Osmunda pulchella Bomfleur, G.W.Grimm et McLoughlin

Plant Fossil Names Registry Number: PFN002758

Act LSID: urn:lsid:plantfossilnames.org:act:2758

Authors: B. Bomfleur, G. W. Grimm & S. McLoughlin

Rank: species

Reference: Bomfleur, B., Grimm, G. W. & McLoughlin, S. (2015): Osmunda pulchella sp. nov. from the Jurassic of Sweden–reconciling molecular and fossil evidence in the phylogeny of modern royal ferns (Osmundaceae). – BMC Evolutionary Biology 15: 126 (25 pp.).

Page of description: 2

Illustrations or figures: figs 1–6

Types

Original diagnosis/description

Rhizome creeping or semi-erect. Stem with ectophloic-dictyoxylic siphonostele and two-layered cortex. Pith entirely parenchymatous. Xylem cylinder about 8–12 tracheids (mostly ca 0.4 mm) thick, dissected by narrow, complete, immediate leaf gaps, containing about twenty xylem segments in a given transverse section. Phloem and endodermis external only. Inner cortex ca 0.5–0.8 mm thick, homogeneous, parenchymatous, containing about ten leaf traces in a given transverse section; outer cortex ca 1.5–2.5 mm thick, homogeneous, sclerenchymatous, containing about 20 leaf traces in a given transverse section. Leaf traces in stem oblong, more or less reniform, adaxially concave, endarch with a single protoxylem strand at the point of emergence from stele, diverging at acute angles of ca 20–40°; protoxylem strand bifurcating only in outermost cortex or upon departure from stem. Petiole bases with adaxially concave vascular strand, one adaxial sclerenchyma band in vascular-strand concavity, parenchymatic cortex, a heterogeneous sclerenchyma ring, and an opposite pair of petiolar wings; adaxial sclerenchyma in inner cortex of petiole appearing in the form of a single patch or arch lining the vascular-bundle concavity with homogeneous thickness, differentiating distally into two thickened lateral masses connected by a thin strip, extending proximally only to base of petiole, not into stem; sclerenchyma ring of petiole base thicker than vascular bundle, heterogeneous, with a crescentic abaxial cap of thicker-walled fibres in the basal petiole portion differentiating distally into two lateral masses and ultimately into two lateral and one abaxial mass; petiolar wings in distal portions containing an elongate strip of thick-walled fibres. Roots diarch, usually arising singly from one leaf trace, containing scattered sclerenchyma fibres.

Etymology

The specific epithet pulchella (Latin diminutive of pulchra =‘beautiful’, ‘fair’) is chosen in reference to the exquisite preservation and aesthetic appeal of the holotype specimen.

Stratigraphy

Jurassic, Lower Jurassic, Pliensbachian
mafic pyroclastic and epiclastic deposits informally named the “Djupadal formation”

Locality

Sweden
Korsaröd lake (55°58’54.6”N, 013°37’44.9”E) near Höör, central Skåne, southern Sweden