VARIABILITY OF HANTZSCHIA AMPHIOXYS (EHR.) GRUN. VAR. RECTA O. MULL.

Abstract

The 321 individuals of Hantzschia amphioxys were collected from the Ongul Islands of the Antarctic in January, 1959. Microphotographs of them were taken to investigate their variations. Many varieties were found. For example, some had shells with straight ventral and dorsal margins; some with straight ventral margin and convex dorsal margin, or vice versa; some with concave ventral margin and convex dorsal margin. In any case, these varieties were linked with many intermediate forms. Therefore, Hantzschia amphioxys of East Ongul Island should be identified as var. recta. There were some individuals which seemed to have some similarities with forma capitate among the collected materials. Generally, var. capitate is a little smaller than var. recta. The measurement of Hantzschia amphioxys of East Ongul Island is: Length of shell : 60-120μ Width of shell : 8-11μ Number of keels in 10μ : 4-10 Number of striae in 10μ : 18-23 The materials of East Ongul Island were larger in size that the materials recorded in the past; however, the number of their keels and striae were less. The specific name of Hantzschia amphioxys f. capitate 0. Muller (not Pantocsek) was corrected to Hantzschia amphioxys var. amphioxys f. mulleri.