Flexammina islandica gen. nov. sp. nov. and some new phylotypes of monothalamous foraminifera from the coast of Iceland

Abstract

Monothalamous (single-chambered) foraminifera comprise a poorly known group, the diversity of which is strongly underestimated according to environmental DNA surveys. The gross morphology of monothalamids offers few distinguishing features; their organic-walled or agglutinated tests are often very delicate and make isolation difficult. Here, we use an integrated taxonomic approach, including morphological and molecular analysis, to examine the diversity of monothalamids in a shallow subtidal area on the coast of Iceland. We report nine new phylotypes of single-chambered foraminifera distinguished by SSU rDNA sequences. Among them, we establish a new genus Flexammina and a new species Flexammina islandica, possessing a very pliable, finely agglutinated test capable of extreme shape transformations. According to molecular data, F. islandica belongs to the monothalamid clade M, which also includes the well-known genus Allogromia. In addition, we provide brief descriptions and illustrations of nine other monothalamous foraminifera isolated from the same area. Three of them are closely related to some unidentified environmental sequences and serve as the first microscopic documentation of these anonymous lineages.

Shallow-marine testate amoebae with internal structures from the Lower Devonian of China

“…Also, monothalamous foraminifera are not as fairly robust as the vase-shaped microfossils in shell wall. In fact, the shell wall of many monothalamous foraminifer species is soft and flexible 26 , 27 , 28 , 29 and always collapsed when dehydrated. Comparable morphological distortions are not seen in our specimens.…”

Newly designed foraminifera primers identify habitat‐specific lineages through metabarcoding analyses

“…This genus, and, in particular, species Hemisphaerammina apta , is known for its preference for specific microenvironments, including attaching to detrital grains of sand in marine shelf environments (McNeil & Neville, 2018). Another genus, Flexammina , is a shallow‐water inhabitant with a flexible agglutinated test and the capacity for extreme shape transformation (Voltski & Pawlowski, 2015).…”

“…The most dominant shared OTUs can be divided into three major categories: Hemisphaerammina (8 OTUs, 129K reads), Flexammina (1 OTU, 27K reads), and Rosalina (3 OTUs, 177K reads), (Table S2, Figure 2). We also detected OTUs from a clade with undetermined Saccamminid isolated from sandy beach or mudflat coast of Iceland (Voltski & Pawlowski, 2015) (3 OTUs, 31K reads).…”

Novel benthic foraminifera are abundant and diverse in an area of the abyssal equatorial Pacific licensed for polymetallic nodule exploration

“…Moreover, many of these undescribed species were rare, making comparisons with other studies difficult. The prevalence of rare undescribed species is a normal feature of the deep-sea benthos4484 but in the case of monothalamids, it is sometimes compounded by intraspecific morphological plasticity8586. We mitigated these challenges as far as possible by photographing every specimen extracted from the samples, and by careful comparison (on the same slide) of those from the same or different samples that appeared similar.…”