by Piter Kehoma Boll
I have already written on the problems of taxonomy in small and not-so-cute groups in a previous post, where I talked about the fact that several species, after being described, are completely ignored for decades or centuries. Here I will focus on the other extreme: the species yet to be described.
This is not a very big problem in very well studied groups, such as vertebrates and flowering plants, but less attractive groups, like worms, suffer a lot by the lack of taxonomists. I am going to use land planarians as an example, again, since it is the group that I work with.
Land planarians have been shown to be important predators of invertebrates in forests, as well as good indicators about the degree of disturbance in those ecosystems, but most species are still unknown. Only in Brazil, more than a hundred species have been described only for the Atlantic Rainforest and possibly at least an equal number is yet unknown. The situation is even worse in other regions of the country or neighbouring countries, where there are almost no species described at all.
Despite this small knowledge of the group, eventually some works regarding community structure are published, where a list of land planarians from the study site is presented. Let’s take a look at some of those lists:
1. Species of land planarians in four different habitats of the National Forest of São Francisco de Paula, southern Brazil. In Carbayo et al., 2001:
There are 28 distinguished species, but only one identified (Geoplana ladislavii), one not sure (Geoplana pavani) and two with the same name, but refering to different species (Notogynaphallia marginata). The others were yet unknown.
2. Species of land planarians in four different habitats of the National Forest of São Francisco de Paula, southern Brazil. In Carbayo et al., 2002:
A similar table, in the same area, by the same authors, about one year later. We can see 3 new species in the study: Geoplana franciscana, Geoplana josefi and Notogynaphallia guaiana, which were described in 2001. They were probably among the species listed in the first study, but which of them? Was Geoplana franciscana the species assigned as Geoplana sp.1, Geoplana sp.2, Geoplana sp.3…?
3. Abundance of species of land planarians in Araucaria Forest of the National Forest of São Francisco de Paula, southern Brazil. In Antunes et al., 2012.
The same area again, 10 years later. We can see that there are more species already described, but many more still awaiting a name.
When we consider a single study about ecological communities by itself, the fact that the species found are not named is not such a big deal, since the main purpose is to measure patterns of abundance, richness and diversity and the interaction of biotic and abiotic factors on the communities. However, when comparing studies, the unidentified species become simply useless data. How can you be certain about what Geoplana sp.5 is in each study?
We urgently need more taxonomists working on those less prestigious groups, so that our ecological studies may have a wider role in conservation and understanding of nature.
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Antunes, M., Leal-Zanchet, A. M. & Fonseca, C. 2012. Habitat structure, soil properties, and food availability do not predict terrestrial flatworms occurrence in Araucaria Forest sites. Pedobiologia, 55 (1), 25-31 DOI: 10.1016/j.pedobi.2011.09.010
Carbayo, F., Leal-Zanchet, A. M. & Vieira, E. M. 2001. Land planarians (Platyhelminthes, Tricladida, Terricola) as indicators of man-induced disturbance in a South Brazilian rainforest. Belgian Journal of Zoology, 131, 223-224
Carbayo, F., Leal-Zanchet, A. M. & Vieira, E. 2002. Terrestrial flatworm (Platyhelminthes: Tricladida: Terricola) diversity versus man-induced disturbance in an ombrophilous forest in southern Brazil. Biodiversity and Conservation, 11 (6), 1091-1104 DOI: 10.1023/A:1015865005604
Sluys, R. 1998. Land Planarians (Platyhelminthes, Tricladida, Terricola) in biodiversity and conservation studies. Pedobiologia, 42, 490-494