downiei as a separate species and did not question the generic assignment, but Kunz, 1990 agreed with Fisher and Riley, 1980.
Holotype: Pocock, 1972, pl.22, figs.1-2; Jan du Chêne et al., 1986, pl.97, figs.7-12
Locus typicus: Imperial Tidewater Carlyle, Western Canada
Stratum typicum: Oxfordian-Kimmeridgian
Original description: Pocock, 1972, p. 87: Gonyaulacysta downiei
Vesicle longer than it is wide; epitheca hemispherical; terminated by a short, blunt process up to 10.0 µm long and 10.0 µm wide; hypotheca more elongate; antapex rounded; no processes developed; transverse furrow well developed; helicoidal, longitudinal furrow more or less parallel-sided; tabulation 4", 6", 6""", 1P, 1""""; archeopyle simple, precingular, with simple free operculum; comprises plate 3"; sutures reflected onto surface of vesicle as low raised ridges about 1 µm wide; bearing rows of pinnate spines 1.5 (3.8) 5.5 µm long, rising from bases about 1 µm wide, spaced 2.0-5.0 µm apart; similar spines flank transverse and longitudinal furrows; vesicle two-layered; capsule thin-walled; smooth, tightly appressed to outer layer; outer layer about 1 µm thick; granulose; color pale yellow; length of vesicle 91.3--99.0 µm (excluding spines); equatorial diameter 72.6 (80.0) 88.0 µm.
Supplemental description: Jansonius, 1986, p.216
(Holotype) 91 x 75 µm, broadly oval, epicyst and hypocyst nearly equal in size; at apex a slight, broad, dome-shaped protrusion, 10 µm wide, 3 µm high. (This is superimposed upon a minute Filisphaeridium which had been taken to form a short but distinct horn in Pocock"s text-fig. 2 and the contouring of his pl. 22, fig. 1,2.)
Paratabulation marked by low ridges (1 µm), all topped by rows of slender spines (1 µm at base, tapering to 1/4 µm at distal tip), 4-5 µm tall, all with a slight broadening and/or bifurcation at the tip. The wall appears single-layered; no evidence of a distinct central body is observed. Wall faintly wavy in outline, in surface view flecked with irregular thickenings that may form a shallow reticulation- foveolation-pitting; the wall of the epicyst is distinctly thinner and smoother. Cingulum 4-5 µm wide, equatorial on dorsal face, somewhat bent antapically near the ventral sulcus. Archeopyle precingular, 3", broad based and triangular in shape but its outline somewhat affected by folding; operculum lost. No ridges or spines at apical pole. Paratabulation of the apicals is difficult to determine (especially 2", 3"). No pre-apicals observed; intercalary plates, if present, indistinct.
Affinities:
Jansonius, 1986, p.216: In the type residue, and in some other samples, specimens belonging to this species are readily identified by the slender parasutural spines and especially by the shallow apical dome. These features differentiate this species from R. cladophora (Defl.) Below; the synonymy of R. canadensis and R. downiei with R. cladophora, as proposed by Fisher and Riley ( 1980, p. 320), is here rejected, as it unnecessarily broadens and distorts the delineation of the latter species.