Back
Trichodinium eisenackii
From Fensome et al., 2019:
Trichodinium eisenackii Burger, 1980a, p.81, pl.37, figs.1,4.
Holotype: Burger, 1980a, pl.37, fig.1.
Age: Aptian.
---------------------------------------------------------------------------------------------------
Original description (Burger, 1990a):
Trichodinium eisenackii sp. novo PI. 37, figs. 1,4
Holotype: GSQ Surat 1, depth 305.3 m (1001 ft 6 in); Wallumbilla Formation, Doncaster Member. Cretaceous, late Aptian. (MFP 5015-1, 329/1180; CPC 16397. PI. 37, fig. 1).
Description: Cyst broadly ellipsoidal; some specimens have a tiny apical horn about 4 µm high, formed by a cluster of processes or by a thickening of the cyst wall, and which bears a few tiny spinules. A large and roundly triangular archaeopyle is usually present at the location of paraplate 3". A paracingulum is faintly outlined, other traces of paratabulation are not visible. Cyst wall single-layered, about 1.5 µm thick, irregularly and finely punctate to faintly fibrous, and sparsely covered with short, conical and some tubiform processes 2-5 µm high, with truncate or acuminate, bifid, digitate or capitate distal ends. Many of the processes are aligned in short anastomosing rows without preference in orientation.
Dimensions: Overall length (17 specimens) 46-(61) -80 µm, width 38-76 µm.
Distribution: A rare to very rare species in the lower and middle intervals of the Odontochitina operculata Zone, more commonly present in the upper interval of the Zone and the Pseudoceratium turneri Zone.
Comments: T. eisenackii sp. novo is smaller than T. intermedium Eisenack & Cookson, 1960. It differs also from T. ciliatum (Gocht, 1959) Eisenack & Klement, 1964, in having traces of a paracingulum, and solid and conical instead of bristly processes. Xenicodinium densispinosum Klement, 1960, has a comparable ornamental arrangement in which the individual processes are aligned into short and curved beads or 'Schnuren', but does not develop either a paracingulum or distinct apical horn. However, all these species are morphologically very close, and Clarke & Verdier (1967) already suggested that intermedium and ciliatum be regarded as synonyms of T. castaneum (Deflandre, 1935) Clarke & Verdier, 1967 (Davey (1974), however, preferred to keep these three species separated). T. castaneum differs from T. eisenackii sp. novo in having a denser spine cover, a broader paracingulum, and more accentuated traces of paratabulation.
Trichodinium eisenackii Burger, 1980a, p.81, pl.37, figs.1,4.
Holotype: Burger, 1980a, pl.37, fig.1.
Age: Aptian.
---------------------------------------------------------------------------------------------------
Original description (Burger, 1990a):
Trichodinium eisenackii sp. novo PI. 37, figs. 1,4
Holotype: GSQ Surat 1, depth 305.3 m (1001 ft 6 in); Wallumbilla Formation, Doncaster Member. Cretaceous, late Aptian. (MFP 5015-1, 329/1180; CPC 16397. PI. 37, fig. 1).
Description: Cyst broadly ellipsoidal; some specimens have a tiny apical horn about 4 µm high, formed by a cluster of processes or by a thickening of the cyst wall, and which bears a few tiny spinules. A large and roundly triangular archaeopyle is usually present at the location of paraplate 3". A paracingulum is faintly outlined, other traces of paratabulation are not visible. Cyst wall single-layered, about 1.5 µm thick, irregularly and finely punctate to faintly fibrous, and sparsely covered with short, conical and some tubiform processes 2-5 µm high, with truncate or acuminate, bifid, digitate or capitate distal ends. Many of the processes are aligned in short anastomosing rows without preference in orientation.
Dimensions: Overall length (17 specimens) 46-(61) -80 µm, width 38-76 µm.
Distribution: A rare to very rare species in the lower and middle intervals of the Odontochitina operculata Zone, more commonly present in the upper interval of the Zone and the Pseudoceratium turneri Zone.
Comments: T. eisenackii sp. novo is smaller than T. intermedium Eisenack & Cookson, 1960. It differs also from T. ciliatum (Gocht, 1959) Eisenack & Klement, 1964, in having traces of a paracingulum, and solid and conical instead of bristly processes. Xenicodinium densispinosum Klement, 1960, has a comparable ornamental arrangement in which the individual processes are aligned into short and curved beads or 'Schnuren', but does not develop either a paracingulum or distinct apical horn. However, all these species are morphologically very close, and Clarke & Verdier (1967) already suggested that intermedium and ciliatum be regarded as synonyms of T. castaneum (Deflandre, 1935) Clarke & Verdier, 1967 (Davey (1974), however, preferred to keep these three species separated). T. castaneum differs from T. eisenackii sp. novo in having a denser spine cover, a broader paracingulum, and more accentuated traces of paratabulation.