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Taxon profile

species

Alviniconcha hessleri T. A. Okutani & S. Ohta, 1988

kingdom Animalia - animals »  phylum Mollusca - mollusks »  class Gastropoda - gastropods »  family Provannidae »  genus Alviniconcha

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Alviniconcha hessleri

Author: Okutani, T.

Alviniconcha hessleri

Author: Warén, A. & Bouchet, P.

Taxon in country check-lists*

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Description

The larval shell is whitish, consists of more than 1,5 whorls (apical part corroded and plugged), neatly sculptured by flexuous axial and spiral ribs. Between the sutures are 8-13 spiral ribs, one stronger rib is concealed by the suture but visible on the body-whorl, and below the sutural rib about seven ribs on the basal surface. The most apical basal rib is of the same strength as the sutural one and twice as strong as the others. The axial ribs are the same strength as the larger of the spiral ones. The peristome is much thickened and evenly rounded. The teleoconch starts smooth, sometimes with 2 or 3 low and broad ribs, mainly formed by angles in the curvature of the whorl. There are also fine incremental lines. Soon the broad ribs disappear and the shell becomes evenly rounded and inflated. This change is subject to much individual variation; in some specimens there is only half a keeled teleoconch whorl, in others almost 2. At a size of 3-6 mm the periostracum starts to develop long, slender and hollow bristles—at first a few, scattered ones. They gradually become more crowded, to finally form a spirally arranged fur at a shell diameter of about 12 mm. Operculum. Up to 55 mm in diameter, attached along a slender area 4 mm from the inner edge. It is rounded, and fan-shaped. The inner edge is almost straight, outer margin corroded, but approximately semi-circular. The spirally coiled nucleus is visible only in young specimens, smaller than about 10 mm and is lost by abrasion in adult specimens.
Radula : The length of the radula of an adult specimen is about 10 mm, and it has about 200 transverse rows with normal taenioglossate arrangement. The central tooth has a comparatively narrow cutting edge, corresponding to 40% of the breadth of the tooth and is equipped with one main and 4-5 lateral denticles on each side. The anterolateral supports are strongly diverging and low. The lateral tooth has a large main cusp, 3-5 inner denticles and the same number of, but twice as large, outer denticles. The 2 marginal teeth are identical, very broad and flat and have about 15-18 apical denticles along the rake-like distal end.
Warén A. & Bouchet P. (1993) New records, species, genera, and a new family of gastropods from hydrothermal vents and hydrocarbon seeps
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 Alviniconcha hessleri Okutani & Ohta, 1988]
Data retrieved on: 23 November 2013

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Explanations

species extinct in area described by check-list