Cyathidium plantei sp. n., an extant cyrtocrinid (Echinodermata, Crinoidea)—morphologically identical to the fossil Cyathidium depressum (Cretaceous, Cenomanian)

Authors

  • THOMAS HEINZELLER,

    1. Thomas Heinzeller & Ulrich Welsch, Ludwig-Maximilians-Universitat. Anatomische Anstalt, Pettenkoferstr. 11. D-80336 Munchen, FRG.
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  • HANS FRICKE,

    1. Hans Fricke, Max Planck-Institut fur Verhaltensphysiologie, 82319 Seewiesen, FRG.
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  • JEAN-PAUL BOURSEAU,

    1. Jean-Paul Bourseau, Université Claude Bernard, Lyon 1, Departement des Sciences de la Terre, 27-43. bld. du 11 novembre, 69622 Villeurbanne Cedex, France.
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  • NADIA AMEZIANE-COMINARDI,

    1. Nadia Améziane-Cominardi, Museum National d'Histoire Naturelle, Lab. de Biologie des Invertébrés Marins et Malacologie, 55. rue de Buffon. 75005 Paris, France.
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  • ULRICH WELSCH

    1. Thomas Heinzeller & Ulrich Welsch, Ludwig-Maximilians-Universitat. Anatomische Anstalt, Pettenkoferstr. 11. D-80336 Munchen, FRG.
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Abstract

A new species of the holopodid genus Cyathidium was found on rocks off Grande Comore in a depth of around 200 m. Based on external morphology of resting animals, the new species Cyathidium plantei sp. n is described, with emphasis on comparison to the only other extant species (C. foresti) as well as to the four extinct representatives of the genus. Concerning morphological characters, the new species is almost identical to the Cretaceous C. depressum. A cladistic analysis of the entire family, including the genus Holopus, shares a peculiar pattern of bending of the arms, which in principle is an apomorphic character of the family and in detail shows variations within the family. In addition, stratigraphic data are used for the determination of the evolutionary direction. This analysis reveals that the two recent species are closely related to each other, and to the fossil C. depressum. from which the entire family is probably derived.

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