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Coracalyptra cervus (Ehrenberg, 1872)

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Benson, 1966, p. 447-450; pl. 30, figs. 3-5:

Coracalyptra cervus (Ehrenberg)

Eucyrtidium cervus Ehrenberg, 1872a, Akad. Berlin, Monatsb. (1872), p. 308; 1872b, Akad. Berlin, Abhandl. (1872), Pl. 9, fig. 21.
Sethoconus rayianus Haeckel, 1887, Challenger Rept., Zool., Vol.. 18, pp. 1291-1292, Pl. 58, fig. 6.
Sethoconus capreolus Haeckel, Lapsus calami.(= S. rayianus Haeckel), 1887, Challenger Rept., Zool., vol. 18, plate explanation for Pl. 58, fig. 6.
Sethoconus cervus Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 1292.
Coracalyptra cervus (Ehrenberg), Popofsky, 1913, Deutsche Südpolar-Exped., vol. 14, pp. 383-384, Pl. 34, Fig. 3.

Test smooth, similar to Theopilium tricostatum Haeckel in the presence of a cephalis, thorax, and abdominal brim. Shape of cephalis less regular than in T. tricostatum but with similar structure including a dorsal sagittal constriction and four collar pores at its base and a pair of external jugular pores at the top of the thorax. Apical horn three-bladed to conical, heavy, in many specimens forked distally; vertical horn heavy, three-bladed to conical; in many tests a pair of divergent, laterally ascending, thin, conical spines originates from the upper surface of the cephalis. Thorax separated from cephalis by a slight stricture; campanulate; with pores similar to those of T. tricostatum but less regular--hexagonally arranged but in a more variable number of transverse rows (6-14), generally hexagonal in shape, smaller proximally, increasing in size distally. Abdominal brim generally more convex outwards (more nearly truncate-conical), less flat than in T. tricostatum (in one specimen with a rectangular outline), with pores similar to those of the thorax--hexagonally arranged in 1-5 or more transverse rows; brim separated from thorax by a distinct angular change in contour and an inner septal ring. Dorsal and primary lateral bars either extend as free spines from the collar ring or as short thoracic ribs terminating in thin, conical spines; thoracic ribs do not extend as far in the thoracic wall as do those of T. tricostatum; secondary lateral bars present as ribs occupying the dorsal part of the collar stricture and in most tests extend laterally as thin, conical spines.

Measurements; based on 23 specimens from stations 27, 34, 91, 133, 336, and 191: length of test 80-185 µm, of cephalis 17-23 µm, of thorax 55-118 µm, of apical horn 2-64 µm, of vertical horn 11-37 µm, of lateral cephalic spines 10-64 µm, of dorsal and primary lateral spines 4-25 µm, of secondary lateral spines 4-18 µm; breadth of cephalis 20-28 µm, of thorax 81-156 µm, of abdominal brim 118-244 µm.

Remarks. The differences between this species and Theopilium tricostatum Haeckel were discussed in the remarks of the latter. I agree with Popofsky's synonymy (1913, pp. 383-384) and his reasons for it, namely, the presence in all of more than two horns with at least one (apical) forked distally and the observation that Haeckel's illustration of Sethoconus rayianus Haeckel shows an incomplete specimen lacking an abdomen.

Distribution. This species is cosmopolitan in the Gulf, being absent only at stations 90, 130, 192, 194, and all those to the north. It is common at stations 91 (2.2%), 93 (2.0%), and 115 (3.6%) where it is the fifth most abundant species, nearly common at stations 106 and 133, and rare at all others. Its increase at stations 91 and 93 is the result of its response to upwelling off the Baja California coast. Its slightly greater frequency in the northern half of the Gulf may be due to its response to upwelling. Its absence or near absence at marginal and northern shelf stations indicates its preference for more nearly oceanic offshore waters
This species was reported from the western tropical part of the Indian Ocean (Haeckel, 1887, p. 1292; Ebrenberg, 1872a, p. 308; Popofsky, 1913, p. 385), the southern tropical Atlantic (Popofsky op. cit.) and the surface of the central Pacific at “Challenger” stations 266-272 (Haeckel, op. cit.). It is, therefore, widespread in Recent tropical seas.
Benson 1966











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