Atalantioxylon thanobolensis, Soomro & Mangi & Panhwer & Jatoi & Khuhro & Khokhar & Khan & Mengal & Shaikh, 2021

Soomro, Noorulain, Mangi, Jamal Uddin, Panhwer, Mahjabeen, Jatoi, Ghulam Hussain, Khuhro, Sajjad Ali, Khokhar, Qamaruddin, Khan, Shabab Ali, Mengal, Ali Nawaz & Shaikh, Nasirudin, 2021, Anatomical characteristics of fossil wood collected from the Manchar Formation (Miocene), Thano Bula Khan, Sindh, Pakistan, Italian Botanist 11, pp. 1-8 : 1

Atalantioxylon thanobolensis sp. nov.

Diagnosis.

Wood diffuse porous, growth ring present, demarcated by a line of terminal parenchyma, vessels small to medium in size, tangential diameter 45-134 µm, radial diameter 67-180 µm, solitary and in radial multiples of 2-5 evenly distributed over 24-30 mm2. Vessel members 150-400 µm long with simple oblique perforation. Intervessel pit pairs about 3-5µm in diameter, bordered alternate, circular to oval in shape. Parenchyma terminal, paratracheal parenchyma sparse. Xylem rays 1-3 (mostly 2) seriate 8-34 cells, 80-550 µm in height, distributed over 5-7 mm2. Ray tissue homogeneous, with only procumbent cells. Fibers moderately thick-walled with lumen 15-20 µm in diameter, polygonal in cross-section, non-septate, 450-660 µm long.

Holotype. The specimen was given the name "TB 35" (holotype shown in Fig. 2 ). It consists of silicified wood collected 10 km south-west of Thano Bula Khan, by the first author.

Horizon.

Manchar Formation. Age: Pliocene to Upper Miocene.

Morphological description.

The present fossil was anatomically identified from a well-preserved secondary wood sample measuring 20 cm in length and 4.5 cm in width. The color of the fossilized wood is light brown with shine indicating deposition of silicates.

Anatomical analysis.

Cross section. Wood diffuse porous, growth ring present, demarcated by a line of terminal parenchyma vessels small to medium in size, solitary and mostly in radial multiples of 2-5, mostly evenly distributed but in some places showing crowding at the beginning of the growth ring, circular to oval when solitary, sometimes elliptical due to pressure during fossilization. Tylosis present, parenchyma paratracheal, terminal, and apotracheal; the latter diffuse, while paratracheal parenchyma is sparse, present as few cells around some of the vessels; terminal parenchyma forms 2-3 seriate continuous lines demarcating the growth rings; diffuse parenchyma very sparse, difficult to locate in cross section, fibers thick-walled and non-septate (Fig. 2 ).

Tangential longitudinal section.

Vessels evenly distributed, 170-390 µm long with oblique ends and 73-273 µm wide. Perforation simple intervessel pit pairs about 3-6 µm diameter, bordered alternate circular to oval in shape. Xylem rays small to medium 1-3 (mostly 2) seriate 5-7 mm2, 8-34 cells, 80 -550 µm in height, separated by rows of fibers. Ray cells polygonal in tangential section often with dark content ray tissue, homogenous made up of procumbent cells; fibers elongated, non-septate, 15-20 µm in diameter, 450-630 µm in length (Fig. 3 ).

Radial longitudinal section.

Vessel segments elongated with oblique end, length of the vessel members, 175-395 µm, width 84-275 µm, vessel walls 10-12 µm thick. Intervessel pit pairs about 4-6 µm in diameter, bordered alternate, circular to oval in shape. Parenchyma cells attached to the vessels 20-25 µm in diameter and 45-60 µm in length. Xylem ray cells 8-34, 80-556 µm long (Fig. 4 ).

Figures

Figure 2. Atalantioxylon thanobolensis sp. nov. Plate 1 - 01: Macrograph of the fossil wood TB 35. Plate 1 - 02: Cross section showing general distribution of vessels and parenchyma (x 40). Plate 1 - 03: Cross section showing general distribution of vessels and parenchyma. (x 100). Plate 1 - 04: Cross section showing details of vessels and parenchyma. (x 200).

Figure 3. Atalantioxylon thanobolensis sp. nov. Plate 2 - 05 Tangential section showing general distribution of xylem rays and fibers (x 40). Plate 2 - 06 Tangential section showing general distribution of xylem rays and fibers (x 100). Plate 2 - 07 Tangential section showing details of xylem rays (x 400). Plate 2 - 08 Tangential section showing general distribution of xylem rays and fibers (x 200).

Figure 4. Atalantioxylon thanobolensis sp. nov. Plate 3 - 09 Radial longitudinal section showing arrangement of fibers (x 40). Plate 3 - 10 Radial longitudinal section showing arrangement of fibers (x 40). Plate 3 - 11 Radial longitudinal section showing vessel end-walls and pits (x 200). Plate 3 - 12 Radial longitudinal section showing pits on wall of vessels (x 100).