Phylogenetic relationships among families of the Scaphopoda (Mollusca)

Reynolds, Patrick D.; Okusu, Akiko

doi:10.1111/j.1096-3642.1999.tb00151.x

Cited by 14 publications

(7 citation statements)

References 17 publications

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“…121. Cuptacula: d p (Reynolds & Okusu 1999). Captacula are small, elongate, retractile feeding tentacles with bulbous ends, characteristic of the Scaphopoda (see Shimek 1988).…”

Section: Number Of Openings: (0) Two; ( I ) Three;mentioning

confidence: 99%

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On bivalve phylogeny: a high‐level analysis of the Bivalvia (Mollusca) based on combined morphology and DNA sequence data

Giribet

Wheeler

2002

Invertebrate Biology

274

213

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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 ( 1 8s rRNA and 28s rRNA), and 1 mitochondria1 coding gene (cytochrome c oxidase subunit I), totaling -3 Kb of sequence data for 76 rnollu bivalves and 14 outgroup taxa). The data have been analyzed separately and in combination by using the direct optimization method of Wheeler (1 996), and they have been evaluated under 1 2 analytical schemes. The combined analysis supports the monophyly of bivalves, paraphyly of protobranchiate bivalves, and monophyly of Autolamellibranchiata, Pteriomorphia, Heteroconchia, Palaeoheterodonta, and Heterodonta s.I., 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.Additional key words: Moll~sca, Bivalvia, Palaeoheterodonta, Heteroconchia, Heterodonta, 18s rRNA, 28s rRNA, cytochrome c oxidase I, morphology, direct optimization, scnsitivity analysis Bivalve molluscs are characterized by a laterally compressed body with an external bivalved shell that is hinged dorsally. The valves are connected by a partially calcified elastic ligament and are held together by 1 or 2 adductor muscles. There is no buccal or radular apparatus, and the mantle lobes are either joined or free ventrally. The spacious mantle cavity extends upwards on each side of the visceral mass and contains a pair of ctenidia suspended laterally. The ctenidia may be enlarged, lamellate and plicate. The mouth and anus are located at opposite ends of the body and the gut is typically convoluted. A pair of a Author for correspondence. E-mail: ggiribet @ oeb.harvard.edu ciliated labial palps connect the ctenidia to the mouth, and direct food particles into it. The extensible foot is either elongated or laterally compressed. These modifications from the plesiomorphic molluscan condition have made it difficult to establish a phylogenetic scheme of th...

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“…121. Cuptacula: d p (Reynolds & Okusu 1999). Captacula are small, elongate, retractile feeding tentacles with bulbous ends, characteristic of the Scaphopoda (see Shimek 1988).…”

Section: Number Of Openings: (0) Two; ( I ) Three;mentioning

confidence: 99%

“…Ctenidia: (0) present; ( I ) absent (Salvini-Plawen & Stejner 1996;Waller 1998). Gills with alternating leaflets or filaments occur in all molluscan classes except Scaphopoda and Solenogastres (Waller 1998;Reynolds & Okusu 1999). Numerous modifications and loss of one or both ctenidia occurred within Gastropoda; heterobranchs do not have ctenidia.…”

mentioning

confidence: 99%

On bivalve phylogeny: a high‐level analysis of the Bivalvia (Mollusca) based on combined morphology and DNA sequence data

Giribet

Wheeler

2002

Invertebrate Biology

274

213

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“…149 Ctenidia: (0) absent; (1) present. Gills with alternating leaflets or filaments occur in all molluscan classes except Scaphopoda and Solenogastres (Waller 1998;Reynolds and Okusu 1999). Numerous modifications and loss of one or both ctenidia have occurred within the Gastropoda.…”

Section: Gill and Palp Characters (Figs 19-22)mentioning

confidence: 99%

Investigating the Bivalve Tree of Life – an exemplar-based approach combining molecular and novel morphological characters

Bieler

Mikkelsen

Collins

et al. 2014

Invert. Systematics

228

211

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Abstract. To re-evaluate the relationships of the major bivalve lineages, we amassed detailed morpho-anatomical, ultrastructural and molecular sequence data for a targeted selection of exemplar bivalves spanning the phylogenetic diversity of the class. We included molecular data for 103 bivalve species (up to five markers) and also analysed a subset of taxa with four additional nuclear protein-encoding genes. Novel as well as historically employed morphological characters were explored, and we systematically disassembled widely used descriptors such as gill and stomach 'types'. Phylogenetic analyses, conducted using parsimony direct optimisation and probabilistic methods on static alignments (maximum likelihood and Bayesian inference) of the molecular data, both alone and in combination with morphological characters, offer a robust test of bivalve relationships. A calibrated phylogeny also provided insights into the tempo of bivalve evolution. Finally, an analysis of the informativeness of morphological characters showed that sperm ultrastructure characters are among the best morphological features to diagnose bivalve clades, followed by characters of the shell, including its microstructure. Our study found support for monophyly of most broadly recognised higher bivalve taxa, although support was not uniform for Protobranchia. However, monophyly of the bivalves with protobranchiate gills was the best-supported hypothesis with incremental morphological and/or molecular sequence data. Autobranchia,

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“…The question whether the dentaliidan muscularhydrostat system or the gadilidan combined muscular retraction vs. hydraulic expansion system represents the basal scaphopod condition remains unsolved, also because scaphopod phylogeny as a whole is still unclear (Steiner, 1992b(Steiner, , 1996Reynolds, 1997;Reynolds and Okusu, 1999). …”

Section: Functionality Of the Scaphopod Foot And Captaculamentioning

confidence: 99%

Muscle development in Antalis entalis (Mollusca, Scaphopoda) and its significance for scaphopod relationships

Wanninger

Haszprunar

2002

Journal of Morphology

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We applied fluorescence staining of F-actin, confocal laser scanning microscopy, as well as bright-field light microscopy, SEM, and TEM to examine myogenesis in larval and early juvenile stages of the tusk-shell, Antalis entalis. Myogenesis follows a strict bilaterally symmetrical pattern without special larval muscle systems. The paired cephalic and foot retractors appear synchronously in the early trochophore-like larva. In late larvae, both retractors form additional fibers that project into the anterior region, thus enabling retraction of the larval prototroch. These fibers, together with the prototroch, disappear during metamorphosis. The anlagen of the putative foot musculature, mantle retractors, and buccal musculature are formed in late larval stages. The cephalic captacula and their musculature are of postmetamorphic origin. Development of the foot musculature is dramatically pronounced after metamorphosis and results in a dense muscular grid consisting of outer ring, intermediate diagonal, and inner longitudinal fibers. This is in accordance with the proposed function of the foot as a burrowing organ based on muscle-antagonistic activity. The existence of a distinct pair of cephalic retractors, which is also found in basal gastropods and cephalopods, as well as new data on scaphopod shell morphogenesis and recent cladistic analyses, indicate that the Scaphopoda may be more closely related to the Gastropoda and Cephalopoda than to the Bivalvia.

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Phylogenetic relationships among families of the Scaphopoda (Mollusca)

Cited by 14 publications

References 17 publications

On bivalve phylogeny: a high‐level analysis of the Bivalvia (Mollusca) based on combined morphology and DNA sequence data

On bivalve phylogeny: a high‐level analysis of the Bivalvia (Mollusca) based on combined morphology and DNA sequence data

Investigating the Bivalve Tree of Life – an exemplar-based approach combining molecular and novel morphological characters

Muscle development in Antalis entalis (Mollusca, Scaphopoda) and its significance for scaphopod relationships

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