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

Tosh, James; Dessein, Steven; Buerki, Sven; Groeninckx, Inge; Mouly, Arnaud; Bremer, Birgitta; Smets, Erik; Block, Petra De

doi:10.1093/aob/mct222

Cited by 27 publications

(18 citation statements)

References 62 publications

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“…3 mm). However, in the study of Tosh et al (2013), I. lagenifructa did not form a monophyletic group with I. homolleae and I. quadrilocularis.…”

Section: -Sf (Tef)mentioning

confidence: 75%

“…530 species (Davis et al 2009) of Ixora, but they do occur in several parts of the distribution range: the Mascarenes (Myonima, Doricera), the Pacific Region (Hitoa), Australia [Ixora baileyana Bridson & L.G.Adams in Adams et al (1987: 214)] and Madagascar (Thouarsiora). The presence of more than two locules is sometimes correlated with dioecy or functional dioecy as in Myonima, Doricera and Ixora baileyana (Adams et al 1987, Tosh et al, 2013, but this is not the case in Hitoa or in the Madagascan species. The phylogenetic analysis published by Mouly et al (2009, p. 152, fig.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, even in Madagascar this switch seems to have occurred more than once. In a molecular study on the Madagascan Ixora, which included three out of the four multilocular species (Tosh et al 2013, Fig. 3), multilocular species did not form a monophyletic group.…”

Section: Introductionmentioning

confidence: 99%

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A synopsis of the multilocular species of Ixora (Rubiaceae) from Madagascar

Block¹

2014

Phytotaxa

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Two new Ixora species from Madagascar are described, Ixora lagenifructa and I. quadrilocularis. Ixora littoralis, previously positioned in the monospecific genus Thouarsiora, is newly named I. homolleae. These three species are characterized by 4-locular ovaries and fruits, 4-lobed stigmas, large fruits with thick walls and well-developed calyces. A fourth species, I. trimera, shows the same characters but its ovaries are 2-, 3-or 4-locular and its stigmas are 2-, 3-or 4-lobed. A dichotomous key, detailed descriptions and distribution maps are given for these four species, the only multilocular ones in Madagascar.

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“…3 mm). However, in the study of Tosh et al (2013), I. lagenifructa did not form a monophyletic group with I. homolleae and I. quadrilocularis.…”

Section: -Sf (Tef)mentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

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A synopsis of the multilocular species of Ixora (Rubiaceae) from Madagascar

Block¹

2014

Phytotaxa

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“…This phenomenon is encountered in more (Madagascan) plant groups and is interpreted as the result of recent rapid radiation (e.g. Malcomber 2002, Mort et al 2007, Janssen et al 2008, Knope et al 2012, Tosh et al 2013). It should be noted, though, that recent studies using next generation sequencing (e.g.…”

Section: Introductionmentioning

confidence: 99%

Four new endemic genera of Rubiaceae (Pavetteae) from Madagascar represent multiple radiations into drylands

Block¹,

Rakotonasolo²,

Ntore³

et al. 2018

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The taxonomic positions and phylogenetic relationships of six Pavetteae species endemic to Madagascar were tested with a phylogenetic study of the Afro-Madagascan representatives of the tribe Pavetteae based on sequence data from six markers rps16, trnT-F, petD, accD-psa1, PI and ITS. The six species were resolved into four well-supported and morphologically distinct clades which we here formally recognise at generic level. The new genera are the monospecific Exallosperma and Pseudocoptosperma, each with a single species, and Helictosperma and Tulearia, each with two species. Each genus is characterised by one or more autapomorphies or by a unique combination of plesiomorphic characters. Mostly, the distinguishing characters are found in fruit and seed; Exallosperma differs from all other Pavetteae genera by the fruit consisting of two stony pyrenes, each with a single laterally flattened seed with irregularly distributed ridges on the surface; Helictosperma is unique by its single spherical seed rolled-in on itself in the shape of a giant pill-millipede. Pseudocoptosperma is characterised by the combination of three ovules pendulous from a small placenta and triangular stipules with a strongly developed awn, whereas Tulearia is characterised by robust sericeous flowers, small leaves, uni- or pauciflorous inflorescences and fruits with two pyrenes, each with a single ruminate seed.The four new genera show marked adaptations to the dry habitats in which they grow. They represent multiple radiations into drylands and highlight the importance of the dry forest and scrub vegetation in western, southern and northern Madagascar for plant biodiversity. The description of the four new genera shows that the tribe Pavetteae exhibits the same pattern as many plant groups in Madagascar, which are characterised by a high proportion of endemic genera comprising a single or a few species.In the four new genera, five new species are described and one new combination is made: Exallosperma longiflora De Block; Helictosperma malacophylla (Drake) De Block, Helictosperma poissoniana De Block, Pseudocoptosperma menabense Capuron ex De Block; Tulearia capsaintemariensis De Block and Tulearia splendida De Block.

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“…Likewise, the Ixora genus 20 originated in South-East Asia, in Borneo in particular (Lorence et al 2007), and its ancestral 21 lineage originated 30 to 50 Mya (Tosh et al 2013). Therefore, the ancestors of Musa and when the ancestors of both genera shared geographical distribution.…”

mentioning

confidence: 98%