Back
Angustidinium acribes
From Fensome et al., 2019:
Angustidinium acribes, (Davey and Verdier, 1971, p.38–39, pl.2, figs.10,12) Goodman and Evitt, 1981, p.48.
Emendation: Goodman and Evitt, 1981, p.48,50,52–53, as Angustidinium acribes.
Holotype: Davey and Verdier, 1971, pl.2, fig.10; Fensome et al., 1993a, fig.1 — p.875.
Originally Deflandrea, subsequently Alterbia (combination illegitimate), thirdly Alterbia? (combination illegitimate), fourthly (and now) Angustidinium, fifthly Moesiodinium. Lentin and Williams (1989, p.17) retained this species in Angustidinium.
Age: early Albian.
Locus typicus: Cotes Noires de Moeslains, NE France
---------------------------------------------------------------------------------------------------
Original description as Deflandrea acribes: [Davey and Verdier, 1971, p. 38-39]:
Diagnosis:
Small spherical cyst possessing thin outer wall surrounding moderately thick walled inner body. Outer wall forms an angular apical horn and two rounded antapical horns. Low ridges on this membrane define a broad cingulum and a ventral furrow. Weak tabulation usually shown by aligned granules. Intercalary archaeopyle sometimes apparent.
Description:
The apical horn is of a characteristic shape, in that there are lateral extensions onto the intercalary area. In one specimen an intercalary archaeopyle (Type I, Evitt, 1967) appeared to be present. However, as a Peridinoid-tabulation may be apparent, it is often possible to observe the intercalary plate 2a in situ. It is probable that this plate is hinged and returned into position after excystment took place. This species was not seen to be stained by safranin.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description as Angustidinium acribes:
Goodman and Evitt, 1981, p. 48, 50, 52:
Description:
Small, bicavate peridinioid cyst with broadly tapering apical horn capped by a short (ca. 1-2 µm), tubular apical projection; antapical horns absent or represented as two ill-defined antapical protrusions of the periphragm. Pericyst outline in dorsoventral view elongate-subpentagonal, the anterolateral angulations ("shoulders") emphasized by local strengthening of parasutural ridges ([Goodman and Evitt, 1981] Fig. 1). Outline in apical view broadly oval to reniform with variable parasulcal depression and slight dorsoventral compression. Endocyst angularly spheroidal, with length and width nearly equal; located either centrally or somewhat anterior to the center of pericyst. Large antapical pericoel and smaller apical pericoel confined to upper region of apical horn; periphragm and endophragm in close contact dorsally, ventrally, and laterally.
Low ridges outline paratabulation of 2pr, 5', 3a, 7", Xc, 5''', 2''''; ridges variably prominent on individual specimens (generally better developed on epicyst), within groups of specimens from individual samples, and between specimens from different localities (ridges weakly defined in French material). Areas within paraplates smooth or ornamented with minute grana.
Archeopyle intercalary (Type I/I; 2a only), with seven-sided, free operculum; openings in periphragm and endophragm similar, walls close together but not appressed in region of the archeopyle ([Goodman and Evitt, 1981] Fig. 6E, F).
Terminal preapical (1pr) includes apex of pericyst formed by tubular tip of apical horn. Second small paraplate, here treated as a second preapical (2pr), is elongate and lies to the right of anterior portion of the first apical. First apical is narrow and long, and does not contact 7"; 3' and 4' are symmetrical and meet along a mid-dorsal parasuture which terminates at apical, gabled limit of 2a; 5' is large, dissimilar to 2', and extends ventrally to contact anterior end of sulcus. Second intercalary is seven-sided but intercalaries relate to precingulars in conventional manner of hexa style paratabulation. Precingulars as usual in peridiniacean pattern except that 7" is four-sided.
Paracingulum defined by bounding ridges but cingular paraplates not delimited; slightly descending, with ends offset about half the paracingulum width."
Parasulcus consists of two longitudinal strips of notably different relief. One, along right side and including most of anterior sulcal paraplate, is about level with adjoining surface of epicyst and hypocyst. The other is deeply excavated and extends posteriorly from left end of paracingulum to common point of paraplates ps, 1'''', and 2'''' ([Goodman and Evitt, 1981] Fig. 6G, J). Best preserved specimens show parasulcus to be subdivided into several areas by parasutures or other linear markings. Most clearly defined are: elongate anterior sulcal paraplate, small right sulcal between flagellar scar area and right end of paracingulum; elongate posterior sulcal, widest between ends of parasutures 1'''/1'''' and 5'''/2''''; and an area between flagellar scar and left end of paracingulum. Last mentioned area may be a distinct sulcal paraplate if its boundary extending from flagellar scar to 1" is a parasuture (as shown on [Goodman and Evitt, 1981] Fig. lB). Alternatively, this area may be a relatively excavated portion of anterior sulcal paraplate separated from remainder of that paraplate by sharp change in surface slope, rather than by a parasuture. Two additional small sulcal paraplates are indicated in occasional specimens by faint parasutures which extend from angulations in left margin of parasulcus. Thus, parasulcus appears to include probably five, but possibly six paraplates.
Hypocyst paratabulation typically peridiniacean. Hypopericyst has two small (ca. 0.5 µm) openings (on California specimens) or areas of thick periphragm (on French specimens), one on each of the antapical paraplates, located just posterior to the common junction of paraplates 1'''', 2'''', and ps.
Dimensions:
Holotype: overall length 27 µm, overall width 22 µm.
Range: overall length 23(26)29 µm, overall width 19(22)26 µm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Fensome et al., 1993, p. 877-878:
In erecting this species, Davey and Verdier (1971, p.39) considered the small overall size and the shape of the apical horn to be distinctive features.
Goodman and Evitt (1981, p.47) erected the genus Angustidinium, with Angustidinium acribes as the type and only species. These authors recognized that Angustidinium acribes has a very distinctive paratabulation and accordingly provided a "revised description".
Goodman and Evitt (1981, p.52) considered the distinctive paratabulation, shape, bicavate nature, small size, and antapical openings or thickenings, as characteristic features of Angustidinium acribes. They noted from their Californian specimens of Angustidinium acribes that both of the antapical plates typically have an opening (about 0.5 µm in diameter) close to the posterior end of the sulcus. This feature was occasionally absent or represented by an indentation, the latter suggesting that the openings may have developed from naturally thin-walled areas. In the topotype material examined by Goodman and Evitt, this feature was represented by a mound or wall-thickening. Goodman and Evitt noted that the significance of this feature is unknown. These authors noted other differences in the detailed morphology between their material (which was from California) and the type material from France, but preferred to consider these variations as representing regional, intraspecific morphologic variation rather than as facets of distinct species.
Stover and Helby (1987, figs.10 I-L), who illustrated specimens of Angustidinium acribes from Australian samples, commented that the southern hemisphere specimens are more similar to the French specimens than to the Californian specimens.
Below (1987a, p.129) stated that the 2a paraplate is variable in shape, being "heptagonal" or "fastigiate". He considered that "... this is unimportant taxonomically, as proven by the known variation ... in Angustidinium acribes (fastigiate outline in Goodman and Evitt 1981, fig.6E)."
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Angustidinium acribes (Davey and Verdier, 1971) Goodman and Evitt, 1981 is a small bicavate cyst with broadly tapering apical horn with apical projection, and antapical horns absent or two ill-defined protrusions. Endocyst angularly spheroidal. Large antapical pericoel and smaller apical pericoel. Low ridges outline paratabulation of 2pr, 5', 3a, 7", xc, 5"’, 2"”.
Size: pericyst length 40-51 µm, width 30-37 µm, endocyst length 19-35 µm, breadth 23-35 µm.
Angustidinium acribes, (Davey and Verdier, 1971, p.38–39, pl.2, figs.10,12) Goodman and Evitt, 1981, p.48.
Emendation: Goodman and Evitt, 1981, p.48,50,52–53, as Angustidinium acribes.
Holotype: Davey and Verdier, 1971, pl.2, fig.10; Fensome et al., 1993a, fig.1 — p.875.
Originally Deflandrea, subsequently Alterbia (combination illegitimate), thirdly Alterbia? (combination illegitimate), fourthly (and now) Angustidinium, fifthly Moesiodinium. Lentin and Williams (1989, p.17) retained this species in Angustidinium.
Age: early Albian.
Locus typicus: Cotes Noires de Moeslains, NE France
---------------------------------------------------------------------------------------------------
Original description as Deflandrea acribes: [Davey and Verdier, 1971, p. 38-39]:
Diagnosis:
Small spherical cyst possessing thin outer wall surrounding moderately thick walled inner body. Outer wall forms an angular apical horn and two rounded antapical horns. Low ridges on this membrane define a broad cingulum and a ventral furrow. Weak tabulation usually shown by aligned granules. Intercalary archaeopyle sometimes apparent.
Description:
The apical horn is of a characteristic shape, in that there are lateral extensions onto the intercalary area. In one specimen an intercalary archaeopyle (Type I, Evitt, 1967) appeared to be present. However, as a Peridinoid-tabulation may be apparent, it is often possible to observe the intercalary plate 2a in situ. It is probable that this plate is hinged and returned into position after excystment took place. This species was not seen to be stained by safranin.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description as Angustidinium acribes:
Goodman and Evitt, 1981, p. 48, 50, 52:
Description:
Small, bicavate peridinioid cyst with broadly tapering apical horn capped by a short (ca. 1-2 µm), tubular apical projection; antapical horns absent or represented as two ill-defined antapical protrusions of the periphragm. Pericyst outline in dorsoventral view elongate-subpentagonal, the anterolateral angulations ("shoulders") emphasized by local strengthening of parasutural ridges ([Goodman and Evitt, 1981] Fig. 1). Outline in apical view broadly oval to reniform with variable parasulcal depression and slight dorsoventral compression. Endocyst angularly spheroidal, with length and width nearly equal; located either centrally or somewhat anterior to the center of pericyst. Large antapical pericoel and smaller apical pericoel confined to upper region of apical horn; periphragm and endophragm in close contact dorsally, ventrally, and laterally.
Low ridges outline paratabulation of 2pr, 5', 3a, 7", Xc, 5''', 2''''; ridges variably prominent on individual specimens (generally better developed on epicyst), within groups of specimens from individual samples, and between specimens from different localities (ridges weakly defined in French material). Areas within paraplates smooth or ornamented with minute grana.
Archeopyle intercalary (Type I/I; 2a only), with seven-sided, free operculum; openings in periphragm and endophragm similar, walls close together but not appressed in region of the archeopyle ([Goodman and Evitt, 1981] Fig. 6E, F).
Terminal preapical (1pr) includes apex of pericyst formed by tubular tip of apical horn. Second small paraplate, here treated as a second preapical (2pr), is elongate and lies to the right of anterior portion of the first apical. First apical is narrow and long, and does not contact 7"; 3' and 4' are symmetrical and meet along a mid-dorsal parasuture which terminates at apical, gabled limit of 2a; 5' is large, dissimilar to 2', and extends ventrally to contact anterior end of sulcus. Second intercalary is seven-sided but intercalaries relate to precingulars in conventional manner of hexa style paratabulation. Precingulars as usual in peridiniacean pattern except that 7" is four-sided.
Paracingulum defined by bounding ridges but cingular paraplates not delimited; slightly descending, with ends offset about half the paracingulum width."
Parasulcus consists of two longitudinal strips of notably different relief. One, along right side and including most of anterior sulcal paraplate, is about level with adjoining surface of epicyst and hypocyst. The other is deeply excavated and extends posteriorly from left end of paracingulum to common point of paraplates ps, 1'''', and 2'''' ([Goodman and Evitt, 1981] Fig. 6G, J). Best preserved specimens show parasulcus to be subdivided into several areas by parasutures or other linear markings. Most clearly defined are: elongate anterior sulcal paraplate, small right sulcal between flagellar scar area and right end of paracingulum; elongate posterior sulcal, widest between ends of parasutures 1'''/1'''' and 5'''/2''''; and an area between flagellar scar and left end of paracingulum. Last mentioned area may be a distinct sulcal paraplate if its boundary extending from flagellar scar to 1" is a parasuture (as shown on [Goodman and Evitt, 1981] Fig. lB). Alternatively, this area may be a relatively excavated portion of anterior sulcal paraplate separated from remainder of that paraplate by sharp change in surface slope, rather than by a parasuture. Two additional small sulcal paraplates are indicated in occasional specimens by faint parasutures which extend from angulations in left margin of parasulcus. Thus, parasulcus appears to include probably five, but possibly six paraplates.
Hypocyst paratabulation typically peridiniacean. Hypopericyst has two small (ca. 0.5 µm) openings (on California specimens) or areas of thick periphragm (on French specimens), one on each of the antapical paraplates, located just posterior to the common junction of paraplates 1'''', 2'''', and ps.
Dimensions:
Holotype: overall length 27 µm, overall width 22 µm.
Range: overall length 23(26)29 µm, overall width 19(22)26 µm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Fensome et al., 1993, p. 877-878:
In erecting this species, Davey and Verdier (1971, p.39) considered the small overall size and the shape of the apical horn to be distinctive features.
Goodman and Evitt (1981, p.47) erected the genus Angustidinium, with Angustidinium acribes as the type and only species. These authors recognized that Angustidinium acribes has a very distinctive paratabulation and accordingly provided a "revised description".
Goodman and Evitt (1981, p.52) considered the distinctive paratabulation, shape, bicavate nature, small size, and antapical openings or thickenings, as characteristic features of Angustidinium acribes. They noted from their Californian specimens of Angustidinium acribes that both of the antapical plates typically have an opening (about 0.5 µm in diameter) close to the posterior end of the sulcus. This feature was occasionally absent or represented by an indentation, the latter suggesting that the openings may have developed from naturally thin-walled areas. In the topotype material examined by Goodman and Evitt, this feature was represented by a mound or wall-thickening. Goodman and Evitt noted that the significance of this feature is unknown. These authors noted other differences in the detailed morphology between their material (which was from California) and the type material from France, but preferred to consider these variations as representing regional, intraspecific morphologic variation rather than as facets of distinct species.
Stover and Helby (1987, figs.10 I-L), who illustrated specimens of Angustidinium acribes from Australian samples, commented that the southern hemisphere specimens are more similar to the French specimens than to the Californian specimens.
Below (1987a, p.129) stated that the 2a paraplate is variable in shape, being "heptagonal" or "fastigiate". He considered that "... this is unimportant taxonomically, as proven by the known variation ... in Angustidinium acribes (fastigiate outline in Goodman and Evitt 1981, fig.6E)."
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Angustidinium acribes (Davey and Verdier, 1971) Goodman and Evitt, 1981 is a small bicavate cyst with broadly tapering apical horn with apical projection, and antapical horns absent or two ill-defined protrusions. Endocyst angularly spheroidal. Large antapical pericoel and smaller apical pericoel. Low ridges outline paratabulation of 2pr, 5', 3a, 7", xc, 5"’, 2"”.
Size: pericyst length 40-51 µm, width 30-37 µm, endocyst length 19-35 µm, breadth 23-35 µm.