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article i nfo Living specimens of Distephanus speculum (Silicoflagellata) were collected in waters of b150 m depth in the Pacific Sector of the Southern Ocean (57°31.6'S, 150°02.9'E), South of Tasman Island, and a biometric study has been conducted. The skeleton of D. speculum has a simple morphology, which can be readily expressed quantitatively. Using a new methodology, repeated measurements were obtained and converted to numer- ical indices. The circumference of the basal rings was the most useful character for subdivision into groups, and using this parameter we recognized two populations in the 620 studied specimens: (1) 500 individuals were placed in Group A, with a basal ring circumference of 53 to 67 µm, and a difference in length of spine axes from 2 to 6 μm; and (2) 120 individuals were placed in Group B (basal ring circumference 80 to 105 µm, difference in length of spine axes 3 to 6 µm). The circumference of the basal ring in Group B is approximately 10 µm smaller than in Distephanus speculum giganteus (Bukry, D., 1979. Comments on opal phytoliths and stratigraphyofNeogeneSilicoflagellatesandCoccolithsatDeepSeaDrillingProjectSite397offNorthwestAfrica. Initial report of the DSDP, Washington, 49:977-1009.), and Distephanus boliviensis (Bukry, D., 1976a. Silico- flagellate and coccolith stratigraphy, Norwegian-Greenland Sea. Initial Report of DSDP LEG 38. Initial report of the DSDP, Washington, 38:843-855.; Bukry, D., 1976b. Silicoflagellate and coccolith stratigraphy, southeastern |
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