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An integrated taxonomic assessment of North Carolina Polysiphonia (Ceramiales, Rhodophyta) species

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Brooke Stuercke (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
D. Wilson Freshwater

Abstract: The rhodomelacean genus Polysiphonia Greville (Ceramiales, Rhodophyta) contains approximately 200 species that are distributed throughout the world’s oceans. Polysiphonia species have been defined by the number of pericentral cells, presence or absence of cortication, nature and arrangement of trichoblasts, origin of branches in relation to trichoblasts, origin of attachment rhizoids, nature of spermatangial branches, number of carpogonial branch cells and arrangement of tetrasporangia. Most systematic studies of Polysiphonia have had a physiological, karyological, morphological, or reproductive basis, but very few have explored molecular characters. In this study, relationships among North Carolina Polysiphonia species were investigated using an integrated taxonomic approach. Thirty-one Polysiphonia samples were collected from various coastal and offshore environments. Analyses of rbcL were used to objectively delimit species collected in North Carolina and the consistency of 22 morphological characters used to identify Polysiphonia species was examined within eight molecularly defined species clades. Phylogenetically informative morphological characters for North Carolina Polysiphonia species included the number of pericentral cells, rhizoid-pericentral cell connection, relationship of lateral branches to trichoblasts, spermatangial axes development, and arrangement of tetrasporangia. The molecular and morphological analyses were used to identify eight North Carolina species, which were found to represent Neosiphonia harveyi, Polysiphonia atlantica, P. breviarticulata, P. denudata sensu Kapraun, P. fucoides, P. scopulorum var. villum, P. subtilissima, and P. urceolata sensu Kapraun. Both rbcL and SSU analyses were used to determine the relationship of North Carolina Polysiphonia species to those collected elsewhere, and these analyses resolved four major clades within Polysiphonia sensu lato. The character states of characters found to be consistent within species were mapped on the rbcL and SSU trees to determine if there were phylogenetically informative morphological characters for the different molecularly defined clades. The clade containing the generitype, P. stricta, was supported by seven morphological characters considered to be taxonomically significant. Two of the resolved major clades had little morphological support, but these clades are probably comprised of heterogeneous mixtures of distinct species whose relationships could not be confidently resolved based upon the limited number of taxa investigated.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
Language: English
Date: 2009
Keywords
Ceramiales--North Carolina--Classification, Polysiphonia--North Carolina--Classification, Red algae--North Carolina--Classification
Subjects
Ceramiales -- North Carolina -- Classification
Polysiphonia -- North Carolina -- Classification
Red algae -- North Carolina -- Classification