Cupressinoxylon sp. 1
|
publication ID |
https://dx.doi.org/10.3897/phytokeys.156.54175 |
|
persistent identifier |
https://treatment.plazi.org/id/982EFA68-5890-57F5-A09D-AA66F9C61E0C |
|
treatment provided by |
|
|
scientific name |
Cupressinoxylon sp. 1 |
| status |
|
cf. Cupressinoxylon sp. 1 Figure 4A-I View Figure 4
Studied material.
MPEF-Pb 10733.
Locality.
LU8 at Laguna del Hunco (Fig. 1 View Figure 1 , Table 1 View Table 1 ), Chubut Province, Argentina.
Stratigraphic provenance.
Tufolitas Laguna del Hunco, Huitrera Formation (Ypresian, early Eocene).
Description.
Growth ring boundaries are distinct (Fig. 4A, B View Figure 4 ), with a gradual transition from earlywood to latewood (Fig. 2B View Figure 2 ). Tracheids are roundish to polygonal as seen in transverse section (Fig. 4C View Figure 4 ). Intertracheary pitting in radial walls is abietinean, predominantly uniseriate (Si = 1.01), very rarely biseriate, non-contiguous (Cp = 7.2%), and opposite when biseriate (Fig. 4D View Figure 4 ). Intertracheary pits are rounded in outline; 13.9 (10.4-15.8, SD = 1.1) μm in vertical diameter (Fig. 4D View Figure 4 ). Tracheid tangential diameter is 24.2 (18.8-32.4, SD= 3.3) μm. Axial parenchyma is present, scarce, and apparently with a tendency to be tangentially zonate (Fig. 4C, G, I View Figure 4 ). Cross-fields have 1-2, mostly one, mean 1.2, pits per cross-field (Fig. 4D-G View Figure 4 ). Cross-field pits are circular and bordered, apparently the border is usually wider than the aperture, and the aperture is rounded; 7.4 (5.2-9.6, SD = 1.2) μm in vertical diameter (Figs 4D-G View Figure 4 , 6B View Figure 6 ). Horizontal walls of ray parenchyma cells are smooth (Fig. 4E-G View Figure 4 ). Average ray height is medium, 4.0 (1-11, SD = 1.9) cells high, rays are exclusively uniseriate (Fig. 4H-I View Figure 4 ) and with a frequency of 6.7 (4-8, SD = 1.2) rays per mm.
Remarks.
Abietinean intertracheary radial pitting and apparently cupressoid pits in the cross-fields (bordered pits with the border wider than the aperture) indicate that this specimen belongs to the genus Cupressinoxylon , following Philippe and Bamford (2008). Cupressinoxylon includes wood with affinity to Cupressaceae and Podocarpaceae , with cupressoid cross-field pits ( Pujana et al. 2014).
Cross-field pit border width is a key character of Cupressinoxylon . The poor preservation of this specimen prevents clear observation of the cross-field pits and also of the axial parenchyma walls; consequently, this specimen cannot be assigned with confidence to this fossil-genus and it is left as cf. Cupressinoxylon . Philippe and Bamford (2008) suggested that specimens in which the pit border is thinner than the aperture can also assigned to Podocarpoxylon Gothan.
The particular specimen studied here seems to be more similar to Podocarpaceae than to Cupressaceae because of the number of pits per cross-field. One, rarely two, pits per cross-field is common in the Podocarpaceae , whereas it is rarely observed in Cupressaceae ( Tainter 1968; Greguss 1972; Meylan and Butterfield 1978; Roig 1992; Vidaurre Echeverría et al. 1987; Woltz et al. 1998; Vásquez Correa et al. 2010). Nevertheless, at this point we are not able to determine with certainty its affinity.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.