Sometimes there are species names that we aren’t entirely sure how to use – the name didn’t really catch on, it’s hard to see why the person who named the plant thought that they had something distinctive just from their description, and the specimen that the name was based on is small, old, and rather the worse for wear.
An example of such a nomenclatural loose end is Riccardia fuscovirens Lindb., a name that was published by Lindberg in 1879, transferred from the genus Riccardia to Aneura as a distinct species in 1893 (Aneura fuscovirens (Lindb.) Steph.), and subsequently downgraded to a variety (Aneura pinguis var. fuscovirens (Lindb.) C.E.O.Jensen) in 1915.
We have chosen a lectoype for Riccardia fuscovirens Lindb. This is a type specimen that is chosen after a name has been published, but from the original specimens or illustrations that the author of the name would have been influenced by when they were first recognizing the taxon as something new and different from all other known taxa.
Our lectotype is a plant that was collected by Lindberg near Helsinki on the 2nd of May 1878 — nearly 150 years ago. The gross morphology of this plant has been preserved in the herbarium specimen (as you can see in the pictures below), but the finer details that can be important for identifying Aneura species, like the oil bodies, have been lost.
Ideally, we would also have chosen an epitype to accompany and “explain” the lectotype — an epitype is a type that does not have to have been seen by the original author of the taxon name, but that makes it easier to identify the species — because we do not have DNA sequence data for the 1878 specimen, so are not able to match it to a genetic lineage.
In the case of Aneura pinguis L., we were able to pick a new collection from a site near where the original plant was described to act as an epitype (Long et al. 2023; see Narrowing down Aneura pinguis – Botanics Stories), and generate DNA barcode sequences from the epitype material. Unfortunately the type locality for Riccardia fuscovirens Lindb. is now in the centre of Helsinki city, so no longer a place that the plant can be found. The lead author of this study, Professor Lars Söderström from the Norwegian University of Science and Technology, Trondheim, spent some time searching a rather wider area around Helsinki in October 2021, but didn’t find any Aneura growing.
However, based on the morphology and what we know about the habitat in which the plant was collected, we believe that Aneura fuscovirens (Lindb.) Steph. is a synonym of Aneura pinguis s.str., as defined in Long et al. 2023. What this means in practice is that the name “fuscovirens” was mistakenly given to something that already had a name, but the name also can’t be reused for any other lineage within Aneura, as a species name can only be used once within any genus whether it’s valid or not.
Long DG, Forrest LL, Hassel K, Séneca A, Söderström L. 2023. Typification of Jungermannia pinguis L. (Marchantiophyta, Aneuraceae). EDINBURGH JOURNAL OF BOTANY 80, Article 1932: 1–11.
Botanics Stories – Aneura