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Morphological classification of foraminifera
established by Valeria I. Mikhalevich et al.

Zoological Institute. Russian Academy of Sciences. Universitetskaja nab. 1, 199034 St-Petersburg, Russia

Introduction

Infaunal living, planispiral: Elphidium de Montfort 1808                   
Elphidium macellum, SmoegenBasis of most foraminiferal classifications nowadays is Loeblich and Tappans 1987/88 published "Foraminiferal genera and their classification". The wall-structure is used as the main criteria for classification. Based on studies on recent foraminifera Mikhalevich/ Debenay 2001 and Mikhalevich 2004 reestablished test-form and -features as the main criteria as it has been done by early foraminiferologists such as d'Orbigny 1826. Mikhalevich proposes a new classification though only outlined in detail for agglutinated foraminifera. It will be roughly presented here and is used at "foraminifera.eu" on the class, subclass and order level.
Importance of the Morpholgy
Infaunal living, tapered and cylindrical: Uvigerina d'Orbigny 1826              
Uvigerina, Smoegen In the last two decades several studies were undertaken to analyse the relation between life-style, habitat and test-form and -features of foraminifera. Corliss and Chen 1988 observed in the Norwegian Sea, that foraminifera living infaunal have rounded planispiral, flattened ovoid or tapered, cylindrical, tapered or spherical test forms. Epifaunal living foraminifera have trochospiral either rounded, plano or biconvex or mioloine tests. Infaunals have a higher surface/mass relation and pores allover in contrast to epifaunal forms due to lower oxygen present in the sediment. They found special depth-patterns for each morphogroup with almost a 100% infaunal forms between 500-1000m and almost a 100% epifaunal forms below 1500m.

Genetical clustering
Infaunal living, rounded trochospiral with many pores: Ammonia Brünnich 1772               
Ammonia, Blaavand Genetical analysis of foraminifera done e.g. by Pawlowski et. al. 2003 have shown the close relationship between calcareous and agglutinated genera with similar test morphology. Rotaliina and Textulariina separated by Loeblich/Tappan are placed by him in one genetical cluster. Analysis of genetical code of more foraminifera in the future may lead to a new classification.

As a conclusion the morphology of the test should be treated as a mayor criteria for classificiation and the wall-structure as a minor characeristic only.


Morphological classification by Valeria I. Mikhalevich et al.

Due to their unique genetical characteristics, test-building ability and typical sexual/asexual cycle in comparison to other protozoans the Foraminifera are lifted to the phylum-level. It has been done too by Margulis/Schwartz 1988 in "Five Kingdoms". Mikhalevich, V.I. 2004 establishes five mayor classes based on the complexity of the test and life-style: Astrorhizata, Spirillinata, Miliolata, Nodosariata and Rotaliata. Her description is as follows:
Astrorhizata Mikhalevich, 1980
Subclasses: Astrorhizana Saidova, 1981 and Lagynana Mikhalevich, 1980

"Tests primitive unilocular, sometimes passing to pseudo- multichambered ones with sub-sphaerical, elongated or very often irregular forms, agglutinated or microgranular wall, often of considerable thickness, aperture simple or sometimes not developed."

Spirillinata Maslakova, 1990
Subclasses: Ammodiscana Mikhalevich, 1980 and Spirillinana Maslakova, 1990

"Tests pseudotwochambered with a lang tubular second chamber or derived from them multichambered, often with a preserved initial tubular part. The higher representatives may have additional apertures and, sometimes, a primitive canal system."

Miliolata Saidova, 1981
Subclasses: Miliamminana Mikhalevich, 1980 and Miliolana Saidova, 1981

"Shells mostly multi-chambered, predominantly with tubular chambers coiled in one of the special miliolide arrangements, usually two, rarely three per volution; sometimes planispiral with more than three broad chambers per whorl in the Order Soritida. The flexostyle is preserved in many representatives. Aperture at the end of the chamber may be simple or complicated by an inner tooth or a special structure. It may also be cribrate. Additional apertures only as an exception; integrative systems presented only by stolons."

Nodosariata Mikhalevich, 1992
Subclasses: Hormosinana Mikhalevich, 1992 and Nodosariana Mikhalevich, 1980

"Shells predominantly multichambered with the prevalence of elongated, mostly monoaxial (uni-, bi- or triserial) arrangements, sometimes in polymorphinoid or plectofrondicularian arrangements, more rarely planispiral (usually involute). Aperture terminal even in coiled forms, simple or complicated: radial, hooded, fissure-like, rarely cribrate. An entosolenian tube may be present in each of these apertural types (except in the cribrate one), only rarely forming inter-connected systems. No additional apertures or canal system are present."

Rotaliata Mikhalevich, 1980
Subclasses: Rotaliana Mikhalevich, 1980, Textulariana Mikhalevich, 1980 and Globigerinana Mikhalevich, 1980


Tests exclusively multi-chambered, mostly planispiral or trochospiral or derived from both of them. Aperture commonly at the base of the apertural face, at least in the earlier stages, single or multiple, may be cribrate, simple or complex with well- developed and diversified inner plates, grooves, valves, often forming inter-connected systems. Additional apertures present, stolons and canal systems well developed. The subclass Rotaliana comprises the genera with calcareous testwalls, the subclass Textulariana those with agglutinated testwalls.
      Classes Mikhalevich, V.I.










Illustrated Catalogues of Genera and Species for
Literature: