Early evolution of Coriariaceae (Cucurbitales) in light of a new early Campanian (ca. 82 Mya) pollen record from Antarctica

RENNER, SUSANNE; BARREDA, V; TELLERÍA, M.C.; PALAZZESI, L., BARREDA, V. Y PRIETO, A.R; SCHUSTER, T.

TAXON

INT ASSOC PLANT TAXONOMY

Lugar: Viena; Año: 2020 vol. 69 p. 87 - 99

0040-0262

Abstract Coriariaceae comprise only Coriaria, a genus of shrubs with nine species in Australasia (but excluding Australia), five inthe Himalayas, Taiwan, the Philippines, and Japan, one in the Mediterranean, and one ranging from Patagonia to Mexico. The sisterfamily, Corynocarpaceae, comprises five species of evergreen trees from New Guinea to New Zealand and Australia. This distributionhas long fascinated biogeographers as potential support for Wegener?s theory of continental drift, with alternative scenarios invokingeither Antarctic or Beringian range expansions. Here, we present the discovery of pollen grains from Early Campanian (ca. 82 Mya)deposits in Antarctica, which we describe as Coriaripites goodii sp. nov., and newly generated nuclear and plastid molecular data formost of the family?s species and its outgroup. This greatly expands the family?s fossil record and is the so far oldest fossil of the orderCucurbitales. We used the phylogeny, new fossil, and an Oligocene flowering branch assigned to a small subclade of Coriaria to generatea chronogram and to study changes in chromosome number, deciduousness, and andromonoecy. Coriaria comprises a Northern(NH) and a Southern Hemisphere (SH) clade that diverged from each other in the Paleocene (ca. 57 Mya), with the SH clade reachingthe New World once, through Antarctica, as supported by the fossil pollen. While the SH clade retained perfect flowers and evergreenleaves, the NH clade evolved andromonoecy and deciduousness. Polyploidy occurs in both clades and points to hybridization, matchingweak species boundaries throughout the genus.