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Dictyophimus sp. cf. D. tripus Benson, 1966

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Benson, 1966, p. 380-382; pl. 25, figs. 2-3; text-fig. 8C:

Dictyophimus cf. tripus Haeckel

?Dictyophimus tripus Haeckel, 1862, Die Radiolarien, pp. 306-307, Pl. 6, fig. 1.

Cephalis elongate, ovoid to ellipsoidal, generally with numerous short spines which are generally thin and conical but a few of which are long (up to 62 Ám), heavy, and three-bladed, having the character of horns. Cephalis separated from a thorny to spiny, conical or campanulate to pyramidal thorax by an indistinct collar stricture but distinct change in contour. Pores of the cephalis subequal, subcircular to subpo1ygonal, subregularly arranged; those of the thorax similar but slightly larger. Three to four collar pores present; cardinal pores of type B (cf. text-fig. 8C for illustration of this species); vertical bar thin when present. Apical bar a heavy, three-bladed to cylindrical, dorsal cephalic rib without larger pores disposed on either side of it; a heavy, three-bladed to conical apical horn or spine extends from and is collinear with the apical bar and originates from the dorsal cephalic face. The vertical spine thin, conical, of variable length and originates from the ventral part of the collar stricture. Dorsal and primary lateral bars extend as heavy, three-bladed ribs in the thoracic wall; heavy, three-bladed foot-like spines extend from these ribs at or just above the basal thoracic margin.

Measurements; based on 10 specimens from stations 27, 34, 60 and 106: length of cephalis 49-70 Ám, of thorax 37-80 Ám; breadth of cephalis 44-55 Ám; of thorax 68-123 Ám; length of apical horn or spine 9-62 Ám, of vertical spine 4-25 Ám, of terminal feet 9-55 Ám.

Remarks. Several specimens of this species are similar to Lithomelissa thoracites but are distinguished by the spiny cephalis and thorax and the presence of the dorsal and primary lateral thoracic ribs which extend as terminal or subterminal foot-like spines. This species differs from Dictyophimus gracilipes in having much shorter, less heavy terminal feet and a larger, spiny cephalis and thorax.
This species is similar to Dictyophimus tripus Haeckel (1862, pp. 306-307, Pl. 6, fig. 1) but differs from it in the presence of three-bladed instead of conical spines, a more distinct collar stricture, a more nearly campanulate than pyramidal thorax, and generally a cephalis with numerous spines, in a few specimens with accessory, three-bladed horns. This species is rare in the Gulf, but the few specimens studied show a wide range of variation.

Distribution. In the Gulf this species is rare but occurs as far north as station 191. It is absent at stations 27, 64, 90, 95, 99, 184, 192, 194, and those to the north. It has a slightly greater frequency in the northern Gulf, particularly at stations 106, and 133; therefore, its distribution appears to be influenced in part by upwelling.
Haeckel (1862, p. 307) reported Dictyophimus tripus from the Mediterranean Sea near Messina. Because reference to species similar to the Gulf species could not be found in the literature, nothing more is known about its world-wide distribution.
Benson 1966


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