Physalis infinemundi Wilf, sp. nov.
Creators: name: Wilf, Peter
name: Carvalho, Mónica R.
name: Gandolfo, María A.
name: N. Rubén Cúneo
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Solanales
Solanaceae
Physalis
Physalis infinemundi

description: <i>Physalis infinemundi</i> Wilf sp. nov. <b>Etymology:</b> Latin, <i>in fine mundi</i>, “at the end of the world,” reflecting provenance from the last stages of the Gondwanan supercontinent and from Patagonia, popularly known as “the end of the world.” <b>Type material:</b> repository Museo Paleontológico Egidio Feruglio, Trelew, Argentina (MPEF-Pb); holotypus hic designatus MPEF-Pb 6434a,b (Fig. 1, A to C) (lowercase letters indicate part and counterpart), from Laguna del Hunco, Huitrera Formation, early Eocene, Chubut Province, Argentina, quarry LH13 (<i>16</i>), collected 7 December 2002 (fig. S 18); paratype MPEF-Pb 6435a,b (Fig. 1, G and H), Laguna del Hunco quarry LH04 (<i>16</i>), 21 November 2006. <b>Description:</b> based on two dispersed, apparently mature, compressed fruiting calyces; only the holotype preserves berry and pedicel remains. Pedicel preserved length 18.8 mm, width 1 mm at inflection point of insertion. Calyx basally invaginated, highly inflated to completely surround the berry, five-lobed, angled, partly open at apex, length by width 2 5.2 mm by 1 3.2 mm (1. 9: 1) on holotype, 21.6 mm by 17.6 mm (ratio 1.2: 1) on paratype. Calyx lobes equally sized, sinuses angular and incised one-quarter to half the total calyx length, tips acute triangular. Venation with one robust primary meridional vein per lobe, terminating at lobe apex and alternating with secondary veins. 1Department of Geosciences, Pennsylvania State University, University Park,PA 16802, USA. 2L. H. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853,USA. 3Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Museo PaleontolÓgico Egidio Feruglio,9100 Trelew, Chubut, Argentina. *Corresponding author. Email: pwilf@psu.edu Secondary veins arising near the base, visually distinct from the primaries and other vein orders, and bifurcating close to the lobe sinuses (Fig. 1 C). Intersecondary veins arising near the base, visually distinct from secondaries and tertiaries, dichotomizing into the random, irregular reticulum of tertiary through at least quinternary veins that fill most of the vein field. Some basal veins compressed into partial detachment from the calyx body, the remnants visible against the matrix. Berry round, flattened and coalified from fossilization, filling the full width of the calyx and appearing by surface relief to extend apically almost to the lobe sinuses; seeds not preserved. The fossils preserve several features that, together, are diagnostic of the Physalinae clade of Solanaceae (<i>20</i>, <i>21</i>, <i>23</i>, <i>25</i>). These include the highly inflated, lantern-shaped, pedicellate, five-parted, angled, regular calyces covering a large, fleshy berry, along with the combination of (i) invaginated base, (ii) robust primary veins that terminate in the lobe tips (not the lobe sinuses), and (iii) secondary veins that fork before the sinus. Nonphysaline species of Solanaceae with ICS lack some or all of these three features (e.g., those in <i>Deprea</i>, <i>Nicandra</i>, <i>Solanum</i>, <i>Withania</i>, and the Juanulloeae clade) (figs. S 5, S 11, and S 13) (<i>23</i>, <i>24</i>). Within Physalinae, there are several problematic species of <i>Physalis</i> s.l. and other genera that diverge below the core <i>Physalis</i> clade (Fig. 2) (equivalent to <i>P.</i> subgenus <i>Rydbergis</i>) of relatively homogeneous species (<i>13</i>, <i>23 – 25</i>). Among these taxa, <i>Alkekengi officinarum</i> calyces are the most similar to the fossils, but they have a much larger size, consistently rounded shape, and nearly closed apex. Otherwise, each of these basal physaline species structurally differs from the fossils and core <i>Physalis</i> (<i>20</i>, <i>24</i>, <i>25</i>) (figs. S 2 to S 17). All these observations highlight the close relationship of the fossils with core <i>Physalis</i>. Both the MP and ML results (Fig. 2 and fig. S 1) support the fossils’ affinity with Physalinae and <i>Physalis</i>. The newly identified species is placed in Physalinae with strong support in both MP and ML analyses and at a basal polytomy of (MP, weak support) or within (ML, strong support) the crown of core <i>Physalis</i>. Both the MP and ML topologies are generally consistent with and reproduced most major clades from (<i>10</i>), with robust support of the critical Physalinae clade. However, each tree recovered the closely related (<i>10</i>) Iochrominae and <i>Deprea</i> as collapsed into a single clade that also included <i>Nicandra</i>, which has <i>Deprea</i> -like calyx morphology but is not closely related to that genus. Nevertheless, the overall agreement of the MP and ML tree topologies with (<i>10</i>) is notable in light of the limitations of the analysis. Notably, no species from outside Physalinae were misplaced among Physalinae, and no Physalinae species were misplaced into other clades. Considering the unknown additional organs of this extinct species, the incomplete knowledge of calyx morphology in extant Solanaceae, and problematic resolution among extant basal species of Physalinae (<i>13</i>, <i>25</i>), we suggest that the newly identified species can be used, conservatively, to constrain the divergence of Physalinae to a minimum of 52.2 Ma. <i>Physalis infinemundi</i> sp. nov. represents a derived lineage of Solanaceae in Gondwanan South America at 52.2 Ma, pushing back considerably the evolutionary timing of the family. Compared with recent molecular divergence estimates (<i>10</i>), these fossils are considerably older than the ~30 Ma crown for the entire Solanaceae family as well as the ~11 Ma divergence of Physalinae. A second recent study similarly placed the Physalinae divergence at only ~9 Ma (<i>13</i>). Our results reinforce the emerging pattern wherein numerous fossil plant taxa from Gondwanan Patagonia and Antarctica are substantially older than their corresponding molecular dates (<i>26</i>, <i>27</i>), demonstrating Gondwanan history for groups conjectured to have post-Gondwanan origins under entirely different paleogeographic and paleoclimatic scenarios. Likewise, the derived position of the newly identified fossil species shows that the origins and diversification of Solanaceae must have taken place at a much earlier time than previously thought, considerably before final Gondwanan breakup. Other regions of Gondwana are also likely to have played prominent roles in Solanaceae evolution, especially Antarctica, which has produced other important asterid fossils (<i>27</i>). Moreover, the newly identified fossils directly help to resolve temporal inconsistencies between the evolutionary timing of Solanaceae and its herbivores and mutualists (<i>28</i>). The large fossil berry strongly implicates trophic associations with animals, as seen in extant <i>Physalis</i> (<i>29</i>). Today, <i>Physalis</i> inhabits South, Central, and North America, and Mexico is its center of diversity (<i>2</i>). Thus, the fossils establish a rare link to extant New World floras from late-Gondwanan Patagonian assemblages, whose living relatives are mostly concentrated in the Old World tropics and subtropics. The discovery of 52.2-Ma fossil inflated calyces demonstrates an ancient history for ICS and implies that the Eocene world was already populated with derived solanaceous reproductive structures. The potential adaptive functions of the inflated calyx are scarcely discussed in the literature (<i>30</i>), but the lakeside rainforest paleoenvironment led us to consider flotation dispersal and protective drying for the berry. Simple kitchen-sink and stream experiments on several <i>Physalis</i> species confirmed that intact calyces hold stable air pockets around the berry, enabling flotation for several days in water and preventing wetting of the berry during rains. These insights suggest potential origins of ICS in ancient humid, riparian environments.
description: Published as part of <i>Peter Wilf, Mónica R. Carvalho, María A. Gandolfo &amp; N. Rubén Cúneo, 2017, Eocene lantern fruits from Gondwanan Patagonia and the early origins of Solanaceae, pp. 71-75 in Science 355 (6320)</i> on pages 1-4, DOI: 10.1126/science.aag2737, http://zenodo.org/record/239112
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