Morphological and Molecular Diversity of the Neglected Genus Rhizomastix Alexeieff, 1911 (Amoebozoa: Archamoebae) with Description of Five New Species

Comparative analysis of mitochondrion-related organelles in anaerobic amoebozoans

Archamoebae comprises free-living or endobiotic amoebiform protists that inhabit anaerobic or microaerophilic environments and possess mitochondrion-related organelles (MROs) adapted to function anaerobically. We compared in silico reconstructed MRO proteomes of eight species (six genera) and found that the common ancestor of Archamoebae possessed very few typical components of the protein translocation machinery, electron transport chain and tricarboxylic acid cycle. On the other hand, it contained a sulphate activation pathway and bacterial iron-sulphur (Fe-S) assembly system of MIS-type. The metabolic capacity of the MROs, however, varies markedly within this clade. The glycine cleavage system is widely conserved among Archamoebae, except in Entamoeba, probably owing to its role in catabolic function or one-carbon metabolism. MRO-based pyruvate metabolism was dispensed within subgroups Entamoebidae and Rhizomastixidae, whereas sulphate activation could have been lost in isolated cases of Rhizomastix libera, Mastigamoeba abducta and Endolimax sp. The MIS (Fe-S) assembly system was duplicated in the common ancestor of Mastigamoebidae and Pelomyxidae, and one of the copies took over Fe-S assembly in their MRO. In Entamoebidae and Rhizomastixidae, we hypothesize that Fe-S cluster assembly in both compartments may be facilitated by dual localization of the single system. We could not find evidence for changes in metabolic functions of the MRO in response to changes in habitat; it appears that such environmental drivers do not strongly affect MRO reduction in this group of eukaryotes.

Phylogenetic position of the pelobiont Mastigamoeba aspera and revision of the family Mastigamoebidae (Archamoebae, Pelobiontida)

In this study, we presented the results of our molecular phylogenetic analysis of Archamoebae using a newly obtained sequence of the 18S rRNA gene of Mastigamoeba aspera, the type species of the genus. In addition, we characterized the general organization of the tubulin cytoskeleton of M. aspera by immunofluorescent microscopy and TEM. Our findings allowed us to revise the family Mastigamoebidae and establish within it two subfamilies: Mastigamoebinae for the genus Mastigamoeba and Seraviniinae subfam. nov. for the genera Seravinia gen. nov., Paramastigamoeba gen. nov., Iodamoeba and Endolimax. The type genera Mastigamoeba and Seravinia are clearly distinguished by the structure of the basal apparatus of flagella. In addition, the tubulin cytoskeleton of several Mastigamoeba spp. contains a rim of microtubules around the nuclei.

Ciliary transition zone evolution and the root of the eukaryote tree: implications for opisthokont origin and classification of kingdoms Protozoa, Plantae, and Fungi

I thoroughly discuss ciliary transition zone (TZ) evolution, highlighting many overlooked evolutionarily significant ultrastructural details. I establish fundamental principles of TZ ultrastructure and evolution throughout eukaryotes, inferring unrecognised ancestral TZ patterns for Fungi, opisthokonts, and Corticata (i.e., kingdoms Plantae and Chromista). Typical TZs have a dense transitional plate (TP), with a previously overlooked complex lattice as skeleton. I show most eukaryotes have centriole/TZ junction acorn-V filaments (whose ancestral function was arguably supporting central pair microtubule-nucleating sites; I discuss their role in centriole growth). Uniquely simple malawimonad TZs (without TP, simpler acorn) pinpoint the eukaryote tree's root between them and TP-bearers, highlighting novel superclades. I integrate TZ/ciliary evolution with the best multiprotein trees, naming newly recognised major eukaryote clades and revise megaclassification of basal kingdom Protozoa. Recent discovery of non-photosynthetic phagotrophic flagellates with genome-free plastids (Rhodelphis), the sister group to phylum Rhodophyta (red algae), illuminates plant and chromist early evolution. I show previously overlooked marked similarities in cell ultrastructure between Rhodelphis and Picomonas, formerly considered an early diverging chromist. In both a nonagonal tube lies between their TP and an annular septum surrounding their 9+2 ciliary axoneme. Mitochondrial dense condensations and mitochondrion-linked smooth endomembrane cytoplasmic partitioning cisternae further support grouping Picomonadea and Rhodelphea as new plant phylum Pararhoda. As Pararhoda/Rhodophyta form a robust clade on site-heterogeneous multiprotein trees, I group Pararhoda and Rhodophyta as new infrakingdom Rhodaria of Plantae within subkingdom Biliphyta, which also includes Glaucophyta with fundamentally similar TZ, uniquely in eukaryotes. I explain how biliphyte TZs generated viridiplant stellate-structures.

Ultrastructure and Molecular Phylogeny of Iotanema spirale gen. nov. et sp. nov., a New Lineage of Endobiotic Fornicata with Strikingly Simplified Ultrastructure

Fornicata (Metamonada) is a group of Excavata living in low-oxygen environments and lacking conventional mitochondria. It includes free-living Carpediemonas-like organisms from marine habitats and predominantly parasitic/commensal retortamonads and diplomonads. Current modest knowledge of biodiversity of Fornicata limits our ability to draw a complete picture of the evolutionary history in this group. Here, we report the discovery of a novel fornicate, Iotanema spirale gen. nov. et sp. nov., obtained from fresh feces of the gecko Phelsuma madagascariensis. Our phylogenetic analyses of the small subunit ribosomal RNA gene demonstrate that I. spirale is closely related to the free-living, marine strain PCS and the Carpediemonas-like organism Hicanonectes teleskopos within Fornicata. Iotanema spirale exhibits several features uncommon to fornicates, such as a single flagellum, a highly reduced cytoskeletal system, and the lack of the excavate ventral groove, but shares these characters with the poorly known genus Caviomonas. Therefore, I. spirale is accommodated within the family Caviomonadidae, which represents the third known endobiotic lineage of Fornicata. This study improves our understanding of character evolution within Fornicata when placed within the molecular phylogenetic context.

Immature stages of giants: morphology and growth characteristics of Goliathus Lamarck, 1801 larvae indicate a predatory way of life (Coleoptera, Scarabaeidae, Cetoniinae)

The third larval instar of Goliathusgoliatus (Drury, 1770), Goliathusorientalis Moser, 1909 and Goliathusalbosignatus Boheman, 1857 are described and illustrated for the first time and compared with the immature stages of other Cetoniinae. Larval development of Goliathusgoliatus is investigated under laboratory conditions, with particular emphasis on food requirements. These results support the obligatory requirement of proteins in the larval diet. The association between larval morphological traits (e. g., the shape of the mandibles and pretarsus, presence of well-developed stemmata) and larval biology is discussed. Based on observations and the data from captive breeds it is concluded that a possible shift from pure saprophagy to an obligatory predaceous way of larval life occurred within the larvae of this genus, which may explain why these beetles achieve such an enormous size.

First multigene analysis of Archamoebae (Amoebozoa: Conosa) robustly reveals its phylogeny and shows that Entamoebidae represents a deep lineage of the group

Archamoebae is an understudied group of anaerobic free-living or endobiotic protists that constitutes the major anaerobic lineage of the supergroup Amoebozoa. Hitherto, the phylogeny of Archamoebae was based solely on SSU rRNA and actin genes, which did not resolve relationships among the main lineages of the group. Because of this uncertainty, several different scenarios had been proposed for the phylogeny of the Archamoebae. In this study, we present the first multigene phylogenetic analysis that includes members of Pelomyxidae, and Rhizomastixidae. The analysis clearly shows that Mastigamoebidae, Pelomyxidae and Rhizomastixidae form a clade of mostly free-living, amoeboid flagellates, here called Pelobiontida. The predominantly endobiotic and aflagellated Entamoebidae represents a separate, deep-branching lineage, Entamoebida. Therefore, two unique evolutionary events, horizontal transfer of the nitrogen fixation system from bacteria and transfer of the sulfate activation pathway to mitochondrial derivatives, predate the radiation of recent lineages of Archamoebae. The endobiotic lifestyle has arisen at least three times independently during the evolution of the group. We also present new ultrastructural data that clarifies the primary divergence among the family Mastigamoebidae which had previously been inferred from phylogenetic analyses based on SSU rDNA.