Bhanumas Chantarasuwan

An Extreme Case of Plant-Insect Codiversification: Figs and Fig-Pollinating Wasps

It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent phylogenetic comparisons have supported this model of diversification for both insect herbivores and specialized pollinators. An exceptional case where contemporaneous plant-insect diversification might be expected is the obligate mutualism between fig trees (Ficus species, Moraceae) and their pollinating wasps (Agaonidae, Hymenoptera). The ubiquity and ecological significance of this mutualism in tropical and subtropical ecosystems has long intrigued biologists, but the systematic challenge posed by >750 interacting species pairs has hindered progress toward understanding its evolutionary history. In particular, taxon sampling and analytical tools have been insufficient for large-scale cophylogenetic analyses. Here, we sampled nearly 200 interacting pairs of fig and wasp species from across the globe. Two supermatrices were assembled: on an average, wasps had sequences from 77% of 6 genes (5.6 kb), figs had sequences from 60% of 5 genes (5.5 kb), and overall 850 new DNA sequences were generated for this study. We also developed a new analytical tool, Jane 2, for event-based phylogenetic reconciliation analysis of very large data sets. Separate Bayesian phylogenetic analyses for figs and fig wasps under relaxed molecular clock assumptions indicate Cretaceous diversification of crown groups and contemporaneous divergence for nearly half of all fig and pollinator lineages. Event-based cophylogenetic analyses further support the codiversification hypothesis. Biogeographic analyses indicate that the present-day distribution of fig and pollinator lineages is consistent with a Eurasian origin and subsequent dispersal, rather than with Gondwanan vicariance. Overall, our findings indicate that the fig-pollinator mutualism represents an extreme case among plant-insect interactions of coordinated dispersal and long-term codiversification. [Biogeography; coevolution; cospeciation; host switching; long-branch attraction; phylogeny.].

A Revision of Ficus Subsection Urostigma (Moraceae)

Abstract The present taxonomic revision of Ficus subsection Urostigma recognizes 27 species, of which three are new: F. chiangraiensis, F. middletonii, F. pseudoconcinna. Two new varieties are distinguished within F. virens, var. dispersa and var. matthewii. Ficus lecardii and L. salicifolia, formerly subspecies of F. cordata, are again reinstated to the species level. Typical characters for the subsection are monoecy, monostaminate flowers, red(-brown) colored ovaries and cystoliths on only the abaxial leaf surface. Ficus amplissima and F. rumphii (section Leucogyne) were formerly part of subsection Urostigma, and they have been added here to the key and descriptions because of their morphological resemblance with the species in F. subsection Urostigma. Molecular based phylogenetic analyses showed that at least F. rumphii is unrelated to subsection Urostigma. The two species only differ from subsect. Urostigma in their whitish ovaries and cystoliths at both sides of the leaf blade and they are pollinated by a different group of wasps, species of Eupristina subg. Parapristina.

A New Classification of Ficus Subsection Urostigma (Moraceae) Based on Four Nuclear DNA Markers (ITS, ETS, G3pdh, and ncpGS), Morphology and Leaf Anatomy

Ficus subsection Urostigma as currently circumscribed contains 27 species, distributed in Africa, Asia, Australia and the Pacific, and is of key importance to understand the origin and evolution of Ficus and the fig-wasp mutualism. The species of subsection Urostigma are very variable in morphological characters and exhibit a wide range of often partly overlapping distributions, which makes identification often difficult. The systematic classification within and between this subsection and others is problematic, e.g., it is still unclear where to classify F. amplissima and F. rumphii. To clarify the circumscription of subsection Urostigma, a phylogenetic reconstruction based on four nuclear DNA markers (ITS, ETS, G3pdh, and ncpGS) combined with morphology and leaf anatomy is conducted. The phylogenetic tree based on the combined datasets shows that F. madagascariensis, a Madagascan species, is sister to the remainder of subsect. Urostigma. Ficus amplissima and F. rumphii, formerly constituting sect. Leucogyne, appear to be imbedded in subsect. Conosycea. The result of the phylogenetic analysis necessitates nomenclatural adjustments. A new classification of Ficus subsection Urostigma is presented along with the morphological and leaf anatomical apomorphies typical for the clades. Two new species are described ─ one in subsect. Urostigma, the other in Conosycea. One variety is raised to species level.

Ficus cornelisiana, a new species of Ficus subsection Urostigma (Moraceae) from theSino-himalayan region

A small fig tree has been misidentified as Ficus orthoneura for a long time. However, morphologically it is distinct from F. orthoneura and F. hookeriana. Typical are the ellipsoid, puberulous receptacle and caducous basal bracts. Leaf anatomy shows a multiple epidermis with the cells in the inner layer much larger than in the outer layer and thus both layers resemble an epidermis with a separate hypodermis. The abaxial cuticle is strongly sculptured, the palisade layer shows some long subdivided cells, and enlarged lithocysts are only present abaxially. Because of these differences we hereby describe it as a new species, named in honour of Cornelis (Cees) Berg: Ficus cornelisiana.

A study on the taxonomy of some stoloniflorousspecies of Ficus subsection Sycocarpus (Moraceae) in Thailand and Malesia

The taxonomy of several, mainly stoloniflorous, Ficus species from Thailand and Malesia is revised resulting in a new species, F. bukitrayaensis C.C. Berg and two new names, F. malayana C.C. Berg & Chantarasuwan and F. ridleyana C.C. Berg & Chantarasuwan. Ficus megaleia Corner and F. uncinata (King) Becc. are redefined and F. heterostyla Merr. is reinstated. Ficus arfakensis King and F. scortechinii King are reduced to synonyms of F. ribes Blume.