On my recent trip collecting nettles in the Dominican Republic we came across what is very likely a new species of Pilea, a group of about succulent nettles. I thought it might be useful to outline what happens from collecting / discovering something new to it being published as a new species, from my own botanical perspective of course. In the case of this species, it has a couple of distinctive features which make it stand out from similar looking Pilea species: 1) a well developed above-ground tuber, up to the size of a small potato, and 2) relatively large male flower clusters for the group of species it is in. This gives me two diagnostic characters to check with in existing collections and in the literature. Pilea is a genus of over 700 species found in tropical and subtropical Asia, Madagascar, Africa and the Americas. All but a few species are restricted to one of these areas or a much smaller area and this knowledge enables me to delimit my search area. In this case, the Greater Antilles (Cuba, Jamaica, the Cayman Islands and Hispaniola).
My second job is to see if the species has already been described. To do this I need to look through the collections of the most appropriate herbaria for this area, starting with the National Herbarium of the Dominican Republic. This can take quite a long time although many collections have been digitised and are available online. I then need to follow this up by reviewing the literature for the region to see if I find any descriptions which match or are close. Once I have done this I should have a list of species that are possible or close matches. These I can then compare in more detail with my possible new species and confirm whether it is new or not. This I will do by looking at the type specimens under a microscope and comparing their key features: leaf and stem shape, the nature of their hairs, the size and shape of the flowers and of course in this case, the presence or not of a tuber. This also provides me with the information I need to write the diagnosis of the new species. Once I am sure that this is a new species I can start writing the description and think of a name. A new species description will include a detailed description of the plant, a line drawing illustrating the diagnostic features and a species conservation assessment which will provide an indication as to how threatened with extinction it is.
Pilea is a genus or group of over 700 species in the nettle family (Urticaceae). It is mainly comprised of succulent herbaceous plants that grow in the shade of forest and is especially diverse in the Greater Antilles and on limestone. Currently over 110 species are recorded for the island of Hispaniola which encompasses the Dominican Republic. They are very variable in their shape and form and probably most people (including many botanists) might not think that they were related to nettles. It is a group that I have been working on for over 15 years and I began work on revising their classification for neighbouring Cuba in 2010. Surveying the species in the herbarium of the National Botanic Garden in Santo Domingo helped me to see how they compared to the species in Cuba.
After a week looking at the collections and sorting them into piles I started to get an idea as to the species present on this amazing island. Of course establishing their correct names involves a whole other body of work but at least I now have an idea as to what there is in the Dominican Republic, what might be conspecific with Cuban species and where there are complexes of closely-related and potentially interbreeding species. Not bad for a week’s work.
For a week now I have been accompanying a team from the Jardín Botánico Nacional and Kew’s Millennium Seed Bank on a field trip to collect seed of plants endemic to Hispaniola for banking at the Jardín Botánico and Kew. I have been taking advantage of this trip to collect nettles but also to learn how to harvest and bank their seeds. The Greater Antilles which includes the Dominica Republic / Hispaniola is a centre for species diversity for nettles and most of the 100 or so species found here are found nowhere else. Given obvious pressure on the island’s forests both in the Dominican Republic as well as in Haiti, banking their seeds could support their reintroduction as a last ditch attempt to prevent their extinction.
The seed bank at Kew which banks the seeds of >50,000 species currently has only 14 sp of nettle which for me seemed a little on the low side given that there are about 2,000 species Worldwide. Support from the Bentham Moxon Trust is helping me to increase this figure significantly, both by enabling me to help develop seed-collecting protocols for nettles and so encourage seed banks to collect them, but also because I am learning from them how to collect seeds, something that I can do myself on future fieldwork in collaboration with other seed banks. Continue reading Collecting nettle seeds, no easy task!→
Alex Monro's blog about the documenting and conservation of biodiversity