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Chatangiella granulifera ssp. tenuis
Chatangiella granulifera ssp. tenuis, (Davey, 1970), Lentin and Williams, 1976
Originally Deflandrea granulifera var. tenuis, subsequently Australiella granulifera ssp. tenuis, thirdly (and now) Chatangiella granulifera ssp. tenuis. The variety was raised to the subspecies level by Lentin and Williams, 1973.
Holotype: Davey, 1970, pl.2, fig.1
Age: Albian
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Original description as Deflandrea granulifera var. tenuis: [Davey, 1970, p. 340-341]:
Diagnosis:
A variety of D. granulifera possessing smooth to lightly granular outer membrane surrounding relatively small, thin- walled inner body.
Description:
D. granulifera var. tenuis has only been obtained from the Saskatchewan samples and appears to be quite variable. The shell is elongate, typically widest in the cingular region and narrowing slightly anteriorly before broadening to form rounded " shoulders ". The epitract terminates with a conical apical horn, blunted distally. The posterior end of the shell is flat to concave, bearing one pointed conical horn and sometimes a second rudimentary one. The slightly spiral cingulum is always well developed and bordered by fairly high ridges possessing knobbly margins. At regular intervals the bordering ridges of the cingulum are absent, thus it is discontinuous. The sulcus is wide and extends anteriorly from the antapical horns. A rounded, hexagonal intercalary archaeopyle is typically present. The outer membrane is thin and may be smooth or densely granular. The inner body is subspherical, has a slightly thicker wall and is usually more heavily granular than the outer membrane. Occasionally the inner body is in contact with the lateral walls of the shell but more often its small size does not permit this.
Dimensions:
Holotype: shell diameter 85 by 60 µm, inner body diameter 39 by 60 µm.
Range: overall length 85-114 µm, overall width 52-63 µm, diameter of inner body 39-60 µm. Number of specimens measured, 8.
Remarks/Affinities:
Manum, 1962 gave a detailed analysis of D. granulifera from the Upper Cretaceous of Arctic Canada and noted that two forms appeared to be present. These forms differed in the density of the granulation and also in the thickness of the inner body wall. Since some intergradation between the two forms existed, Manum considered that both forms should be placed in the single species D. granulifera. The more typical form possesses a dense granulation with an inner body wall of approximately 2 µm in thickness. The other, rarer form, which is the only one represented in the Saskatchewan material, possesses a smooth to lightly granular outer membrane, and an inner body with a thin wall only slightly thicker than the outer membrane. Another differentiating feature is that the inner body is smaller in this form and is not in contact with the lateral walls of the shell.
This form because of these distinguishing features is here created a variety of D. granulifera. D. granulifera var. tenuis is rather similar to D. spectabilis Alberti, 1959, especially in some specimens when the shoulders are not particularly pronounced. The inner body of D. spectabilis, from the Senonian of Germany, is extremely delicate and difficult to discern. Thus D. granulifera var. tenuis, which possesses a light granulation and a thin- walled inner body, appears to occupy an intermediate position between the typical form of D. granulifera and D. spectabilis and warrants its distinction as a variety.
Moderately, well preserved specimens are extremely rare due to the thinness of the shell wall.
Originally Deflandrea granulifera var. tenuis, subsequently Australiella granulifera ssp. tenuis, thirdly (and now) Chatangiella granulifera ssp. tenuis. The variety was raised to the subspecies level by Lentin and Williams, 1973.
Holotype: Davey, 1970, pl.2, fig.1
Age: Albian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Deflandrea granulifera var. tenuis: [Davey, 1970, p. 340-341]:
Diagnosis:
A variety of D. granulifera possessing smooth to lightly granular outer membrane surrounding relatively small, thin- walled inner body.
Description:
D. granulifera var. tenuis has only been obtained from the Saskatchewan samples and appears to be quite variable. The shell is elongate, typically widest in the cingular region and narrowing slightly anteriorly before broadening to form rounded " shoulders ". The epitract terminates with a conical apical horn, blunted distally. The posterior end of the shell is flat to concave, bearing one pointed conical horn and sometimes a second rudimentary one. The slightly spiral cingulum is always well developed and bordered by fairly high ridges possessing knobbly margins. At regular intervals the bordering ridges of the cingulum are absent, thus it is discontinuous. The sulcus is wide and extends anteriorly from the antapical horns. A rounded, hexagonal intercalary archaeopyle is typically present. The outer membrane is thin and may be smooth or densely granular. The inner body is subspherical, has a slightly thicker wall and is usually more heavily granular than the outer membrane. Occasionally the inner body is in contact with the lateral walls of the shell but more often its small size does not permit this.
Dimensions:
Holotype: shell diameter 85 by 60 µm, inner body diameter 39 by 60 µm.
Range: overall length 85-114 µm, overall width 52-63 µm, diameter of inner body 39-60 µm. Number of specimens measured, 8.
Remarks/Affinities:
Manum, 1962 gave a detailed analysis of D. granulifera from the Upper Cretaceous of Arctic Canada and noted that two forms appeared to be present. These forms differed in the density of the granulation and also in the thickness of the inner body wall. Since some intergradation between the two forms existed, Manum considered that both forms should be placed in the single species D. granulifera. The more typical form possesses a dense granulation with an inner body wall of approximately 2 µm in thickness. The other, rarer form, which is the only one represented in the Saskatchewan material, possesses a smooth to lightly granular outer membrane, and an inner body with a thin wall only slightly thicker than the outer membrane. Another differentiating feature is that the inner body is smaller in this form and is not in contact with the lateral walls of the shell.
This form because of these distinguishing features is here created a variety of D. granulifera. D. granulifera var. tenuis is rather similar to D. spectabilis Alberti, 1959, especially in some specimens when the shoulders are not particularly pronounced. The inner body of D. spectabilis, from the Senonian of Germany, is extremely delicate and difficult to discern. Thus D. granulifera var. tenuis, which possesses a light granulation and a thin- walled inner body, appears to occupy an intermediate position between the typical form of D. granulifera and D. spectabilis and warrants its distinction as a variety.
Moderately, well preserved specimens are extremely rare due to the thinness of the shell wall.