Back
Fusiformacysta terniana
Fusiformacysta terniana Riding and Helby, 2001d, p.77,79,81, figs.8A-L,9A-D.
Taxonomic junior synonym: Helbycysta psilata (name not validly published), according to Riding and Helby (2001d, p.79).
Holotype: Riding and Helby, 2001d, fig.8J.
Age: Bathonian-Callovian.
(Riding & Helby, 2001d):
Previous Australian usage: Apteodinium sp. – Lister. Komewuia sp. 55 (smooth) – Helby. Mancodinium sp. 555 – Morgan. Helbycysta psilate – Morgan.
Description: A species of Fustiformacysta with a type 3P Archeopyle, which is biconical or ellipsoidal in outline, with or without relatively short, blunt, distally rounded, apical and antapical horns. Where horns are developed, the antapical horn is normally the longest and occasionally the apical horn may be reduced or entirely suppressed. Generally the species is elongate, but is may also be wider than long or subequant. The only indication of paratabulation is the type 3P Archeopyle. Isolated opercula are frequently present within the loisthocysts. Dark brown accumulation bodies may be present in the cyst. The autophragm is mainly smooth, but may be partially microgranulate to microreticulate,
Dimensions: Two morphotypes of F. terniana were observed. Specimens form as sidewall core in Challus-11 ST1 well at 1552.50m are relatively small, have ellipsoidal outlines and lack polar horns (Fig. 9). However, material from Tern-1 well (sidewall core sample at 1528.28 and ditch cuttings between 1530.11m and 1536.21m) are larger than the Challis-11 ST1 forms and are typically biconical in outline due to the development of apical and antapical horns (Fig. 8). The measurements of five specimen of the small, ellipsoidal forms from Challis-11 ST1 sidewall core sample at 1552050m are as follows:
Dimensions: (µm, n=5): Min.(Mean)Max.
Maximum length of cyst: 65(72)82
Width of cyst at paracingulum: 62(69)79
(Horns are absent in this morphotype)
The dimensions of 29 speciemns from Tern-1 well, sideall core samples at 15528.28m and a ditch cuttings sample between 530.11m and 1536.21m are given below.
Dimensions: (µm, n=29): Min.(Mean)Max.
Maximum length of cyst: 72(94)122
Width of cyst at paracingulum: 67(89)115
Length of apical horn: 0(6)11
Length of antapical horn: 3(8)14
The data for the length and width of both the Challis-11 ST1 wel and Tern-1 well morphotypes, a total of 34 specimens, is a follows:
Dimensions: (µm, n=34): Min.(Mean)Max.
Maximum length of cyst: 65(86)115
Note that horn measurements are not gven in this table because the Challis-11 ST1 forms lack apical and antapical horns.protrusions.
Comments: In most specimens from Tern-1 well, the antapical horn is longer. However, horn lengths are variable and the apical horn may be longer than the antapical protuberance. In several specimen, the area around the antapical horn is micropunctate. Analyses of the shape of the anterior margins of the opercula and the principal archeopyle suture, indicates the presence of a small anterior intercalary paraplate (Fig. 8J). The biconical shape is reduced to a more ellipsoidal shape is some of the older associations, such as the material from Challis-11 ST1 well.
Comparison: Fustiformacysta terniana differs from K. challisiana Riding & Helby (this volume) by the absence of a verrucate and/or reticulate autophragm. The genotype, F. salasii Morgan 1975, is much more slender and has markedly longer apical and antapical horns than F. terniana. F. tumida Backhouse 1988 is also narrower than F. terniana and is granulate.
Derivation of name: From Tern-1 well, from which the holoype was selected.
Holotype and type locality: Figure 8J, CPC 35400, Tern-1 well, sidewall core sample at 1528.28m.
Statigraphical distribution: Fustformacysta terniana is present in the Bathonian to Callivian throughout the Timor Sea region. It ranges from the Wanaea verrucosa Zone (7cia) to the Rigaudella aemula Zone (7ai) (Foster, this volume; Helby & Partridge, in prep.).
Taxonomic junior synonym: Helbycysta psilata (name not validly published), according to Riding and Helby (2001d, p.79).
Holotype: Riding and Helby, 2001d, fig.8J.
Age: Bathonian-Callovian.
(Riding & Helby, 2001d):
Previous Australian usage: Apteodinium sp. – Lister. Komewuia sp. 55 (smooth) – Helby. Mancodinium sp. 555 – Morgan. Helbycysta psilate – Morgan.
Description: A species of Fustiformacysta with a type 3P Archeopyle, which is biconical or ellipsoidal in outline, with or without relatively short, blunt, distally rounded, apical and antapical horns. Where horns are developed, the antapical horn is normally the longest and occasionally the apical horn may be reduced or entirely suppressed. Generally the species is elongate, but is may also be wider than long or subequant. The only indication of paratabulation is the type 3P Archeopyle. Isolated opercula are frequently present within the loisthocysts. Dark brown accumulation bodies may be present in the cyst. The autophragm is mainly smooth, but may be partially microgranulate to microreticulate,
Dimensions: Two morphotypes of F. terniana were observed. Specimens form as sidewall core in Challus-11 ST1 well at 1552.50m are relatively small, have ellipsoidal outlines and lack polar horns (Fig. 9). However, material from Tern-1 well (sidewall core sample at 1528.28 and ditch cuttings between 1530.11m and 1536.21m) are larger than the Challis-11 ST1 forms and are typically biconical in outline due to the development of apical and antapical horns (Fig. 8). The measurements of five specimen of the small, ellipsoidal forms from Challis-11 ST1 sidewall core sample at 1552050m are as follows:
Dimensions: (µm, n=5): Min.(Mean)Max.
Maximum length of cyst: 65(72)82
Width of cyst at paracingulum: 62(69)79
(Horns are absent in this morphotype)
The dimensions of 29 speciemns from Tern-1 well, sideall core samples at 15528.28m and a ditch cuttings sample between 530.11m and 1536.21m are given below.
Dimensions: (µm, n=29): Min.(Mean)Max.
Maximum length of cyst: 72(94)122
Width of cyst at paracingulum: 67(89)115
Length of apical horn: 0(6)11
Length of antapical horn: 3(8)14
The data for the length and width of both the Challis-11 ST1 wel and Tern-1 well morphotypes, a total of 34 specimens, is a follows:
Dimensions: (µm, n=34): Min.(Mean)Max.
Maximum length of cyst: 65(86)115
Note that horn measurements are not gven in this table because the Challis-11 ST1 forms lack apical and antapical horns.protrusions.
Comments: In most specimens from Tern-1 well, the antapical horn is longer. However, horn lengths are variable and the apical horn may be longer than the antapical protuberance. In several specimen, the area around the antapical horn is micropunctate. Analyses of the shape of the anterior margins of the opercula and the principal archeopyle suture, indicates the presence of a small anterior intercalary paraplate (Fig. 8J). The biconical shape is reduced to a more ellipsoidal shape is some of the older associations, such as the material from Challis-11 ST1 well.
Comparison: Fustiformacysta terniana differs from K. challisiana Riding & Helby (this volume) by the absence of a verrucate and/or reticulate autophragm. The genotype, F. salasii Morgan 1975, is much more slender and has markedly longer apical and antapical horns than F. terniana. F. tumida Backhouse 1988 is also narrower than F. terniana and is granulate.
Derivation of name: From Tern-1 well, from which the holoype was selected.
Holotype and type locality: Figure 8J, CPC 35400, Tern-1 well, sidewall core sample at 1528.28m.
Statigraphical distribution: Fustformacysta terniana is present in the Bathonian to Callivian throughout the Timor Sea region. It ranges from the Wanaea verrucosa Zone (7cia) to the Rigaudella aemula Zone (7ai) (Foster, this volume; Helby & Partridge, in prep.).