Asteropollis-

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 : 361-362

Stamen with Asteropollis- type pollen sp. 1

Text-fig. 14a–e

Description and remarks. The species is based on a single stamen with numerous Asteropollistype pollen grains in situ. The stamen is slightly abraded, both apically and also at the base, but is estimated to have been about 1 mm long. The anther is about 0.4 mm broad, tetrasporangiate with two pairs of pollen sacs ( Text-fig. 14a ). Pollen is tetrachotomocolpate, circular in equatorial outline and about 20–23 µm in diameter ( Text-fig. 14b–d ). The arms of the aperture are short and do not reach the equator. The aperture margins are poorly defined and the aperture membrane is covered by irregular verrucae ( Text-fig. 14c, d ). The exine is semitectate-reticulate, columellate, with long, scattered columellae about 0.9 µm long that become thinner toward the base ( Text-fig. 14e ). Lumina are irregular in shape, up to about 1.5 µm in diameter. Muri are about 0.5 µm wide with a rounded profile and are ornamented by minute verrucae aligned in two rows along the margins of the muri ( Text-fig. 14e ).

Affinity and other occurrences. The in situ pollen grains are closely similar in size, shape and aperture configuration to pollen found attached to the surface of specimens of Hedyflora crystallifera from Catefica (above), and also specimens from Buarcos, the type locality for Hedyflora ( Friis et al. 2019b) . We consider it likely that this stamen, and the pistillate structures assigned to H. crystallifera , are from the unisexual flowers of the same plant species. In the size of the pollen grains, pollen shape, aperture configuration and details of the pollen wall the fossil stamen is also closely similar to material from the Torres Vedras locality described as “Stamen with in situ Asteropollis sp. pollen” ( Friis et al. 2019a). Pollen grains associated with H. crystallifera from the Buarcos locality include tetrachotomocolpate as well as trichotomocolpate forms, while in the Catefica mesofossil flora stamens with both tri- and tetrachotomocolpate pollen have not been found. Dispersed pollen grains assigned to Asteropollis cf. asteroides that are reported from early Aptian to middle Albian strata from coastal sections in Portugal are closely similar to the in situ grains from Catefica in both size and their tetrachotomocolpate aperture ( Heimhofer et al. 2007).

Figures

Text-fig. 14. Scanning electron microscope (SEM) images of “Stamen with Asteropollis-type pollen sp. 1”; Catefica locality, Portugal. a) Stamen with pollen in situ; b–d) Pollen in situ in stamen in (a) showing poorly defined tetrachotomocolpate aperture and semitectate-reticulate tectum; e) Detail of pollen wall showing semitectate-reticulate tectum with long, scattered columellae supporting the narrow muri; note two irregular rows of minute verrucae ornamenting surface of muri. Specimen, Catefica 50- S170385 (a–e). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (c, d), 1.5 Μm (e).