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Taxon profile

species

Folinella excavata (Philippi, 1836)

kingdom Animalia - animals »  phylum Mollusca - mollusks »  class Gastropoda - gastropods »  order Allogastropoda »  family Pyramidellidae »  genus Folinella

Scientific synonyms

Chrysallida excavata R. A. Philippi, 1844

Images

Folinella excavata

Author: Jan Delsing

Folinella excavata

Author: Linden, van der & Eikenboom

Folinella excavata

Author: Aartsen, van, Gittenberger & Goud

Folinella excavata

Author: Aartsen, van, Gittenberger & Goud

Taxon in country check-lists*

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Description

Chrysallida excavata: General description (after 1227 shells from 39 localities). — The shape of the shell is variable, but very typical: scalariform with a spiny profile; conical or cylindrical and a blunt top. The protoconch is of type B, tending to C. There are four to six whorls, clearly turreted and, because of the spines on the ribs, with a somewhat concave profile. The ribs are narrow and high, generally rather far from each other, so that the interstices are often twice as broad as the ribs. On the apical level of each whorl, they strongly curve inwards, forming a nearly flat shoulder, to the suture which is wide, deep and moderately oblique. The ribs are prosocline, particularly so at the lower part of the whorl (after crossing the spiral ridge). Sometimes, the ribs continue to the base; sometimes they end on the last whorl at the last spiral ridge; more often, from that point onward to the base, they are reduced to thin lines only. On the initial whorls there are two pronounced spiral ridges (almost equal to the ribs). The upper, broadest one, on the shoulder of the whorls, the other one on 1/3 of their height, in apical direction. The last whorl has five spirals. The initial one is on the shoulder too, the third one is on the same level as the upper side of the aperture, the second spiral ridge is just between them. The last two (sometimes more or less faint) are opposite the aperture, of which the lower one parallels the columellar side of the aperture. Where ribs and spiral cords cross each other, there are spiny tubercles, to such an extent that at the apical side of the whorls, where the most pronounced ridge is located, the largest breadth of the whorl is measured. Within the squares, formed by ribs and spiral ridges, one can see a microsculpture of spiral striae (only visible on fresh shells). The aperture is rhomboid, the outer lip is angulate because of the protruding spirals. The modest tooth is generally only visible after turning the shell. There is no umbilicus.
Length: 1.7-3.6 mm, LW 49-62%, A 26-38%, L/B 1.8-2.5, B/b 1.4-2.0 (based on 28 shells).
Van der Linden, J. & Eikenboom, J.C.A., 1992. On the taxonomy of the Recent species of the genus Chrysallida Carpenter from Europe, the Canary Islands and the Azores (Gastropoda, Pyramidellidae)

Interchangeable taxa

Chrysallida excavata: In spite of its characteristic shape, C. excavata could be con¬fused with other Chrysallida which are provided with very pronounced spiral ridges, e.g. C. fenestrala, which, apart from its totally different, non-scalariform Turbonilla shape, has on the initial whorls two spirals at the bottom of the whorl. Somewhat more difficult is the difference with the (rare) C. ghisottii. This species, however, is more compact, resembles an Alvania and shows three instead of two spiral ridges on the penultimate whorl and on the last whorl above the aperture. Its protoconch is more intoned (clearly type C).
Van der Linden, J. & Eikenboom, J.C.A., 1992. On the taxonomy of the Recent species of the genus Chrysallida Carpenter from Europe, the Canary Islands and the Azores (Gastropoda, Pyramidellidae)
Van Aartsen (1984, pages 136-137) proves this species belongs to Folinella genus (Dall & Bartsch, 1904). Shell easily recognizable even in the juvenile forms. Its aspect is more or less Turricolate. It is peculiar for its sculpture made by spiral and axial ridges of same thickness giving to the shell surface a reticulated sculpture. The only similar species is Folinella ghisotti Van Aartsen, 1984 that is recognizable for having got a less slim outline and, mainly, for its different spiral sculpture showing a third ridge, of smaller thickness, placed between the two stronger ones. The average measures are abt. 3 mm in height.
Scaperrotta, M. ,Bartolini, S. & Bogi, C., 2009. Accrescimenti, Vol. 1. Stages of growth of marine molluscs of the Mediterranean Sea. (secondary description)

Distribution

Chrysallida excavata: Common in the entire Mediterranean, uncommon in the Lusitanian area, north to Brittany (rare). Very rare and probably only in deeper water around the Canary Islands. Fretter, Graham & Andrews (1986) report occurrence north to the British Isles.

Distribution: common all over the Mediterranean. Habitat: usually this species is found in low depths into detrital bottoms.
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 Chrysallida excavata Philippi, 1844]
Data retrieved on: 23 November 2013
IT Repetto G., Orlando F. & Arduino G. (2005): Conchiglie del Mediterraneo, Amici del Museo "Federico Eusebio", Alba, Italy [as Folinella excavata (Philippi, 1836)]
SP Peñas, A. & Almera, J. (2001): Malacofauna asociada a una pradera de Posidonia oceanica (L.) en Mataró (NE de la Península Ibérica) [http://www.molluscat.com/SPIRA/PDF/VOL1/...], Spira, 1(1): 25-31 [as Chrysallida excavata (Philippi, 1836)]
SP Prats Pi, L. (2002): Gastròpodes marins de la cala de Binissafúller, Menorca (Illes Balears) [http://www.molluscat.com/SPIRA/PDF/VOL1/...], Spira, 1(2): 21-24 [as Folinella excavata (Philippi, 1836)]
SP Tarruella Ruestes, A. (2002): Moluscos marinos de Cap Ras y Llançà (Girona, NE de la península Ibérica) [http://www.molluscat.com/SPIRA/PDF/VOL1/...], Spira, 1(2): 1-14 [as Folinella excavata (Philippi, 1836)]

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