Back
Trichodinium hirsutum
From Fensome et al., 2019:
Trichodinium hirsutum Cookson, 1965b, p.139, pl.25, figs.5–13.
Holotype: Cookson, 1965b, pl.25, figs.5–7.
Locus typicus: Pebble Point Formation, SW. Victoria
Stratum typicum: Paleocene
---------------------------------------------------------------------------------------------------
Original description: Cookson, 1965, p.139
Shell almost spherical with a short, straight-sided, branched apical projection, an antapical projection with slanting sides and short, hair-like, terminal branches, an equatorial girdle apparently ending at the lateral margins and a pre-cingular hoof-shaped archeopyle. Shell-membrane relatively thick c. 2.5 µm, ornamented with solid, simple or branched, broad-based, pointed appendages the size and number of which vary according to their position on the shell. They are longest and most numerous along the margins, especially so in the region of the girdle; shorter, well-spaced or in small groups on the dorsal surface, with a tendency towards a linear arrangement parallel to the girdle which they outline (Pl. 25, fig. 10); while on the ventral surface they are very small, sparse and apparently absent from a narrow longitudinal mid-hypothecal zone suggestive of a longitudinal furrow, which they appear to outline (Pl. 25, fig. 12, 13). The cover of the archeopyle bears three or four short, stiff appendages (Pl. 25, fig. 8). The shellmembrane of the dorsal surface is marked into irregularly-shaped areas by ridges and the confluence of appendage bases several of which together form raised thickenings (Pl. 25, fig. 11). The sculptural elements of both surfaces are in the form of unevenly-spaced granules of varying size and shape.
Dimensions:
Holotype overall length c. 125 µm, overall width c. 100 µm, shell c. 90 x 83 µm; anterior projection c. 17.5 µm long, posterior projection c. 25 µm long.
Range: overall length 100-167 µm, overall width 97-105 µm, anterior projection 25-28 µm long, posterior projection 20-30 µm long, appendages 7-25 µm long.
Affinities:
Cookson, 1965, p.139: Of the previously described species of Trichodinium, all of which are from Cretaceous deposits, the one to which T. hirsutum most closely approaches is the type species T. pellitum Eisenack and Cookson 1960. T. hirsutum differs from this species in the development of an antapical as well as an apical projection, its more apparent dorsiventrality, the coarser and longer appendages and the details of wall structure.
Trichodinium hirsutum Cookson, 1965b, p.139, pl.25, figs.5–13.
Holotype: Cookson, 1965b, pl.25, figs.5–7.
Locus typicus: Pebble Point Formation, SW. Victoria
Stratum typicum: Paleocene
---------------------------------------------------------------------------------------------------
Original description: Cookson, 1965, p.139
Shell almost spherical with a short, straight-sided, branched apical projection, an antapical projection with slanting sides and short, hair-like, terminal branches, an equatorial girdle apparently ending at the lateral margins and a pre-cingular hoof-shaped archeopyle. Shell-membrane relatively thick c. 2.5 µm, ornamented with solid, simple or branched, broad-based, pointed appendages the size and number of which vary according to their position on the shell. They are longest and most numerous along the margins, especially so in the region of the girdle; shorter, well-spaced or in small groups on the dorsal surface, with a tendency towards a linear arrangement parallel to the girdle which they outline (Pl. 25, fig. 10); while on the ventral surface they are very small, sparse and apparently absent from a narrow longitudinal mid-hypothecal zone suggestive of a longitudinal furrow, which they appear to outline (Pl. 25, fig. 12, 13). The cover of the archeopyle bears three or four short, stiff appendages (Pl. 25, fig. 8). The shellmembrane of the dorsal surface is marked into irregularly-shaped areas by ridges and the confluence of appendage bases several of which together form raised thickenings (Pl. 25, fig. 11). The sculptural elements of both surfaces are in the form of unevenly-spaced granules of varying size and shape.
Dimensions:
Holotype overall length c. 125 µm, overall width c. 100 µm, shell c. 90 x 83 µm; anterior projection c. 17.5 µm long, posterior projection c. 25 µm long.
Range: overall length 100-167 µm, overall width 97-105 µm, anterior projection 25-28 µm long, posterior projection 20-30 µm long, appendages 7-25 µm long.
Affinities:
Cookson, 1965, p.139: Of the previously described species of Trichodinium, all of which are from Cretaceous deposits, the one to which T. hirsutum most closely approaches is the type species T. pellitum Eisenack and Cookson 1960. T. hirsutum differs from this species in the development of an antapical as well as an apical projection, its more apparent dorsiventrality, the coarser and longer appendages and the details of wall structure.