This chapter provides an introductory biology of marine diatoms, their classification, heteromorphy, evolution, and critical evaluation. It consists of sections on classification as well as generic atlas. A diatom system is based on results from light and electron microscopy and constructed key to the diatom families. Diatoms reproduce vegetatively by binary fission resulting in formation of two new individuals within the parent cell frustule. The probable size range of the diatom cells are species dependent, and the specific variation may be as large as 8–10 times the length of the apical axis or the diameter. Despite the availability of other publications, there is still a need to fill the gap with respect to the global aspect, especially when identifying Marine diatoms at the specific level. The entire discussion aims to meet the morphological need of new diatom information as well as the classical identification literature. This comprehensive volume explores the two Polar Regions and has an ecological interpretation as well as a taxonomic part with the key to the study of marine diatom species. General characteristics of marine diatoms together with their life cycles have also been discussed.

Chapter 2 – Marine Diatoms

Catalogue of the diatom genera

Phytoplankton invasions: comments on the validity of categorizing the non-indigenous dinoflagellates and diatoms in European seas

Strata in the Canadian Arctic contain diverse and moderately well-preserved Late Cretaceous siliceous microfossil as- semblages. One-hundred-twelve samples were analyzed from a composite stratigraphic section (1094m-thick) of the Smoking Hills, Mason River and Kanguk formations. Four sections were examined: (1) Slidre Fjord on Ellesmere Island; (2) Hoodoo Dome on Ellef Ringnes Island; (3) Cape Nares on Eglinton Island; and (4) Horton River on the Anderson Plains, Northwest Territories. Two hun- dred-three diatom taxa were identified in forty-nine productive samples. Four Upper Cretaceous diatom zones are proposed for the Ca- nadian Arctic based on the biostratigraphic distribution of diatoms: (i) the Upper Cenomanian to Upper Santonian(?) Gladius antiquus Concurrent Range Zone, (ii) the Lower Campanian Costopyxis antiqua Partial Range Zone, (iii) the lower Upper Campanian Trinacria indefinita Interval Zone, and (iv) the upper Upper Campanian Stephanopyxis simonseni Partial Range Zone. The diatom assemblages are similar to those of Alpha Ridge (Arctic Ocean), Ural Mountains (Russia), and Campbell Plateau (SW Pacific Ocean), enabling diatom-based biostratigraphical correlations within the northern high-latitudes and to the southern high-latitudes. A fifth biostratigraphic zone, Azpeitiopsis morenoensis Concurrent Range Zone, is also proposed, based on common and widespread distribution of the nominative taxon in lower to upper Maastrichtian sediments. Sufficient data is now available to establish the construction of a diatom-based standard zonal framework for the Upper Cretaceous. Two new combinations, Trochosira denticulatum (Strelnikova) Tapia and Trochosiropsis polychaeta (Strelnikova) Tapia are here proposed.

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Upper Cretaceous diatom biostratigraphy of the Arctic archipelago and northern continental margin, Canada

The ocellate and pseudocellate diatoms in the Eupodiscaceae and Biddulphiaceae (respectively) are common inhabitants of the marine littoral (and plankton zone) with a rich fossil history making them important components of marine stratigraphic studies and good candidates for molecular dating work These diatoms are important for un-derstanding the phylogeny of the diatoms as a whole, as molecular phylogenies have blurred the traditional distinction between the pennate and multipolar non-pennate diatoms However, the convoluted taxonomic history of these groups has the potential to disrupt both stratigraphic and molecular dating studies Although efforts have been made to examine frustule morphology of several ocellate and pseudocellate diatoms and develop a morphological scheme to define genera, very little work has been done to determine how these groups are interrelated In this study, we use nuclear and chloroplast molecular markers to construct a phylogeny of a diverse sampling of Eupodiscaceae and Biddulphiaceae taxa The ocellus-bearing taxa (Eupodiscaceae) are monophyletic, and thus the ocellus may be a useful character in delimiting the Eupodiscaceae, the Biddulphiaceae are polyphyletic and scattered across a number of lineages of multipolar non-pennate diatoms Hypothesis testing aimed at assessing the likeliness of several morphology based hypotheses against the molecular data highlights uncertainty in both types of data We present evidence that there are monophyletic genera within both the Biddulphiaceae and Eupodiscaceae, and recommend the taxa within the Odontella mobilensis/sinensis/regia clade be transferred to a new genus: Trieres Ashworth & Theriot

R. K. Greville

Papers

Descriptions of New and Rare Diatoms. Series XX