Oceaniidae Poletaev, 2015

Poletaev, Vladyslav, 2024, New and revised taxa of Carboniferous spiriferides (Brachiopoda, Spiriferida) from the Donets Basin (Ukraine) and South Urals (Russia), European Journal of Taxonomy 968, pp. 132-155 : 143-145

Family Oceaniidae Poletaev, 2015

Diagnosis

Small or very small-sized, transverse, ventribiconvex shell; smooth and with two simple or compound opposed plica, dissected median parts of both valves on three parts. Fold and sulcus rarely have median opposite ribs; ventral interarea high or very high, flat, catacline or procline with strong vertical crenulations; hinge line denticulate; narrow and high delthyrium partly covered by pseudodeltidium; ornament of growth lamella only; ventral interior with low dental flanges; dorsal with ctenophoridium and short crural base.

Genera included

Johnsoniana nom. nov., possibly Minythyra Brunton, 1984 , Changshunella Sun et al., 2004 .

Remarks

The history of closely related genera and species previously included in the family Verneuiliidae Schuchert in Schuchert & Le Vene, 1929) is long and confusing. Hall & Clarke (1893) established the genus Verneuilia , which included two species: Spirifer cheiropteryx d’Archiac & de Verneuil, 1842 from the Late Devonian of Germany and Spirifer oceani d’Orbigny, 1850 from the Viséan of Belgium. These species, according to the authors of the genus, share common characters: the shell is equibiconvex with each valve “divided externally by two strong divergent ridges into three depressed areas, one central and two lateral” ( Hall & Clarke 1893: 58). Schuchert & Le Vene (1929) placed Verneuilia in a new subfamily and in the family Verneuiliidae of the suborder Spiriferidina (Schuchert in Schuchert & Le Vene 1929). Tiazheva (1960) established Nuguschella Tiazheva, 1960 from the Middle Devonian of the Urals, whose type species Nuguschella polita Tiazheva, 1960 has a cruralium. The genus was placed in the family Verneuiliidae by Ivanova (1960: 272) and Pitrat (1965: H727), but they considered the systematic position of the family uncertain. Ivanova (1960) placed Verneuilia separately in association with the “plicate ambocoeliids”.

Nalivkin (1979: 143) described Verneuilia oceani from the late Tournaisian of the Urals as a member of the family Verneuiliidae and confidently assigned this family to the suborder Spiriferidina . Wang et al. (1966) and Zhang et al. (1983) also examined members of the Verneuiliidae , but assigned them to the family Cyrtinidae Frederiks, 1911 on the basis of internal characters. Brunton (1984: 101) selected specimen B7923 as the neotype among three Belgian topotypes from the NHM collection. He described and illustrated it for the first time as a neotype of Verneuilia oceani . He re-established the family Verneuiliidae , in which he included the new Visean genus Minythyra , but retained for Verneuilia its Devonian type species Spirifer cheiropteryx . Brunton (1984) doubtfully placed the family Verneuiliidae in the superfamily Reticulariacea Waagen, 1883 .

Gourvennec (1994: 576) was the first to show pictures of the holotype of Verneuilia cheiropteryx and some topotypes of V. oceani . He emphasised the presence of a strong vertical crenulation on the interarea of V. oceani in contrast to V. cheiropteryx and concluded: “Detailed study of the available material now allows a clear definition and differentiation of the species cheiropteryx and oceani .” ( Gourvennec 1994: 581). He considered the superfamily Spiriferacea rather than Reticulariacea as the higher taxon for Verneuilia . At the same time, Blodgett & Johnson (1994) described a new species Verneuilia langenstrasseni from the Middle Devonian of Alaska and placed the family Verneuiliidae , including the genera Verneuilia , Minythyra and Nuguschella , in the superfamily Ambocoelioidea George, 1931 . Carter et al. (1994) supported this view.

Sun et al. (2004) described a new genus Changshunella whose type species C. yangi Sun et al., 2004 had a clearly denticulated hinge line and lacked dental plates. In order to place this genus in the family Verneuiliidae , the authors extended the family diagnosis by combining the characters of Changshunella yangi and “ Verneuilia ” oceani , which are absent in the Devonian type species of Verneuilia . Sun et al. (2004) also failed to determine the superfamilial assignment of the family Verneuiliidae and suggested that a new superfamily should be distinguished. Johnson ( Carter et al. 2006: 1746) strongly disagreed with the extension of the family diagnosis and wrote: “The Visean species V. oceani (d’Orbigny) from Belgium is not congeneric with the type species, bearing strong dental flanges, a finely striated cardinal process, lacing crural plates, in having a clearly denticulate ventral interarea with wide perideltidial areas, and possibly a weakly capillate microornament. It belongs in the Spiriferoidea .”. He concluded that these species should not only be placed in different genera, but also in other superfamilies. However, Johnson ( Carter et al. 2006: 1746) did not attempt to identify or describe the new genus he had actually discovered. Poletaev (2015: 17) established the new genus Oceania with Spirifer oceani d`Orbigny, 1850 as the type species. At the same time, he proposed to establish the new family Oceaniidae with the type genus Oceania and, together with Minythyra , to place this family in the superfamily Paeckelmanelloidea . However, the genus name Oceania was already used by Péron & Lesueur (1810) and the family Oceaniidae was established by Eschcheltz (1829). Both the genus and family names proposed by the author in 2015 are thus preoccupied (junior homonymy). Consequently, the genus with Spirifer oceani as type species is here renamed as Johnsoniana nom. nov. and remains type genus of the family Oceaniidae .

Mottequin & Poty (2022) revised old European collections of brachiopods from the historical type locality of Visé, outlining the more correct geographic and stratigraphic positions of this fauna (including the age of “ V.” oceani ) as latest Warnantian (Late Asbian) and published an image of the topotype of “ V.” oceani ( Mottequin & Poty 2022: fig. 11j). Wang et al. (2023) published the results of their research on the Spiriferidae King, 1946 fauna of the Frasnian (Late Devonian) Refrath Formation in the Bergisches Land of Germany, another historical type area for Western European Devonian fauna. They published the first transverse serial sections of two topotypes of Verneuilia cheiropteryx , showing short dental plates and illustrating the ctenophoridium in the ventral valve. They also showed the absence of denticles on the hinge line of the ventral interarea, the crural base and short crus in the dorsal valve, rounded cardinal extremities of mature Verneuilia cheiropteryx and flank plications in young specimens. These are absent in the type species of Johnsoniana oceani .

Wang et al. (2023) proposed an emended diagnosis of the genus Verneuilia and included short dental plates in the ventral valve of V. cheiropteryx , but not the denticulated hinge line of V. oceani . It remains unclear why Wang et al. (2023) did not exclude Spirifer oceani from Verneuilia , as its internal structure does not correspond to the revised diagnosis of the genus. They excluded Verneuilia langenstrasseni from Verneuilia because its internal structure does not correspond to the emended diagnosis of the genus. In my opinion, this species, together with Nugushella Tiazheva, 1960, should have been included under the new generic name in the group of so-called “plicated amboceleids” listed by Ivanova (1960), only without Verneuilia . The main difference between the internal structures of the Late Devonian (middle Frasnian) Verneuilia cheiropteryx (according to Wang et al. 2023) and the Visean “ Verneuilia ” oceani (according to Gourvennec 1994) confirms the necessity to separate the genus Johnsoniana nom. nov. I agree with Wang et al. (2023) that Verneuilia cannot be placed in the Ambocoelioidea . The type species of Verneuilia has been well distinguished and described by Gourvennec (1994) and Wang et al. (2023). Obviously, this genus has weakly plicate flanks, well-developed dental plates and lack of median septum in the ventral valve, non-denticulated hinge line, knob-like ctenophoridium and pair of short plate-like crural bases in the dorsal valve as well as microornament (after Gourvennec 1994: pl. 1 fig. 6) with very fine, regularly spaced growth lines and randomly arranged tiny pits. All these data allow, in my opinion, to place Verneuillia in the family Elythynidae Gourvennec, 1994 of the superfamily Martinioidea .

The next question is what higher taxa could include the genus Johnsoniana nom. nov. and some closely related genera?

Moderate to strong transverse contours of valves with high triangular area, acute or mucronate cardinal extremities and denticulate hinge line preclude the assignment of Johnsoniana and Changshunella to the superfamily Martinioidea . The absence of regular ribs on the flanks, smooth or with high median ridge sulcus and fold bordered by specific opposite plica do not allow to assign both genera to Spiriferoidea , contrary to the opinion of Gourvennec (1994) and Johnson ( Carter et al. 2006: 1746). On the other hand, most of the main characters of Johnsoniana and Changshunella in general are very close to or agree with the diagnosis of the superfamily Paeckelmanelloidea ( Carter et al. 2006: 1812) . Sun et al. (2004) assumed the same for Changshunella yangi , but the presence of unusual opposed ribs on the ventral and dorsal valves of this species led them to reject the assignment of Changshunella to Paeckelmanelloidea . The opposite type of plica on both valves of Changshunella links this genus to Verneuilia . On this basis, Sun et al. (2004) suggest that the above genera could form their own superfamily, namely Verneuilioidea. However, they prefer to include Changshunella in their revised family Verneuiliidae and maintain the verneuiliids as a separate family in the suborder Spiriferidina .

The pentagonal contours and the presence of extraordinary plica-bordered depressions in the central part of both valves of the biconvex shells of “ Oceania ” and Minythyra previously seemed to me sufficient to distinguish a new family Oceaniidae (see Poletaev 2015) and to include it very conventionally in the superfamily Paeckelmanelloidea . In fact, the assignment of this family to Paeckelmanelloidea was wrong, because the characters of Oceaniidae included smooth shells, which were not foreseen in the diagnosis of Paeckelmanelloidea by Ivanova (1972). On the other hand, I agree with Sun et al. (2004) and avoid distinguishing a new superfamily. It will be more reasonable to revise the diagnosis of Paeckelmanelloidea to include “rare smooth forms with opposed ribs or plica on both valves”, which will make a valid inclusion of the family Oceaniidae into this superfamily. The family Oceaniidae includes the genera Jonsoniana, Changshunella and Minythyra , each of which has characters of the emended Paeckelmanelloidea . The family excludes Verneuilia because it has tooth plates and no denticulate hinge line. The smooth flanks and the opposite ribs or plica on both valves distinguish Oceaniidae from Strophopleuridae and Paeckelmanellidae , because the latter also have a ventral median septum, which is absent in Oceaniidae . Furthermore, the Frasnian (Late Devonian) Verneuilia is not less than thirty million years older than the late Tournaisian to Visean Johnsoniana and Changshunella and could perhaps be a distant ancestor of the latter genera.