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26 • "PROTIST—2016
sequences, our strains represent five novel species of Creneis. The species morphologically differ from each other as well as from C. carolina; the diagnostic features include the cell size, character of the flagellum, type and arrangement of pseudopodia, and character of the uroid and uroidal adhesive filaments. At least three new species are able to form the fast-swimming "multiflagellate" form, which, however, possesses only four or five flagella. Our results show that Creneis is a widespread and diverse lineage of anaerobic protists. Because six known species (including C. carolina) are represented by only seven strains, its true diversity is certainly much higher.
PREDATORY CAPABILITIES OF THE FILA-STEREAN CAPSASPORA OWCZARZAKI REVEALS ITS POTENTIAL FOR A FREE-LIVING LIFESTYLE
Harcet M.12, Lopez-Escardo D.1, Sebe-Pedros A.13, Ruiz-Trillo I.1-4-5
1 - Multicellgenome lab, Institut de biologia evolutiva (UPF-CSIC) Pssg. de la Barceloneta 37-49. 08003 Barcelona (Spain)
2 - Division of molecular biology, Ruder Boskovic Institute, Bijenicka cesta 54, 10 000Zagreb, Croatia
3 - Department of Computer Science and Applied Mathematics, Weizmann Institute ofScience, Rehovot 76100, Israel
4 - Institucio Catalana de Recerca i Estudis Avancats, Pg Lluis Companys 23, 08010 Barcelona, Spain
5 - Departament de Genetica, Universitat de Barcelona, 08028 Barcelona, Spain matija.harcet@ibe.upf-csic.es
Capsaspora owczarzaki is one of only two known members of Filasterea — a group of protists closely related to animals. Due to its phylogenetic position, complex life cycle, and wide gene repertoire, it has become an important non-model organism in evolutionary studies, especially on the origin of animals. C. owczarzaki was isolated from several strains of freshwater snail Biomphalaria glabrata. However, it remains unclear whether it is an obligate symbiont or it can have a free-living lifestyle. In order to answer this question, we tested the interaction of C. owczarzaki with bacteria (Enterobacter aerogenes), with other unicellular eukaryotes (Dyctiostelium discoideum and Acanthamoeba castellani), and with
B. glabrata embryonic (BGE) cells. The interactions were observed and documented by microscopy. In addition, we followed the growth of C. owczarzaki in the presence of these organisms. We found that
C. owczarzaki is able to grow on a diet consisting
only of bacteria. Furthermore, it efficiently kills and consumes Dictyostelium discoideum and BGE cells, and ingests material from live Acathamoeba castellanii. We performed RNAseq of C. owczarzaki fed by the organisms mentioned before and found distinct expression profiles for each food type. Our results strongly suggest that C. owczarzaki is not an obligate snail symbiont, but rather an opportunistic predatory organism able to feed on a variety of food types. This research increases the knowledge on the diversity of lifestyles among unicellular holozoans, and has implications on our understanding of the origin of animals.
MORPHOLOGY OF TWO SPECIES OF THE THECATE DINOFLAGELLATE GENUS BLE-PHAROCYSTA EHRENBERG (DINOPHYTA) FROM THE TROPICAL MEXICAN PACIFIC Hernández-Becerril David Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México dhernand@cmarl.unam.mx Species ofthe thecate dinoflagellate genus Blepharo-cysta Ehrenberg are usually globose, spherical to ovoid, and lack a depressed cingulum and sulcus, typical of most dinoflagellates. The five recognized Blepharocysta species are truly marine planktonic forms and are mainly distributed in tropical and subtropical areas. During an oceanographic cruise along tropical coasts of the Mexican Pacific, net phytoplankton samples yielded a number oftropical forms of dinoflagellates, including two Blepharocysta species: Blepharocysta paulseni and B. splendor-maris. Both species were studied by LM and SEM and the general morphology previously described in the literature was confirmed, although the theca ornamentation was observed in detail. The cell shape, more ovoid in Blepharocysta splendormaris and more spherical in B. paulseni, the development of sulcal and theca ornamentation lists, with Blepharocysta paulseni having more reduced lists and a higher pores density, appear as the morphological characters separating both species. Additionally, Blepharocysta splendormaris has been found not only in tropical areas, but also in Antarctic waters. These two species (and probably all Blepharocysta species) showed no chloroplasts and are supposedly heterotrophic. Comparison among all species ofthe genus was made, emphasizing the shape and relative size ofthe cells, the development and ornamentation of the sulcal lists, tabulation and ornamentation of the theca, and the general distribution.
