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Dicroidium irnensis
Taxonomy
Dicroidium irnensis was named by Abu Hamad et al. (2008). It is considered to be a form taxon. Its type specimen is Specimen PbO UmIr 3, illustrated on Plate I, a multi organs (Frond with cuticle), and it is a compression fossil. Its type locality is Wadi Himara, which is in a Lopingian fine channel fill siltstone/claystone in the Um Irna Formation of Jordan.
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 2008 | Dicroidium irnensis Abu Hamad et al. pp. 111-113 figs. Plates I–VII; Plate XVIII, 7; Figs. 2 and 3 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Dicroidium irnensis Abu Hamad et al. 2008
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| A. Abu Hamad et al. 2008 | Fronds small, bifurcated, bipinnate. Primary axis very robust and smooth, bifurcating with an angle of approximately 25° with at least two pairs of pinnae below the bifurcation; frond portions above the bifurcation more or less ovate in outline, tapering towards the apices and with their greatest width in the middle. Pinnae alternating to suboppositely attached, at angles between 45° and 70°, with up to 14 pinnules at each side.
Pinnules densely spaced, sometimes overlapping, in alternat- ing or subopposite position; pinnules obliquely attached with their entire basis, asymmetrical, outline tongue-shaped to rhomboidal with rounded apices. Basiscopic pinnules more obliquely attached than acroscopic pinnules; basal basiscopic pinnules occasionally continuing along the primary rachis. Pinnae ending in elongated, tongue-shaped pinnules and usually consisting of 3–5 strongly fused pinnules. Intercalary pinnules present, asymmetrically triangular to rhomboidal. Venation odontopteroid, lacking a clear midvein, with several veins entering the pinnule; veins rather densely spaced, bifurcating one or two times. Leaves amphistomatic, stomata far more numerous on the lower side. Epidermal cells and stomata of the upper surfaces larger than those of the lower surfaces. Stomata of the upper side mainly restricted to the pinna rachides and basal parts of the pinnules, particularly over the veins, but very rare to absent on the more distal parts of the pinnules. Stomata very abundant on the lower leaf side, occurring all over the pinnule surface but rare or absent under the pinna axes. Stomata of the lower pinnule surfaces normally randomly distributed. Stomata commonly with four subsidiary cells, the lateral ones less strongly cutinised than the polar ones; stomata with a ring of five or six subsidiary cells occur occasionally. Papillae rare, mainly restricted to the lower pinnule surfaces. |
Measurements
No measurements are available
No ecological data are available