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1. Insect herbivore and fungal communities on Agathis (Araucariaceae) from the latest Cretaceous to Recent

   https://doi.org/10.3897/phytokeys.226.99316  

   Donovan, Michael P.; Wilf, Peter; Iglesias, Ari; Cúneo, N. Rubén; Labandeira, Conrad C. (May 2023, PhytoKeys)

   Agathis (Araucariaceae) is a genus of broadleaved conifers that today inhabits lowland to upper montane rainforests of Australasia and Southeast Asia. A previous report showed that the earliest known fossils of the genus, from the early Paleogene and possibly latest Cretaceous of Patagonian Argentina, host diverse assemblages of insect and fungal associations, including distinctive leaf mines. Here, we provide complete documentation of the fossilized Agathis herbivore communities from Cretaceous to Recent, describing and comparing insect and fungal damage on Agathis across four latest Cretaceous to early Paleogene time slices in Patagonia with that on 15 extant species. Notable fossil associations include various types of external foliage feeding, leaf mines, galls, and a rust fungus. In addition, enigmatic structures, possibly armored scale insect (Diaspididae) covers or galls, occur on Agathis over a 16-million-year period in the early Paleogene. The extant Agathis species, throughout the range of the genus, are associated with a diverse array of mostly undescribed damage similar to the fossils, demonstrating the importance of Agathis as a host of diverse insect herbivores and pathogens and their little-known evolutionary history. 

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2. Persistent biotic interactions of a Gondwanan conifer from Cretaceous Patagonia to modern Malesia

   https://doi.org/10.1038/s42003-020-01428-9  

   Donovan, Michael P.; Wilf, Peter; Iglesias, Ari; Cúneo, N. Rubén; Labandeira, Conrad C. (November 2020, Communications Biology)

   Abstract Many plant genera in the tropical West Pacific are survivors from the paleo-rainforests of Gondwana. For example, the oldest fossils of the Malesian and Australasian coniferAgathis(Araucariaceae) come from the early Paleocene and possibly latest Cretaceous of Patagonia, Argentina (West Gondwana). However, it is unknown whether dependent ecological guilds or lineages of associated insects and fungi persisted on Gondwanan host plants likeAgathisthrough time and space. We report insect-feeding and fungal damage on PatagonianAgathisfossils from four latest Cretaceous to middle Eocene floras spanning ca. 18 Myr and compare it with damage on extantAgathis. Very similar damage was found on fossil and modernAgathis, including blotch mines representing the first known Cretaceous–Paleogene boundary crossing leaf-mine association, external foliage feeding, galls, possible armored scale insect (Diaspididae) covers, and a rust fungus (Pucciniales). The similar suite of damage, unique to fossil and extantAgathis, suggests persistence of ecological guilds and possibly the component communities associated withAgathissince the late Mesozoic, implying host tracking of the genus across major plate movements that led to survival at great distances. The living associations, mostly made by still-unknown culprits, point to previously unrecognized biodiversity and evolutionary history in threatened rainforest ecosystems. 

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3. Fossil insect‐feeding traces indicate unrecognized evolutionary history and biodiversity on Australia's iconic Eucalyptus

   https://doi.org/10.1111/nph.20316  

   Giraldo, L_Alejandro; Wilf, Peter; Donovan, Michael_P; Kooyman, Robert_M; Gandolfo, Maria_A (November 2024, New Phytologist)

   Summary Fossilized plant–insect herbivore associations provide fundamental information about the assembly of terrestrial communities through geologic time. However, fossil evidence of associations originating in deep time and persisting to the modern day is scarce.We studied the insect herbivore damage found on 284Eucalyptus frenguellianaleaves from the early Eocene Laguna del Hunco rainforest locality in Argentinean Patagonia and compared damage patterns with those observed on extant, rainforest‐associatedEucalyptusspecies from Australasia (> 10 000 herbarium sheets reviewed).In the fossil material, we identified 28 insect herbivory damage types, including 12 types of external feeding, one of piercing‐and‐sucking, five of galls, and 10 of mines. All 28 damage types were observed in the herbarium specimens.The finding of all the fossil damage types on extantEucalyptusspecimens suggests long‐standing associations between multiple insect herbivore lineages and their host genus spanning 52 million years across the Southern Hemisphere. This long‐term persistence, probably enabled through niche conservatism in wet eucalypt forests, demonstrates the imprint of fossil history on the composition of extant insect herbivore assemblages. Although the identities of most insect culprits remain unknown, we provide a list ofEucalyptusspecies and specific population locations to facilitate their discovery, highlighting the relevance of fossils in discovering extant biodiversity. 

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4. Putative Celtis Leaves from Eocene Patagonia are Allied with Asian Anacardiaceae

   https://doi.org/10.5710/AMGH.21.02.2024.3586  

   Wilf, Peter; González, Cynthia C; Gandolfo, María A; Zamaloa, María C (April 2024, Ameghiniana)

   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. 

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5. A new fossil Acmopyle with accessory transfusion tissue and potential reproductive buds: Direct evidence for ever‐wet rainforests in Eocene Patagonia

   https://doi.org/10.1002/ajb2.16221  

   Andruchow‐Colombo, Ana; Rossetto‐Harris, Gabriella; Brodribb, Timothy J; Gandolfo, María A; Wilf, Peter (August 2023, American Journal of Botany)

   Abstract PremiseAcmopyle(Podocarpaceae) comprises two extant species from Oceania that are physiologically restricted to ever‐wet rainforests, a confirmed fossil record based on leaf adpressions and cuticles in Australia since the Paleocene, and a few uncertain reports from New Zealand, Antarctica, and South America. We investigated fossil specimens withAcmopyleaffinities from the early Eocene Laguna del Hunco site in Patagonia, Argentina. MethodsWe studied 42 adpression leafy‐shoot fossils and included them in a total evidence phylogenetic analysis. ResultsAcmopyle grayaesp. nov. is based on heterophyllous leafy shoots with three distinct leaf types. Among these, bilaterally flattened leaves uniquely preserve subparallel, linear features that we interpret as accessory transfusion tissue (ATT, an extra‐venous water‐conducting tissue). Some apical morphologies ofA. grayaeshoots are compatible with the early stages of ovuliferous cone development. Our phylogenetic analysis recovers the new species in a polytomy with the two extantAcmopylespecies. We report several types of insect‐herbivory damage. We also transferAcmopyle engelhardtifrom the middle Eocene Río Pichileufú flora toDacrycarpus engelhardticomb. nov. ConclusionsWe confirm the biogeographically significant presence of the endangered West Pacific genusAcmopylein Eocene Patagonia.Acmopyleis one of the most drought‐intolerant genera in Podocarpaceae, possibly due to the high collapse risk of the ATT, and thus the new fossil species provides physiological evidence for the presence of an ever‐wet rainforest environment at Laguna del Hunco during the Early Eocene Climatic Optimum. 

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