Glyptostroboxylon CONWENTZ emend. DOLEZYCH et VAN DER BURGH, 2004

Koutecký, Vít & Sakala, Jakub, 2015, New Fossil Woods From The Paleogene Of Doupovské Hory And České Středohoří Mts. (Bohemian Massif, Czech Republic), Acta Musei Nationalis Pragae Series B 71 (3 - 4), pp. 377-398 : 378-379

Glyptostroboxylon CONWENTZ emend. DOLEZYCH et VAN DER BURGH

Glyptostroboxylon rudolphii DOLEZYCH et VAN DER BURGH

Pl. 1, Fig. 4–7, Text-fig. 3

2004 Glyptostroboxylon rudolphii DOLEZYCH et VAN DER BURGH , p. 410–411, text-fig. 6–7, p. 429, pl. II, fig. 1–9, p. 430, pl. III, fig. 1–5.

2008 Glyptostroboxylon rudolphii DOLEZYCH et VAN DER BURGH ; Teodoridis and Sakala, p. 304, fig. 5.13– 5.15.

M a t e r i a l: Bečov 99/04, Nechranice 115/06.

D e s c r i p t i o n. Growth rings distinct, 4–5 mm wide, with earlywood zone distinctly wider than latewood; transition from earlywood to latewood is gradual.

Tracheids: Outline polygonal to hexagonal. Radial diameter of earlywood tracheids 28–64–84 µm (middle value is the mean) and wall thickness 3–5 µm; radial diameter of latewood tracheids is 9–31–47 µm and wall thickness 5–7 µm; tangential diameter of tracheids ranges from 21 to 112 µm (mean 53); number of tracheids between two rays ranges from 1 to 10, most frequently 2–4 (Tab. 1). Pitting in radial tracheid walls uniseriate to biseriate ( Text-fig. 3 ), arranged in discontinuous vertical rows; bordered pits circular in outline, 10–14 µm in diameter, with crassulae occasionally present (sample 115/06).

Rays: Mostly uniseriate, occasionally biseriate, 14–35 µm wide, very low to medium average height (4–5 cells), sensu IAWA Committee (2004). Total height range (Text-fig. 2) between 1 and 17 cells (28–392 µm); large intercellular spaces present (sample 115/06); 4–8 rays per tangential mm and 18– 37 rays per square mm tangentially. Individual ray cells 14– 35 µm high, horizontal and end (tangential) walls thin and smooth, with 3–6 µm thick double wall. Ray tracheids absent. Cross-field pits taxodioid to glyptostroboid (= taxodioid with much reduced borders), 7–10 µm in diameter; 2–4 pits randomly distributed per cross-field.

Axial parenchyma: Apparently in tangential bands in cross-section. Transverse walls thin and smooth.

D i s c u s s i o n. The presence of axial parenchyma and taxodioid pits in a cross-field, as well as the absence of resin canals and spiral thickenings on tracheids place this wood in the family Cupressaceae ( Teodoridis and Sakala 2008: 300) . The bordered pits in radial walls of the tracheids disposed in two lateral discontinuous rows, thin and smooth transverse walls of the axial parenchyma, the homogeneous and mostly uniseriate rays, and the presence of glyptostroboid and taxodioid pits in the cross-field point more exactly to the genus Glyptostroboxylon CONWENTZ emend. DOLEZYCH et VAN DER BURGH ( Dolezych and Van der Burgh 2004) . Two species in this fossil genus have been defined so far: G. tenerum (KRAUS) CONWENTZ and G. rudolphii DOLEZYCH et VAN DER BURGH ( Dolezych and Van der Burgh 2004) . G. tenerum has typical bordered pits arranged in one, rarely two, vertical rows. Its cross-fields usually have only 1–2 (occasionally up to 4) glyptostoboid and taxodioid pits, and the rays are up to 12 cells high ( Dolezych and Van der Burgh 2004). On the other hand, G. rudolphii has up to 3 vertical rows of bordered pits in the radial walls of the tracheids; in a cross-field, there are 1–4 predominantly glyptostroboid, but also taxodioid and cupressoid pits, and the rays are up to 20 cells high. The presence of crassulae and large intercellular spaces between cells of the rays in our wood specimens indicates this second species, which was previously described from the Most Basin by Teodoridis and Sakala (2008). Only the dimensions of tracheid and cross-field pit diameters correspond to those in G. tenerum . However, the quantitative divergence is not very large, and we believe can be explained as intraspecific and individual variation (e.g., Bailey and Faull 1934), which will be discussed more in detail below. Consequently, we designate our wood as Glyptostroboxylon rudolphii DOLEZYCH et VAN DER BURGH.

Glyptostrobus (or Glyptostroboxylon ) is not known from the volcanic areas of Doupovské hory and České středohoří Mts. On the other hand, wood, leaves and reproductive structures are commonly present in the nearby Tertiary coal-basins (e.g., Kvaček and Teodoridis 2007).

Figures

Text-fig. 3. Schema of radial section of G. rudolphii (sample 99/04). t – tracheid, r – ray, bp – bordered pit, tp – taxodioid cross-field pit, gp – glyptostroboid cross-field pit.