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Abstract: The family Phylloporinidae was introduced in the late 19th century to accommodate a small number of Palaeozoic bryozoan genera characterized by irregularly fenestrated colonies generated by anastomosis of unilaminate branches. Among the first named of these genera were Chasmatopora Eichwald, 1855 and Phylloporina Ulrich in Foerste, 1887. The two names have been variously in fashion, and there has been confusion about whether they are subjective synonyms or are distinct genera. This taxonomic confusion has been due in large part to whether the single species (Retepora angulata Hall, 1847) assigned to Phylloporina in Foerste (1887) or the species that Ulrich intended (Retepora trentonensis Nicholson, 1875) is the type species and also because of lack of sufficient information about Foerste’s material to characterize it well. We here redescribe the pertinent species, erect the new species Chasmatopora foerstei for the species that Foerste incorrectly assigned to Phylloporina angulata (Hall), and suggest that Retepora trentonensis Nicholson be retained as type species of Phylloporina based on prevailing usage, until the issue is settled by the International Commission on Zoological Nomenclature.
D uring approximately the first half of the 19th century, various irregularly fenestrated Palaeozoic bryozoans were named as new species of Retepora, an extant genus erected by Lamarck (1801, p. 374). Harmer (1933, p. 618) noted that ‘M[illepora]. cellulosa L., 1767, must be [the type species] of Retepora’ and (p. 616) that ‘the diagnosis is applicable to practically all the species of Retepora auctt. and to certain Cyclostomes’. The diagnosis can be tied to a drawing of Mediterranean material in a mid-18th century monograph that is too generalized to be matched with any of several living reticulate bryozoan species that occur in the Mediterranean Sea (Harmer 1933). Retepora is no longer recognized by bryozoan taxonomists.
Realization that the Palaeozoic bryozoans originally described as species of Retepora needed to be reassigned resulted in the introduction of new generic names. The most important of these are ChasmatoporaEichwald, 1855 and Phylloporina Ulrich in Foerste, 1887, both of which are type genera for different families in the suborder Phylloporinina Lavrentjeva, 1979.
As indicated below, the type species of Phylloporina makes it a junior synonym of Chasmatopora, whereas the intended type species of Phylloporina would have established a distinctly different genus and would match the prevailing usage of the genus Phylloporina. The purpose of this article is to summarize the origins and histories of usage of the genera Chasmatopora and Phylloporina; to redescribe Retepora tenella Eichwald, 1840, R. trentonensis Nicholson, 1875, and R. angulataHall, 1852; to designate type specimens for the latter two species and to discuss the implications of retention of the type species of Phylloporina. Resolution of problems involved in the concept and status of Phylloporina is necessary before revision of the Fenestrata for the Treatise on invertebrate paleontology.
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The name Phylloporina first appeared in print in an article by A. F. Foerste as ‘Genus PHYLLOPORINA, Ulrich’ (1887, p. 150). Only one species, ‘Phylloporina angulata, Hall’ was mentioned in the article; it was described on pages 151 and 152 based on specimens from the Silurian Clinton Group at ‘Soldiers’ Home Quarries, Brown’s Quarry, Fair Haven, Todd’s Fork’, [Dayton], Ohio. Retepora angulataHall, 1852 (p. 49) as applied to Phylloporina by Foerste (1887, p. 151) is therefore by monotypy the type species of Phylloporina according to Article 68.3 of the International Code of Zoological Nomenclature. However, as indicated by Ross (1963, p. 593), ‘The taxonomic position of the specimens assigned by Foerste to P. angulata is not known’. Neither Foerste’s specimens nor Hall’s species have been redescribed, and the original descriptions and illustrations are inadequate to decide whether they are conspecific. Foerste (1887) had intended to illustrate Phylloporina angulata in accompanying plates, which were omitted when the article was published. Plates 15 and 16 were published the following year (1888, Bulletin of the Scientific Laboratories of Denison University, volume 3), but Plate 17 was never published. Unfortunately, the single enigmatic illustration of P. angulata on Plate 15 is a generalized drawing of the ‘small form for which the name P. [sic] Daytonensis was suggested by Hall and Whitfield’ (Foerste 1887, p. 174). Plate 17, which was to include drawings of the obverse and reverse sides as well as a tangential section (Foerste 1887, p. 175), never appeared.
Apparently, E. O. Ulrich shared with Foerste information about his intended new genus Phylloporina, which was part of his large manuscript, Palaeozoic Bryozoa. The article was to be published in the eighth and final volume of Geological Survey of Illinois organized by A. H. Worthen. In Worthen’s transmittal letter for volume 6, it is clear that funding for the Survey itself was exiguous and that support for publication of the volumes was intermittent, leading to delays of various lengths (transmittal letter cited in Kent 1982). Substantial problems plagued the production of volume 8, which does include the large bryozoan article by Ulrich (1890). The Illinois State legislature passed an Act in June 1885 for production of volume 8 within 2 years, but the volume did not go to the printer until early 1889, about a year after Worthen’s death, with a further exasperating delay of a year and a half before printing was accomplished (Lindahl 1890). Ulrich apparently expected a timely publication of the volume and gave access to the contents of his article not only to Foerste but also to at least one other. S. A. Miller’s North American Geology and Palaeontology appeared in 1889 and included all of Ulrich’s 1890 new bryozoan genera in his listing of taxa, and Ulrich himself listed the combination Phylloporina trentonensis (Nicholson) in an article that appeared a year earlier than the volume (Ulrich 1889).
Ulrich (1890, p. 399) not only listed ‘Phylloporina n. gen.’ but established ‘Family Phylloporinidae n. fam.’ based on it when volume 8 finally appeared. In that article, he designated ‘Types: Phylloporina trentonensis Nich. and P. asperato-striata Hall’ (Ulrich 1890, p. 399), illustrating both species in multiple thin section views. He later (Ulrich 1895, p. 208) listed only P. trentonensis as the type species.
Several species were listed as Phylloporina in A Synopsis of North American fossil Bryozoa (Nickles and Bassler 1900), but the only assessment of Chasmatopora Eichwald – cited as 1860 rather than the original 1855 article – was ‘This appears to be a Phylloporina’ (p. 55). A decade later, Bassler (1911, p. 169) had realized, given the precedence of Chasmatopora Eichwald, that Phylloporina needed to be considered as a junior synonym based on the information available. He noted (p. 169), however, that ‘As pointed out by Ulrich, several distinct types of structure are included in Phylloporina. It is therefore probable that with more study, both Phylloporina and Chasmatopora may be recognized’. Foerste (1919) apparently followed Bassler’s acceptance of Phylloporina as a junior synonym of Chasmatopora, including Chasmatopora angulata (Hall) in a taxonomic list, the same species that he had described in 1887 as Phylloporina angulata (Hall).
The first suggestion of particular differences between Chasmatopora and Phylloporina appears to have been given by Bekker (1921, p. 48)‘In the material that I have at my disposal, may be noticed two types. Seen in transverse sections one type has the zooecial tubes more or less regularly disposed on one side of the zoarial rounded branch; this type could include all species of the gen. Chasmatopora. The other type is with zooecial tubes irregularly disposed throughout the whole branch of zoarium. This type could include the species of the gen. Phylloporina Ulrich’.
In 1935, Bassler differentiated Phylloporina from Chasmatopora in the Fossilium Catalogus, but judged Chasmatopora to be a junior synonym of Subretepora d’Orbigny, 1849. However, the type species of Subretepora, Intricaria? reticulataHall, 1847, is unrecognizable from its original description, and the original specimens are not in any of the major repositories of James Hall’s specimens, i.e. New York State Museum, American Museum of Natural History, U.S. National Museum of Natural History, The Field Museum, and University of California Berkeley. At present, Subretepora is unrecognizable.
Chasmatopora and Phylloporina were treated as separate entities in the bryozoan volume of Osnovy paleontologii (Shulga-Nesterenko et al. 1960). Brief characterization of the two genera was based on external and internal features of the type species listed in the volume: Retepora tenella Eichwald for Chasmatopora and Retepora trentonensis Nicholson for Phylloporina. In the synopses, overall colony habit (narrow unilaminate, irregularly anastomosed branches in erect colonies) was given as similar, but a medial wall separating an even number of rows (usually two) per branch was noted as characteristic of Chasmatopora, and Phylloporina was described as having no medial wall and either an odd or even number of rows of zooecia. In that volume, there was no discussion of the history of tangled usage of the names Subretepora, Chasmatopora and Phylloporina. However, with characteristic verve, Nekhoroshev (1961), one of Shulga-Nesterenko’s co-authors for Osnovy paleontologii, discussed and gave his opinions on the main points of the history and applied the names Chasmatopora and Phylloporina to new species consistent with their characterization in Osnovy paleontologii. The characterizations given in the bryozoan volume of Osnovy paleontologii have been the foundation for common understanding of the two genera since its publication.
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Retepora angulata Hall and Phylloporina angulata (Hall) as applied by Foerste (1887) differ in so many character states (Table 3) from R. trentonensis Nicholson that they clearly belong in a different genus. The specimens that Foerste (1887) assigned to Phylloporina angulata (Hall) and are here reassigned to Chasmatopora foerstei sp. nov. comprise the basis for the legal type species of Phylloporina, thereby making Phylloporina a junior subjective synonym of Chasmatopora.
Table 3. Comparison of basic morphological features of Retepora angulata Hall, Phylloporina angulata (Hall) as used by Foerste (1887), and Retepora trentonensis Nicholson.
|Species||Retepora angulataHall, 1852||Phylloporina angulata (Hall) (Foerste 1887)||Retepora trentonensis Nicholson, 1875|
|Zoarial meshwork||Unilaminate, bifurcated, dissepiment or fusion-linked branches||Unilaminate, bifurcated, anastomosed branches||Bilaminate (?), bifurcated, anastomosed branches|
|Number of rows of zooecia||4||4||Variable|
|Endozonal axial wall||Present||Present||Absent|
|Autozooecial budding||From medial wall||From medial wall||From reverse wall|
|Microstyle distribution in lamellar wall of reverse side||(not preserved)||Longitudinal rows||Not in rows|
Many species of Phylloporina have been named since 1890, and the prevailing concept is distinctly different from Chasmatopora. All sufficiently described species or species transferred to Phylloporina since 1890, with one possible exception, have affinities with Ulrich’s intended type species, Retepora trentonensis (Table 4).
Table 4. Morphological affinity with Retepora angulata Hall vs. R. trentonensis Nicholson of most1 species described as or reassigned to Phylloporina.
|Species||Morphology related to R. angulata||Morphology related to R. trentonensis|
|Gorgonia? asperaHall, 1847 (as used by Ulrich 1890)||i|| |
|Intricaria? reticulataHall, 1847 (as used by Ulrich 1890)||e, i|| |
|Retepora hisingeriM’Coy, 1847 (Spjeldnæs 1957)|| ||e|
|Retepora fenestrataHall, 1850 (Nickles & Bassler 1900)|| ||e|
|Retepora asperato-striataHall, 1852 (Ulrich 1890)|| ||e, i|
|Polypora furcataEichwald, 1860 (Toots 1952)|| ||e|
|Phylloporina granistriataUlrich, 1890||i|| |
|Phylloporina halliUlrich, 1890|| ||e, i|
|Phylloporina sublaxaUlrich, 1890|| ||e, i|
|Phylloporina papillosaBekker, 1921|| ||e|
|Chasmatopora punctataBekker, 1921 (Toots 1952)|| ||e, i|
|Phylloporina maximaToots, 1952|| ||e|
|Phylloporina tricellataNekhoroshev, 1955|| ||e, i|
|Phylloporina aluverensisMännil, 1958|| ||e|
|Phylloporina carinataMännil, 1958||e?||e?|
|Phylloporina nekhorosheviMännil, 1958|| ||e|
|‘Phylloporina’devonicaDessilly, 1967|| ||e, i|
|Phylloporina vagaKopaevich, 1975|| ||i|
|Phylloporina kinnekullensisBrood, 1980|| ||e, i|
|Phylloporina longiporaLiu, 1980|| ||e|
|Phylloporina jaelltjaernensisBrood, 1982|| ||i|
|Phylloporina certaKopaevich, 1984|| ||i|
|Phylloporina fragilisLavrentjeva, 1985|| ||i|
|Phylloporina hillistensisLavrentjeva, 1985|| ||i|
|Phylloporina indistinctaLavrentjeva, 1985|| ||i|
|Phylloporina insolitaLavrentjeva, 1985|| ||i|
|Phylloporina estonicaLavrentjeva, 1988|| ||e, i|
|Phylloporina sassitoensisErnst and Carrera, 2008|| ||i|
The characteristics of Retepora angulata have previously been so poorly known that even those who have given Phylloporina angulata as the type species have named new species or discussed established species that have affinities with P. trentonensis rather than with P. angulata. With only a couple of ill-defined 19th century exceptions, the only species that has been either reassigned to Phylloporina or was newly described as Phylloporina and that has generic characteristics broadly related to Retepora angulata is R. angulata itself (Table 4).
We therefore intend to petition the International Commission on Zoological Nomenclature that Reteporina angulata be set aside and replaced by R. trentonensis as type species of Phylloporina, as is possible under Article 81.1 of the International Code of Zoological Nomenclature. Until that time, according to Article 82.1 of the Code, ‘When a case is under consideration by the Commission, prevailing usage ... of names is to be maintained until the ruling of the Commission is published’. Prevailing usage in this case means – for now – the retention in Phylloporina of species allied with Retepora trentonensis rather than with R. angulata.