Paganuccia icatuensis (Rubiaceae), a new genus and species from Bahia, Brazil, with a key to all the genera of the tribe Spermacoceae in the Americas

Abstract

Paganuccia is described as a new genus of Rubiaceae, only known so far from two collections from the continental dunes in the São Francisco River basin, Bahia, north‐eastern Brazil. The morphological and molecular phylogenetic analyses based on nuclear (ETS, ITS) and plastid (atpB‐rbcL, petD, rps16, trnL‐trnF) sequence data, support the recognition of a new genus within the Spermacoce clade (tribe Spermacoceae). Paganuccia is one of several well‐supported lineages, still largely unresolved with respect to each other. We considered that its isolated position in combination with the unique set of morphological character states and biogeographic evidence can fully support its recognition as a new genus. We have provided a formal description of Paganuccia, including SEM observations of the fruit, pollen, and inflorescence structure, together with a distribution map and comments on its conservation. Additionally, the new genus is compared with the other climbing taxa in the tribe, and a key for all the genera of the Spermacoceae in the Americas is provided.

Revisiting Psyllocarpus intermedius (Rubiaceae, Spermacoceae): an updated description with a new synonym

“…Indeed, in a recent molecular phylogenetic study, based on nuclear and plastid regions, P. sect. Psyllocarpus was found sister to Staelia (Nuñez Florentin et al 2022), pending further investigation to unravel the relationships between these taxa.…”

“…sect. Psyllocarpus was found sister to Staelia (Nuñez Florentin et al 2022), pending further investigation to unravel the relationships between these taxa.…”

“…Within the Spermacoce clade, the delimitation of Borreria G.Mey and Spermacoce is regarded as a major challenge. As currently circumscribed, both are speciose, non‐monophyletic taxa whose representatives have been shown to be intermingled with several smaller genera in phylogenetic investigations (Salas et al 2015, Florentín et al 2017, Miguel et al 2018, Nuñez Florentin et al 2022). These studies have identified well‐supported clades that generally correspond to distinct genera.…”

“…sect. Psyllocarpus , despite the limited sampling, and it has been resolved as sister to Spermacoce or Staelia Cham., depending on the study (Salas et al 2015, Florentín et al 2017, Miguel et al 2018, Carmo et al 2022, Nuñez Florentin et al 2022). However, further investigation is needed to test the monophyly of the genus as currently circumscribed, as well as its sections, and the position of P .…”

“…In fact, Borreria as currently circumscribed is not monophyletic, with its species being recovered in two distinct clades (Salas et al 2015, Florentín et al 2017, Miguel et al 2018, Nuñez Florentin et al 2022). But neither is a broader concept of Spermacoce including Borreria and allies, as has been proposed by some authors (Delprete and Jardim 2012), pending further investigation to delimit these genera.…”