Figure 11. Geographic distribution of Acrosphaera spinosa. N: total number of positive records [total number of samples where the species was presumably sought], for water-column (above 150 m and below 150 m; plankton and sediment trap materials) and surface sediment materials. Sources: A, Takahashi (1991); B, Original; C, Original; D, Ishitani and Takahashi (2007).