Crucispina
- Crucispina cruciformis (Leadbeater) (ref. ID; 7107)
Syn; Crucispina cruciformis Espeland & Throndsen, 1986, p.222, figs.38-40 (ref. ID; 7107); Salpingoeca cruciformis Leadbeater, 1974, p.184, pl.Ic,d, fig.1A (ref. ID; 7107)
Synonym
Crucispina cruciformis Espeland & Throndsen, 1986, p.222, figs.38-40 (ref. ID; 7107); Salpingoeca cruciformis Leadbeater, 1974, p.184, pl.Ic,d, fig.1A (ref. ID; 7107)
Descriptions
The morphological characteristics of the organisms collected from Osaka Bay, were basically identical to those of the Norwegian organisms (Espeland & Throndsen 1986), but some differences were found in the structure of the lorica chamber. (1) No variation in number of the costal strips were indicated by Espeland & Throndsen (1986), i.e. the number of strips forming the lorica chamber was 10 and that of the transverse costa was 4 in the Norwegian materials. We observed that these numbers vary respectively from 8 to 12 and from 4 to 5 in the materials collected from Osaka Bay. (2) The delicate longitudinal costae attached to the center of all the costal strips forming the transverse costa have been described in Norwegian materials (Espeland & Throndsen 1986). In our materials, some transverse costal strips, e.g., the strips which connect the two heavier longitudinal costae, have no attachment of the delicate longitudinal costae. (3) The lorica chamber is basically asymmetrical in our material, while it is symmetrical in the Norwegian material (Espeland & Throndsen 1986). Despite the difference of the lorica structure, the essential similarity of the lorica morphology makes it justify to include the organisms collected from Osaka Bay into the specific category of Crucispina cruciformis, and the difference just mentioned may be of an intraspecific variation. (ref. ID; 7107)
Notes
The lengths of the anterior and posterior spines vary correlatively to the density, whereas the length of the heavy longitudinal costal strip of the lorica chamber is almost constant. These facts indicate the seasonal variability of this species, which is controlled by the water density. Although the biological function of the silicified lorica of Crucispina cruciformis has not been revealed, the seasonal variability observed here suggests that the length of the ornamental spine, which is made of a heavy costal strip, has strong relation to floating or the planktonic habitat for this species. On the oher hand, water temperature itself, which may be a physiologically important environmental factor, shows no correlation to the dimensional factor of the lorica.
This species was found from December to May, when the water temperature ranged from 8.6 to 17.2 degrees C. The range of water temperature previously reported for this species was from 7.0 degrees C (Norway: Esperland & Throndsen 1986) to 25 degrees C (Gulf of Elat: Thomsen 1978). This species may be a eurythermal species, although it occurs in the cold-water season in Osaka Bay. (ref. ID; 7107)
Sampling site
Surface seawater samples were collected from the Shioya Coast of Osaka Bay, which faces to the inland sea, Setonaikai. (ref. ID; 7107)