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Siphonosphaera socialis Haeckel, 1887

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Benson, 1966, p. 121-123; pl. 2, fig. 4:

Siphonosphaera cf. socialis Haeckel

?Siphonosphaera socialis Haeckel, 1887, Challenger Rept., Zool., vol. 18. p. 106, Pl. 6, figs. 1, 2.
?Siphonosphaera macrosiphonia Haeckel, 1887, Challenger Rept., Zool., vol. 18.p. 107.

Single, smooth, spherical to ellipsoidal shell with 4-20 or more unbranched hyaline tubules arising from the shell surface and without regular arrangement. Shell with scattered, small, unequal, subcircular to subelliptical pores (2-6 µm in diameter) separated by wide intervening bars; 8-14 pores on half the circumference. Tubules of variable length, cylindrical with generally smooth rims, but in specimens with very long tubules the rims are surmounted by 2-3 short toothlike spines.

Measurements: based on 11 specimens from stations 27, 34, 46, 56,and 60: diameter of shell 87-108 µm, length of tubules 4-21 µm.

Remarks. This species differs from Haeckel's description and illustration of Siphonosphaera socialis (1887, p. 106, Pl. 6, Figs. 1, 2) in having more than four cylindrical tubules, smaller, less regular pores of the latticed shell and a much larger shell diameter. The diameter of the shell and the number of tubules of S. macrosiphonia Haeckel (1887, p. 107) agree with the Gulf specimens, but Haeckel describes its pores as being of equal size and distribution. Without an illustration of this species identification of the Gulf species with it is tentative only. It does occur in the central tropical Pacific whereas S. socialis was reported from the tropical and subtropical eastern Atlantic. Haeckel's illustration of S. serpula Haeckel (1887, p. 107, Pl. 6, fig. 6) is in nearly perfect agreement with the Gulf species, including shell diameter, but the tubules are contorted whereas those of the Gulf specimens are not. It is possible that the tubules of the latter are incomplete but if complete may show contortions. Siphonosphaera tubulosa Müller, according to Haeckel (1887. p. 105), has hyaline tubules but also a hyaline shell, although Brandt's illustration of a form he identified as S. tubulosa (Brandt, 1885, Pl. 7, fig. 33) has a shell with small scattered pores. S. tenera Brandt (1885, pp. 266-268) is described as having very short tubules but slit-like pores on the remainder of the shell (op. cit., Pl. 7, figs. 38, 39, 48). Positive identification of the Gulf species of Siphonosphaera is not possible mainly because its rare occurrence in the Gulf prohibits an adequate analysis of its intraspecific variation.

Distribution: Species of the genus Siphonosphaera have been reported from tropical or subtropical regions of all seas as well as from the Mediterranean Sea. In the absence of further knowledge this species appears to be a tropical oceanic form. In the Gulf it is very rare, occurring only at the southern Gulf stations 27, 34, 46, 56, 60, and 95. It is apparently not influenced by upwelling.

Benson 1966











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