"Chlanidota polyspeira n.sp. (Figs. 292, 293, 313)
MATERIAL EXAMINED: Eltanin Stn 369.
DISTRIBUTION: Known only from the type locality off Isla de los Estados in 247-293 m.
DESCRIPTION: Shell small for genus, fusiform, white, relatively narrow, diameter/height ratios from 48-54. Spire relatively tall for the genus, 0.8 times the height of the aperture. Early whorls of teleoconch rather straightsided, body whorl gently and evenly rounded. Protoconch of 2 ¼ smooth, dome-shaped whorls, of the same type as in C. eltanini and C. bisculpta but of intermediate size. Suture abutting. Sculpture of fine, rather flexuous, closed-spaced, spiral ridges, with low, broad, widely and somewhat irregularly spaced axial ribs. First teleoconch whorl with 14 very fine, evenly spaced spiral ridges, penultimate whorl with fewer (10-11), the first subsutural ridge spaced somewhat from the suture leaving a narrow ramp with a similar space between it and the subsequent spiral. Last whorl and base with 23-29 spiral cords. Penultimate whorl with 16-21 axial ribs, last whorl with 19-23, varying in strength and spacing on the last whorl and becoming obsolete across the base. The ribs are rendered finely nodulous where they are crossed by the first few adapical ridges on the penultimate and last whorls. Numerous fine, regular, axial threads are developed between the major axial ribs on all whorls. Aperture narrowly ovate, outer lip thin, parietal lip well defined, columella short, moderately twisted, smooth, abapical canal broad, shallow and open. Fasciole strong, bounded by a sharp spiral ridge, surface sculptured by strong growth wrinkles.
MEASUREMENTS: See Table 17.
HOLOTYPE: in National Museum of Natural History (USNM 860131).
PARATYPES: in National Museum of Natural History (3, USNM 860132) and in National Museum of New Zealand (one, MF.56617).
REMARKS: Five dead specimens were obtained at Eltanin Stn 369. Without animals it is not possible to be completely certain of the generic position of this species. However, the whole style of shell and the sculptural elements are so similar to those of C. bisculpta that a generic relationship with this species seems certain. The protoconch is intermediate in size between those of C. eltanini and C. bisculpta, and since there seems little variation in size of the protoconch in these three small Magellanic species, this difference is probably significant. The shell in C. polyspeira is narrower than in eltanini or bisculpta as the diameter/height ratios indicate. In eltanini this ratio varies from 59-64 in the material available, from 55-57 in bisculpta and from 48-54 in polyspeira. The spiral ridges are finer and more numerous in polyspeira than in bisculpta, and the axial ridges, although comparable in number in the two species, are much less crisp in polyspeira and become obsolete across the base of the last whorl. Spiral ridges are more numerous in eltanini. than in polyspeira, and eltanini also lacks major axial sculpture.
Chlanidota polyspeira appears to be most closely allied to C. bisculpta, but the distinguishing characters noted above appear to be quite consistent in the reasonable series of both species available."
(Dell, 1990: 186-187)
Excerpt from Table 17. Measurements and shell ratios of species of Chlanidota.
H (mm)
D (mm)
D/H ratio
C. polyspeira
holotype
13.3
6.5
44
paratype
14.4
7.0
48
“
9.0
4.9
54
“
15.3
7.8
51
