Sphenolepis kurriana (Dunker) Schenk

Plant Fossil Names Registry Number: PFN003381

Act LSID: urn:lsid:plantfossilnames.org:act:3381

Author: J. A. Schenk

Rank: species

Basionym: Thuites kurrianus Dunker

Genus:

Reference: Schenk, J. A. (1871): Die fossile Flora der nordwestdeutschen Wealdenformation. – Palaeontographica 19(6): 227–250.

Page of description: 243

Types

Original diagnosis/description

Thuites ramulis erectis irregulariter pinnatis, compressiusculis ultrimque subcarinatis, foliolis crassiusculis imbricatis irregulariter dispositis elongatis subflexuosis apice acutis dorso carinatissubdistatntibus.

Emended diagnosis

Watson and Fischer (2024: Foss. Impr., 80(1): 21):
[Main stem unknown]. Twigs sparsely branched, branches borne irregularly at 50°–70°, branches 1.5–3 mm wide. Leaves in a simple helix, parasitichies 2 + 3 on larger branches, reduced to 1 + 2 on smallest twigs. Leaves scale‑like, adpressed or slightly spreading, arising as a continuation of the homboidal leaf‑base cushion; leaf and basal cushion combined 1 mm × 1 mm on smallest shoots, longer and wider on larger shoots; free part of leaf up to one‑third of total length. Leaf margins entire, converging towards bluntly-pointed or awl-shaped apex, leaf biconvex in section with median keel on abaxial surface of cushion and leaf.
Cuticle thin on all surfaces. Stomata occurring on both surfaces. Abaxial stomata confined to two patches just below free leaf, each midway between keel and margins, stomata within a patch crowded. Stomata on adaxial surface forming a single band on each side of the leaf, converging towards apex. Stomatal apparatus circular, guard cells deeply sunken below ring of 5–8 subsidiary cells with inner anticlinal walls forming an oval stomatal pit. Stomatal apparatus monocyclic; subsidiary cells of adjacent abaxial stomata frequently shared; stomatal orientation irregular. Ordinary epidermal cells within stomatal areas irregular in shape and arrangement; anticlinal walls straight and deeply cutinised. Ordinary epidermal cells of non-stomatal areas on both surfaces varying from isodiametric to rectangular and elongate, with slightly sinuous walls mostly arranged in longitudinal files converging towards leaf apex.
Female cone ovoid to spherical, up to 12.5 mm wide, terminal, borne singly on short lateral branches occurring in a cluster. Cone scales deltoid, arranged in a spiral with blunt, obtusely pointed distal end.

Stratigraphy

Cretaceous, Lower Cretaceous
Berriasian - Valanginian, Bückeberg Formation (Watson and Fischer 2024: Foss. Impr., 80(1): 21)

Locality

Germany
for neotype (Watson and Fischer 2024: Foss. Impr., 80(1): 21): Deister, Lower Saxony, Germany

localities in original publication: Duingen, Osterwald and Deister, Hannover region of Lower Saxony