Catalog entries: Podocyrtis diamesa
Original description: Cephalis elongate-hemispherical, with small pores, bearing a horn of variable length which is bladed in early specimens, conical and robust in late specimens. Collar stricture marked by change in contour. Thorax inflated-conical, with pores circular and in longitudinal rows separated by ridges in early specimens, larger and lacking intervening ridges in late specimens. Thorax and abdomen of variable proportions, but often of approximately the same length. Slight lumbar stricture. Abdomen tapering distally, sometimes slightly inflated. Abdominal pores subcircular in longitudinal rows, in early specimens similar in size to distal thoracic pores and separated by longitudinal ridges, in later specimens larger and lacking longitudinal ridges. Three feet shovel-shaped.
Length of thorax 140-160 µ; total length (excluding horn) 220-390 µ; maximum breadth 130-180 µ. Distinguishing characters (rw): Podocyrtis (P.) diamesa differs from P. (Podocyrtis) papalis in its larger size and the presence of a slight lumbar stricture, from P. (P.) phyxis by the presence of longitudinal ribs between pore rows and the pores being smaller, from P. (P.) ampla in its general form being spindle-shaped rather than conical, and from P. (P.) dorus by not having a strongly constricted mouth. (Sanfilippo et al., 1985) Phylogeny (rw): P. (P.) diamesa is the intermediate form between P. (Podocyrtis) papalis and P. (P.) phyxis in the evolutionary lineage leading to P. (P.) ampla. P. (P.) dorus and P. (P.) platypus are off-shoots from this evolutionary line at about the level of occurrence of P. (P.) diamesa.
Remarks on original description: Horn in early specimens short and bladed, in late specimens conical and robust. Thorax and abdomen of variable proportions, but often of approximately the same length. Slight lumbar stricture. Abdomen tapering distally, sometimes inflated. Thoracic and abdominal pores circular to subcircular in longitudinal rows, in early specimens separated by Podocyrtis (Podocyrtoges) diamesa distinct longitudinal ridges, in late specimens larger, with less distinct ridges. (Sanfilippo et al., 1985)
Last occurrence (top): within Paleogene Period (23.03-66.04Ma, top in Chattian stage). Data source: Lazarus et al. 2015 - "P age group"
First occurrence (base): within Paleogene Period (23.03-66.04Ma, base in Danian stage). Data source: Lazarus et al. 2015 - "P age group"
Plot of occurrence data:
Podocyrtis diamesa compiled by the radiolaria@mikrotax project team viewed: 28-10-2020
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