Discovering new orchids

Botanists have been naming and describing orchids for more than 250 years. Linnaeus' Species Plantarum of 1753 is a useful starting point, because it includes almost all plant species known to science at that time. The orchids were as yet a minor group, with only 69 named species, most of them European.

Although they were not in cultivation in those days, Linnaeus already knew some tropical orchids from herbarium specimens, including the one he named Epidendrum amabile, now called Phalaenopsis amabilis, the moth orchid. This is one of the parents of many of the Phalaenopsis hybrids that are so immensely popular today.

Probably the largest plant family?

Today we know approximately 26,000 species of Orchidaceae, which according to Genera Orchidacearum are classified into nearly 800 genera: an enormous increase compared to the days of Linnaeus. This makes it probably the largest of all plant families, unless you ask a specialist in the Compositae (daisy family), who will claim that this family is the largest. At present it is difficult to decide who is right, because it would be a mistake to think that we are close to a complete inventory of the world's flora. In the year 2013, for example, nearly 370 new orchid species were described, and this was by no means an exceptional year.

It seems safe to predict that a few thousand orchid species still await description. So how can we discover these new species?

How are new species discovered?

1. New species found among herbarium material in scientific institutions

Identifying orchids from herbarium material can be a time-consuming process. In many cases the specimens need to be rehydrated and carefully analysed under a dissecting microscope to establish the diagnostic characters. For most orchid genera there are no modern monographs available, so that searching through the literature for a matching species can take a lot of time. For these reasons, many herbaria have a backlog of hundreds or thousands of orchid specimens that are named only to genus (we call them 'indets', for undetermined). Obviously, these tend to be the more difficult cases; for example, small-flowered species in large genera such as Stelis or Bulbophyllum, or specimens of which the material is poor ('scrappy specimens'). More exciting, however, is that undescribed species also tend to accumulate among the indets. This is to be expected, because if they are undescribed someone would have had to make a mistake for them to end up among the named species.

Therefore, a good place to hunt for new species is among the indets in major herbaria. An example of a striking new orchid found in this way was described in my blog post on Evelyn Cheesman’s blue orchid. Less often, new species come to light when wrongly identified specimens are re-examined.

2. New species found by specialist collectors during expeditions

We have quite a good idea which parts of the globe have been well-explored botanically. It hardly needs saying that there is a better chance of finding new things in under-explored areas. Still, not every under-explored wilderness is equally promising. The probability of discovering new orchids in, say, the Gobi Desert is virtually nil. With our knowledge of biogeography and ecology and with the help of modern techniques like niche modelling we can predict fairly accurately where our best chances of finding new orchids are. In this way, an orchid specialist who is working on a particular group can select target areas where an expedition would be most profitable.

A major problem with fieldwork is that in the tropics in any given month only a small minority of the species are found in flower, typically between 10 and 20%. A specimen without flowers (a sterile specimen) is worthless if it is a new species. The flowers are essential for us to describe it, because many orchids may have very similar vegetative parts (leaves and stems) while their flowers are utterly different.

Ideally, we would like to collect living orchid plants and bring them into cultivation until they flower, at which time they can be photographed, described and turned into a permanent specimen. If that sounds like a euphemism for killing it, that is because it sometimes is. But in most cases we will only preserve the flowers and part of the plant and try to keep it alive to be able to harvest more material in the future and to study other aspects of it.

In terms of the number of permits needed, collecting orchids is far more difficult than most other plant groups; all species are listed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and are often also protected by other legislation. Whereas the transfer of dried herbarium specimens is already difficult, obtaining permits to collect and transfer living specimens, even for scientific purposes, is still harder. Most countries do not allow it, for reasons that are often unrelated to scientific research (e.g. due to the belief that the specimens will secretly be used for commercial purposes). I can attest that it can be quite frustrating for an orchid specialist to be only allowed to make herbarium specimens, while being forced to leave non-flowering, potentially undescribed species in place.

3. New species found in the trade

Although in economic terms the trade in wild orchid species is almost negligible compared to the trade in hybrids, this still concerns thousands of species. From time to time plants turn up on the market that nobody can identify. It is known that there are unscrupulous dealers who create hybrids which they try to pass off as new species; as a result there is a fairly good chance that those un-identifiable plants turn out to be such hybrids. But now and then the orchid is so distinctive and so different from related species that one must conclude that it is an undescribed species, even without conducting genetic analyses.

This creates a dilemma for the bona fide scientist. On the one hand it is in the interest of science to name and describe each new species as soon as possible; on the other hand, handling potentially illegal material can create all kinds of legal problems for the researcher. Most scientists are therefore understandably reluctant to deal with new species in this category.

4. New species that were overlooked

Sometimes, new species are hiding in plain sight. This happens when they are very similar to other, named species, and are mistakenly identified as such. Unlike the previous three categories, new species of this type can even be found in areas that have been thoroughly studied. Most of the surprisingly many 'new' European orchids that have been described in recent decades (for example in the genus Ophrys) belong to this category. Some of these may indeed be good species that are difficult to recognise (so called cryptic species), but it is probable that most are merely local forms of variable and widespread species that were described long ago.

Where should we look for new orchid species?

Evidently, the tropics are where most new species will be found, because 95% of all orchids are tropical. Within the tropics, some countries, or parts of countries, are far better known than others. Not many new species are to be expected from Mexico, Kenya, or the island of Java, for example. India and Thailand are reasonably well-known. Poorly known areas in continental Asia include parts of Laos, Cambodia and Burma, which is where collecting efforts would be most valuable. Indonesia and the Philippines have regions that are still urgently in need of more botanical exploration. In the Pacific, New Guinea is both extremely rich in orchids and heavily under-explored botanically. Africa and Madagascar are reasonably well known, as is Brazil. Parts of Colombia, Ecuador, Peru and Bolivia are still incompletely known botanically, while this part of the world is the global hotspot for orchid diversity. New species are being found there all the time.

How do we know that a species is really new?

The World Checklist of Selected Plant Families lists all known orchid species. Also, thanks to digitisation efforts of many institutions, huge numbers of herbarium specimens and much of the old literature have become available online. But even with these fantastic resources at our fingertips it may still be necessary to go back to the actual type specimens and to analyse them in detail. In many cases one still has to be able to read Latin descriptions as well, because for a surprising number of orchid species that is all the information there is, especially when the type specimens no longer exist. In short, it depends very much on the particular genus and species how confident we can be that something is new.

How can we speed up the process of discovery?

Make an extra effort to identify the indets in herbaria
Carry out targeted collecting in under-explored areas that are expected to be species-rich
Perform genetic studies when the presence of cryptic species is suspected

In my view, we should prioritise collecting efforts in the wild, because tropical forests are still being destroyed on a scale that is barely comprehensible. Not only are we undoubtedly losing species before they are even named, we are also turning our herbarium specimens into the relics of extinct species. While in a sense this makes our herbarium collections even more valuable, it would be so much better if the actual species were still around as living organisms. Finding and naming them are crucial first steps towards their preservation.

References

Pridgeon, A. M., Cribb, P. J., Chase, M. W. & Rasmussen, F. N. (eds) (1999–2014). Genera Orchidacearum. Volume 1–6. Oxford University Press, Oxford.

Schuiteman, A. & de Vogel, E. F. (2003). Taxonomy for Conservation. In: Dixon, K.W., Kell, S.P., Barrett, R.L., Cribb, P.J. (eds.), Orchid Conservation, pp. 55–68. Natural History Publications (Borneo), Kota Kinabalu.