Systematics and Biogeography of Burrowing Bryozoans

Soule, John D.; Soule, Dorothy F.

doi:10.1093/icb/9.3.791

Cited by 33 publications

(20 citation statements)

References 2 publications

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“…A similar structure is present in a few ctenostomes: e.g. the fossil Cardioarachnidium bantai (Taylor, ) and in recent species of the genus Penetrantia (Soule & Soule, , ). In some cheilostomes, the operculum has a calcified internal wall (cryptocyst) (Banta, Gray & Gordon, ).…”

Section: Character Evolutionmentioning

confidence: 60%

Key novelties in the evolution of the aquatic colonial phylum Bryozoa: evidence from soft body morphology

2020

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Molecular techniques are currently the leading tools for reconstructing phylogenetic relationships, but our understanding of ancestral, plesiomorphic and apomorphic characters requires the study of the morphology of extant forms for testing these phylogenies and for reconstructing character evolution. This review highlights the potential of soft body morphology for inferring the evolution and phylogeny of the lophotrochozoan phylum Bryozoa. This colonial taxon comprises aquatic coelomate filter-feeders that dominate many benthic communities, both marine and freshwater. Despite having a similar bauplan, bryozoans are morphologically highly diverse and are represented by three major taxa: Phylactolaemata, Stenolaemata and Gymnolaemata. Recent molecular studies resulted in a comprehensive phylogenetic tree with the Phylactolaemata sister to the remaining two taxa, and Stenolaemata (Cyclostomata) sister to Gymnolaemata. We plotted data of soft tissue morphology onto this phylogeny in order to gain further insights into the origin of morphological novelties and character evolution in the phylum. All three larger clades have morphological apomorphies assignable to the latest molecular phylogeny. Stenolaemata (Cyclostomata) and Gymnolaemata were united as monophyletic Myolaemata because of the apomorphic myoepithelial and triradiate pharynx. One of the main evolutionary changes in bryozoans is a change from a body wall with two well-developed muscular layers and numerous retractor muscles in Phylactolaemata to a body wall with few specialized muscles and few retractors in the remaining bryozoans. Such a shift probably pre-dated a body wall calcification that evolved independently at least twice in Bryozoa and resulted in the evolution of various hydrostatic mechanisms for polypide protrusion. In Cyclostomata, body wall calcification was accompanied by a unique detachment of the peritoneum from the epidermis to form the hydrostatic membraneous sac. The digestive tract of the Myolaemata differs from the phylactolaemate condition by a distinct ciliated pylorus not present in phylactolaemates. All bryozoans have a mesodermal funiculus, which is duplicated in Gymnolaemata. A colonial system of integration (CSI) of additional, sometimes branching, funicular cords connecting neighbouring zooids via pores with pore-cell complexes evolved at least twice in Gymnolaemata. The nervous system in all bryozoans is subepithelial and concentrated at the lophophoral base and the tentacles. Tentacular nerves emerge intertentacularly in Phylactolaemata whereas they partially emanate directly from the cerebral ganglion or the circum-oral nerve ring in myolaemates. Overall, morphological evidence shows that ancestral forms were small, colonial coelomates with a muscular body wall and a U-shaped gut with ciliary tentacle crown, and were capable of asexual budding. Coloniality resulted in many novelties including the origin of zooidal polymorphism, an apomorphic landmark trait of the Myolaemata.Biological Reviews 95 (2020) 696-729

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Section: Character Evolutionmentioning

confidence: 60%

Key novelties in the evolution of the aquatic colonial phylum Bryozoa: evidence from soft body morphology

2020

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“…Similarly, a single species among victorelloideans, Sundanella sibogae , possesses parieto-vaginal bands [67], while other genera have reduced them ( Pottsiella : [68,69]; Victorella : [26,70]). From our current knowledge, all Vesicularioidea lack parieto-vaginal bands ( Bowerbankia : [26,52,59,71,72]; Buskia : [73]; Spathipora : [74]; Terebripora : [75]; Vesicularia : [76]).…”

Section: Discussionmentioning

confidence: 99%

Myoanatomy and serotonergic nervous system of the ctenostome Hislopia malayensis: evolutionary trends in bodyplan patterning of ectoprocta

2011

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BackgroundEctoprocta is a large lophotrochozoan clade of colonial suspension feeders comprising over 5.000 extant species. Their phylogenetic position within the Lophotrochzoa remains controversially discussed, but also the internal relationships of the major ectoproct subclades -Phylactolaemata, Stenolaemata, and Gymnolaemata - remains elusive. To gain more insight into the basic configuration of ectoproct muscle systems for phylogenetic considerations, we analysed the adult myoanatomy and the serotonergic nervous system as well as myogenesis in budding stages of the ctenostome Hislopia malayensis.ResultsIn adults, the serotonergic nervous system is restricted to the lophophoral base with a high concentration in the cerebral ganglion and serotonergic perikarya between each pair of tentacles. Prominent smooth apertural muscles extend from the basal cystid wall to each lateral side of the vestibular wall. The musculature of the tentacle sheath consists of regular strands of smooth longitudinal muscles. Each tentacle is supplied with two bands of longitudinal muscles that show irregular striation. At the lophophoral base several muscles are present: (i) Short muscle fibres that proximally diverge from a single point from where they split distally into two separate strands. (ii) Proximally of the first group are smooth, longitudinal fibres that extend to the proximal-most side of the lophophoral base. (iii) Smooth muscle fibres, the buccal dilatators, traverse obliquely towards the pharynx, and (iv) a circular ring of smooth muscle fibres situated distally of the buccal dilatators. Retractor muscles are mainly smooth with short distal striated parts. The foregut consists mainly of striated ring musculature with only few longitudinal muscle fibres in the esophagus, while the remaining parts of the digestive tract solely exhibit smooth musculature. During budding, apertural and retractor muscles are first to appear, while the parietal muscles appear at a later stage.ConclusionsThe apertural muscles show high similarity within Ectoprocta and always consist of two sets of muscles. Gymnolaemates and Phylactolaemates show clear differences within their digestive tract musculature, the former showing smooth and longitudinal muscles to a much greater extent than the latter. The complex musculature at the lophophoral base appears promising for inferring phylogenetic relationships, but sufficient comparative data are currently lacking.

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“…For example, recent borings may exhibit such detailed morphology that they have routinely been used as the basis of biologic taxa (e.g. Soule & Soule 1969). The 'ctenostome bryozoan families' Spathiporidae and Terebriporidae were founded on the nominate borings Spathipora and Terebripora, respectively (d 'Orbigny 1847;Pohowsky 1978), and are therefore ichnofamilies, not biologic taxa.…”

Section: Ichnofamiliesmentioning

confidence: 99%

Names for trace fossils: a uniform approach

Bertling¹,

Braddy²,

Bromley³

et al. 2006

LET

457

277

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The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic groups concerned. To this aim, trace fossils are rigorously defined with regard to biological taxa and physical sedimentary structures. Potential ichnotaxobases are evaluated, with morphology resulting as the most important criterion. For trace fossils related to bioerosion and herbivory, substrate plays a key role, as well as composition for coprolites. Size, producer, age, facies and preservation are rejected as ichnotaxobases. Separate names for undertracks and other poorly preserved material should gradually be replaced by ichnotaxa based on well‐preserved specimens. Recent traces may be identified using established trace fossil taxa but new names can only be based on fossil material, even if the distinction between recent and fossil may frequently remain arbitrary. It is stressed that ichnotaxa must not be incorporated into biological taxa in systematics. Composite trace fossil structures (complex structures made by the combined activity of two or more species) have no ichnotaxonomic standing but compound traces (complex structures made by one individual tracemaker) may be named separately under certain provisions. The following emendations are proposed to the International Code of Zoological Nomenclature: The term ‘work of an animal’ should be deleted from the code, and ichnotaxa should be based solely on trace fossils as defined herein.

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Systematics and Biogeography of Burrowing Bryozoans

Cited by 33 publications

References 2 publications

Key novelties in the evolution of the aquatic colonial phylum Bryozoa: evidence from soft body morphology

Key novelties in the evolution of the aquatic colonial phylum Bryozoa: evidence from soft body morphology

Myoanatomy and serotonergic nervous system of the ctenostome Hislopia malayensis: evolutionary trends in bodyplan patterning of ectoprocta

Names for trace fossils: a uniform approach

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