INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
Species of Coscinodiscus (Bacillariophyta) from the Gulf of Mexico, Argentina and Antarctic waters: morphology and distribution
FERRARIO, M.E.; LICEA, S.; ALMANDOZ, G.; GARIBOTTI, I.A.
Nova Hedwigia Beihefte, Beiheft
Lugar: Berlin-Stuttgart; Año: 2008 vol. 133 p. 187 - 216
In order to study the morphology and distribution of the Coscinodiscus species, we documented a great number of surface water samples from the Argentinean continental shelf and Antarctica and, in lesser quantities, from the Gulf of Mexico. The greater number of samples was obtained on oceanographic cruises aboard the Argentinean icebreakers A.R.A. Almirante Irizar and A.R.A. Puerto Deseado, within the framework of ARGAU and GEF-Patagonia projects, respectively. Nine species were described by means of light and electron microscopy. Information on their characteristics has been supplemented with environmental data (temperature and salinity). The nine species analyzed, C. alboranii, C. asteromphalus, C. bouvet, C. granii, C. janischii, C. jonesianus var. commutata, C. oculoides, C. radiatus and C. wailesii, present valves with locular areolae, except C. alboranii and C. janischii which have both locular and poroid areolae in the same valve. If we consider one other character discussed in this paper, the pattern of microlabiate processes, we see that all species documented have just one ring of processes on the valves margin, while C. wailesii presents two rings. Another morphological difference among the species is the external projection of the macrolabiate processes (less evident in the microlabiate) which characterizes C. jonesianus var. commutata. In addition, we are submitting details of the girdle on C. janischii which, as far as we can ascertain, have not been included in previous investigations of the species. Most of the Coscinodiscus species discussed in this study have been reported in wide geographic distribution. C. bouvet and C. oculoides have been only found in Antarctic waters and C. alboranii in warm water regions. It is to be noted that of the nine species, only C. wailesii has been found worldwide as an immigrant species and producing harmful events.