Ficus classification

Obermüller, F. A., Kjellberg, F., RØnsted, N., Chantarasuwan, B. & Lut, C. W. J., 2013, In memoriam Cees Berg (2 July 1934 - 31 August 2012), Blumea 57 (3), pp. 199-206 : 201-202

Ficus classification

I first met Kees in 1983, for the first fig meeting. Among others, those in attendance included the late Koos Wiebes and Jacob Galil. A young generation of scientists had just started to work on the fig classification, early 1980. They included Allen Herre, Judith Bronstein and me. Steve Compton soon joined the group, and others would follow. At that time, publications on fig-fig wasp interactions were few. Only two papers on the subject in indexed journals appeared that year, one by Baijnath et al. and one by Berg. Berg’s paper ‘Floral differentiation and dioecism in Ficus (Moraceae) ’ raised a question that would haunt him until his last days: how can monoecious figs produce short-styled and long-styled pistillate flowers mixed together within the same fig? He thought the answer could come from histological studies. “There might be [histological] methods better than Wouter [Verkerke] had at his disposal to supply answers.” Indeed, an answer to his concern may have been provided by the team of Simone Teixeira de Pádua at the last fig meeting. The atypical asclepiate style development observed in Ficus could be the morphological key. The questions around pistillate flower specialization made the figs of monoecious subsection Petenense of section Pharmacosycea particularly fascinating to him: the stigmas of short-styled and long-styled flowers reach different heights. When I sent him a picture of a receptive fig of Ficus adhatodifolia , with the flower arrangement of subsection Petenense , he answered “Dear Finn, in all F. adhatodifolia material the interior of the figs looks like those of all other members of subsection Bergianae . I hope that you collected some material, figs + leaves, of this interesting plant which is not so systematist friendly.” In fact, this F. adhatodifolia was not atypical, but the picture was taken in the field, from fresh material, at receptivity when traits were obvious. In the herbarium with figs later in development, the trait could no longer be seen.

There was quite a bit of frustration in the relationship between fig biologists and the taxonomists during the last two decades of the 20th century. The biologists generally worked very locally and they could see very clear differences among entities that Kees did not recognize in his floristic treatments. The biologist presented his points and Kees put up a broad smile and, apparently, did not change his perspective. The disconnection was partly due to the slow pace of global taxonomic revision. It was also due to the difference between a local perspective and a range-wide perspective. But these were not the only reasons. Kees had decided that he would only recognize species that he could distinguish based on sterile material in herbarium collections. And that is a hard challenge, especially in section Malvanthera . Therefore, for scientists working on New Guinea, his revision of section Malvanthera was a nightmare. The species group of Ficus americana provides a more interesting case: “The fact that “ guianensis ” (highly variable), “ greifiana ”, and “ subapiculata ” co-occur suggests that they are species rather than subspecies. I have not been able to find vegeta- tive characters to distinguish them from each other and from material outside the Amazon basin.” Indeed, in the herbarium in Cayenne, most of the samples are relatively easy to assign to species (if they bear figs), but without figs it becomes really complex, even out in the forest. Further samples from some places look atypical. In fact, we are within a species complex that probably presents quite a bit of geographic differentiation in forms. Calling this a species complex is probably the appropriate taxonomic treatment, pending population genetics studies. Nevertheless, for the field biologist, the lack of clear names for what looked like highly distinct forms in coastal French Guiana was frustrating.

In addition, you often needed a trained eye to detect Kees’ doubts in his taxonomic revisions. And they were many and most of them were legitimate. About the Ficus pertusa complex he wrote me “these species complexes have been a headache”. And more generally about Brazil “by the way, did you ever receive my headache publication Ilicifolia 5, in which there is a survey of the extra-Amazonian Ficus species?”.

The paths of taxonomists and biologists began to converge seriously with the start of the 21st century. Biologists travelled more, saw more variation, began to do some population genetics and hence began to understand better the taxonomy and taxonomic problems. Reciprocally, the biologists provided information that helped the taxonomist to advance. A good photograph of fresh material shortened the discussion.

In his later years, after having clarified his global vision of figs, Kees began to enter more in detail into species groups, and when possible added some observations made in the field. “The auriculata-oligodon-hainanensis assemblage is not easy to disentangle – see my paper in Thai Forest Bulletin 35 (2007). During my recent visit to Thailand I started to change my opinion, but do not know how to tackle the problem. It is not only a matter of inadequate herbarium material.Also in the field the situations are complex.” Indeed, population genetic studies of this species group show that it is a complex with variation, hybrids, and introgression, but also clearly defined entities that coexist locally. For that species group Kees had reached the bottom of the question and understood where population genetic studies should take over.

Another important development was the advances in fig wasp collecting and knowledge of their taxonomy. Berg and Wiebes published a remarkable volume in 1992, African fig trees and fig wasps. It covered all African fig species and quite a number of their pollinating wasps. It raised hopes within the fig biologist community that figs and fig wasps from other parts of the world would soon be properly described and properly arranged into well-organized taxonomic groups. This has yet to happen. Wiebes finalized his taxonomic treatment of The Indo-Australian Agaoninae (pollinators of figs) in 1994, and the one on The New World Agaoninae (pollinators of figs) in 1995. Kees took much more time. He published his treatment for Flora Malesiana in 2005. His treatment of the flora of the Americas was not yet published by the time of his death. However, Kees’ treatments were much more thorough and as objective as possible. He did not take hints from the classification of associated pollinating wasps and from molecular results. In an interesting twist, Kees classified F. menabeensis (and F. humbertii ) from Madagascar as belonging to section Conosycea , suggesting an Asian origin, while Wiebes thought the pollinator belonged to genus Platyscapa , which could have come from Africa as was the case for all other figs and fig wasps from Madagascar. I have always assumed that Wiebes named the species Platyscapa bergi as an inside joke, convinced that history would prove Kees to be wrong. Current developments suggest Kees was right and Wiebes wrong. In another interesting twist, Kees never believed the molecular results that have pervaded fig literature since 1996; these separated section Pharmacosycea and its pollinators from section Oreosycea and its pollinators. The results were simply not acceptable to him, and he just put up a large smile, as usual. Recent results suggest he may have been right. Highly intensive collection of fig wasps only began recently. Someone like Astrid Cruaud saw more Ficus species in the field in her three years of PhD than Corner ever saw in his life and Jean-Yves Rasplus, one of the two current fig wasp taxonomists with Simon van Noort, has seen huge numbers of fig species, especially during the last 10 years. China has woken up, especially in Yunnan, a region that could be the cradle of Ficus diversification. This means that it has been only recently that fig wasp taxonomy has made new advances, with many more years to go before a global revision is done, and it is only recently that fig scientists have really looked at fig variation among islands, countries or continents.

Someone told me a few years ago that you can only tell a good taxonomist at the end of his life. Kees was a good taxonomist. Quite a number of times he defended positions that seemed backward but turned out to be true. The last few years, a few other fig taxonomists have seen enough fig species in the field from all over the world to help Kees finalize his taxonomic perceptions. These years were few, but Kees enjoyed them, because he was no longer the only field botanist who understood figs based on field work.

FINN KJELLBERG