The ‘ didymocarpoid Gesneriaceae ’ (traditional subfam. Cyrtandroideae excluding Epithemateae) are the largest group of Old World Gesneriaceae, comprising 85 genera and 1800 species. We attempt to resolve their hitherto poorly understood generic relationships using three molecular markers on 145 species, of which 128 belong to didymocarpoid Gesneriaceae. Our analyses demonstrate that consistent topological relationships can be retrieved from data sets with missing data using subsamples and different combinations of gene sequences. We show that all available classifi cations in Old World Gesneriaceae are artifi cial and do not refl ect natural relationships. At the base of the didymocarpoids are grades of clades comprising isolated genera and small groups from Asia and Europe. These are followed by a clade comprising the African and Madagascan genera. The remaining clades represent the advanced Asiatic and Malesian genera. They include a major group with mostly twisted capsules. The much larger group of remaining genera comprises exclusively genera with straight capsules and the huge genus Cyrtandra with indehiscent fruits. Several genera such as Briggsia , Henckelia , and Chirita are not monophyletic; Chirita is even distributed throughout fi ve clades. This degree of incongruence between molecular phylogenies, traditional classifi cations, and generic delimitations indicates the problems with classifi cations based on, sometimes a single, morphological characters.

A preliminary phylogeny of the 'Didymocarpoid Gesneriaceae' based on three molecular data sets: incongruence with available tribal classifications

Based on molecular data and a morphological evaluation, evidence is provided that the species of eleven, mostly small-sized and monotypic genera of Chinese Gesneriaceae (Ancylostemon, Bournea, Briggsia s.str., Dayaoshania, Deinocheilos, Isometrum, Opithandra, Oreocharis, Paraisometrum, Thamnocharis, Tremacron) form a highly-supported group in which the species interrelationships run across traditional generic boundaries. The data confirm previous doubts on the naturalness of some of these genera and, after a detailed discussion of the particular genera, the conclusion is reached that the whole group is best regarded as a single genus, Oreocharis, which is thus expanded to comprise over 80 species. A list of the species is given and the necessary transfers are made. The new delimitation provides a framework for studying the species relationships and working out an infrageneric classification. Oreocharis provides an excellent example of a major monophyletic group that has experienced a rapid radiation early in its evolution and shows manifold convergences in floral characters (corolla form and coloration, fertility of stamens, anther shape and dehiscence mode), apparently reflecting different pollination strategies, but has little variation in vegetative habit and fruit structure.

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A new delineation for Oreocharis incorporating an additional ten genera of Chinese Gesneriaceae

Summary


Genome size variation is of fundamental biological importance and has been a longstanding puzzle in evolutionary biology. Several hypotheses for genome size evolution including neutral, maladaptive, and adaptive models have been proposed, but the relative importance of these models remains controversial.
Primulina is a genus that is highly diversified in the Karst region of southern China, where genome size variation and the underlying evolutionary mechanisms are poorly understood. We reconstructed the phylogeny of Primulina using DNA sequences for 104 species and determined the genome sizes of 101 species. We examined the phylogenetic signal in genome size variation, and tested the fit to different evolutionary models and for correlations with variation in latitude and specific leaf area (SLA).
The results showed that genome size, SLA and latitudinal variation all displayed strong phylogenetic signals, but were best explained by different evolutionary models. Furthermore, significant positive relationships were detected between genome size and SLA and between genome size and latitude.
Our study is the first to investigate genome size evolution on such a comprehensive scale and in the Karst region flora. We conclude that genome size in Primulina is phylogenetically conserved but its variation among species is a combined outcome of both neutral and adaptive evolution.

https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/nph.12726

Adaptive and nonadaptive genome size evolution in Karst endemic flora of China.

Using a time-calibrated phylogenetic hypothesis including 768 Gesneriaceae species (out of [Formula: see text]3300 species) and more than 29,000 aligned bases from 26 gene regions, we test Gesneriaceae for diversification rate shifts and the possible proximal drivers of these shifts: geographic distributions, growth forms, and pollination syndromes. Bayesian Analysis of Macroevolutionary Mixtures analyses found five significant rate shifts in Beslerieae, core Nematanthus, core Columneinae, core Streptocarpus, and Pacific Cyrtandra These rate shifts correspond with shifts in diversification rates, as inferred by Binary State Speciation and Extinction Model and Geographic State Speciation and Extinction model, associated with hummingbird pollination, epiphytism, unifoliate growth, and geographic area. Our results suggest that diversification processes are extremely variable across Gesneriaceae clades with different combinations of characters influencing diversification rates in different clades. Diversification patterns between New and Old World lineages show dramatic differences, suggesting that the processes of diversification in Gesneriaceae are very different in these two geographic regions.

/pdf/distinct-processes-drive-diversification-in-different-clades-vmbfppy10o.pdf

Distinct Processes Drive Diversification in Different Clades of Gesneriaceae.

Based on molecular studies, the small Chinese genus Petrocodon (two species and one variety) has been recently enlarged to include the monotypic genera Calcareoboea, Paralagarosolen and Tengia. It is shown here that the (6-7) species of Lagarosolen, the monotypic Dolicholoma, a few species of Didymocarpus, and a number of new species that have recently been published (but not formally described) under Petrocodon and Lagarosolen should be included in this genus. This raises the size of the genus from five to around 20 species. With respect to the floral diversity (corolla form, size, and coloration; with the exception of Tengia, the androecium is always diandrous) and inferred pollination syndromes (different forms of melittophily, ornithophily, psycho- and/or sphingophily), Petrocodon represents one of the most varied genera of Old World Gesneriaceae, comparable to some New World genera.

A new definition of the genus Petrocodon (Gesneriaceae)

The polyphyletic genus Chirita is remodelled after an extensive molecular phylogenetic study of species assigned to it and to other associated genera. Most of Chirita sect. Chirita and the monotypic Hemiboeopsis are amalgamated with Henckelia sect. Henckelia , resulting in a very differently circumscribed genus Henckelia and the synonymisation of Chirita. The remaining species of Chirita sect. Chirita are accommodated in the revived genus Damrongia. Chirita sect. Liebigia is recognised as the genus Liebigia. Chirita sect. Microchirita is recognised as the genus Microchirita. Chirita sect. Gibbosaccus is, together with Chiritopsis and Wentsaiboea , included in the originally monotypic and now enormously expanded genus Primulina. The necessary combinations are made and a general list showing the present accommodation of the species previously described under Chirita , Chiritopsis , Hemiboeopsis , Primulina and Wentsaiboea is provided.

Molecular systematics and remodelling of Chirita and associated genera (Gesneriaceae)

Rhododendron obscurum Sleumer (Ericaceae) is a species endemic to Peninsular Malaysia. This name is a later homonym of Rhododendron obscurum Franch. ex Balf.f. In preparation of a revision of the Ericaceae for the Flora of Peninsular Malaysia and of a Red List assessment of this species by the Global Conservation Consortium for Rhododendron, a new name, Rhododendron benomense Rafidah & A.C.Elliott, is proposed here.

A.R. Rafidah

Papers

Molecular systematics and remodelling of Chirita and associated genera (Gesneriaceae)

Rhododendron benomense rafidah & a.c.elliott (ericaceae), a new name for rhododendron obscurum sleumer, a species endemic to peninsular malaysia

The correct name for Pseuderanthemum lilacinum, P. teijsmannii and P. teysmannii (Acanthaceae) in Peninsular Malaysia