Cunninghamia nakatonbetsuensis S.Y.Jiang & T.Yamada, 2024

Jiang, Songyao, Shigeta, Yasunari, Matsunaga, Kelly K. S. & Yamada, Toshihiro, 2024, A new species of Cunninghamia (Cupressaceae) from the Upper Cretaceous (Maastrichtian) of Hokkaido, Japan, Phytotaxa 664 (1), pp. 1-11 : 2

Cunninghamia nakatonbetsuensis S.Y.Jiang & T.Yamada , sp. nov. ( Figs. 1–4 ).

Holotype: — JAPAN. Hokkaido: Nakatonbetsu town, Heitaro-zawa Creek, River float at 44.980°N, 142.252°E, 70 m elevation, 10 June 2005, NSM PP-9178 ( NSM PP!).

Diagnosis: —Seed cone ovoid, ca. 35 mm long and ca. 30 mm wide. Bract-scale complexes swollen to form a mound around the apical third, supplied with a single vascular strand from cone axis, which firstly divides into abaxial and central adaxial bundles; central adaxial bundle bifurcating once horizontally; abaxial bundle dividing horizontally into 8–10 smaller bundles; 2 lateral adaxial bundles, each branched from abaxial bundle on a lateralmost side; resin canal placed both adaxial and abaxial to the vascular strands. Ovuliferous scale fused to bract except for each lateral margin; apical part trilobed.

Stratigraphic horizon: —the lower Maastrichtian Heitaro-zawa Formation of the Hakobuchi Group.

Etymology: —The specific epithet is named after the town where the sample was collected.

Slides: —NSM PP-9178-a01–a14, b01–b69, c01–c34.

Figures

FIGURE 1. Cunninghamia nakatonbetsuensis. A. Longitudinal section of seed cone.A ovuliferous scale would be attached on the surface between two arrowheads. Bracket shows a stalk-like part of cone scale. Slide #c34. B. 3D reconstructed image of cone. C. Cross section through the basal part of cone. Slide #a14. D. Primary xylem tracheids in cone axis. Slide #c32. E. Secondary xylem tracheids in cone axis. Slide #c34. F. Rays (asterisks) in secondary xylem of cone axis. Slide #c34. G. Close-up of C, showing a resin canal in cortex with resin residue inside. Abbreviations: c, cortex; p, pith; r, resin canal; v, vascular tissue.

FIGURE 2. Anatomy of bract-scale complex in Cunninghamia nakatonbetsuensis. A. 3D reconstructed image of bract-scale complex with adaxial face up. Red asterisk shows a mound. Lobes of ovuliferous scale are coloured green in a section. B. Paradermal section showing serrate margin. Slide #c21. C. Cross section through basal stalk-like part. Slide #c30. D. Cross section through middle stalk-like part. Slide #c20. E. Cross section through middle part. Slide #c4. F. Cross section through swollen part (red asterisk). Slide #b31. Abbreviations: as, apical spine; bv, abaxial vascular bundle; cdv, central adaxial vascular bundle; mv, main vascular bundle; r, resin canal; sd, sclereid.

FIGURE 3. Anatomy of bract-scale complex in Cunninghamia nakatonbetsuensis. A. Cross section of bract-scale complex highlighting marginal free parts (arrows) and grooves (double-arrowheads) between lobes of ovuliferous scale. Slide #c34. B. Close up of 1A, showing a disintegrated region of cone scale (between two arrowheads), possibly formed by detachment of ovuliferous scale. Red asterisk shows a mound. Slide #c34. C. Cross section of bract-scale complex with two aborted ovules (o). Note that two circular structures in the middle are not ovules but hollow made by disintegration.

FIGURE 4. Anatomy of vascular bundles and resin canals in Cunninghamia nakatonbetsuensis. A. Cross section of main vascular bundle just diverging from vascular cylinder of cone axis. Slide #c27. B. Cross section of main vascular bundle with the central adaxial bundle diverging. Slide #c28. C. Cross section of bract-scale complex with central adaxial strand dividing (arrows). Slide #c13. D. 3D reconstructed image of vascular system in basal part of bract-scale complex. Adaxial vascular bundles are coloured red and abaxial bundles in yellow. Note bifurcate central adaxial bundle (arrows). Arrowhead shows lateral adaxial vascular bundle. E. Resin canals adaxial and abaxial to vascular strands. Note transfusion tissue connecting vascular strands. F. Cross section of bract-scale complex with two lateral adaxial bundles (arrowheads) diverging. Slide #c5. G. Cross section through stalk-like part of bract-scale complex. Slide #c27. H. 3D reconstructed images of vascular system and resin canal system. Cone scale is positioned with the adaxial side up and the apical direction to the right. Resin canals abaxial or adaxial to a row of vascular strands are coloured cyan or blue, respectively. Vascular bundles are coloured as 4D. I, J. Cross sections of the same bract-scale complex through its apical part. Section in J (slide #b56) is apical to that in I (slide #b53). Two abaxial resin canals are fused as they run into more apical part (asterisks).Abbreviations: bv, abaxial vascular bundle; cdv, central adaxial vascular bundle; mv, main vascular bundle; ph, phloem; px, primary xylem; r, resin canal; sx, secondary xylem; tt, transfusion tissue.