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The nomenclature and status of the fossil-genus Sparganiaceaepollenites Thiergart 1937 and several of its species are problematic. We confirm the status of the genus and provide an emended description for it to accommodate new characters that were recently described in some species. We note that (i) the name Sparganiaceaepollenites microreticulatus Grabowska and Wa?y?ska 2009 from the Miocene of Poland is illegitimate according to the rules of the International Code of Nomenclature for algae, fungi, and plants, as a later homonym of Sparganiaceaepollenites microreticulatus Kar and Jain 1981 from the Miocene of India; (ii) the name Sparganiaceaepollenites reticulatus Samant et al. 2022 from the Maastrichtian of India is illegitimate as a later homonym of Sparganiaceaepollenites reticulatus Doktorowicz-Hrebnicka 1960 ex Krutzsch and Vanhoorne 1977 from the Miocene of Poland; and (iii) the name Sparganiaceaepollenites annulatus Thakre et al. 2024 from the Danian of India is illegitimate as a later homonym of Sparganiaceaepollenites annulatus De Benedetti 2023 from the Maastrichtian?Danian of Argentina. We propose the new names (i) Sparganiaceaepollenites oczkowicensis nom. nov. subst. pro Sparganiaceaepollenites microreticulatus Grabowska and Wa?y?ska; and (ii) Sparganiaceaepollenites intertrappeansis nom. nov. subst. pro S. reticulatus Samant et al. (an emended description is provided). Additionally, Sparganiaceaepollenites annulatus Thakre et al. is considered a heterotypic synonym of Sparganiaceaepollenites intertrappeansis nom. nov. 

A palynological study was carried out based on 157 samples collected from four representative stratigraphic sections of the Maastrichtian-Danian deposits of the La Colonia Formation outcropping in northern Chubut Province, Patagonia, Argentina. About 240 palynomorphs were recognized. Plant communities were dominated in terms of richness by ferns and angiosperms, but algae and gymnosperms are also well-represented. In this contribution, we present the systematic study of bryophyte, lycophyte, and fern spores. Bryophytes comprise eight species (10% of spore diversity), including representatives of Marchantiophyta, Bryophyta, and Anthocerotophyta. Lycophytes encompass 15 species (20% of spore diversity) and are represented by the families Lycopodiaceae and Selaginellaceae. Ferns comprise 53 species (70% of spore diversity), including members of Anemiaceae, Dicksoniaceae, Dipteridaceae, Gleicheniaceae, Lygodiaceae, Marsileaceae, Matoniaceae, Osmundaceae, Polypodiaceae, Salviniaceae, and Schizaeaceae, among others of uncertain affinities. Four new species are erected: a lycophyte (Neoraistrickia loconiensis sp. nov.), a salvinialean (Thecaspora polygonalis sp. nov.), and two fern species of unknown affinities (Clavatosporis varians sp. nov. and Microreticulatisporites patagonicus sp. nov.). The recorded palynoflora reinforces previous environmental interpretation of the La Colonia deposits as coastal plains bathed by shallow seas and barrier island/lagoon complexes and the presence of freshwater bodies where aquatic plant communities developed. The vegetational history of the bryophytes, lycophytes, and ferns in the studied sections of the La Colonia Formation indicates the lack of a significant floristic change across the K–Pg interval at the local scale. 

There are few studies focused on spore and pollen clumps in paleopalynological samples, and these are only reports from the Northern Hemisphere. These aggregates may be of animal or floral origin. The goal of this contribution is to provide the first detailed study of spore and pollen clumps from the Southern Hemisphere, and to discuss their possible origin, botanical affinities, and pollination modes, based on their morphological characteristics, preservation and comparison with putative living representatives. Three fern spore clumps and 18 angiosperm pollen clumps were recognized in Maastrichtian-Danian La Colonia Formation sediments that outcrop at Chubut Province, Patagonia, Argentina. Most clumps are monospecific and composed of undamaged elements but some of them have two types of spore/pollen with corroded and/or fragmented exines. These findings represent the most diverse and abundant record of fern and angiosperm clumps from the Late Cretaceous and early Paleocene so far known from South America and the Southern Hemisphere. These results are indicative of the need for comprehensive large-scale studies on pollination of modern taxa and careful processing of palynological samples to lessen the already large bias in paleopalynological interpretations. The paucity of information on clumps in the fossil record has impaired our comprehension of dispersion/pollination in deep time. 

The most common macrofossils in the highly diverse flora from Laguna del Hunco (early Eocene of Chubut, Argentina) are “Celtis” ameghinoi leaves, whose true affinities have remained enigmatic for a century. The species accounts for 14% of all plant fossils in unbiased field counts and bears diverse insect-feeding damage, suggesting high biomass and paleoecological importance. The leaves have well-preserved architecture but lack cuticles or reproductive attachments. We find that the fossils only superficially resemble Celtis and comparable taxa in Cannabaceae, Ulmaceae, Rhamnaceae, Malvaceae, and many other families. However, the distinctive foliar morphology conforms in detail to Dobinea (Anacardiaceae), a genus with two species of shrubs and large herbs ranging from India’s Far East and Tibet to Myanmar and central China, and we propose Dobineaites ameghinoi (E.W. Berry) gen et. comb. nov. for the fossils. This discovery strengthens the extensive biogeographic links between Eocene Patagonia and mainland Asia, provides the first fossil record related to Dobinea, and represents a rare Gondwanan macrofossil occurrence of Anacardiaceae, which was widespread and diversified in the Northern Hemisphere at the time. The diverse leaf architecture of Anacardiaceae includes several patterns usually associated with other taxa, and many other leaf fossils in this family may remain misidentified.