Taxonomic problems

In general, division of the Baltic into districts follows the recommendation of the BMB WG21 as published in Nielsen et al. (1995), but for presentation in Section 16.3, these districts were grouped. 

Probably the most comprehensive recent survey of macrophytobenthos species of the Baltic Sea was published by Nielsen et al. (1995). In this survey, 422 species of macroalgae living in the Baltic Sea are listed. However, no such comprehensive survey exists about the aquatic higher plants that are the dominant component in areas with low salinity. 

Comparison between the earlier surveys listed above and the recent one by Nielsen et al. (1995) is hampered by two facts first, problems in the definition of the term macroalgae and second, problems in taxonomy. 

Since the workof Lakowitz (1929), listing more than 40 endemic species, the discussion whether or not special morphological and physiological feamres of Baltic algae allow delineation of endemic Baltic species or not is a still hot topic. 

However, in the discussion Russell (1985) put his findings in the context of the knowledge about physiological dines in macroalgae in general (e.g., Bolton, 1979, 1983 Sheath and Cole, 1984) and came to the conclusion that the observed shift in salinity tolerance is clinal in character as well. On a broader point of view, he doubts the existence of endemic Baltic species in general because 

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Icacinaceae are a moderate-sized, primarily tropical family consisting of 52 genera, many of which are monotypic, and 300 species. Additional background on taxonomic problems surrounding the family can be found in the 1991 paper by Kaplan et al. Chemical data have been used by Dahlgren (1980) to assess these relationships with related families, but the application involved simple presence or absence data (iridoids) and did not touch upon the dynamic nature of the pathways involved. 

R. Fisher, The use of multiple measurements in taxonomic problems. Annals of Eugenics, 7 (1936) 179-188. 

Several papers on the taxonomy of the Ranunculaceae have been published.2-8 These clarify some of the nomenclatural and taxonomic problems of this Family, particularly of those species found in the eastern and south-eastern United States. 

Bryozoans are sedentary, colonial invertebrates that are widely distributed throughout the marine environment, but are less common in freshwater. There are about 4000 living species and over 10000 as preserved fossils. Marine colonies are generally found on rocky shores in the shallow sublittoral zone although they also occur in the ocean depths [1]. Colonies are often small (typically less than 5 cm), inconspicuous and infrequent. For these reasons and because of the taxonomic problems experienced when working with this phylum, bryozoans are frequently overlooked or ignored. 

Several holothurins are specific for different taxonomic groups of sea cucumbers and structural characteristics of triterpene glycosides have been used to resolve taxonomic problems in the class Holothuroidea [57, 58]. For example, the triterpenoid glycosides distribution has been successfully applied in the reclassification of Stichopus mollis into the genus Australostichopus [59] and in the taxonomy of sea cucumbers belonging to the genus Cucumaria [60]. 

Evans HC, Samson RA, The genus Verticillium taxonomic problems in species with invertebrate hosts. In Samson RA, Vlak JM, Peters D, eds. Fundamental and Applied Aspects of Invertebrate Pathology. Veldhoven, The Netherlands Foundation of the 4th International Colloquium of Invertebrate Pathology, 1986b. 

Questions like these were raised explicitly and systematically in 1812 by Berzelius, and a few years later by the French chemist Michel Eugene Chevreul (we will discuss their approaches later in the chapter). As Berzelius pointed out shortly afterward, a solution for these problems could not be expected from quantitative elemental analysis alone. In their attempts to solve taxonomic problems, both Berzelius and Chevreul pointed to the limits of quantitative elemental analysis and the theoretical underpinnings of the Lavoisierian analytical program for plant and animal chemistry-limits that some twenty years earlier had been invisible. 

The biogeographical patterns we have recognized are presented in Table 13.2. The geographical distributions of the Chamela flora used here were based on critical review of herbarium records and on the recent literature. Only the 1064 species considered native were included in the analysis. We excluded species with unresolved taxonomic problems, species probably new to science but not yet adequately studied, species not determined because of lack of sufiScient material for identification (Daphnopsis sp., Schoepfia sp.), or for lack of other kinds of reliable information. This assured a conservative estimate of the number of endemic species. 

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