“Prosipho spiralis Thiele, 1912 (Fig. 337)
Prosipho spiralis Thiele, 1912: 209, pl. 13, fig. 2; Hedley, 1916: 57; Powell, 1958: 197; Powell, 1960: 153; Egorova, 1982: 46, figs 195, 196.
MATERIAL EXAMINED: NZOI Stns A449, A456, A463, A527, A528; Eltanin 1995, 1996, 1997, 2005, 2070; USNM 613135, 72°08'S, 172°10'E, 433 m.
DISTRIBUTION: Previously known from the shores of the antarctic continent between 49°E and 143°E in 193-731 m, P. spiralis can now be recorded from the Ross Sea in 238-987 m.
REMARKS: Prosipho spiralis and P. chordatus Strebel, 1908 (Fig. 335) from off South Georgia share many characters. On the material available, chordatus appears to be the more elongate, with diameter/height ratios ranging from 42 to 48. Strebel's published measurements of his largest specimen (presumably the type) give a ratio of 57, but the proportions of his figure show a ratio of 48. The equivalent ratios for six specimens of spiralis range from 49 to 54. There are three spiral cords on the first teleoconch whorl in chordatus (4-5 in spiralis), four cords on the penultimate (4-5 in spiralis), five major cords on last whorl (5-6 in spiralis) with eight subsidiary cords across the base (8-11 in spiralis). The spiral cords are heavier and deeper in spiralis, the suture is more impressed and the body whorl is more inflated. In addition, the protoconch is taller in chordatus. The two forms require critical comparison when more material of chordatus is available, especially if specimens from intermediate localities are obtained.”
(Dell, 1990: 197-198)
