Etallon, 1859, p. 74/ 474
Conocoenia is synonym but was not used since d’Orbigny 1850 and is then considered as a nomen oblitum
Heliocoenia variabilis Etallon, 1859, p. 75/475; Subsequent Designation
Type Specimen: Syntype; ; Lost; Unknown
Type Locality: Kimmeridgian (Upper Jurassic) from Valfin, (Jura, France)
The type-specimen was described in Étallon, 1859 with a high degree of precision. Subsequently, in their posthumous work, Thurmann and Etallon 1864 figured the species but their figure does not correspond to the description of 1859. The type species was redescribed in Roniewicz, 1966, Beauvais, 1994, Zaman 2012 in accordance with the 1859 concept. Presently no type-specimen is available. The specimen n° S1399 of the Musée Jurassien des Sciences naturelles de Porrentruy (Switzerland) belongs to the Koby’s collection could be a syntype and we intend to publish this specimen as a neotype.
Corallum massive with different forms, ramose and irregular and different sizes, plocoid; with circular - elliptic (adults) to circular (young) corallites. Surface of peritheca, granulated or smooth. Radial elements are compact, mostly free, attenuated or auriculated costosepta. The inner edges of septa are ornamented with koutaliform auriculae. Lateral faces are sometimes ornamented with some strong acute irregularly distributed granules. Septa in hexameral or octameral arrangement, with bilateral symmetry marked by elongation of corallites and columellas and the unequal sectors. Often, 1 to 5 S1 join the columella at the same horizontal level and always the plan of symmetry correspond to the axis of elongation of the columella. Columella flat, lamellar, compressed or styliform. Wall etallonothecal. Endotheca subtabular. Peritheca composed of trabecular layers vertically alternating with vesicular tissues. Trabecular layers composed of spines (each spine is a trabecula). Septal and columellar microstructure with a median irregularly zigzag line.
Heliocoenia is very close of Stylina from which it is not always easy to distinguish. Nevertheless, we keep these genera distinct on the basis of several characters: symmetry bilateral (H.) versus radial (S.), peritheca granulated or smooth (H.) versus costulate (S.), columella rather flattened and attached to septa (H.) or rather styliform and detached from septa (S.), septa more (H.) or less (S.) ornamented.
32 Jurassic and 11 Cretaceous nominal species
This page has been in preparation since 19-Aug-2009 13:26
This version was contributed by Bernard Lathuilière on 10-Nov-2014 09:26.
Page authors are: Bernard Lathuilière Shaahin Zaman Ewa Roniewicz. Please contact the editor if you would like to contribute to the diagnosis of this taxon.
The editor is: Bernard Lathuilière