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Ceratocyrtis stoermeri Goll and Bjørklund, 1989

Description - Add description

The skeleton consists of two thick-walled lattice cham­bers. Cephalis is small, porous, densely spinous, and partially recessed in the thoracic cavity. Upper surface of massive thorax swells gradually, is densely spininous, and perforated by small round pores. Maximum lattice shell width is at the mid-length of the thorax, where the irregu­larly arranged pores are also largest. Below this point, the thorax tapers slightly, and the distal termination is straight, with a sieve plate covering the basal aperture on some specimens. The external surfaces of the tho­racic lattice bars bear broad ridges which form polygonal pore frames for the larger pores.

Diagnosis:
A species of Ceratocyrtis characterized by its massive cyclindrical thorax with prominent lattice bar ridges forming polygonal pore frames.

Etymology:
The species is named posthumously in honor of Profes­sor Leif Størmer, 1905-1979, University of Oslo.

Remarks:
Specimens of Ceratocyrtis mashae have more loosely trellised and less massive thoracic composition.

Occurrences:
Ceratocyrtis stoermeri occurs in the C. broeggeri Zone of: Section 104-642B-22H, CC to Sample 104-642B-22H-6, 75-77 cm; Samples 104-642C-24H-4, 25-27 cm to -24H-3, 25-27 cm; and 104-642D-2X-6, 25-27 cm.
Size. 156-167 µm, maximum lattice height; 128-145 µm, maximum thoracic width.

Holotype:
PMO 117.586; Sample 104-642B-23X-1, 25-27 cm; En­gland Finder T49/0; PI. 5, Figs. 5-7.

Goll and Bjørklund 1989
Test large, two-segmented form with ambiguous external stricture. The first segement very small, pierced by small, circular to subcircular pores set in thick frames from which arise small by-spines. The second segment large, campanulate, more or less tapering distally, pierced by large, subcircular to polygonal-shaped thick frames: the upper part is spinous; the middle part, where the thorax is widest and the ridges of the pores frames are sharpest, has the largest diameter of the pores; and the lower part is rather smooth in outline. The termination of the second segment is in line in lateral view, often accompanied by a delicate sieve plate at the base. The segments internally partitioned by PR which is composed of distinct arches but nearly horizontal. MB relatively short. A makes a nearly right angle from the horizontal, and merges into PR. D extends downward with a large angle from the horizontal, and may have one, rarely a few branches in the distal part. Two L extending slightly downward, having distinct L-R in the middle part, and may branch off in distal part like D. L' rarely present. V connects with PR. Ax thick, long, usually bifurcated in the distal part.

Remarks
Morphology of this species is quite stable except for the development of the basal sieve plate.
Dimensions (in µm). Based on 11 specimens examined by SEM. Height of test; 120-150. Maximum width of test; 105-140. Maximum diameter of PR; 20-30.

Occurence:
OD-17, 18 (very rare in abundance) and OD-26, 27 and 28 (rare in abundance).
Sugiyama 1993


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