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Theocorys veneris
Haeckel, 1887
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Description - Add description
Benson, 1966, p. 492-494; pl. 33, figs. 12-13:
Theocorys veneris Haeckel
Theocorys veneris Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 1415, Pl. 69, fig. 5; Popofsky, 1913, Deutsche Südpolar-Exped., vol. 14, p. 399, text fig. 119.
Relatively small test consisting of a cephalis, thorax, and abdomen. Cephalis hemispherical, generally smooth but rough in a few tests, with small, subequal, circular pores. Apical horn eccentric, three-bladed, long but not robust, extends from the apical bar that is a dorsal cephalic rib coincident with a dorsal sagittal furrow in the cephalis. Vertical spine when present is short, inconspicuous. Four collar pores present. Dorsal and primary lateral bars extend as thoracic ribs coincident with slight furrows in the wall of the thorax; in a few tests the ribs extend as and are collinear with short, thin spines (6-12 µm) that originate above the base of the thorax. Cephalis separated from thorax by a distinct contour change or by a constriction. Thorax smooth to slightly rough, inflated, truncate-conical to campanulate or irregular, separated from abdomen by a distinct constriction coincident with an internal septal ring. Abdomen smooth, ranging from inflated cylindrical with its distal portion tapering inward to nearly cylindrical with its proximal portion broader; outline irregular in a few tests. Terminal margin of abdomen incomplete; distal portion not turned sharply inward, in some tests straight-sided. Pores of thorax and abdomen similar, ranging from small, circular, equal, hexagonally arranged in longitudinal rows to subequal, with circular to irregular shapes and arranged only approximnately in longitudinal rows.
Measurements; based on 6 specimens from stations 34 and 81: maximum length of test 91-130 µm; length of cephalis 16-18 µm, of thorax 34-46 µm, of abdomen 31-66 µm; breadth of cephalis 16-25 µm, of thorax 58-63 µm, of abdomen 55-91 µm; length of apical horn 7-31 µm, of vertical spine 2-6 µm.
Remarks. Specimens from the Gulf with regular, equal pores and and an inflated cylindrical thorax and abdomen conform to Haeckel’s illustration of Theocorys veneris Haeckel. Those with less regular outline and a campanulate thorax and with less regular pores correspond to Popofsky's illustration of the same species. No specimens from the Gulf have large pores and long, conical horns as in Brandt's (1935, pp. 57-58, Pl. 10, figs. 16, 17) illustrations of T. veneris Haeckel from the upper Eocene.
Distribution. This species is cosmopolitan but very rare in the Gulf. It is absent at stations 64, 90, 91, 99, 130, 184, 194, and all those to the north. Its absence at marginal stations in the Gulf indicates its preference for offshore, more nearly oceanic waters. In the northern Gulf it is present only at those stations located within the diatomite facies. Although very rare at these stations, its distribution in this region of the Gulf may be influenced by upwelling. It apparently does not respond to upwelling in the southern half of the Gulf.
Haeckel (1887, p. 1415) states that this species is cosmopolitan, occurring at the surface at many of the "Challenger" stations in the Atlantic, Pacific, and Indian Oceans. Haeckel does not state the latitudinal range of this species, but it may be confined to low latitudes.
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