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Clathrocanium coarctatum Ehrenberg, 1860

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Benson, 1966, p. 394-397; pl. 26, figs. 1-2:

Clathrocanium cf. coronatum Popofsky

?Clathrocanium coronatum Popofsky, 1913, Deutsche Südpolar-Exped., vol. 14, pp. 342-343, Pl. 33, fig. 1.

Cephalis dome-shaped to globular; with short, thin, conical spines scattered over its surface; with small, subequal but irregularly shaped pores; with ribs in its wall the same as in Callimitra emmae and Clathrocorys murrayi; four collar pores present at its base. Vertical bar thin, extends as a short, thin, three-bladed to conical vertical spine. Apical bar a central columella, extends as a centrally located, three-bladed apical spine. The dorsal and primary lateral feet originate from the distinct collar ring, are straight, relatively stout but short, three-bladed, and broadly divergent. Thorax with three large gates each between adjacent feet; the distal margins of the gates defined by convex downward arched bars developed between adjacent feet. Lattice of the thorax consists of relatively small, unequal, circular to subcircular pores and is developed between three closely spaced, parallel, arched bars including the first arch mentioned above. The second arched bar originates from the feet near their distal terminations as spines; it is located downward and outward a short distance from the first arched bar. The third arched bar, which does not originate from the feet, is located downward but inward a short distance from the second; all three of the third arches are joined by short, horizontal bars, each located below each foot. Between the feet the thorax, therefore, consists of a convex downward, arched lattice, L-shaped in section; the two sides of the "L" are latticed and meet at an angle that points outward. Below each foot the thorax consists of a convex outward, triangular lattice whose sides are defined by the proximal portions of adjacent second arches and the horizontal bar joining the adjacent third arched bars. In two specimens only a small portion of the keels present between the apical horn and each foot was observed; in all other tests the only suggestion of their presence is branches originating from the blades of the apical horn and the outer blade of each foot.

Measurements; based on 4 specimens from stations 81 and 115: height of cephalis 28-44 µm; length of thorax 49-65 µm; breadth of cephalis 37-52 µm, of thorax 90-98 µm; length of apical horn 32-53 µm, of feet 49-76 µm.

Remarks. The incompletely developed keels between the apical horn and feet were observed with large proximal gates or pores, not unlike those of Clathrocorys murrayi Haeckel from the Gulf. Popofsky's (1913, Pl. 33, fig. 1) illustration of Clathrocanium coronatum Popofsky shows incompletely developed keels which are the same as those present in the Gulf specimens. His species differs from the Gulf species only in the presence of polygonal frames surrounding the pores of the cephalis. This feature was not observed in the Gulf specimens but may be an intraspecific variation. This species is very rare in the Gulf sediments; consequently, its complete range of variation was not determined. C. ornatum Popofsky (1913, pp. 343-344, Pl. 33, fig. 2) differs from C. coronatum in the presence of apparently a different type of keel. Popofsky's illustration of the former is of an incompletely developed specimen; therefore, the true structure of the keel is unknown.

Distribution. Specimens identified as C. cf. coronatum Popofsky are very rare in the Gulf, being present only at stations 34, 56, 60, 64, 71, 81, 91, 92, 93, 106, 115, 133, and 184. They are of more general occurrence in the southern half of the Gulf; therefore, this species has a greater affinity for oceanic than for Gulf waters.
Popofsky (1913, p. 343) reported both C. coronatum and C. ornatum from the western tropical part of the Indian Ocean. If the Gulf species is conspecific with the former of the two species, its apparent geographic range includes the tropical parts of the Pacific and Indian Oceans. No other record of its occurrence was found.
Benson 1966











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