Amoebozoa Research Articles (Page 1)

Arcellinida are free-living lobose amoebae that produce an outer shell (test). Here, we describe a conspicuous new species, Arcella gandalfi sp. nov, from Brazilian continental waters, along with a morphological and biometrical characterization. Test diameter and test height are on average 81 and 71 respectively. This new species has an apical conical extension, which differentiates it from other Arcella species. A. gandalfi seems to be closely-related to A. brasiliensis, due to the distinct marginal ring (test brim) present only in these two species. Since A. gandalfi is easily identified by morphological features and due to its apparent geographic restriction to South America, we discuss its possible use as a new flagship species.

We describe a new protosteloid amoeba, Luapeleamoeba hula. Protosteloid amoebae, sometimes called protostelids, are sporocarpic amoebae that make fruiting bodies that consist of a stalk and one to a few spores. This new taxon was cultured from dead leaves of mamaki (Pipturus albidus) from the Manuka Natural Area Reserve, Hawaii, USA. Light microscopic examination showed that this amoeba has a short, rigid stalk with a small apophysis and a spore that changes shape continuously until it is shed and crawls away from the stalk. In addition, this amoeba was initially observed to maintain a diurnal rhythm in which fruiting body formation occurred primarily in the late afternoon. This new species is unique in both its amoebal and fruiting body morphology. Spore deciduousness appears to be a result of shape changes in the spore itself. This is the fourth species of protosteloid amoeba described with a clearly described diurnal rhythm. In addition, previous molecular phylogenetic analyses suggested that this new species has SSU rRNA gene sequences that clearly separate it from any other protosteloid amoebae and place it as sister to Protacanthamoeba bohemica among the Acanthamoebidae family in Centramoebida of Amoebozoa. Because this new amoeba species does not fit into any of the centramoebid genera, we have proposed a new genus Luapeleamoeba.

Some amoebae were recovered from freshwater samples on agar plates. Due to a fungal contamination tightly associated with these amoebae, it was impossible to correctly characterize them on a morphological base, but sequences of the small subunit ribosomal RNA gene (SSU rDNA) were successfully obtained from three strains. Phylogenetic analysis performed on these SSU rDNA allowed to identify these amoebae as members of a new lineage, related to the Dermamoebida, which includes also several other environmental SSU sequences.

In order to study the diversity of eukarytic nanoplankton in the sea area for scallop culture,and clarify the relationship between eukaryotic nanoplankton and transmission of zhikong scallop(Chlamys farreri)acute viral necrosis virus(AVNV),seawater samples were collected monthly in 2009 and 2010 from Qingdao Liuqing River Bay's sea area.3-25 μm plankton components were filtered and amplified 18S rDNA variable region sequences from filtered samples were analyzed by DGGE technique.The results show that the main eukaryotic nanoplankton in the sea area included Dinozoa,Ciliophora,Euglenozoa,Haptophyta,Ochrophyta,Labyrinthulomycota,Cryptista,Choanozoa,Amoebozoa and Cercozoan.The amount of Dinozoa and Ciliophora was the highest at 41% and 38.2%,respectively.The cluster analysis based on mensal DGGE bands shows that the plankton community from May to November 2009 is similar in the diversity of eukarytic nanoplankton.According to the studied results on scallop AVNV,Skeletonema costatum was taken to be a vector of transmission of AVNV,and it distributed during the period of scallop massive death.However,the role of Dinozoa and Ciliophora during the transmission of AVNV has yet to be determined.

Five amoeba strains isolated from organs of fish were selected by morphology as possible members of the genus Vexillifera Schaeffer, 1926. Phylogenetic analyses of SSU rDNA sequences revealed that four of these strains form a best supported clade together with Vexillifera minutissima (strain CCAP 1590/3) and V. bacillipedes (sequence of the type culture was newly generated in this study). Comparison of trophozoite morphology and SSU rDNA sequences identified one of the five fish-isolated strains as closely related to V. bacillipedes, and characteristics of another three strains allowed to establish three new species: Vexillifera multispinosa, V. fluvialis and V. tasmaniana. The enlargement of dataset of Vexillifera SSU rDNA sequences enables us to doubt the identification of ATCC strain 50883 designated as V. armata. Since sequence of this strain branched in our analysis in a distant phylogenetic position within Korotnevela and Neoparamoeba clade, the Vexillifera origin of this sequence is called in question. The same applies to the newly generated sequence of the type strain of V. expectata, previously characterised by its morphology only.

The purpose of this study is to provide a checklist and a synthesis of the geographic distribution of the species within Centropyxidae, Trigonopyxidae and Plagiopyxidae (Protozoa, Amoebozoa, Rhizopoda). A total of 24 infra-generic taxa were listed, of which 15 belong to the genus Centropyxis , 5 to Cyclopyxis , 2 to Bullinularia , 1 to Hoogenraadia and 1 to Trigonopyxis . Some taxonomic information is also provided. Centropyxis aculeata, C. constricta and C. marsupiformis presented widespread distribution in the freshwater environments in Brazil

The purpose of this paper is to increase the knowledge on testate amoebae in Brazilian inland waters, specifically the family Arcellidae (Protozoa, Amoebozoa, Rhizopoda). In this paper the current occurrence and geographical distribution of this family in Brazil is discussed. A total of 26 infra-generic taxa was recorded, among them 24 taxa belong to the genus Arcella and 2 to Pyxidicula. Arcella vulgaris Ehrenberg, A. gibbosa Penard, A. megastoma Penard, A. dentata Ehrenberg, A. discoides Ehrenberg, A. brasiliensis Cunha and A. crenulata Deflandre were the species with greater number of records. Some taxonomic information is also provided

(1960). Taxonomic Position of the Eccrinales and Related Fungi. Mycologia: Vol. 52, No. 3, pp. 410-428.