Clavatipollenites-

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 : 357

Stamens with monocolpate Clavatipollenites- type pollen sp. 1

Text-fig. 10a–d

Description and remarks. The material comprises two stamen fragments that have a long, narrow, elongated tetrasporangiate anther ( Text-fig. 10a ) with in situ Clavatipollenites - type pollen ( Text-fig. 10b–d ). The anther is about 1.3 mm long and about 0.2 mm broad. Pollen is monoaperturate, almost circular in equatorial outline and about 17–20 µm in diameter. The aperture is about 12 µm long, with an irregular, indistinctly delimited margin and a colpus membrane covered by irregular verrucae that grade into the non-apertural reticulum ( Text-fig. 10b, c ). The exine is semitectate-reticulate with a homobrochate reticulum ( Text-fig. 10b–d ). Lumina are irregular, up to about 1.4 µm in diameter. Muri are narrow, 0.2–0.4 µm wide, and ornamented with minute verrucae arranged in a single longitudinal row. Columellae are long, about 0.6 µm, and widely spaced (Textfig. 10d). Orbicules observed on the inner surface of the anther wall are tiny, spherical and with fine spines.

Affinity and other occurrences. The general shape of the pollen grains, as well as their semitectate reticulate pollen wall, indistinctly delimited aperture, and aperture membrane covered by irregular verrucae, is closely similar to dispersed pollen assigned to the extinct pollen genus Clavatipollenites and pollen of extant Ascarina ( Walker and Walker 1984) . Based on these similarities these fossils are included here in the Chloranthales .

The four staminate structures described here from Catefica that have monocolpate Clavatipollenites - type pollen differ from each other in size and shape of anthers and in details of the pollen wall ( Tab. 1 ). Similar Clavatipollenitestype pollen grains are also present in the palynological preparations from Catefica. Clavatipollenites - type pollen observed on Canrightiopsis crassitesta from Catefica is much smaller and with a more open reticulum (see above).

Figures

Text-fig. 10. Scanning electron microscope (SEM) images of isolated “Stamen fragment with Clavatipollenites-type pollen sp. 1”; Catefica locality, Portugal. a) Fragment of tetrasporangiate stamen with pollen in situ; b) Detail from stamen fragment showing distal and proximal surfaces of in situ pollen grains and tiny orbicules on the inner surface of the anther wall (arrows); c) Pollen grains in distal view showing short colpi with irregular margins and aperture membrane with irregular verrucae; d) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation. Specimen, Catefica 50-S170387 (a–d). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (c), 1.5 Μm (d).