Eolimna

Name

Eolimna

Rank

Genus

Authors (Pub.)

Schiller W. Lange-Bertalot H.  

Publication

Eolimna martinii n. gen., n. sp. (Bacillariophyceae) aus dem Unter-Oligozän von Sieblos/Rhön im Vergleich mit ähnlichen rezenten Taxa [1997/10]

Journal

Paläontologische Zeitschrift

Volume

71

Issue

3–4

Page number

166

Year

1997

Parent Taxon

[Phylum] Bacillariophyta

Fossil Status

valves

Type

Eolimna martinii

Diagnosis

Cells living solitary in freshwater habitats, indications for forming aggregations lacking. In girdle view narrow to very narrowly rectangular. So far known all populations produce only comparatively small cells; length rarely up to 20 lam but often less than 10 tam, breadth 2-7 jam, breadth of the girdle 1- ca. 2.5 ~m. Valve outlines comparatively less variable than in other genera, elliptic or elliptic-lanceolate to broadly lanceolate with more acutely or obtusely to broadly rounded apices, which are not protracted (as far as known recently). Central raphe system conforms with other naviculoid genera with simple inner raphe fissures. Terminal fissures and central raphe endings outside the valve curving in opposite direction. Raphosternum and transapical costae internally forming a shallow comparatively very simple ,alveolate rib system'. The external face of the valve is plane, or with narrow shallow grooves running directly parallel to the median costa (sternum), however without a distinct conopeum. Areolae in single or double rows in radiate arrangement exclusively. Voigt fault hardly to discriminate or lacking. Foramina variable in outline, medium sized or larger in relation to the very small valve surface rather than regularly circular and narrowly spaced. Foramina lips (flaps) facultatively. Hymenes in a medium position countersunk in the short canals of the valve. Thus they are visible inside and outside of the valve. Only a few areolae run across the margins of the valve face onto the mantle. The girdle of each theca consists of 2-4 (very) narrow open elements. The valvocopula or other copulae additionally are perforated by a single row of areolae, often more or less irregular, and in closer position to each other than on the valve.