Akshinthala K.S.K. Prasad

The centric diatom genus Cyclotella, (Stephanodiscaceae: Bacillariophyta) from Florida Bay, USA, with special reference to Cyclotella choctawhatcheeana and Cyclotella desikacharyi, a new marine species related to the Cyclotella striata complex†

A.K.S.K. Prasad and J.A. Nienow. 2006. The centric diatom genus Cyclotella, (Stephanodiscaceae: Bacillariophyta) from Florida Bay, USA, with special reference to Cyclotella choctawhatcheeana and Cyclotella desikacharyi, a new marine species related to the Cyclotella striata complex. Phycologia 45: 127–140. DOI: 10.2216/05-13.1 A new marine species of the centric diatoms of the genus Cyclotella, Cyclotella desikacharyi A.K.S.K. Prasad collected from several localities in Florida Bay, USA, where it is a dominant part of the planktonic assemblage, is described by means of light and scanning electron microscopy. Cyclotella desikacharyi is characterized by the presence of dense striae (14–19 in 10 µm) in the marginal zone and small granules all through the surface of the valve, including the central area, fultoportulae on the valve mantle located on every second or third interstria, each surrounded by three satellite pores, a pronounced tangential undulation, 3–17 valve-face fultoportulae in an arc on the uplift of the undulation and numerous discoid plastids. The new species is compared with Cyclotella striata complex; C. desikacharyi closely resembles C. striata in valve dimensions and in the structure and arrangement of alveolate striae, and in the presence of three satellite pores surrounding each fultoportula on the valve mantle; it differs from it in the stria density and the presence of siliceous granules on the entire valve surface. The new species is compared with the other closely related marine members of the genus, Cyclotella stylorum and Cyclotella litoralis. Cyclotella choctawhatcheeana Prasad, originally described from the northern Gulf Coast of Florida, is also recorded in several localities in Florida Bay and its global distribution is discussed. The evolution of euryhalinity in the genus Cyclotella is also discussed in brief.

Plicate Species of the Diatom Genus Thalassiosira (Bacillariophyta) from the Atlantic and Gulf Coasts of Southeastern United States, with the Description of T. livingstoniorum sp. nov.

ABSTRACT. Long-term observations of a marine planktonic plicate Thalassiosira species, T. cedarkeyensis Prasad, from the Gulf coasts of Florida, Alabama, and Mississippi and the Atlantic coasts of Florida and Georgia demonstrate its wide occurrence in the southeastern United States and its ability to form extensive blooms. We also report for the first time its ability to form typical Thalassiosira chains, linking sibling cells by threads of chitin. A closely related and co-occurring diatom, T. livingstoniorum, is described on the basis of investigations conducted during 2000–2011 as a new species from many localities in Apalachee Bay on the Gulf coast and Indian River Lagoon on the Atlantic coast of Florida. It differs from T. cedarkeyensis in areola density, presence of continuous cribra on loculate areolae, arrangement and distribution of valve processes, and the number of satellite pores surrounding the valve-face fultoportulae. We have not yet found any evidence of chain formation in T. livingstoniorum. Thalassiosira cedarkeyensis and T. livingstoniorum can be easily distinguished in Naphrax-mounted preparations in light microscopy (LM), and they represent two different groups (lineages?) of plicate species with reference to internal cribrum structure of the loculate areolae. Their differences may justify placement in two different genera. Although T. cedarkeyensis (which has individual cribra on the proximal siliceous layer like T. hyperborea) is abundant and widespread on the Gulf and Atlantic coasts of the southeastern United States, T. livingstoniorum (which has continuous cribra like T. lacustris) has been found, thus far, only in Florida coastal waters. Comparisons are made between these two species and the other morphologically similar extant and extinct plicate species. Thalassiosira livingstoniorum and T. cedarkeyensis, although widespread and frequently encountered during warmer months, may be easily overlooked sources of primary production in the nutrient-rich northeastern Gulf of Mexico.

Livingstonia (Thalassiosirales, Bacillariophyta), a new genus of fultoportulate centric diatoms from an Atlantic coastal plain river in Florida, southeastern United States

Prasad A.K.S.K and Nienow J.A. 2011. Livingstonia (Thalassiosirales, Bacillariophyta), a new genus of fultoportulate centric diatoms from an Atlantic coastal plain river in Florida, southeastern United States. Phycologia 50: 264–280. DOI: 10.2216/09-89.1 A morphological and taxonomic account of Livingstonia palatkaensis, a new genus and species of centric diatoms belonging to the order Thalassiosirales Glezer & Makarova, is provided. Descriptions are based on material collected from the St. Johns River, a major, highly colored blackwater river in the Atlantic coastal plain in the southeastern United States. Scanning electron microscopic observations clearly show that although the valve structure in Livingstonia shares broad similarities with the genera Thalassiosira and Skeletonema, the types of the two fultoportulate families Thalassiosiraceae and Skeletonemataceae, respectively, it is sufficiently dissimilar to warrant the description of a new genus. Livingstonia is characterized by the presence of compound marginal processes, each formed from the external extension of a fultoportula and a semielliptical hyaline hood or cover. The areolae have semicontinuous internal cribra. A single rimoportula is present near the valve center. No fultoportulae are found at or near the center of the valve face. Furthermore, Livingstonia lacks connecting threads of marginal fultoportulae and an external extension of the rimoportula on the valve face, a combination of features that is unusual in the genus Skeletonema. Livingstonia is also distinguished from two recently described freshwater genera in the Thalassiosiraceae from the southeastern United States, Cyclotubicoalitus and Spicaticribra, in having a rimoportula away from the margin but close to the center of the valve and in other key characteristics. A note on another freshwater, co-occurring, more frequent and widespread, chain-forming, closely related diatom, Skeletonema potamas, is also included. Livingstonia is tentatively placed in the family Thalassiosiraceae.

RIMOPORTULAE IN EUPODISCUS RADIATUS (BACILLARIOPHYCEAE) FROM THE NORTHEASTERN GULF OF MEXICO1

Specimens of Eupodiscus radiatus Bailey from the northeastern Gulf of Mexico were examined with light and scanning electron microscopy. In contrast to previous studies of this taxon, we report the presence of two, rarely one, rimoportulae (labiate processes) between consecutive ocelli. This finding changes our understanding of the phylogenetic relationships in the family Eupodiscaceae.

The International Phycological Society Secretaries: the first fifty years

As clarified by Silva & Papenfuss (1981) and Wynne & Woelkerling (2001) in their excellent accounts of the first 20 years and 40 years, respectively, of the International Phycological Society (IPS), the roots of the Society go back to the mid-1950s, though the official founding occurred on 1 January 1961. The last half century has witnessed a remarkable development in the field of phycology. Our Society has been full participant in these developments. Many distinguished phycologists with diverse research backgrounds have come together under its auspices to work for the growth and development of the Society and to promote phycology and international cooperation among phycologists and phycological institutes. This article conveys our congratulations to all members of the IPS for an outstanding half century of progress. The spirit shown by the members during the first 50 years augurs well for additional significant activities in the next 50. In celebration of a half century of successful organization of the IPS, it is healthy and appropriate to acknowledge and appreciate the unconditional services of the secretaries of the society. A total of 14 secretaries, elected by the membership, have rendered their services to ensure the efficient governance of the Society over the past 50 years. This article is intended to honor each of them with a brief biographical sketch. The brief biographic information is provided in the format established previously by Wynne & Woelkerling (2001, 2011) in articles honoring past IPS Presidents.The same format has been adopted by Chapman (2011) for his article on the Society’s Treasurers. Of the 14 secretaries, three have also had the distinction of serving as IPS Presidents in the later years, including Richard Norris (1976–1979), Carolyn J. Bird (1998–1999) and M. Dennis Hanisak (2004–2005). In an effort to save space and avoid repetition, the reader is referred to the biographic information provided previously [see Wynne & Woelkerling (2001) for R. E. Norris and C. J. Bird and Wynne & Woelkerling (2011) for M.D. Hanisak]. New or different photos are included here. This compilation would not have been possible without the timely help from a number of people who kindly provided biographic information and appropriate photos for the anniversary issue. I owe my sincere appreciation and thanks to Robert A. Andersen, Carolyn J. Bird, Anthony R.O. Chapman, Richard E. Norris, Robert F. Scagel, Richard B. Searles, John A. West, Suzanne Fredericq (all former IPS secretaries), Candice Bjur, Adam Bonner, Juliet Brodie, William Farnham, Robert Fletcher, Michael D. Guiry, Chris A. Maggs and James A. Nienow. I would like to extend my especial thanks to John J. Bolton, Russell L. Chapman, M. Dennis Hanisak, Alan J. K. Millar, Makoto M. Watanabe, William J. Woelkerling and Michael. J. Wynne for their enthusiastic support and encouragement and for their extreme patience and understanding. I would also like to acknowledge with thanks, the timely gift of the IPS records of our first secretary, Joséphine Th. Koster, held at Rijks Herbarium, arranged through the courtesy of Willem Prud’homme van Reine. I would also like to express my sincere thanks and admiration to Paul C. Silva for being a constant source of inspiration to me for more than three decades. I would like to acknowledge the timely advice and help from staff members of Allen Press (Kansas), especially, Peter Burns, Jeff Mercer, Kay Rose and Alaina Webster throughout my term as IPS Secretary.

The first fifty years of the International Phycological Society: The Organizing Committee, Executive Councils/Boards of Directors, ad hoc Committees, Editorial offices, International Phycological Congresses

This article is based on the current edition of the Board of Directors operating manual [updated and revised by the current International Phycological Society (IPS) Secretary, A. K. S. K. Prasad 2011]. The IPS Executive Council Operations Manual was prepared mainly by the Society Officers of 1998–1999, for first distribution in March 2000. Since then, it was revised and updated by then Society Officers in 2003, 2005, 2009 and 2011. The Manual is intended as a guide for Board members and Officers and is subject to periodic revision and update to incorporate future decisions of the Board and further information based on suggestions from Board members. When the IPS was incorporated as a nonprofit organization in California (on 17 July 2007), the revised Bylaws of the society were adopted by the IPS membership. As per the new Bylaws (Article XVI), the Executive Council was renamed the ‘Board of Directors’ and the council members became ‘ordinary directors’.