Arnaud Mouly

Evolutionary trends, major lineages, and new generic limits in the dioecious group of the tribe Vanguerieae (Rubiaceae): Insights into the evolution of functional dioecy

Abstract New generic circumscriptions of the Paleotropical tribe Vanguerieae in the subfamily Ixoroideae s.l. (Rubiaceae) have recently been established as a result of a series of phylogenetic studies conducted by Lantz and Bremer. The genus Canthium Lam. was shown in their study to be highly polyphyletic, and a largely dioecious group was for the first time identified within Vanguerieae. The dioecious group sensu Lantz and Bremer comprises about 140 species classified in eight genera: Canthium (Canthium subg. Bullockia Bridson), Dinocanthium Bremek., Leroya Cavaco, Neoleroya Cavaco, Peponidium (Baill.) Arènes, Pseudopeponidium Homolles ex Arènes, Pyrostria Comm. ex Juss., and Scyphochlamys Balf. f. We sequenced 79 Vanguerieae taxa and performed phylogenetic analyses based on sequence data from two nuclear (ETS and ITS) markers to: (1) pinpoint the phylogenetic positions of the Comorean and Indian Ocean Canthium and the Southeast Asian Canthium confertum Korth. group in Vanguerieae; (2) evaluate the phylogenetic utility of three taxonomic characters (bract type, locule number, and fruit shape) previously and currently used for delimiting genera in the dioecious group; and (3) assess the evolution of functional dioecy in Vanguerieae. The results support a further disintegration of Canthium s.l., as the Comorean and Malagasy Canthium species are shown for the first time to be closely related to Peponidium. Similarly, C. confertum appears to have a close affinity with Cyclophyllum Hook. f. The combined analyses show that the dioecious group can be subdivided into four morphologically distinct clades formally recognized as genera: Bullockia (Bridson) Razafim., Lantz & B. Bremer, here elevated from Canthium subgen. Bullockia Bridson, as well as Cyclophyllum, Peponidium (including all Comorean, Malagasy, and Seychellean Canthium species), and Pyrostria (including Dinocanthium, Leroya, Neoleroya, Pseudopeponidium, and Scyphochlamys). All described species of Canthium subgen. Bullockia are transferred to Bullockia: B. dyscriton (Bullock) Razafim., Lantz & B. Bremer, B. fadenii (Bridson) Razafim., Lantz & B. Bremer, B. impressinervia (Bridson) Razafim., Lantz & B. Bremer, B. mombazensis (Baill.) Razafim., Lantz & B. Bremer, B. pseudosetiflora (Bridson) Razafim., Lantz & B. Bremer, and B. setiflora (Hiern) Razafim., Lantz & B. Bremer. Furthermore, the results seem to point to a single origin of functional dioecy followed by subsequent reversals back to the hermaphroditic conditions at least within the Cyclophyllum–Canthium confertum clade and Pyrostria s.l. The Malagasy Bullockia species seem to have an African ancestor, whereas the Comorean Peponidium and the African Pyrostria appear to have originated from Malagasy progenitors.

Phylogeny and classification of the species-rich pantropical showy genus Ixora (Rubiaceae-Ixoreae) with indications of geographical monophyletic units and hybrids

Species-rich genera often have various conflicting circumscriptions from independent regional flora treatments. Testing the monophyly of these groups of plants is an important step toward the establishment of a phylogenetic classification. The genus Ixora of the tribe Ixoreae in the subfamily Ixoroideae (coffee family or Rubiaceae) is a species-rich pantropical genus of ca. 500 species. Phylogenetic analyses of Ixoreae based on combined sequence data from one nuclear (nrETS) and two chloroplast (rps16 and trnT-F) markers reveal the paraphyly of Ixora as presently delimited and also show that the tribe can be subdivided into three major clades: the Mascarene/neotropical/Malagasy/African clade, the Pacific clade, and the Asian clade. Given the lack of morphological synapomorphies supporting the different Ixora clades and the morphological consistency of the ingroup taxa, we propose a broad circumscription of Ixora including all its satellite genera: Captaincookia, Doricera, Hitoa, Myonima, Sideroxyloides, Thouarsiora, and Versteegia. The current infrageneric classification of Ixora is not supported. The different Ixora subclades represent geographical units. Nuclear and chloroplast tree topologies were partially incongruent, indicating at least four potential natural hybridization events. Other conflicting positions for the cultivated species are most likely due to anthropogenic hybridization.

Paraphyly of Ixora and new tribal delimitation of Ixoreae (Rubiaceae): Inference from combined chloroplast (rps16, rbcL and trnT-F) sequence data

Abstract We performed phylogenetic analyses of DNA sequences of three chloroplast markers: rbcL, rps16, and trnT-F, to rigorously test the monophyly of competing circumscriptions of the tribe Ixoreae. Several genera traditionally or currently associated with the type genus Ixora L. were included in the analyses. Ixora as currently circumscribed appears paraphyletic, as many other genera are nested within it with strong support: Captaincookia N. Hallé, Doricera Verdc., Hitoa Nadeaud, Myonima Comm. ex Juss., Sideroxyloides Jacq., Thouarsiora Homolle ex Arènes, and Versteegia Valeton. Further, Aleisanthia Ridl., Aleisanthiopsis Tange, and Greenea Wight & Arn. are more closely related to Ixora and allies than the monotypic genus Scyphiphora C. F. Gaertn. Consequently, Ixoreae fide Andreasen and Bremer (2000) is not monophyletic without an exclusion of Scyphiphora. Ixoreae fide Robbrecht and Manen (2006) is not monophyletic unless Captaincookia and Doricera are included. The monophyly of a morphologically heterogeneous Ixoreae alliance consisting of Ixora and its relatives Aleisanthia, Aleisanthiopsis, and Greenea is, however, strongly supported. In order to recognize monophyletic and morphologically consistent groups, we adopt a narrow circumscription of Ixoreae (including Bemsetia Raf., Captaincookia, Charpentiera Vieill., Doricera, Hitoa, Ixora, Myonima, Pancheria Montrouz., Sideroxyloides, Thouarsiora, Tsiangia But, H. H. Hsue & P. T. Li, and Versteegia), and two new tribes are erected for Aleisanthia + Aleisanthiopsis and Greenea, respectively. The Indo-Malesian Aleisanthieae and the pantropical Ixoreae s. str. are sister groups, and the Southeast Asian Greeneeae is sister to the Ixoreae–Aleisanthieae clade.

Phylogenetic structure and clade circumscriptions in the Gardenieae complex (Rubiaceae)

In this study we investigate the large and diverse Rubiaceae-Gardenieae and closely related tribes Bertiereae, Coffeeae, Cremasporeae, Octotropideae, and Pavetteae. Some of the tribes or groups have been shown to be monophyletic and strongly supported, but the phylogeny of this large complex is still far from being satisfactorily elucidated particularly for Gardenieae, both in terms of intertribal relationships as well as tribal delimitations. We reconstruct the phylogeny of the complex using an extensive sampling of 108 genera and five plastid DNA regions. Phylogenetic relationships demonstrate that Gardenieae sensu Andreasen & Bremer is polyphyletic, as Burchellia, Didymosalpinx, Monosalpinx, and Mantalania are closer to Octotropideae-Cremasporeae. In addition, Pavetteae and the investigated members of Aulacocalyceae are nested in a supported but partially unresolved Gardenieae-Pavetteae clade. Within this clade, several strongly supported groups are resolved: an Aidia group, an Alibertia group, a Gardenia group, Pavetteae including Pelagodendron, a Porterandia group, a Randia group, a Rothmannia group (including Aulacocalyx and Heinsenia), a Sherbournia group, and the two isolated genera Massularia and Schumanniophyton. The latter genus presented a high rate of genetic substitutions, which resulted in perturbations of the phylogenetic reconstruction. A revised tribal circumscription is given for Gardenieae, the Alibertia group is recognized at tribal level as an emended Cordiereae, and a new tribe, Sherbournieae, is described to accommodate the members of the Sherbournia group.

Evolutionary history of the Afro-Madagascan Ixora species (Rubiaceae): species diversification and distribution of key morphological traits inferred from dated molecular phylogenetic trees

BACKGROUND AND AIMS Previous work on the pantropical genus Ixora has revealed an Afro-Madagascan clade, but as yet no study has focused in detail on the evolutionary history and morphological trends in this group. Here the evolutionary history of Afro-Madagascan Ixora spp. (a clade of approx. 80 taxa) is investigated and the phylogenetic trees compared with several key morphological traits in taxa occurring in Madagascar. METHODS Phylogenetic relationships of Afro-Madagascan Ixora are assessed using sequence data from four plastid regions (petD, rps16, rpoB-trnC and trnL-trnF) and nuclear ribosomal external transcribed spacer (ETS) and internal transcribed spacer (ITS) regions. The phylogenetic distribution of key morphological characters is assessed. Bayesian inference (implemented in BEAST) is used to estimate the temporal origin of Ixora based on fossil evidence. KEY RESULTS Two separate lineages of Madagascan taxa are recovered, one of which is nested in a group of East African taxa. Divergence in Ixora is estimated to have commenced during the mid Miocene, with extensive cladogenesis occurring in the Afro-Madagascan clade during the Pliocene onwards. CONCLUSIONS Both lineages of Madagascan Ixora exhibit morphological innovations that are rare throughout the rest of the genus, including a trend towards pauciflorous inflorescences and a trend towards extreme corolla tube length, suggesting that the same ecological and selective pressures are acting upon taxa from both Madagascan lineages. Novel ecological opportunities resulting from climate-induced habitat fragmentation and corolla tube length diversification are likely to have facilitated species radiation on Madagascar.

Phylogenetic placement of Rhopalobrachium (Rubiaceae: Ixoroideae): evidence from molecular (rps16 and trnT-F) and morphological data

Abstract Rhopalobrachium is an endemic New Caledonian genus of Rubiaceae with controversial tribal position, because its protologue was apparently based on two distantly related species, Rhopalobrachium fragrans and Rhopalobrachium congestum. Despite its new circumscription as a monotypic genus (Rhopalobrachium fragrans) the tribal placement of Rhopalobrachium remained unknown. We investigated, for Rhopalobrachium fragrans, all morphological characters currently used for circumscribing tribes in the subfamily Ixoroideae sensu lato. The species has axillary inflorescences, with valvate flower aestivation, drupaceous fruits with a single pendulous ovule per locule, and 3-pororate pollen grains. We also performed Bayesian and parsimony analyses based on two chloroplast markers, rps16 intron and trnT-F region, to assess the phylogenetic position of Rhopalobrachium within Ixoroideae sensu lato. These analyses produced well-resolved and strongly supported topologies. The results of both the morphological survey and phylogenetic analyses indicated a position of Rhopalobrachium fragrans in the tribe Vanguerieae and a close relationship with the Pacific genus Cyclophyllum.

Recent changes in mountain grasslands: a vegetation resampling study

Understanding how land‐use changes affect different facets of plant biodiversity in seminatural European grasslands is of particular importance for biodiversity conservation. As conclusions of previous experimental or synchronic observational studies did not converge toward a general agreement, assessing the recent trends in vegetation change in various grassland systems using a diachronic approach is needed. In this resurvey study, we investigated the recent changes in grassland vegetation of the French Jura Mountains, a region with a long tradition of pastoralism. We compared the floristic composition of 150 grassland plots recorded between 1990 and 2000 with new relevés made in 2012 on the same plots. We considered taxonomic, phylogenetic and functional diversity as well as ecological characteristics of the plant communities derived from ecological indicator values and life strategies of the species. PCA of the floristic composition revealed a significant general trend linked to the sampling year. Wilcoxon paired tests showed that contemporary communities were generally more dominated by grass species and presented a higher tolerance to defoliation, a higher pastoral value, and a higher nutrient indicator value. Comparisons revealed a decrease in phylogenetic and functional diversity. By contrast, local species richness has slightly increased. The intensity of change in species composition, measured by Hellinger distance between pairs of relevés, was dependent on neither the time lag between the two surveys, the author of the first relevé nor its location or elevation. The most important changes were observed in grasslands that previously presented low pastoral value, low grass cover, low tolerance to defoliation, and high proportion of stress‐tolerant species. This trend was likely linked to the intensification of grassland management reported in the region, with a parallel increase in mowing frequency, grazing pressure, and fertilization level. More restrictive specifications should be applied to agricultural practices to avoid overexploitation of mountain species‐rich grasslands and its negative consequences on their biodiversity and resilience.

Molecular phylogeny and taxonomic revision of the Philippine endemic Villaria Rolfe (Rubiaceae)

The little known Rubiaceae genus Villaria is endemic mostly to the coastal forests of the Philippines. Traditionally, it has been placed in the tribe Gardenieae. Later it was transferred to Octotropideae sensu Robbrecht and Puff. Villaria was placed among the “primitive” genera of the tribe, which are essentially characterized by large fruits, horizontal ovules and numerous seeds. Parsimony and Bayesian analyses of the combined plastid (rps16 and trnT-F) dataset strongly support the inclusion of Villaria in Octotropideae as well as monophyly of the genus. However, our molecular results do not conform to the current informal groups of the tribe delimited by fruit size, ovule position, number of seeds and exotesta thickenings. Instead, a close relationship between Villaria and two “central genera” (Hypobathrum and Pouchetia) is revealed for the first time. This clade is sister to a group comprising “primitive” (Fernelia), “advanced” (Kraussia and Polysphaeria) and “central” (Feretia) representatives. In addition, our combined tree strongly supports a sister taxa relationship between Canephora and Paragenipa. Villaria is characterized by unilocular ovaries, parietal placentation and strictly horizontal ovules. These features are unique within the Octotropideae. We recognize a total of five Villaria species, one new species (V. leytensis) is described here, and two species (V. philippinensis and V. rolfei) are transferred into synonymy with V. odorata. Each species is fully described, and a key to the species, a distribution map and illustrations are provided.

Deux espèces nouvelles de Thiollierea (Rubiaceae) restreintes aux sols hypermagnésiens du massif du Boulinda (Nouvelle-Calédonie)

Barrabé L., Mouly A. & Munzinger J. 2011. — Deux espèces nouvelles de Thiollierea (Rubiaceae) restreintes aux sols hypermagnésiens du massif du Boulinda (Nouvelle-Calédonie). Adansonia, sér. 3, 33 (1): 135–148. ABSTRACT Two new species of Thiollierea (Rubiaceae) restricted to hypermagnesian soils of Boulinda massif (New Caledonia). Two new species of Thiollierea (Rubiaceae) endemic from New Caledonia are described and illustrated. A key to all species of the genus Thiollierea is provided, Thiollierea rigaultii sp. nov. and T. dagostinii sp. nov. belong to the group of Thiollierea with white and purplish flowers, Thiollierea rigaultii sp. nov. has several unique morphological characters, never recorded before in the group: 1-flowered inflorescences, colleters totally covering the internal face of the calyx, and large and coriaceous corollas, Thiollierea dagostinii sp. nov. is characterized by a new and original combination of morphological characters: colleters totally covering stipules adaxially, sub-winged hypanthium, calyx tube obvious without secondary tear, hirsute and cylindrical filament indumentum. Both species are endemic to Boulinda, an ultramafic massif on the North-Western coast of New Caledonia. Their populations are restricted to small forest edges, on hypermagnesian soils, where microendemism is important. The evaluation of IUCN status of these two rare species placed them in the category “critically endangered” (CR).

Reinstatement of the endemic New Caledonian genus Thiollierea Montrouz. (Rubiaceae) necessitated by the polyphyly of Bikkia Reinw. as currently circumscribed

Barrabé L., Mouly A., Lowry II P. P. & Munzinger J. 2011. — Reinstatement of the endemic New Caledonian genus Thiollierea Montrouz. (Rubiaceae) necessitated by the polyphyly of Bikkia Reinw. as currently circumscribed. Adansonia, sér. 3, 33 (1): 115–134. ABSTRACT The genus Bikkia Reinw. as currently circumscribed comprises 20 species distributed throughout the western Pacific Ocean, with a center of diversity in New Caledonia (11 species, all but one endemic). Two recent phylogenetic studies based respectively on molecular and morphological data have shown that Bikkia s.l. is polyphyletic, comprising two lineages: coastal Bikkia from the western Pacific (including the type species of the genus, B. tetrandra (L.f.) A.Rich.) and endemic New Caledonian Bikkia, a situation that necessitates the resurrection of the generic name Thiollierea Montrouz., the oldest available for the second of these groups. An emended description is provided for Thiollierea as well as a summary of the features that distinguish it from Bikkia s.s., and seven new combinations are proposed (T. kaalaensis (N.Hallé & Jérémie) Barrabé & Mouly, T. lenormandii (N.Hallé & Jérémie) Barrabé & Mouly, T. neriifolia (Brongn.) Barrabé & Mouly, T. pachyphylla (Guillaumin) Barrabé & Mouly, T. parviflora (Schltr. & K.Krause) Barrabé & Mouly, T. retusiflora (Brongn.) Barrabé & Mouly and T. tubiflora (Brongn.) Barrabé & Mouly).