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species

Sansonia iejimensis T. Kase, 1998

kingdom Animalia - animals »  phylum Mollusca - mollusks »  class Gastropoda - gastropods »  order Littorinimorpha »  family Pickworthiidae »  genus Sansonia

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Sansonia iejimensis

Author: Kase

Sansonia iejimensis

Author: Okutani

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Description

Shell small, colorless, elongate trochiform, with conical spire, consisting of about 8 whorls; protoconch of rounded and smooth 1.5 whorls, separated by impressed suture; protoconch II spirally sculptured; sinusigera notch shallow without everted lip. Teleoconch whorls weakly convex, with slightly grooved suture; early half of first teleoconch whorl bears many blunt, faint, weak axial rugae that progressively become axial riblets in later teleoconch whorls; axial riblets prosocline, thick, extending from adapical suture to position slightly above abapical suture in second teleoconch whorl, becoming split incompletely into two slightly elongate nodose tubercles which appear as weak spiral groove in 3rd and later teleoconch whorls; axial riblets on penultimate and last whorls consist of two completely separate rows of tubercles, the abapical one located at middle of whorl. Last whorl occupying 55% of total shell height, with two rows of tubercles and spiral cords at basal periphery, becoming slightly obsolete behind outer lip. Base slightly convex, sculptured with two smooth spiral cords and one thick, circumumbilical spiral swelling. Umbilicus small, but distinct. Aperture circular, rimmed, protruded slightly forward, surrounded by smooth peristome. Outer lip with a more or less thickened varix. Shell surface without microsome granules. Holotype: H = 2.30 mm; D = 1.39 mm.
Kase, T. 1998; The Family Pickworthiidae (Gastropoda Caenogastropoda) from Tropical Pacific Submarine Caves ; Four New Species of Sansonia

Interchangeable taxa

This species has so far been collected only at the type locality of Ie Island, Okinawa. It is quite similar to Sansonia andrei Jousseaume, 1921 in many important ways. S. andrei had been synonymized with Pickworthia kirkpatricki Iredale, 1917 (e.g. Bavay, 1921; Ekawa, 1993). However, it has become clear on the basis of many specimens collected widely from the Pacific that S. kirkpatricki and S. andrei are distinct from each other. The shell characteristics of S. iejimensis that separate it from S. andrei are 1) more deeply impressed suture, 2) more strongly inflated whorls, 3) rounded basal periphery, 4) slightly convex base, 5) sculpture of spire whorls consisting of two rows of tubercles and a simple abapical cord, and 6) a less expanded outer lip.
There is another possible interpretation, that this species is merely a variation of S. andrei. At the type locality of "Shodokutsu" cave (where the biotope is a small, almost closed cave), however, this species is associated with ubiquitous dead specimens of S. andrei that are characterized by a uniformly rather lower trochoid shell outline, a unique basal sinuation behind the outer lip, and no spiral cord between the basal keel and umbilical cord. There is no intermediary between the two forms of Sansonia, so the two species are regarded as separated.
S. iejimensis is also similar to Sansonia umbilicata Jousseaume, 1921, and both species have been found in the same submarine cave. 5. umbilicata has three distinct rows of tubercles on the last whorl, slightly coelconoid spire whorls, tuberculate basal periphery, wider umbilicus, and the protoconch is yellowish brown in color, so that the distinction between the two species is clear.
Kase, T. 1998; The Family Pickworthiidae (Gastropoda Caenogastropoda) from Tropical Pacific Submarine Caves ; Four New Species of Sansonia
Author: Jan Delsing

Links and literature

EN Galli C.: WMSDB - Wolrdwide Mollusc Species Data Base July 10, 2013 [http://www.bagniliggia.it/WMSD/WMSDhome....] [as Sansonia iejimensis Kase, 1998]
Data retrieved on: 22 November 2013

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