Neotropical Rubiaceae: Synthesis of Chromosome Data from Costa Rican Taxa, with Insights on the Systematics of the Family

Abstract

Recent molecular systematic studies have significantly improved our understanding of the large, complex, and cosmopolitan plant family Rubiaceae, comprising about 13,000 species. Besides the obvious importance of DNA phylogenetic data, cytological studies have long added important basic information on the circumscription of clades and relationships within the family. In light of recent changes affecting a large number of tribes and genera, the current knowledge on the systematics of Neotropical Rubiaceae is reviewed with a focus on Costa Rica, which harbors an exceptionally rich Rubiaceae flora including most of the genera and biogeographic elements present in the Neotropics. Based on this systematic framework, previously published chromosome counts on Costa Rican taxa are reviewed and 49 new chromosome counts are reported. In total, 110 accessions of 75 species or infraspecific taxa representing 36 genera of Costa Rican Rubiaceae are discussed and supplemented by new counts for extraterritorial taxa when appropriate. Altogether the present study includes the first chromosome counts reported for the tribes Cordiereae and Hillieae, as well as for 10 genera and 27 species, providing new aspects of Rubiaceae systematics.

Evolution of distyly breakdown in Palicoureeae Robbr. & Manen and Psychotrieae Cham. & Schltdl. (Rubiaceae)

“…Both breeding systems and ecological information were retrieved from literature and direct field observations. We added chromosome number information whenever possible based on CCDB (http://ccdb.tau.ac.il), Correa et al (2010), and Kiehn & Berger (2020), and compared the data with chromosome numbers and ploidy levels observed for the genera and the Rubiaceae as a whole (Naiki 2012;Kiehn & Berger 2020). We tested if there was a relationship between ploidy levels and breeding system by contingency analysis and chi-square independence test (Sokal & Rohlf 1994).…”

Alkaloid diversification in the genus Palicourea (Rubiaceae: Palicoureeae) viewed from a (retro-)biogenetic perspective

“…The new generic concepts within Palicoureeae and Psychotrieae are now widely accepted in floristic and systematic literature (e.g. Borhidi 2019; Kiehn and Berger 2020;Taylor 2014). Thus, most secondary metabolites previously reported from Psychotria were actually isolated from species now assigned to Palicourea, which needs to be considered when interpreting chemical characters for both genera (Berger et al 2021).…”

New chromosome counts on Rubiaceae from Africa and the Western Indian Ocean islands

“…for the genus Coffea L., have been published since then (Pierozzi et al 2012), our knowledge of the cytology of the group in this geographical area is still extremely limited. This is despite the fact that cytological data can help to understand the complex trends and evolutionary relationships within the large coffee family (Kiehn 1986, 1995, 1996, Kiehn and Berger 2020). As an example, different basic numbers ( x = 17 versus x = 10 or 11, Kiehn and Berger 2020) support the differentiation of the morphologically well‐defined Neotropical tribes Cinchoneae DC.…”

“…This is despite the fact that cytological data can help to understand the complex trends and evolutionary relationships within the large coffee family (Kiehn 1986, 1995, 1996, Kiehn and Berger 2020). As an example, different basic numbers ( x = 17 versus x = 10 or 11, Kiehn and Berger 2020) support the differentiation of the morphologically well‐defined Neotropical tribes Cinchoneae DC. and Isertieae A.…”