"Falsimargarita georgiana n.sp. (Figs 156, 157)
MATERIAL EXAMINED: Eltanin Stns 723, 726.
DISTRIBUTION: Known only from off South Georgia in 2663-2855 m.
DESCRIPTION: Shell large, depressed turbinate, rather more depressed than F. gemma, fragile, whitish, with underlying iridescent layer showing through, umbilicate. Whorls five, including a protoconch of a single, smooth, glossy rounded whorl. First whorl of teleoconch with two strong peripheral
Table 6. Measurements of species of Falsimargarita.
H (mm) D (mm) H/D ratio F. gemma Eltanin Stn 1949 22.5 24.6 91 Eltanin Stn 1002 16.5 18.6 87 Eltanin Stn 1003 16.1 17.8 90 Eltanin Stn 439 11.6 13.0 89 F. thielei NZ01 Stn A450 17.1 17.8 96 NZ01 Stn A456 8.3 10.7 77 “ “ 10.4 11.5 94 NZ01 Stn A520 7.2 8.0 90 Eltanin Stn 1084 18.0 19.5 92 Eltanin Stn 2005 13.7 15.5 88 Eltanin Stn 2065 19.5 21.5 92 Eltanin Stn 2085 19.8 22.0 90 “ “ 18.7 20.8 89 Eltanin Stn 2088 16.2 17.8 91 F. georgiana Eltanin Stn 723 (holotype) 26.4 31.3 84 “ “ (paratype) 22.0 27.1 81 “ “ (paratype) 16.0 20.8 77 Eltanin Stn 726 (paratype) 17.3 22.3 77 F. benthicola Eltanin Stn 1511 (holotype) 15.3 20.8 73
cords, a weaker subsutural cord and a weaker spiral thread on the shoulder. Cords increase in number on subsequent whorls until there are eight on the penultimate whorl, with a subsidiary cord between each pair. On the last whorl there are nine subequal cords with a single subsidiary cord between each pair, from the level of the adapical margin of the aperture upwards; 30 weak cords between the periphery and the umbilicus. Spiral cords crossed by oblique growth lines that render major cords minutely granulose Whorls evenly rounded, suture slightly impressed. Umbilicus strongly developed, deep and perspective, walls finely spirally lirate, relatively wider than in F. gemma or F. thielei. Aperture oblique, rather expanded, parietal callus spread thinly across last whorl, columella thin, strongly reflected across part of umbilicus as described by Smith for F. iris.
MEASUREMENTS: See Table 6.
HOLOTYPE: from Eltanin Stn 723 in National Museum of Natural History (USNM 860094)
PARATYPES: One paratype from Eltanin Stn 723 (USNM 89006) and one from Eltanin Stn 726 (USNM 860095) in National Museum of Natural History; one from Stn 723 (MF.56643) in National Museum of New Zealand.
REMARKS: This new species seems most closely allied to F. iris (Smith, 1915) and F. gemma (Smith, 1915). It differs from both in its more depressed shell, the wider umbilicus, its very marked discrepancy in the strength of spiral sculpture on the last whorl, and its stronger spiral sculpture on the spire whorls. It also differs from F. iris in the granulose nature of the major spiral cords.
The radula is of the typical Falsimargarita form."
(Dell, 1990: 95-96)
Falsimargarita georgiana is a species of sea snail, a marine gastropod mollusk in the family Calliostomatidae.[1]
The size of the shell varies between 20 mm and 31 mm. It has a rounded whorl profile and a uniform spiral sculpture.
This marine species occurs off the South Georgia Islands at depths between 2718 m and 2818 m.
Falsimargarita georgiana is a species of sea snail, a marine gastropod mollusk in the family Calliostomatidae.
