Proencistemon sp.

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

Proencistemon sp.

Text-fig. 9h–j

Description and remarks. The material includes a single staminate inflorescence fragment consisting of about seven tightly packed, stamens that lack a well-developed filament and have anthers that are almost sessile ( Text-fig. 9h ). Anthers are elongate, narrowly obtriangular, and 0.45 mm broad. Their full length is not preserved, but they are more than 0.8 mm long. Pollen grains are trichotomocolpate, about 16 µm in diameter, and semitectate-reticulate ( Text-fig. 9i, j ). These grains are very similar to pollen found in situ in the stamens of Proencistemon portugallicus .

Affinity and other occurrences. Pollen grains of Proencistemon sp. are closely similar in size, shape, aperture configuration and details of pollen wall to those found in situ in Proencistemon portugallicus , but the anthers are longer and differ in their narrow obtriangular shape. More material is needed to determine if a new species should be recognized formally. We have not observed similar stamens and pollen in other Early Cretaceous mesofossil floras from Portugal.

Figures

Text-fig. 9. Scanning electron microscope (SEM) images of stamens and pollen of Proencistemon portugallicus gen. et sp. nov. (a–g) and Proencistemon sp. (h–j); Catefica locality, Portugal. a) Fragment of stamen whorl from staminate inflorescence showing almost sessile anthers; note short bracts at the base of the stamen whorl (arrow) and apparent paired arrangement of the stamens; b) Fragment of stamen whorl showing almost sessile anthers and apparent paired arrangement of the stamens; c) Pollen in situ from stamen whorl in (b) showing poorly defined trichotomocolpate aperture and semitectate-reticulate tectum; d–g) Distal views of pollen in situ from pollen clump showing poorly defined trichotomocolpate aperture, semitectate-reticulate tectum (d–f), and fractured pollen wall with long, scattered columellae supporting narrow muri (g); h) Fragment of staminate inflorescence with narrow, almost sessile, stamens; i, j) Pollen from fragment of staminate inflorescence in (h) showing poorly defined trichotomocolpate aperture (i), semitectate-reticulate tectum (i, j) and long, scattered columellae supporting narrow muri (j). Specimens, Catefica 49-S266015 (a), Catefica 342-S122086 (b, c), Catefica 50-S170394 (d–g), Catefica 49-S107783 (h–j). Scale bars = 600 Μm (a, b, h), 6 Μm (c–f, i), 1.5 Μm (g, j).