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Lampromitra quadricuspis Haeckel, 1887

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Benson, 1966, p. 455-457; pl. 30, fig. 11; pl. 31, fig. 1:

Lampromitra quadricuspis Haeckel

Lampromitra quadricuspis Haeckel, 1887, Challenger Rept., Zool., vol.18, pp. 1214-1215, Pl. 58, fig. 7.

Smooth to thorny, elongate, ellipsoidal cephalis separated from a low, broad, conical, smooth thorax by an angular change in contour. Pores of cephalis subequal, subcircular to subelliptical or subpolygonal, smaller than those of the proximal portion of the thorax. A long, heavy, conical to three-bladed horn originates from the top of the cephalis and is apparently unrelated to the apical bar which is present as a short rib in the dorsal cephalic wall. The apical spine extending from this rib is short, thin, conical and originates from the dorsal face of the cephalis. The vertical spine is thin, conical, of variable length and either originates from the base of the cephalis or its proximal portion extends for a short distance as a rib in the proximal portion of the thorax; it generally is nearly horizontal or has a slight downward curvature. The dorsal and primary lateral bars originate from a short median bar that is present within the proximal portion of the thoracic cavity. The primary lateral bars join the thorax below the collar region and extend as distinct ribs in the thoracic wall that are prolonged into conical terminal spines, although in a few tests one or both of these spines originate from the thorax above its base; the dorsal bar joins the thoracic wall at a lower level and likewise extends as a distinct thoracic rib prolonged into a conical terminal spine; these spines are not different from the 10-22 (generally 18-20) long, conical terminal spines originating from the basal margin of the thorax. Thorax with large subpolygonal to subcircular pores, increasing in size distally, arranged in approximate transverse rows (7-10), the pores of each row being of nearly the same size. Basal margin of thorax with irregular, more or less zig-zag outline; terminal spines with a few small, distal branches.

Measurernents; based on 11 specimens from stations 34, 46, 56, 60, 115, and 133: length of cephalis 34-43 µm, of thorax 43-187 µm; breadth of cephalis 31-36 µm, of thorax 129-351 µm; length of cephalic horn 18-62 µm, of vertical spine 9-32 µm, of dorsal and primary lateral spines 22-98 µm, of accessory terminal spines 12-37 µm.

Remarks. The only difference between this species and Lampromitra quadricuspis Haeckel is the presence in the latter of three divergent lateral branches of the cephalic horn that are directed upward and correspond in position to the thoracic ribs. Because this species is rare in the Gulf and most of the tests have their cephalic horns broken, the constancy of this character within the species could not be determined.

Distribution. This species is cosmopolitan but generally rare in the Gulf, occurring as far north as station 208. It is absent at stations 27, 64, 90, 95, 130, 194, 203, 206, and 214. Its absence or very rare occurrence at most marginal localities indicates its preference for more nearly oceanic, offshore waters. It has a slight1y higher average frequency in the northern half of the Gulf and is common (2.0%) at station 106 which is located within the diatomite facies; therefore, it may respond to upwelling in the northern Gulf. It is nearly common at station 81 in the southern Gulf, a fact which may indicate a response to upwelling along either coast.
Haeckel (1887, p. 1215) reported this species from the surface of the Atlantic near the Canary Islands; therefore, it is apparently widespread in Recent Tropical seas.
Benson 1966











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