Bivalvia -- a look at the Branches

Invertebrate Biology, 2005

Abstract. Bivalve classification has suffered in the past from the crossed-purpose discussions among paleontologists and neontologists, and many have based their proposals on single character systems. More recently, molecular biologists have investigated bivalve relationships by using only gene sequence data, ignoring paleontological and neontological data. In the present study we have compiled morphological and anatomical data with mostly new molecular evidence to provide a more stable and robust phylogenetic estimate for bivalve molluscs. The data here compiled consist of a morphological data set of 183 characters, and a molecular data set from 3 loci: 2 nuclear ribosomal genes (18S rRNA and 28S rRNA), and 1 mitochondrial coding gene (cytochrome c oxidase subunit I), totaling ∼3 Kb of sequence data for 76 molluscs (62 bivalves and 14 outgroup taxa). The data have been analyzed separately and in combination by using the direct optimization method of Wheeler (1996), and they have been evaluated under 12 analytical schemes. The combined analysis supports the monophyly of bivalves, paraphyly of protobranchiate bivalves, and monophyly of Autolamellibranchiata, Pteriomorphia, Heteroconchia, Palaeoheterodonta, and Heterodonta s.l., which includes the monophyletic taxon Anomalodesmata. These analyses strongly support the conclusion that Anomalodesmata should not receive a class status, and that the heterodont orders Myoida and Veneroida are not monophyletic. Among the most stable results of the analysis are the monophyly of Palaeoheterodonta, grouping the extant trigoniids with the freshwater unionids, and the sister-group relationship of the heterodont families Astartidae and Carditidae, which together constitute the sister taxon to the remaining heterodont bivalves. Internal relationships of the main bivalve groups are discussed on the basis of node support and clade stability.

American Malacological Bulletin, 2013

Bivalves share many of the “deeper” questions with the other molluscan groups – issues such as their origin and sister-group relationships within the Mollusca, and their suitability to explore molecular data in a “known” fossil framework. Other questions are more specific to bivalves, a group that radiated so successfully and nowadays predominantly specializes as infaunal and sessile epifaunal suspension feeders. This paper highlights and explores unanswered questions, from the seemingly trivial and mundane (e.g., how many species are actually out there?), to exploring enigmatic clades about which we know extremely little besides their shells, to macroevolutionary questions that could best be addressed by bivalve-based data. Fast-developing molecular approaches, including the fi rst genome-level and transcriptomic data, a resurgence of detailed morphological and soft-anatomical research, and a renewed focus on Bivalvia by biological and paleontological workers provide us with an opportunity to address such issues. Coordination of efforts – and reciprocal illumination – across traditional disciplinary boundaries will be key factors in such endeavors.

2002

The long history of both zoological and palaeontological research on the bivalves has revealed a startling degree of convergence and parallel evolution which has hampered the interpretation of their evolutionary history. However new discoveries and developments make it timely for a new concerted effort to integrate zoological and palaeontological techniques to improve comprehension of the evolutionary history of the class.

Treatise Online, 2012

CAMBRIAN ARCHETYPE (STEM-GROUP) BIVALVES ORIGIN OF CAMBRIAN ARCHETYPE BIVALVES Since the publication of the Bivalvia volumes of the Treatise on Invertebrate Paleontology in 1969 (Cox, nuTTall, & TrueMan, 1969), with the exclusion of Lamellodonta Vogel, 1962, from the Bivalvia, and with dramatic increases in our knowledge of Cambrian and Ordovician bivalves and their close relatives, much progress has been made in our understanding the origin and early evolution of this class. The Diasoma hypothesis of runnegar and PojeTa (1974) has been overturned by evidence that the Scaphopoda and Cephalopoda are sister groups within Cyrtosoma

During the study of the Pliocene malacofaunas of the Mediterranean Basin, it was ascertained that the name Spondylus ferreolensis Fontannes, 1882 cannot be used as a substitute for S. concentricus Bronn, 1831 of which the type material is here represented for the first time. The validity of Acanthocardia perrugosa (Fontannes, 1882) is also proposed, of which it was possible to view the type material, a species previously considered synonymous with A. paucicostata (GB Sowerby, 1841), or A. bianconiana (Cocconi, 1873) or A. aculeata (Linnaeus, 1758).

Paleontological …, 2011

The following classification summarizes the suprageneric taxonomy of the Bivalvia for the upcoming revision of the Bivalvia volumes of the Treatise on Invertebrate Paleontology, Part N. The development of this classification began with assistance from the United States National Science Foundation, conducted large-scale morphological phylogenetic analyses of mostly Paleozoic bivalves, as well as molecular phylogenetic analyses of living bivalves. During the past several years, their initial phylogenetic framework has been revised and greatly expanded through collaboration with many students of bivalve biology and paleontology, many of whom are coauthors. During this process, all available sources of phylogenetic information, including molecular, anatomical, shell morphological, shell microstructural, bio-and paleobiogeographic as well as stratigraphic, have been integrated into the classification. The more recent sources of phylogenetic information include, but are not limited to, . This work has also benefited from the nomenclator of bivalve families by Bouchet and Rocroi (2010) and its accompanying classification by Bieler, Carter, and Coan . This classification strives to indicate the most likely phylogenetic position for each taxon. Uncertainty is indicated by a question mark before the name of the taxon. Many of the higher taxa continue to undergo major taxonomic revision. This is especially true for the superfamilies Sphaerioidea and Veneroidea, and the orders Pectinida and Unionida. Because of this state of flux, some parts of the classification represent a compromise between opposing points of view. Placement of the Trigonioidoidea is especially problematic. This Mesozoic superfamily has traditionally been placed in the order Unionida, as a possible derivative of the superfamily Unionoidea (see The present classification gives preference to typified names over descriptive names above the family-group, following the recommendation by . Typified names are more useful than descriptive names, because their

Historical Biology, 1995

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Zoological Journal of The Linnean Society, 2006

The evolutionary relationships of the Recent Pterioidea are inferred from a phylogenetic analysis of representatives of all pterioidean genera based on original observations of anatomy and shell morphology, and an extensive survey of bivalve literature. The well-resolved cladogram supports monophyly for the superfamily, but renders all but one family (the monotypic Pulvinitidae) polyphyletic. In addition, these results reveal a considerable level of convergence and parallelisms through the Pterioidea. The branching order of pterioid genera in the morphological analysis is largely corroborated by the sequence of their appearance in the fossil record. The palaeontological evidence provides important information on dating lineage splitting events and transitional taxa. The proposed phylogeny integrates the cladistic analysis of the Recent Pterioidea with the fossil record and suggests that the crown-group pterioideans probably originated in the Triassic from the Bakevelliidae, an extinct paraphyletic stem group from which the Ostreoidea are also ultimately derived. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 148, 253–312.

Molecular Biology and Evolution, 1997