S3

Disolenia quadrata (Ehrenberg)

Tetrasolenia quadrata Ehrenberg, 1872a, p. 320; 1872b, p. 301, pl. x, fig. 20

Disolenia quadrata (Ehrenberg), Nigrini, 1967, p. 19, pl. 1, fig. 5

DESCRIPTION "Shell smooth, thin-walled, subspherical, with numerous small irregular pores having no definite arrangement. Pored tubules, 3-8 (usually 5), approximately as long as broad or longer, 0.2-0.3 shell diameter. Tubules cylindrical or subcylindrical, sometimes slightly expanded distally; outer apertures truncated, smooth." (from Nigrini, 1967).

DIMENSIONS "Diameter of shell 63-90mu. Maximum length of tubules 18-36mu; their maximum breadth 18-27mu." (from Nigrini, 1967).

REMARKS

1. For a more complete synonymy see Nigrini, 1967.

2. Benson's (1966) description and dimensions of this species (Disolenia cf. variabilis (Haeckel) in Benson, p. 123) are consistent with the above.

Plate 1, figure 2

S4

RECENT DISTRIBUTION

1. Benson, 1966 (Disolenia cf.varabilis); "In the Gulf of California this species is very rare and occurs only at 5 southern Gulf Stations... It is apparently a tropical oceanic form."

2. Nigrini, 1967, fig. 6; "Indian Ocean occurrences - D. quadrata is sparsely distributed in the eastern tropics, but increases in abundance (up to 6 percent of the described population) west of 75degE. The species is absent from middle latitude samples."

3. Molina-Cruz, 1975, Code S39, counted together with D. zanguebarica and used in factor analysis of southeast Pacific assemblages, cf. Appendix 10 for percent S39 at each station.

4. Morley, 1977 (Disolenia sp.), Fig. I-2; counted together with D. zanguebarica; "Both ... species seem to be found within the same habitat. D. zanguebarica occurs less frequently in most samples.

"These species load highest in factor 1 (tropical). At present they occur most frequently between the equator and 10degS, and are absent south of 35degS. At 18,000 YBP their abundance decreased drastically and they were absent in all samples south of 8degS."