Notonuphar antarctica, an extinct water lily (Nymphaeales) from the Eocene of Antarctica

Else M Friis,Ari Iglesias,Thomas Mörs,Marcelo A Reguero

doi:10.1007/s00606-017-1422-y

Abstract

A new genus and species, Notonuphar antarctica, is described from the Eocene of Seymour (Marambio) Island, the Antarctic Peninsula and assigned to the Nymphaeales based on well-preserved seeds. This is the first record of a water lily from Antarctica and the first record of a Gondwanan plant with close link to the genus Nuphar (Nymphaeaceae), which is restricted today to the Northern Hemisphere. Critical features for systematic placement of Notonuphar are the presence of a germination cap with closely spaced hilar scar and micropyle, anatropous, bitegmic and exotestal seed organization, exotesta composed of one cell layer of high sclerenchymatic palisade-shape cells, mesotesta of smaller, low parenchymatic cells, a few cell layers deep, and a thin tegmen. The seeds of Notonuphar are particularly similar to seeds of extant and fossil Nuphar in the straight, unfolded anticlinal wall of the exotestal cells and the presence of a narrow zone of exotestal tissue between hilum and micropyle. Other seed features including the very tall exotestal cells and strongly thickened cell walls of exotesta also link Notonuphar to Brasenia and related fossil taxa (Cabombaceae). This character mosaic observed in Notonuphar corroborates the transitional position of Nuphar between Cabombaceae and Nymphaeaceae. Notonuphar is the only member of Nymphaeales recorded from Antarctica and so far the only fossil seeds of Nymphaeales known from the Southern Hemisphere. The discovery of this extinct Gondwanan taxon with features suggesting close relationship with extant Northern Hemisphere genus Nuphar is a further evidence for the relictual nature of the extant group.

Highlights

The Nymphaeales include nine genera and about 82 extant species of aquatic herbs in three families, the Hydatellaceae (Trithuria Hook.f.), Cabombaceae (Brasenia Schreb., Cabomba Aubl.) and Nymphaeaceae (Barclaya Wall., Euryale Salisb., Nymphaea L., Nuphar Smith, Ondinea Hartog, Victoria Lindl.)
Critical features for systematic placement of Notonuphar are the presence of a germination cap with closely spaced hilar scar and micropyle, anatropous, bitegmic and exotestal seed organization, exotesta composed of one cell layer of high sclerenchymatic palisadeshape cells, mesotesta of smaller, low parenchymatic cells, a few cell layers deep, and a thin tegmen
Trithuria is Gondwanan with species in India, Australia and New Zealand, Ondinea is restricted to Western Australia and Victoria restricted to South America; Cabomba occurs in North and South America; Nuphar is widely distributed in temperate regions of the Northern Hemisphere; and Barclaya and Euryale are restricted to eastern Asia (Fassett 1953; Schneider and Williamson 1993; Rudall et al 2007; Lohne et al 2008)

Summary

Introduction

The Nymphaeales include nine genera and about 82 extant species of aquatic herbs in three families, the Hydatellaceae (Trithuria Hook.f.), Cabombaceae (Brasenia Schreb., Cabomba Aubl.) and Nymphaeaceae (Barclaya Wall., Euryale Salisb., Nymphaea L., Nuphar Smith, Ondinea Hartog, Victoria Lindl.). Trithuria is Gondwanan with species in India, Australia and New Zealand, Ondinea is restricted to Western Australia and Victoria restricted to South America; Cabomba occurs in North and South America; Nuphar is widely distributed in temperate regions of the Northern Hemisphere; and Barclaya and Euryale are restricted to eastern Asia (Fassett 1953; Schneider and Williamson 1993; Rudall et al 2007; Lohne et al 2008). The fossil record of Nymphaeales is based mainly on the occurrences of seeds with a hard seed coat similar to Brasenia, Nuphar, Nymphaea and Euryale (e.g., Kirchheimer 1957; Mai 1964, 1995; Dorofeev 1974; Friis 1985; Gee and Mors 2001; Chen et al 2004). The presence of an extinct relative to the Northern Hemisphere genus, Nuphar, in the Eocene of Antarctica is interesting in emphasizing the relictual nature of the living taxa and may explain difficulties in reconstructing geographic dispersal patterns based on extant species alone

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