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Eucyrtidium asanoi Sakai, 1980

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Eucyrtidium asanoi Sakai, new species
(Plate 7, Figures 12a, 12b, 13a, 13b, 13c, 14a, 14b)

Description: Shell is spindle-shaped and thin walled. It is covered by longitudinal ridges which are made of thin hyaline plates and consists of five or more segments that are distinguished by internal lumbar strictures. There is an external constriction between the second (thoracic) and third (abdominal) segments that divides the shell into the cephalothoracic and postthoracic part.

The cephalis is subspherical to hemispherical; has small, circular, widely spaced pores; and bears a tiny apical horn. Collar stricture is indistinct. Thorax is conically inflated, slightly rough surfaced, and bears hexagonally arranged circular pores. There is a very thin, porous plate (wing) on the thorax which continues to the internal spine at the proximal portion. Abdomen is truncate-conical in outline. Two or more post-abdominal segments are subcylindrical without externally expressed strictures. Thin-plated ridges are arranged longitudinally on the postthoracic part. Postthoracic pores are circular and are arranged in longitudinal rows. There are two or three pores between each pair of parallel ridges. The shell is widest around the fourth segment, with some variation occurring somewhere between the third and fifth

Dimensions: Measurements are based on 12 specimens from Samples 436-36-4 (35-37 cm), 436-36-7 (25-27 cm), and 436-37, CC (13-15 cm). Width of cephalis is 15 to 20 μ; thorax, 45 to 55 μ; abdomen, 65 to 80 μ; fourth segment, 75 to 90 μ and fifth segment, 75 to 80 μ. Maximum width of shell is 75 to 90 μ. Length of cephalis to the distal end of thorax is 40 to 45 μ; to end of abdomen, 80 to 95 μ; to end of the fourth segment, 110 to 125 μ; and to end of the fifth segment (on 7 specimens), 140 to 155 μ. Diameter of pores is 1 to 2 μ on cephalis and 4 to 6 μ on remaining segments.

Remarks: This species is distinguished from others of the genus by its longitudinal ridges separating rows of pores into sets. This species is named in honor of Professor Kiyoshi Asano, who established a foundation for research in smaller foraminifera in the Far East and constantly encouraged my own research on radiolarians.

Holotype: Plate 7, Figures 13a, 13b, 13c (IGPS coll. cat. no.73817) from Sample 436-36-4, 35-37 cm.
Sakai 1980











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