Majonica alpina nov. sp.

nomenclatorial act: 
protologue/first publication
Page: 
380
diagnosis: 

Shoots bearing spirally arranged bifacial leaves. Observed width of axes
up to 5 mm; axes together with leaves up to 30 mm. Leaves slightly overlapping,
straight. Different shapes and dimensions of leaves indicating heterophylly:
(1) Shape narrow-subtriangular with acute apex; observed dimensions up to 35 mm
long, 6 mm wide; leaf base rhomboid, slightly decurrent; this type of leaves
possibly originating from main axes; (2) Shape ovate, apex obtuse, observed
dimensions up to 10 mm long, 4 mm wide, margin sometimes sinuate; (3) Shape
lanceolate, sometimes tapering, apex obtuse (to acute), observed dimensions up
to 30 mm long, 3 mm wide. Leaf bases of (2) and (3) decurrent and completely
covering the axes.

Bracts up to 10 mm long, 6 mm wide, margin of apical part obviously
sinuate.

Ovuliferous dwarf-shoots up to 10 mm long, 6mm wide, 3mm thick, mostly
projecting beyond the bracts. Dwarf-shoots provided with 1 5 sterile scales,
(narrow) triangular in shape with acuminate apex; shape of fertile scales ovate
with obtuse apex; place of ovule-attachment lateral, diameter 1-1.5 mm.

Ovule/seed in cross-section narrow triangular, up to 15 mm long, 5 mm
wide; length of wing up to 9 mm. Specimens mostly laterally compressed with a
boomerang-like outline.

Polliniferous cones up to 20 mm long, 10 mm wide. Distal part of
microsporophyll up to 4 mm long, 4 mm wide, subpeltate with obviously sinuate
margin.

Pollen bisaccoid, observed length 50 70 µm. Nexine smooth with proximal
dilete mark. Proximal sexine differentiated into two taeniae, which do not
extend beyond the equator of the nexinal body. Taeniae characteristically of
unequal shape, resulting in a subtriangular sexine-free area.

Basal parts of bracts, dwarf-shoots and proximal parts of
microsporophylls non-stomatiferous. Apical and marginal stomata-free zones
present on bracts and microsporophylls, up to 500 µm long and 750 µm wide
respectively. Frequency of stomata/mm² ranging from 65 on leaves of type (1)
and (2) to 20 on leaves of type (3), measured halfway along an abaxial surface.
On adaxial surfaces frequency always higher. Stomata arranged in more or less
interrupted rows on leaves of type (1) and (2) and adaxial surface of leaves of
type (3), on bracts and microsporophylls; on abaxial surfaces of leaves of type
(3) arrangement in rows hardly recognizable. Adjacent stomatal complexes
occurring rarely sharing a subsidiary cell.

Diameter of stomatal complex approximately 75 µm sometimes slightly
smaller on adaxial surfaces. Guard cells slightly sunken, mostly longitudinally
orientated; 5-10 subsidiary cells, narrow trapezoid, bearing outwards pointing
converging solid papillae, strongly developed on leaves of type (3), bracts and
scales. Inner part of subsidiary cells forming a shallow pit, sometimes
widening outwards. Straight to convex distal walls of subsidiary cells
sometimes overlapping epidermal cells. Subsidiary cells as strong as or
slightly more cutinized than epidermal cells. Mean number of subsidiary cells
per stomatal complex, measured on a single abaxial surface, ranging from 7.4-8,
for adaxial surfaces this number is smaller.

Epidermal cells larger on abaxial surfaces of long leaves (type 3);
isodiametric, sometimes slightly stretched between stomatal rows, more stretched
on leaf bases and abaxial surfaces, shorter on adaxial surfaces. Solid,
distally placed epidermal papillae frequently occurring, but less developed or
absent on leaves of type (2). Anticlinal walls of epidermal cells on leaves
(type 1, 2) approximately 4 µm thick, thinner on other elements.

Margin scarious, denticulate at bracts and microsporophylls. Cuticle
thick, especially on leaves of type (1) and (2). Hypodermis present.

systematic position: 
Majonicaceae, Majonica
typeseries: 
Holotype: Prep. 755, Laboratory of Palaeobotany and Palynology of the State University of Utrecht, The Netherlands., (Plate I, 1).
stratigraphy: 
Classification: 

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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith