Foveosporites ryosekiensis Legrand, Pons, Nishida & Yamada, 2011

Legrand, Julien, Pons, Denise, Nishida, Harufumi & Yamada, Toshihiro, 2011, Barremian palynofloras from the Ashikajima and Kimigahama formations (Choshi Group, Outer Zone of south-west Japan), Geodiversitas 33 (1), pp. 87-135 : 102-104

Foveosporites ryosekiensis Legrand, Pons, Nishida & Yamada n. sp. ( Fig. 8D, E , H-J)

Foveosporites sp., Legrand, Palynologie des dépôts Jurassique supérieur et Crétacé inférieur du Japon, et provinces paléofloristiques du sud-est asiatique: 149, pl. V, fig. 16; pl. VI, figs 1, 2 (2009).

TYPE MATERIAL. — Site II, horizon 2, slide a; slides SEM-a, SEM-b ; holotype ( II2 a-U63; Fig. 8D, E ) ; paratypes ( SEM-II2 a, SEM-II2 b; Fig. 8H, I ) .

Collection de Paléobotanique-UPMC, Paris, France .

ETYMOLOGY. — The species name is after the Ryosekitype Province of Japan , of which this species seems to be characteristic.

OCCURRENCE. — Ashikajima and Kimigahama Fm (common).

TYPE LOCALITY. — Hatoyama, SE Choshi Peninsula, Chiba Prefecture, Japan .

STRATIGRAPHIC HORIZON. — Ashikajima Fm (Barremian) .

DIAGNOSIS

Trilete microspore. Amb triangular with straight to slightly convex sides. The laesurae are undulating, slightly raised (1-2.5 µm), and extend to the 3/4 of the spore radius. The contact area is psilate or can sometimes present one tubercule, and is delimited by a triangular thickening of the exine (3-4 µm wide), which overhangs and includes the trilete mark, and can extend to the apices. Beyond this thickening, the exine is psilate on the proximal face and forms a broad equatorial flange. The equator and the distal face are densely pitted to foveolate. On the distal face, the foveolae are more or less rounded, coarser near the equator (0.5 to 1.5 µm wide). The exine is 3 to 4 µm thick. Equatorial diameter = 35-45 µm; equatorial flange width = 5-7 µm.

REMARKS

Foveosporites labiosus Singh, 1971 has a thickening on its distal face similar to that observed in F.ryosekiensis , but its location is different. The equatorial flange reminds the Cyatheales (Lophosoriaceae) figured by Tryon & Tryon (1982).

BOTANICAL AFFINITIES

Lycopodiales , Lycopodiaceae .

Figures

FIG. 8. — Spores from the Barremian of south-west Japan: A-C, Retitriletes sp. (A, proximal face, Kimigahama Fm, SEM-I1a; B, lateral view, Kimigahama Fm, SEM-I1a; C, distal face, Kimigahama Fm, SEM-I1c); D, E, H-J, Foveosporites ryosekiensis n. sp. (D, E, proximal and distal faces,Ashikajima Fm,II2a-U63;H, proximal face,Ashikajima Fm,SEM-II2a;I, proximal face,Ashikajima Fm,SEM-II2b;J, lateral