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Holocoenia

Milne Edwards and Haime, 1851, p. 99

Holocoenia Milne Edwards and Haime, 1851, p. 99 is a nomen dubium (unavailable).

Type Species

Astrea micrantha Roemer, 1841: 113.; Original Designation Milne Edwards and Haime, 1851: 99

Type Specimen: Holotype; unknown; Not Traced; Unknown

Type Locality: Upper Valanginian – Lower Hauterivian of Germany.

The holotype of the type species is lost and the type locality does not exist anymore.

Remarks

The original description of Holocoenia by Milne Edwards and Haime (1851) is rather insufficient in that it only consisted of the remarks that this taxon differed from Thamnasteria in having a prominent styliform columella and entire septa. As a consequence from this definition, Holocoenia would have to show all characteristics of Thamnasteria with the exception of these two features, which would make Holocoenia a genus that is characterized by thamnasterioid polyp integration; extra- and intracalicinal budding; (non-costate) compact and confluent, entire septa; a prominent styliform columella; vesicular and tabulate endothecal dissepiments; either no wall or an incomplete synapticulotheca present (see Roniewicz, 1982, and Bertling, 1993, for information on Thamnasteria). In 1857, de Fromentel provided the first more extensive description based on non-type material, in which he included the presence of characteristics like ‘septocostae strongly granulated laterally’, ‘corallites united by their walls, appearing polygonal, and ‘septa developed in 2 with a beginning third cycle'; the first two characteristics of which would have to be considered as differing from the generic concept by Milne Edwards and Haime. Recently, a revision on Holocoenia was carried out by Löser (2009). According to him, the holotype of the type species was lost and the type locality did not exist anymore. In his revision, Löser gave a generic description of Holocoenia, following both the model by Milne Edwards and Haime, 1851, and the emended version provided by de Fromentel, 1857. He gave the following generic diagnosis for Holocoenia based on non-type material from a locality other than the type locality: “Cerioid colony with small calices. Septa compact, in radial symmetry, and always in two generations. Septal face with few granules. Wall incomplete, made of synapticulae and septa. Columella styliform. Endotheca present, made of thin dissepiments. Budding extracalicinal. Septal microstructure unknown.” In addition, Löser included material that has both costate and non-confluent septa, and shows incomplete septothecal walls. That means that his material differs from both of the generic concepts he says he is following: 1) In having a cerioid polyp integration, only extracalicinal budding, both costate and septothecal developments, the presence of non-confluent septa, and an unknown septal structure, it differs from the generic concept by Milne Edwards and Haime and, in addition, is inconclusive regarding one of the most important features defined by Milne Edwards and Haime--entire septa--- in their original diagnosis for Holocoenia; 2) In having a maximum of 2 cycles of septa, that are not only confluent but also non-confluent, and are strongly granulated laterally, it differs from the emended version provided by de Fromentel. In addition, Löser (2009) grouped the genera Stereocoenia Alloiteau, 1952 (=genus originally placed in the Thamnasteriidae) and Paretallonia Sikharulidze, 1972 (=genus originally placed in the Acroporidae), as junior synonyms of the genus Holocoenia. Moreover, he placed Holocoenia in the Thamnasteriidae. However, because of the fact that Milne Edwards and Haime mentioned in their original description that Holocoenia had ‘entire septa’, excludes this genus from the family Thamnasteriidae, which, consequently, excludes Stereocoenia from the synonymy with Holocoenia. In addition, because Löser’s revision is based on 1) non-type material from localities other than the type locality (for Holocoenia micrantha), that 2) is in contradiction to both of the taxonomic models he is following, and 3) lacks the very necessary re-study of the type material of both Stereocoenia Alloiteau, 1952, and Paretallonia Sikharulidze, 1972, it can only be concluded that: a) Holocoenia is an unrecognizable taxon which makes any decision regarding any junior synonyms impossible, b) the taxonomic position of the material described in Löser (2009) remains unknown, and c) the taxonomic information provided in the original documentations for Stereocoenia Alloiteau, 1952, and Paretallonia Sikharulidze, 1972, remain valid because no information proving otherwise has been given. Baron-Szabo (2002, p. 81 and p. 116) previously pointed out the morphological similarities between Stereocoenia Alloiteau and Paretallonia Sikharulidze, but made clear that they only applied to their macromorphological appearances. Furthermore, because the material described by Löser (2009) is inconsistent with what is known of the former name-bearing type including both the original description and other sources (ICZN 75.3.5), it disqualifies from being used as a potential candidate for a neotype (Baron-Szabo, 2014, p. 86).

This page has been in preparation since 02-Jun-2007 12:36

This version was contributed by Rosemarie Baron-Szabo on 24-Dec-2014 19:01.

Page authors are: Rosemarie Baron-Szabo. Please contact the editor if you would like to contribute to the diagnosis of this taxon.

The editor is: Rosemarie Baron-Szabo

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