Two new species from Gabon show the need to reduce Commitheca to the synonymy of Pauridiantha (Rubiaceae, Pauridiantheae)

Abstract

Two new Pauridiantha species (Pauridiantheae, Rubiaceae) from Gabon are described and illustrated. Pauridiantha pleiantha is characterized by a combination of entirely glabrous stems, stipules with a narrow base, and large inflorescences. Pauridiantha smetsiana is characterized by entirely glabrous stems, narrow, early deciduous stipules, leaves red‐tinged when dry, and small inflorescences. The two new species, especially P. smetsiana, close the morphological gap between Commitheca and Pauridiantha in combining typical Commitheca characters, such as glabrous stems and a narrow stipular base, with Pauridiantha characters, such as eucamptodromous venation. A detailed morphological comparison (including ovary structure, seed morphology, exotesta anatomy, and pollen morphology) between the two genera is given; in conclusion, Commitheca is relegated to the synonymy of Pauridiantha. The necessary new specific combinations are provided. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 141, 105–117.

Molecular systematics and incongruent gene trees of Urophylleae (Rubiaceae)

“…Likewise, the genera Commitheca (treated as Pauridiantha liebrechtsiana in the present study) and Pamplethantha (treated as Pauridiantha viridiflora) are also shown to be ingroups in Pauridiantha (Fig. 2, node g), confirming the conclusions based on morphological data (Hallé, 1966;Ntore & al., 2003;Ntore, 2008). The type species for all of these four small genera are represented in the analyses and the phylogenetic support for the paraphyly of Pauridiantha is strongly based on both cpDNA and nrDNA.…”

“…Of special interest is the question whether the two large genera Pauridiantha and Urophyllum are monophyletic, or if other smaller genera are nested inside them, which has been suggested by previous phylogenetic studies (Smedmark & al., 2008;Sonké & al., 2008). We also want to test the conclusions based on morphology that Pamplethantha (included in the present study under the synonym Pauridiantha viridiflora) and Commitheca (included under the synonym Pauridiantha liebrechtsiana) are ingroups in Pauridiantha (Hallé, 1966;Ntore & al., 2003).…”

“…Of Bremekamp's segregate genera, Pravinaria Bremek., with single-flowered, axillary inflorescences, and Maschalocorymbus Bremek., with a ring of hairs in the corolla throat and trichotomously corymbose inflorescences, have been shown by molecular phylogenetic methods to be nested inside Urophyllum (Smedmark & al., 2008). Pamplethantha Bremek., with terminal inflorescences, and Commitheca Bremek., with four carpels and thickened radial walls of the exotesta, have both been included in Pauridiantha based on morphology (Hallé, 1966;Ntore & al., 2003). However, for the other nine genera described by Bremekamp the relationships to Urophyllum and Pauridiantha are still not known, mainly because of the difficulty in obtaining plant material.…”

A new species of Colletoecema (Rubiaceae) from southern Cameroon with a discussion of relationships among basal Rubioideae

“…Based on the present analyses, it seems that most, if not all, satellite genera of Pauridiantha will have to be merged with Pauridiantha. This was already done for Commitheca by Ntore et al (2003) and suggested for Poecilocalyx, Rhipidantha, and Stelechantha by Ntore (2004Ntore ( , 2008. A more fine-tuned phylogeny of the group is needed, however, before making taxonomic changes (see also Smedmark et al 2008).…”