Back
Hystrichokolpoma torquatum
Hystrichokolpoma torquatum Damassa, 1979
Holotype: Damassa, 1979, pl.3, fig.1
Paratypes: Damssa, 1979
Locus typicus: Costal Belt, Franciscan Complex, California, USA
Stratum typicum: Early-Middle Eocene
Original diagnosis: Damassa, 1979, p. 825
Subspherical cyst, characterized by short, hollow, boxlike processes, encircled at base by depressed penitabular bands. Low parasutural ridges separate adjacent penitabular bands. Archeopyle margin shows a sixth precingular notch rather than an anterior sulcal notch. Large lobate structure occupies entire opercular area.
Original description: Damassa, 1979, p. 825
A species of Hystrichokolpoma characterized by short boxlike processes, encircled at the base by depressed penitabular bands. Width of penitabular bands 2-3 Ám. Low parasutural ridges separate adjacent penitabular bands. Cyst subspherical. Endocyst, 53 X 52 Ám, average of 23 specimens (range = 41-66 X 38-63 Ám). Endophragm may form a small tubercle beneath the apical and antapical processes. Endophragm about 1 Ám in thickness, endophragm plus periphragm about 2 Ám in thickness. Processes short, hollow, intratabular, one per paraplate for precingular, postcingular, and sulcal series and for antapical paraplate. Length of large processes 10-31 Ám, width at base 12-27 Ám. Processes generally broader at the base than they are long. except for antapical process. A large lobate structure. formed by fusion of four apical processes, occupies the entire opercular area. Cingular series represented by 2 or 3 small processes per paraplate, up to 17 Ám in length. Processes 1"-5" large. polygonal in cross section; processes 6" and as (anterior sulcal) smaller, longitudinally elongate, 6" shorter than as. Sulcal and cingular processes small, conical; 1""" and 1p resemble sulcal processes. 2"""-6""" and 1""" large, polygonal in cross section; 2"""" smaller than other postcingular processes (except 1""") Large processes closed distally except for one or two small openings of oval to reniform outline and smooth margin. Corners of these processes may be drawn out into small spine like projections. Surface of cyst granulate, granules ordered into closely spaced subparallel lines along the length of the processes. Ends of paracingulum offset on ventral surface by a distance approximately equal to the width of the paracingulum. Archeopyle Type (tA), formed by loss of paraplates 1"-4"; operculum simple, free. Edge of archeopyle shows a sixth precingular notch rather than the usual anterior sulcal notch (PI 3, fig. 1; Text-fig. 7), and corresponding extension on operculum is formed by fourth apical rather than first apical paraplate (PI 3. fig. 2). Process formula--1", 6", xc, 1p, 5s, 6""", 1"""". Inferred thecal tabulation- 4", 6", 6c, 1p, 5s, 6""", 1"""".
Affinities:
Damassa, 1979, p. 825: Hystrichokolpoma torquatum most closely resembles H. salacia Eaton, 1976, but differs in the following: 1) short, boxlike processes which are wider at the base than they are high; 2) low parasutural ridges and accompanying penitabular bands; 3) small openings at the distal ends of the large processes; 4) the distinctive character of the ventral side of the archeopyle margin (i.e., the "sixth precingular notch"). The lobate structure at the apex (on the operculum) formed by fusion of 1"-4" is highly variable in shape. In many specimens infolding and the development of lobes indicate the relative sizes of the apical paraplates (PI. 3, figs. 2-6) 1" and 4" are more or less equal in size, and smaller than 2" and 3", which are also approximately equivalent in size.
H. torquata is unusual, and perhaps unique, among gonyaulacacean dinoflagellates with respect to the archeopyle margin. In this species the most adcingular part of the archeopyle margin on the ventral surface is not the parasulcal notch, but the upper margin of the sixth precingular paraplate (PL 3, figs. 1, 2; Text-fig. 7). The identity, of the anterior sulcal process is established by its relationship to the 1", 1c and remaining sulcal processes.
Holotype: Damassa, 1979, pl.3, fig.1
Paratypes: Damssa, 1979
Locus typicus: Costal Belt, Franciscan Complex, California, USA
Stratum typicum: Early-Middle Eocene
Original diagnosis: Damassa, 1979, p. 825
Subspherical cyst, characterized by short, hollow, boxlike processes, encircled at base by depressed penitabular bands. Low parasutural ridges separate adjacent penitabular bands. Archeopyle margin shows a sixth precingular notch rather than an anterior sulcal notch. Large lobate structure occupies entire opercular area.
Original description: Damassa, 1979, p. 825
A species of Hystrichokolpoma characterized by short boxlike processes, encircled at the base by depressed penitabular bands. Width of penitabular bands 2-3 Ám. Low parasutural ridges separate adjacent penitabular bands. Cyst subspherical. Endocyst, 53 X 52 Ám, average of 23 specimens (range = 41-66 X 38-63 Ám). Endophragm may form a small tubercle beneath the apical and antapical processes. Endophragm about 1 Ám in thickness, endophragm plus periphragm about 2 Ám in thickness. Processes short, hollow, intratabular, one per paraplate for precingular, postcingular, and sulcal series and for antapical paraplate. Length of large processes 10-31 Ám, width at base 12-27 Ám. Processes generally broader at the base than they are long. except for antapical process. A large lobate structure. formed by fusion of four apical processes, occupies the entire opercular area. Cingular series represented by 2 or 3 small processes per paraplate, up to 17 Ám in length. Processes 1"-5" large. polygonal in cross section; processes 6" and as (anterior sulcal) smaller, longitudinally elongate, 6" shorter than as. Sulcal and cingular processes small, conical; 1""" and 1p resemble sulcal processes. 2"""-6""" and 1""" large, polygonal in cross section; 2"""" smaller than other postcingular processes (except 1""") Large processes closed distally except for one or two small openings of oval to reniform outline and smooth margin. Corners of these processes may be drawn out into small spine like projections. Surface of cyst granulate, granules ordered into closely spaced subparallel lines along the length of the processes. Ends of paracingulum offset on ventral surface by a distance approximately equal to the width of the paracingulum. Archeopyle Type (tA), formed by loss of paraplates 1"-4"; operculum simple, free. Edge of archeopyle shows a sixth precingular notch rather than the usual anterior sulcal notch (PI 3, fig. 1; Text-fig. 7), and corresponding extension on operculum is formed by fourth apical rather than first apical paraplate (PI 3. fig. 2). Process formula--1", 6", xc, 1p, 5s, 6""", 1"""". Inferred thecal tabulation- 4", 6", 6c, 1p, 5s, 6""", 1"""".
Affinities:
Damassa, 1979, p. 825: Hystrichokolpoma torquatum most closely resembles H. salacia Eaton, 1976, but differs in the following: 1) short, boxlike processes which are wider at the base than they are high; 2) low parasutural ridges and accompanying penitabular bands; 3) small openings at the distal ends of the large processes; 4) the distinctive character of the ventral side of the archeopyle margin (i.e., the "sixth precingular notch"). The lobate structure at the apex (on the operculum) formed by fusion of 1"-4" is highly variable in shape. In many specimens infolding and the development of lobes indicate the relative sizes of the apical paraplates (PI. 3, figs. 2-6) 1" and 4" are more or less equal in size, and smaller than 2" and 3", which are also approximately equivalent in size.
H. torquata is unusual, and perhaps unique, among gonyaulacacean dinoflagellates with respect to the archeopyle margin. In this species the most adcingular part of the archeopyle margin on the ventral surface is not the parasulcal notch, but the upper margin of the sixth precingular paraplate (PL 3, figs. 1, 2; Text-fig. 7). The identity, of the anterior sulcal process is established by its relationship to the 1", 1c and remaining sulcal processes.