Vestimentifera inhabit hydrothermal vents, cold-water seeps and other marine reducing habitats. The objectives of this study were to analyse phylogenetic relationships among the extant species and their affinities to perviate and moniliferan Pogonophora and Polychaeta. The phylogeny was reconstructed using morphological characters to test phylogenetic hypotheses based on molecular data. Morphological characters were partly extracted from the literature and partly gained throughout study of gross morphological and anatomical investigations and light, transmission and scanning electron microscopy. Three aspects of morphology were examined in detail in nine vestimentiferan species. The excretory system differs among the vestimentiferan species in the number of excretory pores, absence/presence of excretory papillae and grooves and shape of the excretory ducts. The anatomy of the excretory system resembles that shared by the polychaete families Serpulidae, Sabellidae and Sabellariidae. Chaetal ultrastructure and chaetogenesis show patterns similar to uncini in polychaetes. Contrary to published accounts, the septa dividing the opisthosomal segments only bear musculature on their posterior faces. A rudimentary gut and anus are present in opisthosomes of specimens up to adult size. The blood vascular system includes an intravasal body in the dorsal vessel with ultrastructural characteristics similar to intravasal tissue in Terebellidae, Ampharetidae, Flabelligeridae and Serpulidae, and is probably involved in hemoglobin production. Hemocytes were detected in many blood vessels, most of them attached to the vascular lamina. The sinus valvatus is a specialised region of the anterior ventral vessel, apparently unique to vestimentiferans. The wall of the dorsal vessel is formed by myoepithelial cells, representing a coelomyarian type of double obliquely striated musculature. Phylogenetic analyses including a total of 17 vestimentiferan species and three perviate species as outgroups support molecular interpretations that the vestimentiferan species inhabiting basalt-hosted vents of the Eastern Pacific represent a derived monophyletic clade. According to the reconstructed phylogeny, the ancestral habitat of Vestimentifera was deep-water sedimented vent sites in the Western Pacific. Analysis of the relationships among Pogonophora and six polychaete families placed Pogonophora at the base of a clade including Sabellidae, Serpulidae and Sabellariidae. The Oweniidae represent the sister group to this clade. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/9105 |
| Date | 01 March 2018 |
| Creators | Schulze, Anja |
| Contributors | Tunnicliffe, Verena Julia |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
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