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 : 360-361

Stamens with monocolpate Clavatipollenites- type pollen sp. 4

Text-fig. 13a–d

Description and remarks. The material comprises a fragment of a staminate structure with more than ten closely packed stamens that have in situ Clavatipollenitestype pollen. There are no well-developed filaments. The shape of the fragment indicates that the anthers were sessile or almost sessile and that the stamens were originally borne in whorls in a multistaminate inflorescence ( Text-fig. 13a ). The anthers are strongly compressed, obovate in outline, about 0.5 mm long and 0.2 mm broad. Pollen is monoaperturate with a poorly delimited aperture ( Text-fig. 13b, c ). The grains are about 14–17 µm in diameter. The exine is semitectatereticulate with a homobrochate reticulum ( Text-fig. 13b–d ). Lumina are irregular, up to about 1 µm in diameter. Muri are narrow, about 0.3 µm wide ornamented with minute verrucae arranged in one to two rows. Columellae are long, about 0.7 µm, and widely spaced ( Text-fig. 13d ). Orbicules were not observed.

Affinity and other occurrences. See comments on “Stamens with monocolpate Clavatipollenitestype pollen sp. 1” above. The pollen is closely similar to dispersed fossil grains assigned to the extinct genus Clavatipollenites , as well as pollen of extant Ascarina . The stamens are similar to those in the staminate inflorescences of Proencistemon portugallicus and Proencistemon sp. from Catefica (above) in being arranged in dense whorls and having sessile or almost sessile anthers. However, pollen in situ within stamens of Proencistemon differs in having a trichotomocolpate aperture, and stamens of Proencistemon are longer than those of the staminate structure described here. The estimated number of stamens per whorl is also fewer than in Proencistemon .

Figures

Text-fig. 13. Scanning electron microscope (SEM) images of “Staminate inflorescence fragment with Clavatipollenites-type pollen sp. 4”; Catefica locality, Portugal. a) Fragment of stamen whorl from staminate inflorescence showing several closely packed, almost sessile stamens that lack a well-developed filament; b, c) Distal and proximal views of pollen grains showing poorly defined aperture with verrucate aperture membrane; 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 49-S107782 (a–d). Scale bars = 600 Μm (a), 6 Μm (b, c), 1.5 Μm (d).