Morphoclines of living operculinid foraminifera based on quantitative characters

  title={Morphoclines of living operculinid foraminifera based on quantitative characters},
  author={Elza K. Yordanova and Johann Hohenegger},
Abstract Growth-independent test characters of the genera Operculina, Planoperculina, and Planostegina were investigated to determine relations to water depth in form of morphoclines. All characters describing test form – thickness, initial vector of the test spiral that is correlated to proloculus size, and radius expansion rate describing test contour – are correlated. The investigated Operculina and Planoperculina species (O. ammonoides, O. elegans, O. complanata, P. heterosteginoides… 


Test the hypothesis that some of the observed morphological differences may reflect environmental conditions rather than evolutionary changes, and apply morphometric analysis to equatorial sections of megalospheric Heterostegina depressa tests from the reef slope of Sesoko-Jima, NW-Okinawa.

Growth-invariant Meristic Characters Tools to Reveal Phylogenetic Relationships in Nummulitidae (Foraminifera)

Growth-independent and growth-invariant parameters were developed to model planispirally enrolled tests using living nummulitids from the West Pacific, where the molecular genetic relations are known and demonstrate a perfect correlation with biological species.

Operculina and Neoassilina: A Revision of Recent Nummulitid Genera Based on Molecular and Morphological Data Reveals a New Genus

Analysis of ribosomal SSU rDNA data of eight recent nummulitid genera confirms the obtained high troughput sequencing results and shows that Palaeonummulites venosus builds a clade with O. complanata that branches at the base of other Nummulitidae containing Planostegina, Planoperculina, Cycloclypeus, Heterosteginas, Operculinella and Neoassilina.

Morphometric analysis of Eocene nummulitids in western and central Cuba: taxonomy, biostratigraphy and evolutionary trends

Based on further discriminant analysis, an increase in proloculus size was detected in Nummulites striatoreticulatus from the middle Eocene to early late Eocene, supporting this important evolutionary pattern in many lineages of Nummurites.

Morphospace of foraminiferal shells: results from the moving reference model

The analysed theoretical morphospace verifies the moving reference model, indicating the fundamental role of apertures in the morphogenesis of foraminifera.

Depth related adaptations in symbiont bearing benthic foraminifera: New insights from a field experiment on Operculina ammonoides

Results show that O. ammonoides exhibit morphological plasticity when constructing thinner chambers after relocated to low light conditions, and adding more weight per area after relocation to high light conditions.

Functional shell geometry of symbiont-bearing benthic Foraminifera.

An important function of symbiont-bearing benthic foraminifera is to provide their endosymbiotic microalgae with light, and they react to decreasing light intensity and water motion by the transition in shell form from spherical to extremely flat tests.

Why did some larger benthic foraminifera become so large and flat?

Biostromes and low‐relief bioherms, some of which are characterized by exceptionally large, flat specimens of larger benthic foraminifera, are common in Palaeogene and Miocene carbonates, most

Studies on settling, traction and entrainment of larger benthic foraminiferal tests: implications for accumulation in shallow marine sediments

Settling and traction velocities were measured on optimally preserved tests of larger foraminifera using a settling tube and flume tank. Within larger foraminifera with porcelaneous tests, the

Interpreting Morphologically Homogeneous (Paleo-)Populations as Ecological Species Enables Comparison of Living and Fossil Organism Groups, Exemplified by Nummulitid Foraminifera

Living and fossil representatives of nummulitid foraminifera were chosen to demonstrate complete reconstruction of morphology using metrical growth-invariant and growth-independent characters, and 6 models were established to define ecological species in living and fossil species.



Distribution of Living Larger Foraminifera NW of Sesoko‐Jima, Okinawa, Japan

. Living, symbiont-bearing, larger foraminiferids restricted to the photic zone incorporate mechanisms blocking solar radiation and water current transportation. They can be divided in two groups


Living Nummulitidae achieve their highest diversity in the subtropical and tropical West Pacific. Although all house symbiotic microalgae, they avoid highly illuminated areas near the water surface,

Analyse von Wachstumskurven von Heterostegina depressa (Foraminifera: Nummulitidae)

Chamber formation in individuals of the large foraminifer Heterostegina depressa was studied to explain the different shapes of growth curves established for groups of individuals.

Displacement of Larger Foraminifera at the Western Slope of Motobu Peninsula (Okinawa, Japan)

Abstract Living and death assemblages of selected benthic, symbiont-bearing foraminiferal species were compared at a NW-Pacific island slope. Two transects with different morphologies were chosen,


The phylogenetic relationships of five Recent nummulitid genera were investigated and it is suggested that chamber subdivisions developed several times independently in the evolutionary history of the Nummulitidae, providing an example of parallel evolution in Foraminifera.

Taphonomy of larger foraminifera: Relationships between living individuals and empty tests on flat reef slopes (Sesoko Island, Japan)

SummaryThe depth distributions of larger foraminifera (27 species) were investigated along two transects in the fore reef areas of a NW Pacific fringing reef. One transect is distinguished by a


Paleodepth interpretations based on larger foraminiferal assemblages should be based on environmental evidence for climate, terrigeneous influence, water transparency, and hydrodynamic conditions based on sedimentology, geochemistry, and associated fossil biota.

Habitats of larger foraminifera on the upper reef slope of Sesoko Island, Okinawa, Japan

Clines: An auxiliary method in taxonomy

The principle of harmoniously stabilized gene-complexes will account for the extension of the range of particular genecombinations beyond the areas for which they were initially selected, and the restriction of intermediates to narrow zones between the ranges of the favoured stabilized combinations.