Decacoenia
Orbigny, 1849, p. 33
Type Species
Decacoenia magnifica d’Orbigny 1850, p. 33; Subsequent Designation Alloiteau 1948, p. 706 ?
Type Specimen: Lectotype; MNHN A26575; Verified; Dry Preserved
Type Locality: Oxfordian (Upper Jurassic) from Chatel Censoir, Wagnon, France
Cottreau 1931 illustrated for the first time D. magnifica and designated the lectotype. Alloiteau 1948 (p. 706) described the type material on the basis of some thin sections.
Classification
Description
Massive plocoid corallum with circular corallites. Wide surface of peritheca costulate near the corallite then granulated in the outward prolongation of costae. Radial elements are compact, free, bicuneiform. The inner edges of septa are slightly enlarged but auriculae are not observed. Lateral faces are ornamented with some strong acute irregularly distributed granules. Septa in radial (decameral arrangement in the largest corallite observed, octameral in the smallest one), with bilateral symmetry slightly marked by elongation of the fossa and shorter S1 in the larger corallite observed. Columella styliform to parietal made of some isolated trabecules. Parathecal wall. Endotheca made of abundant vesicular dissepiments . Peritheca composed of vertically continuous costae and abundant vesicular dissepiments. Septal microstructure with a median irregular line but without auriculae.
Comparisons
Decacoenia was synonymized with Stylina for Milne Edwards 1851 and Fromentel (1861) and more recently by Zaman (2012). Alloiteau 1948 (p. 706) considered Decacoenia as a distinct genus. On the basis of the vesiculose endotheca and peritheca, the rather parietal columella and the absence of auriculae this position is tenable and a non ambiguous statement needs a better documentation of the variability.
Remarks
Two jurassic nominal species known
Distribution
- Western Europe; Late Jurassic
This page has been in preparation since 21-Aug-2009 13:26
This version was contributed by Bernard Lathuilière on 03-Apr-2014 09:49.
Page authors are: Bernard Lathuilière Ewa Roniewicz Shaahin Zaman. Please contact the editor if you would like to contribute to the diagnosis of this taxon.
The editor is: Bernard Lathuilière
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