COCCONEIS COSTATA VAR. SUBANTARCTICA VAR. NOV., A NEW MARINE DIATOM OFF KERGUELEN ARCHIPELAGO (SOUTHERN OCEAN, INDIAN SECTOR)

Cocconeis costata var. subantarctica var. no v., a rare taxon from the Kerguelen Archipelago (Southern Ocean, Indian sector), is described using light and scanning electron microscope observations and was compared to related taxa. Apart from the wide-elliptical central area devoid of striae, the raphe valve features highly resemble those of the C. costata complex: the open crista marginalis is similar to the one occurring in other varieties of C. costata, whereas the slightly dissymmetric and hook-like central raphe endings are a distinctive feature. This Subantarctic diatom has a two-layered sternum valve, with alveolate striae consisting of elongated chambers internally open through marginal elliptical wide and regular foramina. On the external side, striae of the sternum valve vary from biseriate to triseriate near the margin, and are not restricted to the foramina location. The resemblance of our new taxon with C. costata var. paciflca and C. barleyi, which also possess more or less extended SV chambers, is discussed. The epizoic diatom genera Bennettella and Epipellis, previously assigned to the genus Cocconeis Ehrenberg, also show such alveolate-chambered striae, but are associated with several other very specific features. Several small sized Cocconeis taxa from Antarctic and Subantarctic environments, such as C. costata var. antarctica and C. melchiori, show a certain morphological similarity to Cocconeis costata var. subantarctica var. nov., but they have marginal short striae on the sternum valve and lack a two-layered sternum valve or chambers.

[1]  A. Wulff,et al.  TWO NEW MARINE SPECIES OF THE DIATOM GENUS COCCONEIS EHRENBERG: C. MELCHIOROIDES SP. NOV. AND C. DALLMANNII SP. NOV., FROM KING GEORGE ISLAND, ANTARCTICA , 2008 .

[2]  M. D. Stefano,et al.  A comparative study of Cocconeis scutellum Ehrenberg and its varieties (Bacillariophyta) , 2008 .

[3]  A. Witkowski,et al.  COCCONEIS GERMAINII SP. NOV. AND A RELATED TAXON FROM KERGUELEN ARCHIPELAGO (AUSTRAL OCEAN, INDIAN SECTOR) , 2007 .

[4]  O. Romero,et al.  A survey of alveolate species of the diatom genus Coccineis (Ehr.) with remarks on the new section Alveolatae , 2005 .

[5]  C. Riaux-Gobin,et al.  TWO MARINE COCCONEID DIATOMS FROM KERGUELEN'S LAND (AUSTRAL OCEAN, INDIAN SECTOR): CAVINULA KERGUELENSIS NOM. NOV. AND COCCONEIOPSIS WRIGHTII , 2004 .

[6]  M. de Stefano,et al.  Morphology and taxonomy of Amphicocconeis gen. nov. (Achnanthales, Bacillariophyceae, Bacillariophyta) with considerations on its relationship to other monoraphid diatom genera , 2003 .

[7]  C. Riaux-Gobin,et al.  Marine Cocconeis Ehrenberg (Bacillariophyceae) - species and related taxa from Kerguelen's Land (Austral - Ocean, Indian Sector) - , 2003 .

[8]  O. Romero,et al.  COCCONEIS EHRENBERG AND PSAMMOCOCCONEIS GARCIA (BACILLARIOPHYTA) FROM THE GULF OF SAN MATÍAS, PATAGONIA, ARGENTINA , 2003 .

[9]  K. Sabbe Diatom flora of marine coasts I. , 2002 .

[10]  M. Garcia PSAMMOCOCCONEIS, A NEW GENUS OF BACILLARIOPHYTA FROM BRAZILIAN SANDY BEACHES , 2001 .

[11]  J. Tanaka,et al.  Morphology of the marine epiphytic diatom Cocconeis heteroidea (Bacillariophyceae) , 2001 .

[12]  J. Tanaka,et al.  A new marine diatom, Cocconeis shikinensis sp. nov. (Bacillariophyceae) from Japan , 2001 .

[13]  J. Tanaka,et al.  MORPHOLOGY OF THE MARINE DIATOM COCCONEIS PSEUDOMARGINATA GREGORY VAR. INTERMEDIA GRUNOW , 2001 .

[14]  M. de Stefano,et al.  Marine taxa of Cocconeis on leaves of Posidonia oceanica, including a new species and two new varieties , 2000 .

[15]  H. LANGE-BERTALOT,et al.  Diatom flora of marine coasts I , 2000 .

[16]  James G. Richman,et al.  Location and dynamics of the Antarctic Polar Front from satellite sea surface temperature data , 1999 .

[17]  M. Fieux,et al.  Thermohaline structure of the Antarctic Surface Water/Winter Water in the Indian sector of the Southern Ocean , 1998 .

[18]  O. Romero,et al.  MORPHOLOGY AND TAXONOMY OF THREE VARIETIES OF COCCONEIS COSTATA AND C. PINNATA (BACILLARIOPHYCEAE) WITH CONSIDERATIONS OF PLEURONEIS , 1996 .

[19]  P. Compère,et al.  OBSERVATIONS SUR LE POLYMORPHISME DE COCCONEIS CALIFORNICA GRUNOW, AUX ÎLES KERGUELEN , 1996 .

[20]  Young‐Hyang Park,et al.  Frontal structure, water masses, and circulation in the Crozet Basin , 1993 .

[21]  David G. Mann,et al.  Diatoms: Biology and Morphology of the Genera , 1990 .

[22]  R. Holmes The morphology of diatoms epizoic on cetaceans and their transfer from Cocconeis to two new genera, Bennettella and Epipellis , 1985 .

[23]  F. E. Round,et al.  Variability in the structure of the genus Cocconeis Ehr. (Bacillariophyta ) with special reference to the cingulum , 1982 .

[24]  D. Mann Sieves and flaps : siliceous minutiae in the pores of raphid diatoms , 1981 .

[25]  D. Wujek,et al.  Catalog of the Fossil and Recent Genera and Species of Diatoms and Their Synonyms , 1968 .

[26]  J. Frenguelli,et al.  Diatomeas y silicoflagelados del sector antártico sudamericano , 1958 .

[27]  S. L. Vanlandingham,et al.  Catalogue of the fossil and recent genera and species of diatoms and their synonyms : a revision of F.W. Mills' "An index to the genera and species of the Diatomaceae and their synonyms" , 1934 .

[28]  H. V. Heurck Synopsis des Diatomées de Belgique , 1885 .