Protelicoxylon asiaticum ( Serra, 1969 ) Philippe, 1995

Akkemik, Ünal, Kandemir, Raif, Philippe, Marc, Güngör, Yildirim & Köroğlu, Fatih, 2022, Palaeobiogeographical implications of the first fossil wood flora from the Jurassic of Turkey, Acta Palaeontologica Polonica 67 (3), pp. 745-766 : 753-757

Protelicoxylon asiaticum ( Serra, 1969) Philippe, 1995

Figs. 6–8 .

Material.—One silicified wood fragment numbered as ISTO-FW-00242 from Jurassic of Turkey, locality Yeşilbağlar of the city of Oltu in the province of Erzurum. It is deposited at t he Department of Forest Botany , Faculty of Forestry, Istanbul University-Cerrahpasa, Istanbul, Turkey .

Description.—Growth ring boundaries distinct, with 2–4 rows of flattened latewood tracheids. Transition from earlywood to latewood gradual. Tracheid cross sections circular to polygonal ( Fig. 6A, B ). Tangential and radial widths of tracheids are 27 (18–36) µm and 23 (15–32) µm in the earlywood, and 22 (16–27) µm and 6 (3–10) µm in latewood, respectively. Double wall thicknesses are 8 (5–10) µm in earlywood and 4 (2–7) µm in latewood, respectively. Axial resin canals absent ( Fig. 6A, B ).

Rays exclusively uniseriate, very rarely partly biseriate for some levels. Rays 3–7 (1–10) cells and 104 (32–217) µm high, and 28 (17–46) µm wide ( Fig. 6C, D ). Axial parenchyma present ( Fig. 7A, B ). Intertracheary pits present, sparse and uniseriate on tangential walls ( Fig. 7 C ). Rays 7 (5–9) per mm. Spiral thickenings common, often paired or even grouped by three, thin (1–4 µm wide), with a low angle to the horizontal (30°) ( Fig. 7D, E ). A few isolated or paired callitroid thickening were observed.

Rays homogenous ( Fig. 7F ). Cross-fields are araucarian, with 3–13 cupressoid pits per cross-field. Diameters of cross-field pits are 4 (3–6) µm. Intertracheary pits on radial walls predominantly araucarian and uniseriate, very rarely biseriate, and then opposite (abietinean). The radial intertracheary pitting is of the mixed-type. Diameters of intertracheary pits on radial walls are 14 (11–18) µm in diameter ( Figs. 7F , 8A–D ).

Remarks.— Protelicoxylon Philippe, 1995 , is a genus de- signed for woods that are characterized by mixed-type pitting on the radial walls of the tracheids and different types of tertiary thickenings: spirals, crassulae or thin horizontal bars. The genus has cross-fields with cupressoid to dacry- dioid pits and might features axial parenchyma. This genus was recently reviewed by Philippe (1995) ( Table 2).

Our wood is most similar to Protelicoxylon asiaticum ( Serra, 1969) Philippe, 1995 in having predominantly araucarian type of radial intertracheary pitting, presence of axial parenchyma, 2–5 cupressoid oculipores per field, and presence of callitroid thickenings ( Table 3). The wood described by Nadjafi (1982), from the Middle Jurassic of Elburz ( Iran) is also strikingly similar to our material.

Figures

Fig. 6. Taxacean wood sections of Protelicoxylon asiaticum (Serra, 1969) Philippe, 1995 (ISTO-FW-00242) from Jurassic of the Yesilbaglar locality of the province of Erzurum, Turkey.A1,A2, transversal sections with distinct growth ring boundary;A3,A4, tangential sections with predominantly uniseriate and short rays.

Fig. 7. Taxacean wood sections of Protelicoxylon asiaticum (Serra, 1969) Philippe, 1995 (ISTO-FW-00242) from Jurassic of the Yesilbaglar locality of the province of Erzurum, Turkey.A1,A2, axial parenchyma in tangential sections;A3, intertracheary pits in tangential section;A4,A5, spiral thickening on tracheid walls; A6, homogenous ray, araucarian and uniseriate intertracheary pits on radial walls.

Fig. 8. Taxacean wood sections of Protelicoxylon asiaticum (Serra, 1969) Philippe, 1995 (ISTO-FW-00242) from Jurassic of the Yesilbaglar locality of the province of Erzurum, Turkey.A1–A4, homogenous ray, araucarian and uniseriate intertracheary pits on radial walls; A1,A3,A4, araucarian cross-fields pits with 3-13, each of them cupressoid in cross-fields.