Molecular and Morphological Data Improve the Classification of Plantagineae (Lamiales)

The smallest area shaped a big problem: a revision of the placement of the Ventania sky island in the biogeography of South America

The placement of the southern border of the Neotropical region, called the Subtropical Line, is a long-lasting point of discussion. Its most debatable section runs around the Pampean province, where an isolated mountain system called Ventania has Andean connections surrounded by Neotropical biota. To answer where to place the Subtropical Line, a thorough revision of the biogeography of Ventania is needed. Thus, we characterized Ventania as an area of endemism and conducted a similitude analysis to compare it with surrounding systems using stenoic taxa. Then we compiled the disjunct distributions in Ventania and the phylogenetic information of its endemic taxa to know with which other areas it is related. We also compared the biogeographic differences with Tandilia, the nearest mountain system. We found that Ventania is a small but well-defined area of endemism mostly related to the Andean and South American Transition Zone (SATZ) provinces. Relatedness with the Pampean province is less than had been thought. We suggest that Ventania is a SATZ sky island province, and the smallest continental province of the world. The Subtropical Line should therefore be placed in the southern border of the Pampean province, with Ventania as a SATZ island inside the Neotropical region.

Complete Mitogenomes of Two Aragoa Species and Phylogeny of Plantagineae (Plantaginaceae, Lamiales) Using Mitochondrial Genes and the Nuclear Ribosomal RNA Repeat

Aragoa, comprising 19 high-altitude North Andean species, is one of three genera in the Plantagineae (Plantaginaceae, Lamiales), along with Littorella and Plantago. Based primarily on plastid data and nuclear ITS, Aragoa is sister to a clade of Littorella + Plantago, but Plantagineae relationships have yet to be assessed using multigene datasets from the nuclear and mitochondrial genomes. Here, complete mitogenomes were assembled for two species of Aragoa (A. abietina and A. cleefii). The mitogenomes of both species have a typical suite of genes for 34 proteins, 17 tRNAs, and three rRNAs. The A. abietina mitogenome assembled into a simple circular map, with no large repeats capable of producing alternative isoforms. The A. cleefii mitogenomic map was more complex, involving two circular maps bridged by a substoichiometric linear fragment. Phylogenetics of three mitochondrial genes or the nuclear rRNA repeat placed Aragoa as sister to Littorella + Plantago, consistent with previous studies. However, P. nubicola, the sole representative of subg. Bougueria, was nested within subg. Psyllium based on the mitochondrial and nuclear data, conflicting with plastid-based analyses. Phylogenetics of the nuclear rRNA repeat provided better resolution overall, whereas relationships from mitochondrial data were hindered by extensive substitution rate variation among lineages.