N101

Botryostrobus auritus/australis (Ehrenberg) group

Lithocampe aurita Ehrenberg, 1844a, p. 84

Lithocampe australe Ehrenberg, 1844b, p. 187

Lithostrobus seriatus Haeckel, 1887, p. 1474, pl. 79, fig. 15; Petrushevskaya, 1967, p. 145, pl. 82, figs. I-IV; 1971, pl. 24, figs. 6-8.

Botryostrobus auritus/australis (Ehrenberg) group, Nigrini, 1977, p. 246, pl. 1, figs. 2-5.

DESCRIPTION

"Shell approximately cylindrical, may be either thick or thin walled, rough or smooth surfaced. Cephalis hemisperical with a few subcircular pores, small, thorn-like apical horn and a well-developed cylindrical vertical tube directed obliquely upward at about 45 degrees. Tube may have a slight distal flare. Vertical spine often visible as are well-developed axial rods wich often extend well beyond the abdomen. Collar stricture indistinct.

"Thorax inflated with 3 to 4 transverse rows of subcircular pores. Lumbar stricture distinct and marked, as are subsequent strictures, by a poreless band. Shell has a well-developed network of surface sculpture which can be seen most easily on the poreless bands of the heavily shelled forms; it is more difficult to see the surface sculpture on hyaline forms.

"Three or more post-thoracic segments of more or less uniform size with 4 to 5 transverse rows of subcircular pores per segment. Termination ragged." (from Nigrini, 1977).

DIMENSIONS "Total length 123-195 microns; maximum breadth 53-70 microns." (from Nigrini, 1977).

REMARKS

1. "The individuals included in this species group are quite variable. Attempts by the present author and by others (e.g., Caulet, 1971, 1974; Petrushevskaya and Kozlova, 1972; Petrushevskaya, 1975) to divide them into a number of species are not thought to be entirely satisfactory. Petrushevskaya (1975) distinguished between individuals which were widest at the fourth segment (B. australis) and those which attained maximum shell breadth at the fifth or six segment (B. auritus). Unfortunately, many individuals are so nearly cylindrical that it is often impossible to make this distinction with certainty. It is, however, true that in younger sediments (Pliocene to Recent) there tend to be more decidedly conical specimens and this may indeed be a useful intraspecific variation, but seems too vague for specific distinction. The present author has attempted to subdivide the group on the basis of number of pore rows per segment, but there are too

Plate 27, figures 2a-d

N102

many transitional forms for this to be a reliable division. Caulet (1971) tried a similar subdivision, but he also had some misgivings about the validity of such a division. There is, however, a tendency for there to be more individuals with a smaller number of pore rows per segment in younger sediments.

"A few individuals which are markedly wider and shorter have been observed, but are too rare in the present material for an adequate description. A good example of such a form is shown in Petrushevskaya and Kozlova, 1972, pl. 24, fig. 19 and has been called by them Botryostrobus lithobotrys Haeckel. A number of additional names and references which may refer to this same form are listed below:

Eucyrtidium euporum Ehrenberg, 1872a, p. 291; 1872b, pl. 4, fig. 20.

Lithocampe eupora (Ehrenberg), Haeckel, 1887, p. 1502; Petrushevskaya, 1967, p. 141, pl. 80, figs. I-V.

Lithostrobus lithobotrys Haeckel, 1887, p. 1475, pl. 79, fig. 17.

Lithostrobus botryocyrtis Haeckel, 1887, p. 1475, pl. 79, figs. 18, 19; Petrushevskaya, 1967, p. 143, pl. 73, figs. IV-VI; pl. 80, figs. VI; pl. 81, figs. I-IV.

"There is one other closely related form which is also generally shorter and broader with very regular transverse pore rows and a thinner shell wall. Again this species is not adequately represented in the present material, but has been well illustrated and described by Caulet (1971, 1974) and has the following synonymy:

Eucyrtidium seriatus Jorgensen, in Gran, 1902, p. 150.

Stichocorys seriatus (Jorgensen), Jorgensen, 1905, p. 140, pl. 18, figs. 102-104.

Siphocampe seriatum (Jorgensen), Caulet, 1971, p. 4, pl. 1, figs. 1-5; pl. 2, figs. 1, 2.

Botryostrobus seriatus (Jorgensen), Caulet, 1974, p. 236, pl. X, figs. 1, 2.

Finally, another form which is more sinuous in outline has been observed and may constitute another species." (from Nigrini, 1977).

2. For a more complete synonymy see Nigrini, 1977.

RECENT DISTRIBUTION

1. Sachs, 1973, Code 19N (Lithostrobus ? seriatus Haeckel); "Scattered, but tends toward SE sector. Maximum abundance less than 5%, and loads lightly onto bottom-influenced factor, which is most developed in the SE."

2. Molina-Cruz, 1975, Code N18 (Lithostrobus (?) botryostrobus, Lithostrobus (?) lithobotrys and Lithostrobus (?) seriatus); used in factor analysis of southeast Pacific assemblages; cf. Appendix 10 for percent N18 at each station." ...mostly abundant in waters of equatorial upwelling (divergence)."