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Homotryblium floripes
Homotryblium floripes (Deflandre and Cookson, 1955, p.276, pl.7, figs.1–2,7) Stover, 1975, p.36.
Originally Hystrichosphaeridium, subsequently Cordosphaeridium, thirdly (and now) Homotryblium.
Taxonomic junior synonym: Homotryblium plectilum, according to Bujak in Bujak et al. (1980, p.64) — however, Stover in Lentin and Williams (1985, p.168) retained Homotryblium plectilum.
Holotype: Deflandre and Cookson, 1955, pl. 7, fig. 1
Locus typicus: near Denmark, Western Australia
Stratum typicum: Early Tertiary
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Homotryblium floripes (Deflandre and Cookson, 1955) Stover, 1975. According to Stover (1975), has a wall thickness of 2.5-3.0 µm which is scabrate with minute projections, setae or coni, on parts. Tabulation 4', 6", 6c, 6"’, 1p, 1"”, 3s. Only 5 processes on the postcingulars. Archeopyle 2A + 6P. Processes hollow, open distally, 20-30 µm long and 2.5 to ca 5 µm wide at midpoint. Some processes consist of a single trumpet-shaped tube, with or without 4 to 6 distal fimbriae; these relatively simple processes occur almost exclusively on the ventral surface. More characteristic are processes composed of 2 to 6 (usually 3 to 4) tubes joined centrally along the long axis of the process. Near the distal end individual tubes separate, bend slightly outwards; each tube is generally flared and may have fimbriae as in single tubed processes. Size: hypotracts exclusive of processes 55-75 µm in diameter, overall 102-124 µm.
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Original description: Deflandre and Cookson, 1955, p. 276: Hystrichosphaeridium floripes
Shell globular, with about 16-18 tubular processes not communicating with the interior. Processes generally consisting of from 2 to several tubes joined along the greater part of their length, the individual tubes widening and sometimes separating from one another distally. Proximally the peripheral tubes widen considerably as they fuse with the membrane of the shell, forming on its surface a clearly defined flower-like design. Sometimes the processes may consist of a single tube with a rounded base. Membrane of shell thin and finely reticulate.
Revised description: Stover, 1975, p. 37-38
Cysts spherical or nearly so, and composed of 2 appressed wall layers. Endophragm about 0.5, µm thick, homogeneous, and unsculptured; periphragm approximately 2 µm to 2.5, µm thick, irregularly scabrate, and attenuated locally to form 26 intratabular processes. Wall layering seen best at bases of processes and in optical section. Minute projections (setae or coni) occur as part of the periphragm, whose outer surface is definitely uneven; scabration lacking beneath processes, which are closed proximally by the endophragm and apparently by part of the periphragm; consequently, they do not communicate with endocoel.
Positions of intratabular processes and sutural pattern on epitract reflect gonyaulacacean tabulation 4', 6'', 6c, 6''', I, 1'''' and 3s; however, because process development is lacking for the first postcingular position, only 5 processes are present in the postcingular series.
Suture of the combination archeopyle, Type 2A + 6P, occurs along apical margin of reflected singular plates, and the completely detached operculum, consisting of apical and precingular plates, is separated further. Usually precingular plates and first apical plate dissociate as 7 individual opercular pieces; the other 3 apical plates remain together as eighth opercular piece. A thickening or even a short process corresponding to a reflected preapical plate (?pore-closing platelet) may occur at intersection of the 3 attached apical plates.
The 16 processes on the hypotract include 6 cingular, 5 postcingular, 1 posterior intercalary, 1 antapical, and 3 sulcal processes. Cingular processes occur in a ring immediately below archeopyle margin and are more or less evenly spaced along the circumference. On some specimens singular reflected plate boundaries are indicated by V-shaped notches along the archeopyle margin, and, similarly, boundaries between some precingular plates are marked by minute chevron-shaped tabs. Below cingular processes, and also in a ring, are 5 postcingular processes; below them at the antapical end are 3 more processes arranged as a triangle. The almost centrally located one (as seen in apical-antapical view) is the ant apical process, and between it and the fifth postcingular process (designated 6''' on Text-fig. 1 ) lies the posterior sulcal process. The remaining process of the 3 is the posterior intercalary process. An anterior sulcal process, in line with the singular processes, occurs on a small projection extending above the archeopyle margin, and to the left of a depression that corresponds to the low position of reflected plate 6''. A third sulcal process is present between the anterior and posterior sulcal processes.
Processes hollow, open distally, 20 µm to 30 µm long, expanded proximally and distally, and are 2.5 µm to slightly more than 5 µm wide at mid length. Some processes consist of a single trumpet shaped tube with or without 4 to 6 distal fimbriae; these relatively simple processes occur almost excluslively on the ventral surface. More characteristic of the species are processes composed of 2 to 6 (usually 3 or 4) tubes joined centrally along the long axis of the process. Near the distal end, individual tubes separate, bend slightly outward; each tube is generally flared and may have fimbriae, as in single-tubed processes. Bases of multi-tubed processes are flared, and a rosette-like pattern is commonly formed where processes merge with rest of cyst. In general, single and two-tubed processes apparently reflect small plate areas, such as those in cingular series. Multi-tubed processes are associated with large reflected plates of epitract; on lower part of hypotract, they indicate large plate areas.
Hypotracts, exclusive of processes, 55 µm to 75 µm in diameter, with majority of specimens in 58 µm to 63 µm-size range. Overall size of hypotracts 102 µm to 124 µm.
Variability: The clarity of the rosette-like pattern at the bases of processes ranges from barely perceptible to fairly evident. In general the pattern is most discernible on specimens in which there is partial destruction of the periphragm. Texturing of the periphragm varies from exceptionally hue, with setae, coni, and intervening areas less than 0.5 Ám across, to coarse, with granule up to nearly 2 µm in diameter. Except for variability in size, other features of the species are essentially constant. These include the thickness of the endophragm and periphragm, the number of processes, the position of the processes and, for the epitract, the shape of the reflected plates. Disarticulate precingular and apical plates, if favourably oriented, can be identified as to number and series.
Affinities:
Deflandre and Cookson, 1955, p. 276
None of the specimens is perfectly preserved; the number of processes as well as the dimension of the shell must therefore be considered as only approximate. H. floripes is a very clearly defined species, easy to recognize and quite distinct from any other known form.
Originally Hystrichosphaeridium, subsequently Cordosphaeridium, thirdly (and now) Homotryblium.
Taxonomic junior synonym: Homotryblium plectilum, according to Bujak in Bujak et al. (1980, p.64) — however, Stover in Lentin and Williams (1985, p.168) retained Homotryblium plectilum.
Holotype: Deflandre and Cookson, 1955, pl. 7, fig. 1
Locus typicus: near Denmark, Western Australia
Stratum typicum: Early Tertiary
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Homotryblium floripes (Deflandre and Cookson, 1955) Stover, 1975. According to Stover (1975), has a wall thickness of 2.5-3.0 µm which is scabrate with minute projections, setae or coni, on parts. Tabulation 4', 6", 6c, 6"’, 1p, 1"”, 3s. Only 5 processes on the postcingulars. Archeopyle 2A + 6P. Processes hollow, open distally, 20-30 µm long and 2.5 to ca 5 µm wide at midpoint. Some processes consist of a single trumpet-shaped tube, with or without 4 to 6 distal fimbriae; these relatively simple processes occur almost exclusively on the ventral surface. More characteristic are processes composed of 2 to 6 (usually 3 to 4) tubes joined centrally along the long axis of the process. Near the distal end individual tubes separate, bend slightly outwards; each tube is generally flared and may have fimbriae as in single tubed processes. Size: hypotracts exclusive of processes 55-75 µm in diameter, overall 102-124 µm.
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Original description: Deflandre and Cookson, 1955, p. 276: Hystrichosphaeridium floripes
Shell globular, with about 16-18 tubular processes not communicating with the interior. Processes generally consisting of from 2 to several tubes joined along the greater part of their length, the individual tubes widening and sometimes separating from one another distally. Proximally the peripheral tubes widen considerably as they fuse with the membrane of the shell, forming on its surface a clearly defined flower-like design. Sometimes the processes may consist of a single tube with a rounded base. Membrane of shell thin and finely reticulate.
Revised description: Stover, 1975, p. 37-38
Cysts spherical or nearly so, and composed of 2 appressed wall layers. Endophragm about 0.5, µm thick, homogeneous, and unsculptured; periphragm approximately 2 µm to 2.5, µm thick, irregularly scabrate, and attenuated locally to form 26 intratabular processes. Wall layering seen best at bases of processes and in optical section. Minute projections (setae or coni) occur as part of the periphragm, whose outer surface is definitely uneven; scabration lacking beneath processes, which are closed proximally by the endophragm and apparently by part of the periphragm; consequently, they do not communicate with endocoel.
Positions of intratabular processes and sutural pattern on epitract reflect gonyaulacacean tabulation 4', 6'', 6c, 6''', I, 1'''' and 3s; however, because process development is lacking for the first postcingular position, only 5 processes are present in the postcingular series.
Suture of the combination archeopyle, Type 2A + 6P, occurs along apical margin of reflected singular plates, and the completely detached operculum, consisting of apical and precingular plates, is separated further. Usually precingular plates and first apical plate dissociate as 7 individual opercular pieces; the other 3 apical plates remain together as eighth opercular piece. A thickening or even a short process corresponding to a reflected preapical plate (?pore-closing platelet) may occur at intersection of the 3 attached apical plates.
The 16 processes on the hypotract include 6 cingular, 5 postcingular, 1 posterior intercalary, 1 antapical, and 3 sulcal processes. Cingular processes occur in a ring immediately below archeopyle margin and are more or less evenly spaced along the circumference. On some specimens singular reflected plate boundaries are indicated by V-shaped notches along the archeopyle margin, and, similarly, boundaries between some precingular plates are marked by minute chevron-shaped tabs. Below cingular processes, and also in a ring, are 5 postcingular processes; below them at the antapical end are 3 more processes arranged as a triangle. The almost centrally located one (as seen in apical-antapical view) is the ant apical process, and between it and the fifth postcingular process (designated 6''' on Text-fig. 1 ) lies the posterior sulcal process. The remaining process of the 3 is the posterior intercalary process. An anterior sulcal process, in line with the singular processes, occurs on a small projection extending above the archeopyle margin, and to the left of a depression that corresponds to the low position of reflected plate 6''. A third sulcal process is present between the anterior and posterior sulcal processes.
Processes hollow, open distally, 20 µm to 30 µm long, expanded proximally and distally, and are 2.5 µm to slightly more than 5 µm wide at mid length. Some processes consist of a single trumpet shaped tube with or without 4 to 6 distal fimbriae; these relatively simple processes occur almost excluslively on the ventral surface. More characteristic of the species are processes composed of 2 to 6 (usually 3 or 4) tubes joined centrally along the long axis of the process. Near the distal end, individual tubes separate, bend slightly outward; each tube is generally flared and may have fimbriae, as in single-tubed processes. Bases of multi-tubed processes are flared, and a rosette-like pattern is commonly formed where processes merge with rest of cyst. In general, single and two-tubed processes apparently reflect small plate areas, such as those in cingular series. Multi-tubed processes are associated with large reflected plates of epitract; on lower part of hypotract, they indicate large plate areas.
Hypotracts, exclusive of processes, 55 µm to 75 µm in diameter, with majority of specimens in 58 µm to 63 µm-size range. Overall size of hypotracts 102 µm to 124 µm.
Variability: The clarity of the rosette-like pattern at the bases of processes ranges from barely perceptible to fairly evident. In general the pattern is most discernible on specimens in which there is partial destruction of the periphragm. Texturing of the periphragm varies from exceptionally hue, with setae, coni, and intervening areas less than 0.5 Ám across, to coarse, with granule up to nearly 2 µm in diameter. Except for variability in size, other features of the species are essentially constant. These include the thickness of the endophragm and periphragm, the number of processes, the position of the processes and, for the epitract, the shape of the reflected plates. Disarticulate precingular and apical plates, if favourably oriented, can be identified as to number and series.
Affinities:
Deflandre and Cookson, 1955, p. 276
None of the specimens is perfectly preserved; the number of processes as well as the dimension of the shell must therefore be considered as only approximate. H. floripes is a very clearly defined species, easy to recognize and quite distinct from any other known form.