Juniperoxylon pachyderma ( Goeppert, 1850 ) Kraeusel, 1949

Kłusek, Marzena, 2014, Miocene coniferous woods of the Polish Carpathian Foredeep, Acta Palaeontologica Polonica 59 (3), pp. 697-708 : 700-701

Juniperoxylon pachyderma ( Goeppert, 1850) Kraeusel, 1949

Fig. 4A–F .

1850 Cupressinoxylon pachyderma Goeppert, 1850 ; Goeppert 1850: 199, pl. 25: 1, 2.

1872 Cupressoxylon pachyderma ( Goeppert, 1850) Kraus, 1872 ; Kraus 1872: 374.

1890 Cupressinoxylon (Glyptostrobus) neosibiricum Schmalhausen, 1890 ; Schmalhausen 1890: 21, pl. 2: 44–49.

1850 Cupressinoxylon fissum Goeppert, 1850 ; Goeppert 1850: 200, pl. 25: 3–5.

1872 Cupressoxylon fissum ( Goeppert, 1850) Kraus, 1872 ; Kraus 1872: 375.

1913 Cupressinoxylon juniperoides Kraeusel, 1913 ; Kraeusel 1913:

35. 1913 Juniperus silesiaca Prill, 1913 ; Prill 1913: 30. 1919 Juniperoxylon silesiacum ( Prill, 1913) Kraeusel, 1919 ; Prill and

Kraeusel 1919: 297, pl. 22: 10. 1913 Juniperus pauciporosa Prill, 1913 ; Prill 1913: 35. 1919 Juniperoxylon pauciporosum ( Prill, 1913) Kraeusel, 1919 ; Prill and Kraeusel 1919: 302, pl. 22: 5–6. 1920 Juniperoxylon sp. ; Kraeusel 1920: 420, pl. 29: 4; pl. 36: 8. 1931 Juniperoxylon sp. ; Jurasky 1931: 161. 1937 Juniperoxylon sp. ; Roessler 1937: 77. 1944 Juniperoxylon neosibiricum ( Schmalhausen, 1890) Selling,

1944; Selling 1944: 14. 1949 Juniperoxylon pachyderma ( Goeppert, 1850) Kraeusel, 1949 ;

Kraeusel 1949: 177.

Material.—Eight small specimens (2–10 cm long) of coalified and to a small extent silicified wood (MZ LXXa–h) from Zgłobice site. Description is based on specimen MZ LXXc ( Fig. 4A–F ).

Description.—The wood constitutes fragments of trunks or large branches. Growth rings are narrow. Transition between earlywood and latewood zones is gradual. Axial parenchyma is abundant and arranged in tangential rows ( Fig. 4A ). Transverse walls of parenchyma cells have beadlike thickenings ( Fig. 4F ).

Tracheids are thick-walled and rounded. On radial and tangential walls of tracheids occur uniseriate bordered pits ( Fig. 4C ). Pits on radial walls of tracheids posses circular borders (9–11 μm in diameter) and oval apertures. On tangential walls of tracheids pits are scattered and circular in outline (diameter 6–7 μm). These pits have oval or slit-like, obliquely oriented apertures ( Fig. 4D ).

Rays are uniseriate, 1–15 cells tall, usually between 4 and 9 cells high ( Fig. 4E ). They consist of very thick and usually smooth transverse walls. Tangential walls contain beadlike or dentate thickenings. Indentures are absent. Crossfield regions possess 1–2 pits, arranged in one row ( Fig. 4B ). Pits have circular or oval outlines (7–8 μm in diameter) and oblique apertures. Rays often include resinous filling.

Remarks.—The lack of resin ducts, abundant axial parenchyma, type of tracheids pitting, cupressoid pits in the cross field, lack of ray tracheids and presence of thickenings in tangential walls of ray cells makes it possible to establish that the analysed wood belongs to the species Juniperoxylon pachyderma ( Goeppert, 1850) Kraeusel, 1949 . The basionym of this taxon is Cupressinoxylon pachyderma species which was created by Goeppert in 1850 on the basis of Miocene wood from Łażany. Juniperoxylon pachyderma was established by Kraeusel (1949), who transferred to this new species numerous previously described woods (see list of synonyms). However he has not determined its holotype. Juniperoxylon pachyderma does not have also an unambiguous nearest living relative. Most probably, it is closely related to the present-day Juniperus virginiana Linnaeus, 1753 wood ( Müller-Stoll 1951). However, it is quite anatomically diversified and encompasses trees belonging to different contemporary genera ( Prill and Kraeusel 1919). The specimens analysed have features characteristic of the group embracing Cupressus Linnaeus, 1753 , Diselma Hooker, 1857 , Fitzroya Hooker ex Lindley, 1851 , Juniperus Linnaeus, 1753 , and Libocedrus Endlicher, 1847 wood. In consideration of the significant similarity that exists within this group, the slight differences in their wood anatomy are used to identify the particular genera.

The species belonging to Diselma and Fitzroya are distinguished from the analysed specimen because of the smaller amount of axial parenchyma, pitted transverse walls of ray cells, more pits in the cross field and the presence of indentures. Additionally, Diselma is characterised by the presence of ray tracheids, while Fitzroya often possesses vestured pits. Cupressus and Libocedrus , in turn, are usually devoid of thickenings in tangential walls of ray cells; they often have pitted transverse walls of ray cells and possess indentures ( Greguss 1955). The structure that shows greatest similarity to the analysed specimen is that of species of the genus Juniperus . Juniper is characterised by the presence of pronounced beadlike thickenings in the tangential walls of ray cells and it also possesses intercellular spaces visible in the cross-section of wood ( Phillips 1941). Large intercellular spaces and rounded tracheids can also signify the presence of compression wood ( Schweingruber 1996). The analysed specimens have intercellular spaces, but do not otherwise show features typical of reaction wood. Thus this detail of anatomical structure supports its classification to Juniperus .

Stratigraphic and geographic range.— Tertiary; Europe and East Asia.

Figures

Fig. 4. Microphotographs of fossil wood Juniperoxylon pachyderma (Goeppert, 1850) Kraeusel, 1949 from Zgłobice, Middle Miocene; specimen MZ LXXc. A. Growth rings with abundant axial parenchyma (TS). B. Crossfield pitting (RLS). C. Uniseriate pits on tracheid walls (RLS). D. Bordered pits (arrow) on tangential walls of tracheids (TLS). E. Uniseriate rays (TLS). F. Beadlike thickenings (arrow) on axial parenchyma horizontal walls (TLS). Scale bars 50 μm.