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Dictyophimus crisiae
Ehrenberg, 1854
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Description - Add description
Benson, 1966, p. 412-414; pl. 28, figs. 4-6:
Pterocorys ? sp.
Cephalis subhemispherical to cylindrical, separated from a conical to campanulate thorax by a distinct change in contour but not by a stricture. Pores of cephalis small, circular, in a few tests in-filled; cephalic wall of variable thickness (up to 5 µm); surface of cephalis smooth to rough, with scattered spines in a few specimens. A heavy, generally conical, long, straight or slightly curved, nearly vertical apical horn originates from the top of the cephalis and extends from the apical bar which is either a dorsal rib in the cephalic wall or an internal columella. A short, thin, conical vertical spine is present. Six collar pores including a pair of very small jugular pores were observed in two specimens. Thorax of variable length and breadth, campanulate to conical, with wall of variable thickness (up to 9 µm) and a surface ranging from smooth to spinose. In a few specimens the thorax turns inward slightly at its base, and a cylindrical abdomen extends from it; in one specimen a trace of an inner septal ring was observed, but in most specimens the distinction between thorax and abdomen cannot be made other than that the latter is not joined to the feet which originate from the broadest portion of the thorax at its base. Pores of both thorax and abdomen similar, large, subequal to unequal, subpolygonal to circular or elliptical, subregularly arranged in approximate longitudinal rows, separated by heavy, smooth to spinose intervening bars. Basal margin of abdomen not observed as complete. The dorsal and primary lateral bars of the collar region extend as indistinct ribs in the wall of the thorax and terminate in relatively long and heavy, conical or cylindrical feet which diverge widely and are either straight or curve slightly outward.
Measurements; based on 9 specimens from stations 27 and 46: length of cephalis 18-31 µm, of thorax 62-117 µm, of abdomen 27-119 µm; breadth of cephalis 23-46 µm, of thorax 86-185 µm, of abdomen 81-191 µm; length of apical horn 15-81 µm, of vertical spine 5-10 µm, of feet 37-148 µm.
Remarks. The general structure of this species, e.g., long feet originating from near the terminus of the thorax and a cylindrical abdomen below, is similar to two species of Pterocorys Haeckel, namely P. aquila Haeckel (1887, pp. 1317-1318, Pl. 71, fig.5) and P. hirundo Haeckel (1887, p. 1318, Pl. 71, fig. 4). For this reason the Gulf species is tentatively assigned to Pterocorys although other species of this genus are very different from the two mentioned above.
Lychnocanium arabicum Ehrenberg (1872a, p. 316; l873b, Pl. 10, fig. 3) from the western tropical Indian Ocean is similar to the Gulf Species but its cephalis is separated from the thorax by a distinct collar stricture. In size of pores, width of intervening bars, and character of feet and horn a few specimens of the Gulf species are similar to Dictyophimus mawsoni Riedel (1958, p. 234, Pl. 3, figs. 6, 7) from Antarctic waters, but Riedel's species does not have a definite cephalis, and the pores are much more irregular than those of the Gulf species. Because this species is very rare in the Gulf, its complete range of variation was not determined. For this reason and its possible identification with Lychnocanium arabicum Ehrenberg, a new name is not proposed.
Distribution. This species is very rare in the Gulf, occurring only at stations 27, 34, 46, and 60. It is, therefore, an oceanic species without affinity for Gulf waters.
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