Sublepidodendron songziense

Name

Sublepidodendron songziense

Rank

Species

Generic Name

[Genus] Sublepidodendron

Authors (Name)

Chen G.-X.  

Authors (Pub.)

Wang Q. Hao S.-G. Wang D.-M. Wang Y. Denk T.  

Publication

A Late Devonian arborescent lycopsid Sublepidodendron songziense Chen emend. (Sublepidodendraceae Kräusel et Weyland 1949) from China, with a revision of the genus Sublepidodendron (Nathorst) Hirmer 1927 [2003/12]

Journal

Review of Palaeobotany and Palynology

Volume

127

Issue

3-4

Page number

299

Year

2003

Fossil Status

stems

Stratigraphy

Famennian

Strat. comment

Wutung Formation

Location

Huangkuang, Songzi City, Hubei Province, China

Paleoregion

Cathaysia (South)

Data for Holotypus

Repository

Beijing University, Department of Geology, Beijing, China

Repository Number

WQ-001A

Num

2: 1

Pub.

A Late Devonian arborescent lycopsid Sublepidodendron songziense Chen emend. (Sublepidodendraceae Kräusel et Weyland 1949) from China, with a revision of the genus Sublepidodendron (Nathorst) Hirmer 1927 [2003/12]

Diagnosis

Arborescent lycopsid, about 4^8 m high. Two basic branching patterns: pseudomonopodial in trunk and continuously 6^8 times dichotomous at 25^35‡ angles within lateral branching systems. Trunk with Ulodendron-scars, umbilicus-like with a central vascular trace, 1^2 cm in diameter, acropetally longitudinal distance between two successive scars from 5.5 to 6.5 cm. Associated rhizomorph assigned to Stigmaria, with round or elliptical rootlet scars, 4^8 mm long, 3^5 mm wide. Lateral branching system biseriate, sub-opposite to alternate, forming an excurrent canopy. Lateral branches caducous ca. 2^ 25 mm wide, distance between successive fork ca. 100^150 mm long. Leaves ca. 10^15 mm long, 0.7^1.2 mm wide, dorsiventrally £attened, entire, unforked at top and often persistent, decurrent at base. Leaf cushion (LC)very small, 1.0^3.5 mm long, 0.8^1.5 mm wide, and their morphology and arrangement varying with ontogeny of axis. Thinner and younger axes often with fusiform to longitudinally rhomboid or oval LC, arranged compactly in low spirals. Well developed false leaf scars (FLS)in middle or slightly higher part of LC and longitudinal groove or ridge mainly in middle^lower ¢eld. Thicker main stem often having longitudinally fusiform or elliptical to lensshaped LC, loosely arranged in high spirals, with no or indistinct FLS and longitudinal median keels in middle^lower part of LC. The presence of ligule pit can not be excluded. Possibly separate monosporangiate strobili, showing bimodal size distribution, terminating distal branches, heterosporous. Microsporangiate strobili 80^120 mm long, 8^12 mm wide, cylindrical or cigarshaped with tapering top, and possible megasporangiate strobili thinner and longer, about 100^ 150 mm long, 6^9 mm wide. Sporophyll pedicel 1.5^5.0 mm long, with alations, horizontally attached to strobilus axis in low spirals. Sporangium oval or elliptical, ca. 3.0^4.0 mm long, 1.6^2.4 mm high, adaxially attached to sporophyll pedicel, partly enclosed by upward and inward folding of margins of sporophyll. Round or roundly triangular microspore with triradiate mark, granulate ornamentations and narrow cingulum, ca. 18^42 Wm, assigned to Lycospora-type. Spheroidal megaspore with a raised laesurae, ca. 250^550 Wm in diameter, sparsely echinate contact-face forming an apical prominence (gula)and densely papillate and somewhat reticulate distal surface. Branch with medullated or solid exarch protostele and cortex. Main stem possessing distinct secondary xylem and homogeneous periderm, siphonostele with lateral branch gaps, and cortex with indistinctive zonation. Pith consisting of irregularly oriented or ¢lamentous cells, sub-divided into two zones. Outer zone, 4^12 or more cells wide and in contact with metaxylem, composed of larger parenchymatous cells. Inner zone often degraded or partially separated from outer zone. Cell walls of pith parenchyma seemingly secondarily thickened. Primary xylem exarch maturation and protoxylem distributed continuously at periphery of metaxylem, without distinctive coronae. Tracheids mainly with scariform thickening, and between horizontal bars characterized by ‘Williamson’s striations’. Multiseriate rays with scalariform thickening, 4^6 cells wide and 4^5 cells high, across secondary xylem.