Diplonemids were recently found to be the most species-rich group of marine planktonic protists. Based on phylogenetic analysis of 18S rRNA gene sequences and morphological observations, we report the description of new members of the genus Rhynchopus - R. humris sp. n. and R. serpens sp. n., and the establishment of two new genera - Lacrimia gen. n. and Sulcionema gen. n., represented by L. lanifica sp. n. and S. specki sp. n., respectively. In addition, we describe the organism formerly designated as Diplonema sp. 2 (ATCC 50224) as Flectonema neradi gen. n., sp. n. The newly described diplonemids share a common set of traits. Cells are sac-like but variable in shape and size, highly metabolic, and surrounded by a naked cell membrane, which is supported by a tightly packed corset of microtubules. They carry a single highly reticulated peripheral mitochondrion containing a large amount of mitochondrial DNA, with lamellar cristae. The cytopharyngeal complex and flagellar pocket are contiguous and have separate openings. Two parallel flagella are inserted sub-apically into a pronounced flagellar pocket. Rhynchopus species have their flagella concealed in trophic stages and fully developed in swimming stages, while they permanently protrude in all other known diplonemid species.

• MeSH
• Euglenozoa klasifikace   genetika   MeSH
• fylogeneze MeSH
• mitochondriální DNA genetika   MeSH
• RNA ribozomální 18S genetika   MeSH
• sekvenční analýza DNA MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Japonsko MeSH

Until now, Hemistasia phaeocysticola was the only representative of the monogeneric family Hemistasiidae available in culture. Here we describe two new axenized hemistasiids isolated from Tokyo Bay, Japan. Like in other diplonemids, cellular organization of these heterotrophic protists is characterized by a distinct apical papilla, a tubular cytopharynx contiguous with a deep flagellar pocket, and a highly branched mitochondrion with lamellar cristae. Both hemistasiids also bear a prominent digestive vacuole, peripheral lacunae, and paraflagellar rods, are highly motile and exhibit diverse morphologies in culture. We argue that significant differences in molecular phylogenetics and ultrastructure between these new species and H. phaeocysticola are on the generic level. Therefore, we have established two new genera within Hemistasiidae - Artemidia gen. n. and Namystynia gen. n. to accommodate Artemidia motanka, sp. n. and Namystynia karyoxenos, sp. n., respectively. A. motanka permanently carries tubular extrusomes, while in N. karyoxenos, they are present only in starving cells. An additional remarkable feature of the latter species is the presence, in both the cytoplasm and the nucleus, of the endosymbiotic rickettsiid Candidatus Sneabacter namystus.

• MeSH
• Eukaryota * klasifikace   genetika   fyziologie   ultrastruktura   MeSH
• fylogeneze * MeSH
• pohyb MeSH
• zátoky parazitologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Japonsko MeSH