Linings of agglutinated Foraminifera from the Devonian: taxonomic and biostratigraphic implications

K N Bell,T M Winchester-Seeto

doi:10.1144/jm.18.1.27

Abstract

Abstract. The organic linings of agglutinated foraminiferans from the Devonian are documented and described. These linings have been recovered in palynological residues from Australia, France, Pakistan and Siberia and range from the Lochkovian to the Frasnian. Six species are described as new: Hemisphaerammina coolamon, Psammosphaera garraay, Reophanus proavitus, Saccammina mea, Saccammina wingarri and Thurammina mirrka. Three species, with a wide geographical spread and a relatively limited stratigraphic range, may prove to have some utility in intercontinental correlation: Inauris tubulata Conkin &amp; Conkin, Saccammina mea n. sp. and Saccammina wingarri n. sp.

Highlights

The organic linings of rotalid foraminifera from the Permian to the Recent are well documented (Stancliffe, 1989), but only recently have linings of Palaeozoic agglutinated foraminifera been reported (Winchester-Seeto & Bell, 1994)
Bender (1995) has shown that most agglutinated genera have an inner organic lining and our specimens are obviously congeneric with described agglutinated genera, but do not have any agglutinant covering
The purpose of this study is to describe and document the inner, organic linings of agglutinated foraminifera, recovered in palynological processing of Devonian material, and to examine their taxonomic and biostratigraphic implications

Summary

Introduction

The organic linings of rotalid foraminifera from the Permian to the Recent are well documented (Stancliffe, 1989), but only recently have linings of Palaeozoic agglutinated foraminifera been reported (Winchester-Seeto & Bell, 1994). In earlier works reporting organic linings they have been referred to as microforaminifera because of their small size (typically < 200 pm) We believe that such a term is unwarranted as foraminifera are known to form part of the sub-63 pm fauna (Gooday, 1986a,b; Pawlowski, 1991) and Burnett (1979) refers to foraminifera of the 1 0 15pm range; these smaller forms are part of the entire foraminiferan size range (albeit a size range seldom studied) and require no special name. Bender (1995) has shown that most agglutinated genera have an inner organic lining and our specimens are obviously congeneric with described agglutinated genera, but do not have any agglutinant covering. This absence of outer wall material may be an environmental response, or just a preservational or procedural artefact. At present we cannot differentiate between these possibilities, so we prefer to use established genera and to ignore the absence of agglutinating wall material. Hohenneger (1990) has suggested that the Allogromiidae and simple Astrorhizidae (in which our specimens are classified) may be more closely related than previously thought and that the amount of agglutinated material present may have little significance and even be environmentally controlled; our studies support this view

Objectives

Methods

Findings

Discussion

Conclusion