Endressistemon sp. 1

Friis, Else Marie, Crane, Peter R., Pedersen, Kaj Raunsgaard, Mendes, Mário Miguel & Kvaček, Jiří, 2022, The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms, Fossil Imprint 78 (2), pp. 341-424 : 383

cf. Endressistemon sp. 1

Text-fig. 29a, b

D e s c r i p t i o n a n d r e m a r k s. The material includes a pair of compressed stamens resembling the staminate structures of Endressistemon cateficensis described above.The stamens are up to 0.8 mm long including the apical projection, and about 0.3 mm broad. The apical projection is longer than the thecae, about 0.45 mm long, and tapers to a long, pointed tip ( Text-fig. 29a ). The two stamens adhere together closely, but their bases are missing, and whether the stamens had separate distinct bases or a shared base, or whether the base was lost during fossilization, is not known. Anther dehiscence is longitudinal.

Pollen grains observed in situ ( Text-fig. 29b ) are monocolpate, semitectate-reticulate, circular in equatorial view, about 9 µm in diameter. The aperture is long, reaching almost to the equator, and the aperture margin is distinct. The reticulum is homobrochate ( Text-fig. 29b ).

A f f i n i t y a n d o t h e r o c c u r r e n c e s. The stamens and in situ pollen are closely similar to those of Endressistemon cateficensis described above, but the pollen sacs are more rounded and the apical projection is much longer. Because of the missing stamen base it is uncertain whether the two taxa are closely related.

Figures

Text-fig. 29. Scanning electron microscope (SEM) images of stamens and pollen grains of cf. Endressistemon sp. 1 (a, b), cf. Endressistemon sp. 2 (c, d) and cf. Endressistemon sp. 3 (e–g); Catefica locality, Portugal. a) Two adhering stamens, each with a long, pointed extension of the connective; b) Monocolpate, reticulate pollen in situ in stamen from stamen pair in (a); c) Fragment of stamen with prominent apical extension of the connective; d) Reticulate, apparently monocolpate, pollen in situ in stamen fragment in (c); e) Stamen with basifixed anther, perhaps sessile, and with prominent, wing-like apical extensions of the connective; note the dehisced thecae with the anther wall curved back; f, g) Monocolpate, reticulate pollen in situ in stamen in (e). Specimens, Catefica 49-S107780 (a, b), Catefica 49-S107784 (c, d), Catefica 49-S107781 (e–g). Scale bars = 600 Μm (a, c, e), 6 Μm (b, d, f, g).