Abstract Detail

Fossil plants at the intersection of evo-devo and phylogeny: celebrating the contributions of Gar W. Rothwell to biodiversity and evolution

Jud , Nathan A [1], De Benedetti, Facundo [2], Hermsen, Elizabeth J. [3], Gandolfo, Maria A [4].

An organismal concept for fossil Azolla from the early Paleocene (Danian) Salamanca Formation, Patagonia, Argentina.

Mosquito ferns (Azolla Lam.) comprise 5–7 extant species and more than 70 fossil species (based primarily on isolated mega- and microspores). Recent molecular phylogenetic studies using chloroplast sequence data have converged on a well-supported model of the systematic relationships among the living species of Azolla; however, many of the fossil species have combinations of characters not seen among the extant species. Phylogenetic analyses that include both living and fossil Azolla thus have the potential to yield important insights. Despite the rich fossil record of the genus, our understanding of its evolution is historically constrained by a paucity of sporophyte fossils from which organismal concepts of extinct species can be developed. Here, we present an organismal concept for a new fossil Azolla from the early Paleocene Salamanca Formation of Patagonia, Argentina. We compared the fossils with fully articulated extant relatives, as well as reconstructed fossil plants; fossil taxa include A. schopfii and A. stanleyi, previously described from the Paleocene of Canada, and an unnamed species from the Maastrichtian of Argentina. The Salamanca Azolla fossils share several characters with the extinct species A. schopfii and extant African species A. nilotica that are not present in other species of Azolla. These include fascicled roots, a sparse-leaved main stem, leaves with a wide hyaline margin, a ventral leaf lobe with a central chlorophyllous zone and prominent midvein, ventral leaf lobe nearly as large as or larger than the dorsal lobe, and microspore massulae with simple (hair-like) glochidia.

1 - Cornell University, Plant Biology Section School of Integrative Plant Science, 410 Mann Library, Ithaca, NY, 14853, USA
2 - Museo Paleontológico Egidio Feruglio, Avenida Fontana 140, Trelew, U, 9100, Argentina
3 - Ohio University, Department Of Environmental And Plant Biology, Porter Hall 315, Athens, OH, 45701, United States
4 - Cornell University, Plant Biology, 410 Mann Library Building, Plant Biology Section, SIPS, Cornell University, Ithaca, NY

Keywords:
Whole plant reconstruction
fern
Salviniales
morphology
aquatic plants.

Presentation Type: Colloquium Presentations
Session: C11a, Fossil plants at the intersection of evo-devo and phylogeny: celebrating the contributions of Gar W. Rothwell to biodiverstiy and evolution Part 1
Location: 110/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 10:45 AM
Number: C11a009
Abstract ID:820
Candidate for Awards:None