Back
Tacca umeri
Tacca umeri A.D. Pan, B.F. Jacobs, Currano Bot. J. Linn. Soc., 175(1): 22. 22 Apr 2014
- Name
- Tacca umeri
- Rank
- Species
- Original spelling
- umerii
- Generic Name
- [Genus] Tacca
- Authors (Pub.)
- Pan A. D.
Jacobs B. F.
Currano E. D.
- Publication
- Dioscoreaceae fossils from the late Oligocene and early Miocene of Ethiopia [2014/4]
- Journal
- Botanical Journal of the Linnean Society
- Volume
- 175
- Issue
- 1
- Page number
- 22
- Year
- 2014
- Fossil Status
- leaves
- Stratigraphy
- Chattian
- Location
- Guang River, Chilga, North Gondar Zone, Amhara Region, north-western Ethiopia; [12° 30′ N, 37° 7′ E]
- Paleoregion
- Africa (East)
Data for Holotypus
- Repository
- National Museum of Ethiopia, Addis Ababa, Ethiopia
- Repository Number
- MU22-29
Data for Paratypus
- Repository
- National Museum of Ethiopia, Addis Ababa, Ethiopia
- Repository Number
- MU22-2(Fig.10), MU36-33 (Fig.11) and MU16-19A & B (counterparts; Fig.12)
- Diagnosis
- Mesophyllous to macrophyllous, untoothed, palmately lobed leaves with 9–11 lobes. Fragments 57.2–139.1 mm in length and 65.4176.3 mm in maximum width. The leaf length to width ratio is generally 2:3. Lobes are elliptic to oblong, possess acutely angled convex apices and decrease in size away from the central lobe. Distal lobes are multiveined (consisting of the central and marginal primaries) and are generally 1.5–2.5 times shorter than the central lobe. The symmetrical base is complex and shows both concavoconvex and lobate characteristics. A relatively long and robust petiole is present and attached to the leaf at the margin. Primary venation is palinactinodromous with basal veins forming shallow helicoid branching away fromthe central primary vein. Secondary venation is mainly eucamptodromous with some distal branches becoming brochidodromous near the lobe apices. Lobe secondaryand intersecondary veins arise at angles of between 65 and 85° from the primary veins and have excurrent attachment. CUTICLE: Cells ontheabaxial surfaceare 8–23μm in length and 4−12μm in width, have straight to rounded anticlinal cell walls and are four- to seven-sided. Axillocytic stomatal complexes are present and common. Other stomatal complex types, including anomocytic and possibly anomotetracytic, are also present. Stomata are round to oval, ranging from 9 to 11 μm in length and 8 to 9 μm in width.The adaxial cuticle was not available for observation.
