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Kachaikestrobus acuminatus
Kachaikestrobus acuminatus Del Fueyo, S. Archang., Llorens, Cúneo Int. J. Pl. Sci., 169(6): 800. Jul - Aug 2008
- Name
- Kachaikestrobus acuminatus
- Rank
- Species
- Generic Name
- [Genus] Kachaikestrobus
- Authors (Pub.)
- Del Fueyo G. M.
Archangelsky S.
Llorens M.
Cúneo N. R.
- Publication
- Coniferous ovulate cones from the Lower Cretaceous of Santa Cruz Province, Argentina [2008/7-8]
- Journal
- International Journal of Plant Sciences
- Volume
- 169
- Issue
- 6
- Page number
- 800
- Year
- 2008
- Fossil Status
- cones (ovuliferous)
- Stratigraphy
- Albian
- Location
- Arroyo Caballo Muerto Creek (Estancia Kachaike),
Santa Cruz Province, Argentina
- Paleoregion
- America (South)
Data for Holotypus
- Repository
- Museo Paleontologico Egidio Feruglio, Trelew, Argentina
- Repository Number
- MPEF-Pb 859A, MPEF-Pb PM 859A 1–5,
MPEF-PbMEB 859A 1, MPEF-Pb MET 859A 1–2
Data for Paratypus
- Repository
- Museo Paleontologico Egidio Feruglio, Trelew, Argentina
- Repository Number
- MPEF-Pb 859B, MPEF-Pb PM 859B 1–16,
MPEF-Pb MEB 859B 1–4, MPEF-Pb MET 859B 1–3, MPEF-Pb
863, andMPEF-Pb PM 863 1–11
- Diagnosis
- Conifer branches bearing scalelike leaves, adpressed,
helically arranged, ovate with distinctive acuminate
apex; 3.6–4 mm long and 2 mm wide. Leaf margins entire at
basal part and serrate toward apex. Papillae present on distal
part of leaves; more numerous on adaxial than on abaxial epidermis.
Leaves amphistomatic, stomata randomly disposed, sparse
at apex; apertures parallel, obliquely and transversely oriented.
Stomatal apparatus elliptical-rounded; monocyclic, with four
or five subsidiary cells, radially placed; up to 35 mm long and
27 mm wide. Suprastomatal aperture elliptical, 26 mm long
and 13 mm wide. Florin ring present. Guard cells sunken,
41 mm long and 7 mm wide. Epidermal cells of leaves isodiametric,
27 mm long and 24 mm wide, and rectangular-elongate,
62 mm long and 15 mm wide. Ovulate cones single and terminal
on twigs up to 1.6 cm long and 3.5 mm wide, cylindrical
elongate, 1.7 cm long and 1 cm wide. Cone axes bearing 40
cone scales, dense and helically disposed. Bracts acuminate,
overlapping adjacent bracts, 4–5 mm wide and 7 mm long;
amphistomatic, stomata in rows with features as for leaves.
Common epidermal cells of three shapes: rectangular-elongate,
64 mm long and 18 mm wide; quadrangular, 24 mm long and
20 mm wide; rectangular-narrow elongate, 105 mm long and
14 mm wide. Ovuliferous dwarf shoots broadly elliptical,
5 mm long and 4–5 mm wide, shorter than and fused to bracts
at base; consisting of eight scales, two small and six large; two
large, probably fertile, emerging laterally; three emerging
adaxially and three abaxially. Scale apices triangular, acute to
blunt, 0.8 mm long and 0.7 mm wide. Apices with serrate
margins and papillae. Ovuliferous dwarf shoots amphistomatic;
stomata scarce, random, present only on distal part.
Stomatal features as for leaves and bracts. Epidermal cells quadrangular,
26 mm long and 18 mm wide. Epimatium emerging
as outgrowth of two adaxial larger scales, ;3.2 mm long and
2.0 mm wide, formed by two layers of rectangular-elongate
cells; outer layer, 51 mm long and 18 mm wide; inner layer, 64
mm long and 10 mm wide. Epimatium covering one ovule,
which has an outer integument layer with rectangular cells,
69 mm long and 12 mm wide. A thick structureless megaspore
membrane is present. Cuticle ultrastructure of bracts and ovuliferous
dwarf shoot scales composed of three layers: external
layer with loosely disposed fibrillar elements; middle layer
with compactly arranged fibrils; inner layer with fibrillar element,
more dense and of parallel disposition.
