Clavatipollenites (Walker and Walker, 1984) COUPER

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 : 363-364

Stamens with Asteropollis- or Clavatipollenites - type pollen sp. 1

Text-fig. 16a–c

Description and remarks. The material consists of a single tetrasporangiate stamen with Asteropollisor Clavatipollenites - type pollen in situ ( Text-fig. 16a–c ). The filament is lacking, and the anther was probably sessile or almost sessile. The anther is elongate elliptical, about 1 mm long and 0.3 mm broad. None of the grains shows the aperture clearly exposed, which creates the uncertainty about their generic assignment, but the grains were probably monoaperturate. Pollen is circular in equatorial view, about 17–20 µm in diameter ( Text-fig. 16b ). The exine is semitectate-reticulate with a homobrochate reticulum (Textfig. 16b, c). Lumina are irregular and up to about 0.9 µm in diameter. Muri are narrow, about 0.3 µm wide, ornamented with minute verrucae arranged in one row, or sometimes in two longitudinal rows, separated by a line of fine perforations ( Text-fig. 16c ). Columellae are short, about 0.4 µm, and widely spaced ( Text-fig. 16c ). Orbicules are tiny, spherical with a verrucate to spiny surface ornamentation ( Text-fig. 16c ).

Affinity and other occurrences. The pollen wall is closely similar to that of pollen in situ in Proencistemon portugallicus , and also pollen in situ in the unnamed stamens and inflorescence fragments with Clavatipollenites- and Asteropollis - type pollen. The pollen is typically chloranthoid, but is distinct from all other chloranthoid pollen from Catefica, as well as from chloranthoid pollen recorded from other mesofossil floras from Portugal, in the line of fine perforations on top of the muri. The distinctiveness of this feature would support the recognition of a separate species, but the lack of information on the aperture configuration precludes closer comparison with pollen of extant Chloranthaceae and also the relevant genera of fossil pollen.

Figures

Text-fig. 16. Scanning electron microscope (SEM) images of “Stamen fragments with in situ Clavatipollenites- or Asteropollis-type pollen” (sp. 1: a–c; sp. 2: d–f; sp. 3: g–i); Catefica locality, Portugal. a) Stamen fragment showing pollen sacs; b) Distal view of pollen grain from (a) showing semitectate-reticulate tectum; c) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered, columellae supporting muri with fine pits and rounded supratectal ornamentation; note orbiculae with a finely spiny surface (arrows); d) Stamen showing very short filament, lateral pollen sacs and short apical extension of the narrow connective; e) Folded pollen grain from (d) showing semitectate-reticulate tectum; f) Detail of pollen wall from (d) showing the semitectatereticulate tectum and muri with fine rounded ornamentation; g) Stamen fragment; h, i) Detail of pollen grains from (g) showing the semitectate-reticulate tectum with smooth muri, long scattered columellae and tiny scattered orbicules (arrow). Specimens, Catefica 50-S170395 (a–c), Catefica 49-S172561 (d–f), Catefica 50-S170390 (g–i). Scale bars = 600 Μm (a, d, g), 6 Μm (b, e, h), 1.5 Μm (c, f, i).