Reaffirming the phyllocladoid affinities of Huncocladus laubenfelsii (Podocarpaceae) from the early Eocene of Patagonia: A comment on Dörken et al. (2021)

Abstract

We discuss a recent assessment by Dörken et al. (2021) regarding the affinities of the Eocene fossil species Huncocladus laubenfelsii from Laguna del Hunco (Patagonia, Argentina). We originally (Andruchow-Colombo et al., 2019) assigned this species to the conifer family Podocarpaceae as the first certain South American macrofossil record of the phyllocladoid lineage (Huncocladus+Phyllocladus), based on a combination of numerous macro-and micromorphological vegetative characters. However, Dörken et al. (2021) rejected the podocarpaceous affinity of H. laubenfelsii and considered it to be more closely related to the cycad genera Bowenia or Eobowenia. Their assessment was based almost entirely on two cuticular characters, with only superficial consideration of the abundant additional evidence available that included several diagnostic macromorphological features. We review the two characters mentioned by these authors, and other features, and find that their suggestion is contradicted by the available evidence, maintaining our original assignment. Critical characters include presence/absence of a midvein, secondary venation pattern, arrangement and general morphology of the photosynthetic structures, and morphology and disposition of epidermal cells.