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Single-chambered (monothalamous) foraminifera are poorly known compared to their multichambered relatives. In this first study of monothalamids from Greenland, we describe one new genus and two new species belonging to different clades from the Nuuk fjord system. Nujappikia idaliae Gooday & Holzmann gen. nov. sp. nov. (Clade Y) has a bottle-shaped test terminating in a single aperture located on a short neck. The flexible wall is basically organic but with a very fine agglutinated veneer. Bathyallogromia kalaallita Gooday & Holzmann sp. nov. (Clade C) has a broadly ovate test with an organic wall and a mound-like apertural structure. It is larger and genetically distinct from the two other Bathyallogromia species, both from the Southern Ocean. A survey of the morphological diversity of monothalamids in our samples revealed 49 morphospecies, of which 19, including the two new species, yielded DNA sequences. Five were assigned to the genera Bathysiphon, (Clade BM), Micrometula. (Clade BM), Psammophaga. (Clade E), Hippocrepinella (Clade D) and Crithionina (Clade J). The remaining twelve represented unknown taxa branching in clades A, C, F, and Y and one new clade. Our results add to growing evidence that monothalamids are common and diverse in fjords and other high-latitude settings., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

The foraminiferal order Carterinida is characterized by agglutinated tests consisting of calcareous spicules. Four species have so far been described from the tropical Pacific and the Caribbean Sea. We report here the first occurrence of Carterina from the Southeastern Levantine Shelf of the Mediterranean Sea. Based on molecular and morphological results, we describe Carterina labinea sp. nov., which is characterized by a trochospiral test with a conical, tapered spiral side and a concave umbilical side. The test is composed of elongate fusiform calcareous spicules. Tests have a mean diameter of 720 μm, which is twice the vertical height, and spicules vary in length and width from 112/15 μm to 73/14 μm. Our results show that the genus Carterina extends its distribution beyond tropical Seas and might be more widely distributed than previously thought. Moreover, the appearance of the new species in the study area suggests it is a new colonizer as continuous biomonitoring studies in the area show that it is absent in sediment samples taken before 2020. Our results highlight the importance of ongoing monitoring programs in high-risk basins such as the Levantine to gain more information about the biodiversity changes and improve environmental conservation of Eastern Mediterranean littoral areas progressively colonized by tropical species., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Based on molecular and morphological data, we describe three new genera and four new species of monothalamids from the sublittoral zone (21-250 m) in South Georgia fjords that belong to different monothalamid clades. Limaxia alba gen. nov. sp. nov. (Clade A) has an elongate, subcylindrical test, 359-688 µm long, with some detritus attached to the organic wall. Hilla argentea gen. nov. sp. nov. (Clade Y) has a cylindrical, finely agglutinated test, 535-755 µm long. Pseudoconqueria lenticularis gen. nov. sp. nov. branches separately. It has a spindle-shaped, finely agglutinated test, 280-574 µm long. Bathyallogromia olivacea sp. nov. (Clade C) has an ovate organic-walled test, 369-433 µm long. We present the first genetic data on two monothalamid species originally described from South Georgia, Hippocrepinella alba (Clade C) and Hippocrepinella hirudinea (Clade D), as well as a single sequence for C. delacai (Clade J) originally described from McMurdo Sound, Antarctica. In addition, we report nine undescribed species branching in six different monothalamid clades (A, B, BM, C, J, Y), eight of them sampled around South Georgia and one collected from the Falkland Islands near Stanley., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Non-marine foraminifera are among the least known groups of protists and only a handful of species have been described since the 19th century. We collected one naked and five morphologically almost identical organic-walled monothalamid species from freshwater and terrestrial environments from Germany and Austria. One of the species was identified as Lieberkuehnia wageneriClaparède and Lachmann, 1859. As its original description is ambiguous and its type specimen has been lost, a neotype is proposed. We describe four new organic-walled monothalamous foraminifera and a novel Reticulomyxa species both morphologically and genetically. Analyses of molecular data of the different isolates revealed that they are distributed across six different clades. Two new genera, Claparedellus gen. nov. and Velamentofex gen. nov., and five new monothalamous families, Lacogromiidae fam. nov., Limnogromiidae fam. nov., Lieberkuehniidae fam. nov., Edaphoallogromiidae fam. nov. and Velamentofexidae fam. nov., are established., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

The Clarion-Clipperton Zone (CCZ) occupies a vast swathe of the Pacific with extensive polymetallic nodule deposits. Eastern and central parts host diverse assemblages of xenophyophores (megafaunal agglutinated foraminifera). Here we describe xenophyophores obtained using a Remotely Operated Vehicle from the western CCZ. Eleven distinct forms include two known species, Stannophyllum zonarium Haeckel, 1888 and Aschemonella monile Gooday and Holzmann in Gooday et al., 2017b. Another four are described as new species based on morphological and genetic data. In Abyssalia foliformis gen. nov., sp. nov. and Abyssalia sphaerica sp. nov. the flattened or spherical test comprises a homogeneous framework of sponge spicules. Psammina tenuis sp. nov. has a delicate, thin, plate-like test. Moanammina semicircularis gen. nov., sp. nov. has a stalked, fan-shaped test and is genetically identical to 'Galatheammina sp. 6' of Gooday and co-workers from the eastern CCZ. Sequence data revealed a spherical 'mudball', which disintegrated and cannot be formally described, to be a novel xenophyophore. Finally, four morphospecies are represented by dead tests: Psammina spp., Reticulammina sp., and an unknown genus with a unique test structure. This collection enhances our knowledge of Pacific xenophyophore diversity and provides the first genetic confirmation of wide geographic ranges for abyssal species., (Copyright © 2020 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Two marine members of the genus Vexillifera Schaeffer, 1926 (Amoebozoa, Dactylopodida) are described. Vexillifera abyssalis n. sp. originates from an abyssal sample of the Western Atlantic 4.5 km deep, which is the first unambiguous record of a deep-sea Vexillifera. The second species, V. kereti n. sp. was isolated from the soft bottom sediments of the White Sea (depth 106 m). An analysis of available data on the genus Vexillifera shows that it comprises many different species, yet they are very unevenly studied. The majority of species have only been described using light microscopy, and their phylogenetic relationships with other amoebae are unclear. However, available small-subunit (SSU) rRNA gene sequences of Vexillifera spp. form a robust, yet very heterogeneous clade in the phylogenetic tree. These species demonstrate a wide range of morphological and ultrastructural characters and originate from diverse habitats, suggesting that Vexillifera may need to be subdivided into several genera in the future. In addition to the described species, we sequenced the COI gene of original CCAP strains of Vexillifera bacillipedes, V. minutissima and Pseudoparamoeba pagei, thereby performing a phylogenetic reconstruction of the Dactylopodida based on a decent taxonomic sampling., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Most foraminifera inhabit marine habitats, but some species of monothalamids have been described from freshwater environments, mainly from Swiss water bodies over 100 years ago. Recent environmental DNA surveys revealed the presence of four major phylogenetic clades of freshwater foraminifera. However, until now only one of them (clade 2) has been associated to a morphologically described taxon-the family Reticulomyxidae. Here, we present morphological and molecular data for the genera representing the three remaining clades. We describe two new agglutinated freshwater genera from China and the Netherlands, Lacogromia and Limnogromia, which represent clades 3 and 4, respectively. We also report the first ribosomal DNA sequences of the genus Lieberkuehnia, which place this genus within clade 1. Our study provides the first morphotaxonomic documentation of molecular clades of freshwater foraminifera, showing that the environmental DNA sequences correspond to the agglutinated monothalamous species, morphologically similar to those described 100 years ago., (Copyright © 2017 Elsevier GmbH. All rights reserved.)

Amoebae of the genus Korotnevella are covered with scales, the structure of which is believed to be species-specific and allows distinguishing species reliably at the morphological level. We studied members of this genus in order to assess the genetic structure of the local populations of amoebae. For the present study we isolated nine freshwater strains of Korotnevella, belonging to three species, from two locations in North-Western Russia. In order to obtain data on the population structure of these amoebae, we identified all isolates based on the light-microscopic morphology and scale structure and investigated both inter-strain and intra-strain polymorphism of Cox I and 18S rRNA genes. Results show that both genes provide congruent patterns of population structure. The Cox I gene appears to be more reliable DNA barcode while the 18S rRNA gene shows an interesting pattern of polymorphism, which may represent phylotypes of amoebae. Local population of amoebae in every studied species consists of a number of genetic lineages (phylotypes), some shared between the populations while others are unique to a local habitat., (Copyright © 2016. Published by Elsevier GmbH.)

This paper describes a new genus, Cunea n. g., of marine naked amoebae with two cryptic species, Cunea profundata and Cunea thuwala, isolated from distant localities in the ocean and different depths (Brazilian abyssal plain, Western Atlantic Ocean, depth >5km and the Red Sea off the Saudi Arabian coast, depth ca. 58.7m). Both species are very similar to each other in the set of light microscopic and ultrastructural characters and might be described as a single species, yet their genetic divergence based on 3 molecular markers (small-subunit ribosomal RNA, actin and cytochrome c oxidase subunit 1) corresponds to the level of variation typically observed between different morphospecies of Amoebozoa. In addition, the studied strains differ strongly in their temperature tolerance ranges, C. profundata isolated from the cold Atlantic deep-sea habitat being able to reproduce under lower temperatures than C. thuwala isolated from the warm Red Sea benthos. Molecular phylogenetic analysis based on SSU rRNA gene shows that the new genus robustly branches within the Dactylopodida, but forms an independent clade within this order that does not group with any of its known genera., (Copyright © 2015 Elsevier GmbH. All rights reserved.)

A new monothalamous (single-chambered) soft-walled foraminiferal species, Arnoldiellina fluorescens gen. et sp. nov., was isolated from samples collected in the Gulf of Eilat, Israel. The species is characterized by a small elongate organic theca with a single aperture of allogromiids. It is characterized by the emission of green autofluorescence (GAF) that has so far not been reported from foraminifera. Phylogenetic analysis of a fragment of the 18S rDNA indicates that the species is related to a group of monothalamous foraminiferans classified as clade I. Although the morphology of the new species is very different compared to the other members of this clade, a specific helix in 18S rRNA secondary structure strongly supports this position., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

A new species of Leptomyxida, named Rhizamoeba neglecta was found during studies of the amoeba fauna of the inner Lake Leshevoe located at Valamo archipelago (The Lake Ladoga, North-Western Russia). Light-microscopical and ultrastructural studies indicated that it represents a new species of Leptomyxida. The partial 18S rDNA sequence of this amoeba is very similar to that of Leptomyxa reticulata.. These organisms, however, are very different in LM morphology and biology. Organisms assigned to the genus Rhizamoeba do not form a single clade in the 18S rDNA tree. This may indicate that the genus is an artificial grouping or that a number of studied strains were misidentified. The phylogeny and the systematics of leptomyxids require further investigation.

Macroevolutionary relations among main lineages of Foraminifera have traditionally been inferred from the small subunit ribosomal genes (SSU rDNA). However, important discrepancies in the rates of SSU rDNA evolution between major lineages led to difficulties in accurate interpretation of SSU-based phylogenetic reconstructions. Recently, actin and beta-tubulin sequences have been used as alternative markers of foraminiferal phylogeny and their analyses globally confirm results obtained with SSU rDNA. In order to test new protein markers, we sequenced a fragment of the largest subunit of the RNA polymerase II (RPB1), a nuclear encoded single copy gene, for 8 foraminiferal species representing major orders of Foraminifera. Analyses of our data robustly confirm previous SSU rDNA and actin phylogenies and show (i) the paraphyly and ancestral position of monothalamid Foraminifera; (ii) the independent origin of miliolids; (iii) the monophyly of rotaliids, including buliminids and globigerinids; and (iv) the polyphyly of planktonic families Globigerinidae and Candeinidae. Additionally, the RPB1 phylogeny suggests Allogromiidae as the most ancestral foraminiferal lineage. In the light of our study, RPB1 appears as a valuable phylogenetic marker, particularly useful for groups of protists showing extreme variations of evolutionary rates in ribosomal genes.