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Angiosperm mesofossils are described from the Lower Cretaceous Almargem Formation exposed near the village of Catefica, Portugal, and are thought to be of Aptian-early Albian age. The mesofossil assemblage from Catefica is diverse and, in addition to the angiosperms described here, also contains a rich assemblage of non-angiosperm fossils, including leafy axes of bryophytes and lycopsids, lycopsid and salvinialean megaspores, and sporangia, sori and leaf fragments of ferns. Thereare also twigs, cones, cone scales, seeds and sporangia of several kinds of conifers. Other seed plants include 11 species of chlamydospermous seeds and vegetative axes related to the BEG group (Bennettiales-Erdtmanithecales-Gnetales). In terms of the number of plant fragments identified, angiosperms are most abundant in the Catefica assemblage and account for morethan half of all specimens. Angiosperms also dominate in number of species, but because the non-angiosperm fossils have notbeen studied in detail the total number of species in the flora is not yet established. Sixty-seven species of angiosperms arerecognized. Angiosperm diversity is mainly at the level of non-eudicots, including ANA-grade angiosperms, Chloranthaceae and magnoliids. Remains of chloranthoid angiosperms are especially common, both in the number of specimens and in numberof species recognized. About 40 % of the specimens, and more than 25 % of the species are chloranthoids. Remains of magnoliid angiosperms (Magnoliales, Laurales, Canellales, Piperales) are also prominent among the angiosperms. Eudicots are subordinate: only 3–4 % of all angiosperm specimens can be assigned confidently to eudicot angiosperms. Five new genera and six new species of angiosperms are established (Canrightia foveolata sp. nov., Elasmostemon paisii gen. et sp. nov., Endressistemon cateficensis gen. et sp. nov., Ibericarpus cuneiformis gen. et sp. nov., Proencistemon portugallicus gen. et sp. nov., Valvidistemon globiferus gen. et sp. nov.)., We thank the Paul Scherrer Institute, Villigen,Switzerland for provision of synchrotron radiation beamtime at the TOMCAT beamline X02DA of the SwissLight Source. We are also grateful to Federica Marone forher help at the beamline (project 20070197, 20080872,20100167,20110963, 20130185, 20141047, 20160140,20171476, 20190071, 20211671 to P. C. J. Donoghue, S.Bengtson, E. M. Friis and M. Rücklin), Anna Lindström forhelp with the SRXTM analyses, and Pia Bomholt Jensenfor her help with SEM at the University of Aarhus. Wealso thank Patrick S. Herendeen and Steven R. Manchesterfor valuable comments to the manuscript. Support for thisresearch was also obtained from the Swedish ResearchCouncil (2014-5228 to E. M. Friis), United States NationalScience Foundation (BSR-8708460, DEB-9616443, DEB-1348456, DEB-1748286, to PRC and colleagues) the OakSpring Garden Foundation, the Czech Grant Agency (project20-06134S) and the Portuguese Science Foundation (FCT),under the projects UIDB/04292/2020 and UIDP/04292/2020,granted to MARE, and LA/P/0069/2020, granted to theAssociate Laboratory ARNET.

Here we describe a new Lower Cretaceous palynoflora from the Lusitanian Basin, located in the westernmost sector of the Iberian Peninsula. The spore-pollen assemblage was extracted from samples collected in the Carregueira clay pit complex, located near the village of Juncal, western Portugal, from sedimentary deposits belonging to the Figueira da Foz Formation. A rich and well-preserved palynoflora, typical of non-marine fluvial environments, was recovered. Fifty-eight species and morphological groups of palynomorphs in 43 genera were recognized. The palynoflora is dominated by fern spores and conifer pollen. Angiosperm pollen is scarce and mainly represented by Afropollis, Clavatipollenites, Stellatopollis and Senectotetradites. Comparisons with described marine sections in Portugal suggest that the fossil horizon is lower Albian, corresponding to a hiatus between Zone I and Zone II in the Potomac Group of the eastern USA. The same beds contain a mesofossil flora dominated by angiosperm seeds, fruits and flowers. A similar contrast in the relative abundance of angiosperm mesofossils and pollen is seen at other Portuguese localities but is not evident in the Potomac Group. The palynoflora and the sedimentological data suggest deposition in wet lowland environments in a moderately humid regional setting., This research was supported by grants from the Amadeu Dias Foundation, the Portuguese Science Foundation (FCT) through the project UIDB/04292/2020 to MARE - Marine and Environmental Sciences Centre, the Czech Grant Agency (project 20-06134S) and by the Swedish Research Council (VR, grant no. 2019-4061).

Angiosperm mesofossils are described from the Lower Cretaceous Almargem Formation exposed near the village of Catefica, Portugal, and are thought to be of Aptian-early Albian age. The mesofossil assemblage from Catefica is diverse and, in addition to the angiosperms described here, also contains a rich assemblage of non-angiosperm fossils, including leafy axes of bryophytes and lycopsids, lycopsid and salvinialean megaspores, and sporangia, sori and leaf fragments of ferns. Thereare also twigs, cones, cone scales, seeds and sporangia of several kinds of conifers. Other seed plants include 11 species of chlamydospermous seeds and vegetative axes related to the BEG group (Bennettiales-Erdtmanithecales-Gnetales). In terms of the number of plant fragments identified, angiosperms are most abundant in the Catefica assemblage and account for morethan half of all specimens. Angiosperms also dominate in number of species, but because the non-angiosperm fossils have notbeen studied in detail the total number of species in the flora is not yet established. Sixty-seven species of angiosperms arerecognized. Angiosperm diversity is mainly at the level of non-eudicots, including ANA-grade angiosperms, Chloranthaceae and magnoliids. Remains of chloranthoid angiosperms are especially common, both in the number of specimens and in numberof species recognized. About 40 % of the specimens, and more than 25 % of the species are chloranthoids. Remains of magnoliid angiosperms (Magnoliales, Laurales, Canellales, Piperales) are also prominent among the angiosperms. Eudicots are subordinate: only 3–4 % of all angiosperm specimens can be assigned confidently to eudicot angiosperms. Five new genera and six new species of angiosperms are established (Canrightia foveolata sp. nov., Elasmostemon paisii gen. et sp. nov., Endressistemon cateficensis gen. et sp. nov., Ibericarpus cuneiformis gen. et sp. nov., Proencistemon portugallicus gen. et sp. nov., Valvidistemon globiferus gen. et sp. nov.)., We thank the Paul Scherrer Institute, Villigen,Switzerland for provision of synchrotron radiation beamtime at the TOMCAT beamline X02DA of the SwissLight Source. We are also grateful to Federica Marone forher help at the beamline (project 20070197, 20080872,20100167,20110963, 20130185, 20141047, 20160140,20171476, 20190071, 20211671 to P. C. J. Donoghue, S.Bengtson, E. M. Friis and M. Rücklin), Anna Lindström forhelp with the SRXTM analyses, and Pia Bomholt Jensenfor her help with SEM at the University of Aarhus. Wealso thank Patrick S. Herendeen and Steven R. Manchesterfor valuable comments to the manuscript. Support for thisresearch was also obtained from the Swedish ResearchCouncil (2014-5228 to E. M. Friis), United States NationalScience Foundation (BSR-8708460, DEB-9616443, DEB-1348456, DEB-1748286, to PRC and colleagues) the OakSpring Garden Foundation, the Czech Grant Agency (project20-06134S) and the Portuguese Science Foundation (FCT),under the projects UIDB/04292/2020 and UIDP/04292/2020,granted to MARE, and LA/P/0069/2020, granted to theAssociate Laboratory ARNET.

Here we describe a new Lower Cretaceous palynoflora from the Lusitanian Basin, located in the westernmost sector of the Iberian Peninsula. The spore-pollen assemblage was extracted from samples collected in the Carregueira clay pit complex, located near the village of Juncal, western Portugal, from sedimentary deposits belonging to the Figueira da Foz Formation. A rich and well-preserved palynoflora, typical of non-marine fluvial environments, was recovered. Fifty-eight species and morphological groups of palynomorphs in 43 genera were recognized. The palynoflora is dominated by fern spores and conifer pollen. Angiosperm pollen is scarce and mainly represented by Afropollis, Clavatipollenites, Stellatopollis and Senectotetradites. Comparisons with described marine sections in Portugal suggest that the fossil horizon is lower Albian, corresponding to a hiatus between Zone I and Zone II in the Potomac Group of the eastern USA. The same beds contain a mesofossil flora dominated by angiosperm seeds, fruits and flowers. A similar contrast in the relative abundance of angiosperm mesofossils and pollen is seen at other Portuguese localities but is not evident in the Potomac Group. The palynoflora and the sedimentological data suggest deposition in wet lowland environments in a moderately humid regional setting., This research was supported by grants from the Amadeu Dias Foundation, the Portuguese Science Foundation (FCT) through the project UIDB/04292/2020 to MARE - Marine and Environmental Sciences Centre, the Czech Grant Agency (project 20-06134S) and by the Swedish Research Council (VR, grant no. 2019-4061).

Premise of research: Accumulating data from phylogenetic analyses of living taxa and from paleobotany (pollen, leaves, and floral structures) has greatly improved our understanding of the Cretaceous rise to dominance of the angiosperms. Relatives of the near-basal family Chloranthaceae were conspicuous in the Early Cretaceous. These include female flowers and adhering pollen (Asteropollis) that resemble those of the genus Hedyosmum, but male structures with in situ pollen are not well known. Here we focus on the morphology and ultrastructure of pollen from a spike of unistaminate, ebracteate flowers from the Aptian–Albian Catefica locality and its evolutionary implications. Methodology: The coalified mesofossil was isolated from unconsolidated sediment by sieving and was cleaned with HCl, HF, and water. In situ pollen was studied using LM, SEM, and TEM. The phylogenetic relationships of the fossil were evaluated with parsimony analysis of a morphological data set with arrangements of living taxa based on molecular studies. Pivotal results: The pollen aperture is often poorly defined but is most commonly a three-armed sulcus. The exine is reticulate-columellate with a nanoverrucate supratectal sculpture. The nonapertural nexine consists of a thicker foot layer and a thin but continuous endexine that thickens and becomes lamellated under the aperture; the total nexine thickness is less than in most extant Chloranthaceae. Despite some uncertainty due to the thin nexine and similarities between the staminate structure and that of Ceratophyllum, phylogenetic analyses are most consistent with a position attached to the stem lineage of Hedyosmum. Conclusions: The variable but mainly three-armed sulcus of the Catefica fossil may represent an intermediate stage in the transformation from the ancestral simple sulcus of Chloranthaceae to the four- to six-armed sulcus of typical Asteropollis pollen and living Hedyosmum. Dispersed trichotomosulcate pollen with a chloranthaceous

A new species of spore, Costatoperforosporites friisiae sp. nov., is described from the Early Cretaceous (late Aptian–early Albian) deposits of Catefica in the Lusitanian Basin, western Portugal. Although the morphology of the muri is clearly of the Cicatricosisporites type, the presence of micropores on these sculptural elements and within the intervening grooves is a particularly distinctive feature and more typical of spores that have been attributed previously to Costatoperforosporites. As a result, this genus is emended not only to accommodate Costatoperforosporites friisiae but also to differentiate it more clearly from other, similar, murornate genera. It is considered to represent the family Anemiaceae. So far, Costatoperforosporites friisiae has only been encountered in the Catefica palynoflora. The presence of many other pteridophyte spores, especially of schizaealean derivation, together with abundant cheirolepidiacean remains at this locality, strongly suggests a warm, moist climate and diverse source vegetation.

A new species of spore, Costatoperforosporites friisiae sp. nov., is described from the Early Cretaceous (late Aptian–early Albian) deposits of Catefica in the Lusitanian Basin, western Portugal. Although the morphology of the muri is clearly of the Cicatricosisporites type, the presence of micropores on these sculptural elements and within the intervening grooves is a particularly distinctive feature and more typical of spores that have been attributed previously to Costatoperforosporites. As a result, this genus is emended not only to accommodate Costatoperforosporites friisiae but also to differentiate it more clearly from other, similar, murornate genera. It is considered to represent the family Anemiaceae. So far, Costatoperforosporites friisiae has only been encountered in the Catefica palynoflora. The presence of many other pteridophyte spores, especially of schizaealean derivation, together with abundant cheirolepidiacean remains at this locality, strongly suggests a warm, moist climate and diverse source vegetation.