ABSTRACT Foraminifera are among the most prolific calcifying protists, yet while adult calcification has been studied extensively, shell formation in juvenile stages remains poorly understood. This study investigates the calcification strategy of the first chamber (proloculus) in Amphistegina during multiple fission. We demonstrate that newly-formed juveniles are housed within a specialized, membrane-enclosed ‘brood chamber’ that shields them from the surrounding milieu. Within this microenvironment, the parent cell provisions offspring with essential calcification substrates: a mineral precursor in the form of magnesium-rich amorphous calcium carbonate (Mg-ACC), an organic matrix, and symbiotic algae. This Mg-ACC is synthesized nocturnally by the parental cell and subsequently released along with the cytoplasm during reproduction. By supplying the mineral precursor, the parent facilitates the rapid and effective construction of prolocular shells, facilitating reproductive success.
The Museum of Natural History (London) holds an obscure unfinished work by the 19th century naturalist Edward Waller on the benthic foraminifera of Ireland and Scotland. It is dated 1870, a few years before his death. It contains plates by J.J. Wild, later the artist of the Challenger Expedition, showing over a hundred specimens, all without names or descriptions. The plates, some complete, some in progress, ended up in a document with Edward Heron-Allen's bookplate, along with a variety of notes, signed and unsigned. Here is given an expos & eacute; of this intriguing work, apparently only ever mentioned in Sherborn's 1888 Bibliography of the Foraminifera. It appears possible that figures include those of presently unknown species, or unknown morphotypes of known species, making close inspection of the plates with the goal of identifying the forms a significant challenge, but of potential interest.
Abstract Benthic foraminifera of the genus Asterigerinoides have applications as stratigraphic markers in the North Sea Basin, yet their taxonomy and paleoecology remain insufficiently understood. This study explores ecological traits potentially contributing to the high abundance of Asterigerinoides guerichi during the Chattian and of Asterigerinoides staeschei during the Miocene. The phylogenetic relationships between A. guerichi, A. staeschei, and Asterigerinoides frankei (Asterigerina frankei) were studied through literature and morphological comparison with collection specimens using SEM and optical microscopy. Morphological features such as equally biconvex tests and teeth-like apertural granules of Asterigerinoides potentially indicate shallow-epibenthic lifestyles with endosymbiotic multitrophic feeding strategies. Stable isotope analyses expand these paleoecological interpretations with regard to paleotemperature and possible vital effects. Based on morphological features in the three Asterigerinoides species, we conclude that A. frankei belongs to Asterigerinoides rather than Asterigerina. These insights will ultimately improve the comprehension of these species as biostratigraphic markers.
We investigate trends in foraminiferal phenology using a 12-year (2008-2020)! well-resolved (7 to 28-day resolution) time series of planktonic foraminiferal fluxes from a U.S. Geblogical Survey sediment trap in the northern Gulf of America (Gulf of Mexico; 27.5 degrees N, 90.3 degrees W). The total foraminiferal flux declined over this time. We used Horn-Morisita dissimilarity analysis, principal coordinate analysis, and correlation matrices to show that fall assemblages became more similar in composition to summer assemblages (July-September) over the 12 years. As a result, winter (January-March) and fall (October-December) assemblages, which dominate the total annual foraminiferal flux, became more dissimilar in composition. This pattern is consistent with multidecadal, non-uniform trends of increasing seasonal sea surface temperatures, affecting the seasonality and com-position of foraminiferal communities through changing species phenology. We speculate that similar phenological changes across plankton communities might have led to trophic mismatch, causing the decline in total foraminiferal flux.
ABSTRACT It is commonly stated in foraminiferal literature that the first written record of foraminifera was by Herodotus (5th century BCE), who observed Nummulites gizehensis in the pyramids of Egypt and believed they were petrified lentils dropped by the builders. This is false; Herodotus makes no mention of Nummulites spp., and both aspects of this story in fact originate from Strabo (1st century BCE). The origins of this remarkably persistent error are traced.
