Is Cyclocardia (Conrad) a wastebasket taxon? Exploring the phylogeny of the most diverse genus of the Carditidae (Archiheterodonta, Bivalvia)

Abstract

The carditid genus Cyclocardia is currently the most diverse genus of the family, including nearly 180 nominal species encompassing wide stratigraphical (Cretaceous-Recent) and geographical (Antarctica, South and North America, Europe, Africa, Alaska, Russia, Japan and New Zealand) ranges. Due to the lack of autapomorphies in the diagnosis of the genus and its large account of species, we re-evaluate the systematic and phylogenetic status of Cyclocardia. We applied three approaches: bibliographic revision, phylogenetic analysis and an exploration of morphological disparity. We used a shell-character matrix comprising 65 taxa (2 outgroups, 29 non-Cyclocardia carditids and 28 species of Cyclocardia) for phylogenetic and disparity analyses. Maximum Observable Rescaled Distances was used to construct a distance matrix to compare Cyclocardia species and other carditid groups. According to our results, Cyclocardia represents a non-monophyletic taxon and is thus a

The incubatory chamber of marsupial carditids (Bivalvia: Carditidae: Thecaliinae) as an exaptation

“…Nevertheless, sexual dimorphism is poorly developed on bivalve shells (Kauffman and Buddenhagen 1969). Internal brooding of larvae was reported for several groups of carditids without any specialized structure associated, such as some species of the genera Cyclocardia Conrad, 1867, Coanicardita Pérez and Giachetti, 2020, Crassicardia Conrad, 1838, Hippocampocardia Pérez and Giachetti, 2020, Glans , and Cardita (Dall 1903; Lamy 1922; Jones 1963; Yonge 1969; Schneider 1993). In some taxa (e.g., species of the Rotundicardia Heaslip, 1968, Claibornicardia Stenzel and Krause, 1957, and Darwinicardia Pérez and del Río, 2017) shell differences could be noticed between males and females based on the presence of more inflated shells near to the umbonal region (Heaslip 1968, 1969; Pérez et al 2017).…”

“…We revised 46 fossil and extant carditid species (listed in the Appendix) from the following collections: Palaeontological Research Institution (PRI), Ithaca, New York, USA; American Museum of Natural History (AMNH-Fi and AMNH-In), New York, USA; University of Florida (UF), Gainesville, Florida; Yale Peabody Museum (YPM), New Haven, Connecticut, USA; National Museum of Natural History of the Smithsonian Institution (UNSM.Mo), Washington, D.C., USA; Natural History Museum of Rotterdam (NMR), Rotterdam, Netherlands; Australian Museum (AUK), Sydney, Australia; Auckland War Memorial Museum (AK), Auckland, New Zealand; the Natural History Museum of London (NHMUK), London, UK; Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (MACN-In and MACN-Pi), Buenos Aires, Argentina; Cátedra de Paleontología de la Universidad de Buenos Aires (CPBA), Buenos Aires, Argentina; and Museo de La Plata (MLP), La Plata, Argentina. We follow the systematic proposal of Pérez (2019), which includes the subfamilies Carditamerinae, Thecaliinae and Carditinae in the large group Cardiobyssata Pérez and Giachetti (2020) (= Carditida Pérez, 2019). Specimens belonging to the genera Cardita Bruguière, 1792, Beguina Röding, 1798, Birkelundita Heinberg, 1993, Thecalia , Milneria , and Powellina were considered as the in-group of the analyses (subfamilies Carditinae and Thecaliinae).…”

Imbricated shell sculpture in benthic bivalves

“…These species belong to the genera Coanicardita, Crassicardia, and Cyclocardia. Other authors who have considered carditid shell characters in detail did not comment on any asymmetrical elements of sculpture in this family (see Pérez, 2019;Pérez & Giachetti, 2020;Pérez & Monti, 2022;Pérez & RÍO, 2017;Yonge, 1969).…”

Phylogenetic relationships of Malarossia Berezovsky (Eocene, Ukraine) and trends in the size evolution of the carditids (Bivalvia, Carditidae)

“…The remaining 79 species‐level terminals are carditids representing all carditid subfamilies: Palaeocarditinae (genus Palaeocardita Conrad, 1867), Thecaliinae (genus Thecalia Adams & Adams, 1857), Carditinae (genera Cardita and Beguina Röding, 1798), Carditamerinae (genera Carditamera Conrad, 1838; Byssomera Olsson, 1961; Glans and Centrocardita Sacco, 1899), Venericardiinae (genera Xenocardita Vokes, 1946; Purpurocardia Maxwell, 1969; Cardiocardita Anton, 1838; Paraglans Chavan, 1941; Arcturellina Chavan, 1951; Venericardia , Darwinicardia Pérez & del Río, 2017a; Kalelia Pérez & del Río, 2017b; Baluchicardia Rutsch & Schenck, 1943; Rotundicardia Heaslip, 1968; Claibornicardia Stenzel & Krause, 1957; Glyptoactis Stewart, 1930; Cardites Link, 1807; Megacardita Sacco, 1899; Venericor Stewart, 1930; Neovenericor Rossi de García et al ., 1980; Leuroactis Stewart, 1930 and Pacificor Verastegui, 1953), and the subfamilies with small‐sized taxa, Scalaricarditinae ( Scalaricardita Sacco, 1899; Vimentum Iredale, 1925; and Coripia de Gregorio, 1885) and Miodomeridinae ( Miodomeris ; Miodontiscus Dall, 1903; Pteromeris , and Kolmeris Pérez & del Río, 2017a). Additionally, several genera without reliable subfamily assignments but which are part of the Cyclocardida clade were included: Pleuromeris Conrad, 1867; Cyclocardia ; Oesterheldia Pérez & Giachetti, 2020; Hippocampocardia Pérez & Giachetti, 2020 and Crassicardia Conrad, 1838. Among the taxa mentioned there are several Eocene species, such as A. asperula (Deshayes, 1825), C. alticostata (Conrad, 1833), D. angusticostata (Deshayes, 1824), L. pilsbryi Stewart, 1930, M. cossmanni (Chavan, 1936), P. calcitrapoides (Lamarck, 1806), R. rotunda (Lea, 1833), V. eudaedalea (Bayan, 1873), V. imbricata Lamarck, 1801, and V. planicosta (Lamarck, 1801).…”

“…Phylogenetic definitions of major clades follow Pérez (2019a), and the systematic scheme proposed herein is also considered. Clades Cardiobyssata (Pérez & Giachetti, 2020) and Eucarditida are replacement names for ‘Carditida’ and ‘Eucarditidae’, both defined in Pérez (2019a). The definition of Cyclocardia s.l .…”