We can just about fit a tour of 15 sites spread across four catchments in the Lake District into a single day of fieldwork if we start early and take only a short break for lunch. However, my task on these trips is to survey the visible algal communities and, as the day progresses, I am conscious that my concentration wanes as tiredness sets in. It can be a struggle to keep focus for the River Irt, the final river we examine. Fortunately, it is one that usually has some conspicuous and unusual algal growths to hold my attention.
This time, I noticed some brownish-green growths on the tops of granite boulders. I had not seen them here before, although that is not quite the same as saying that they are new arrivals (see “On fieldwork …”). Let’s just agree that they are conspicuous enough that, even at the end of a busy day, I should have noticed them if they were there on previous visits. I could not identify them with confidence in the field but, when I got a specimen under my microscope, my first thought was that it as a species of Batrachospermum (see “algae … cunningly disguised as frog spawn”) although this one looked different to most I had seen previously.
Batrachospermum usually has a characteristic “beaded” appearance, caused by whorls of side branches along a main stem. This one had much shorter lateral branches and longer internodes, so the beading was not visible with the naked eye, and only just visible with a hand-lens. Evidence pointed to Batrachospermum atrum, according to the Freshwater Algal Flora of Britain and Ireland, but that book is now a decade old and, as happens frequently in algal taxonomy, names have changed.
In this particular case, there are two reasons for the change in name. The first is that molecular analyses have revealed that variation within the genus Batrachospermum is greater than previously expected, leading workers to pick off some of the groups and put them into newly described genera. That’s data-driven science and, as in this case, molecular evidence makes us think again at traditional criteria used in classification. In the time since the Flora was published, some UK and Irish Batrachospermum species have been moved to Sheathia, whilst B. atrum is now Torularia atra.
The other aspect is the niggly bureaucracy of taxonomy. In this case, the scientists who recognised that B. atrum was distinct from other Batrachospermum created a new genus, Setacea, which was later found to be invalidly published. They then tried again with another genus name, Atrophycus, but then Michael Wynne pointed out that B. atrum had, itself, been placed in a separate genus, Torularia, way back in the 19th century, rendering all these modern names irrelevant. And, just to stir in a little more confusion, the name Torularia was also used for a genus of flowering plants until relatively recently.
Frequent name-changes was a frequent cause of confusion during our algae identification course at Windermere. We pointed out that, in many cases, there are good grounds for re-evaluating the limits of traditional genera (as is the case here). Nonetheless, these name changes make it difficult for anyone (beginners especially) using older identification guides. The Freshwater Algal Flora of Britain and Ireland, hardly counts as “old”, a mere decade after publication. However, an update has just had to be published, detailing the many nomenclatural changes since the book went to print. Almost inevitably, that update will, itself, be out of date very soon too. For this reason, we point our students to Algaebase, an excellent resource that keeps track of the taxonomic literature and allows you to check very quickly whether a name is current usage or has been superseded. In the case of Torularia atra, there are no less than six synonyms each with a separate entry and each with a hyperlink that takes you back to T. atra.
This short tale encapsulates the history of algae studies. We’ve spent the last 350 years trying to make sense of what we see as we peer through our microscopes. Over that time, microscopes have gradually improved and, each time, we’ve seen a little more. Whenever that happens, ideas about what constitutes a “species” have shifted. That might bring us a little closer to scientific truth but, seen from the perspective of those for whom the species are a means to understand habitats, each change of name sows a little more confusion. Within the last 50 years, this process has speeded up inexorably with the introduction of, first, electron microscopy and, then, molecular genetics to the taxonomist’s toolkit. What we “see” – in the sense of light patterns hitting the retina – does not change; what we “see” – in the sense of how our brains process messages from the optic nerve – is forever shifting (see “Do we see through a microscope?”). Some confusion is inevitable: better that we learn to live with this rather than expect to be presented with a naively simplistic view of the world.
References
John, D. M., Guiry, M. D., Wilbraham, J., & Krokowski, J. (2022). The 2011 edition of “The Freshwater Algal Flora of the British Isles”: additions, corrections, nomenclatural and taxonomic changes. Applied Phycology 3: 36-71. []
Léonard, J. (1986). Neotorularia Hedge & J. Léonard nom générique nouveau de Cruciferae. Bulletin du Jardin botanique national de Belgique/Bulletin van de Nationale Plantentuin van Belgie 56: 389-395.
Rossignolo, N. L., & Necchi Jr, O. (2016). Revision of section Setacea of the genus Batrachospermum (Batrachospermales, Rhodophyta) with emphasis on specimens from Brazil. Phycologia 55: 337-346.
Rossignolo, N.L., Necchi, O., Jr. & Guiry, M.D. (2017). Atrophycus, a new genus name for “Setacea (De Toni) Necchi & Rossignolo”. Notulae Algarum 26: 1-2.
Wynne, M. J. (2019). Torularia Bonnnemaison, 1828, a generic name to be reinstated for Atrophycus Necchi & Rossignolo, 2017. Notulae algarum 89: 1-4.
Some other highlights from this week:
Wrote this whilst listening to: Nick Cave’s Seven Psalms and Gwenno’s Tresor
Currently reading: The Girl at the Lion d’Or by Sebastian Faulks. Just finished Gillian McAllister’s Wrong Place, Wrong Time which is a crime novel with an intriguing difference.
Cultural highlight: Durham Miner’s Gala (below), back for the first time in three years.
Culinary highlight: home-cooked vegetarian Sichuan meal: fish-fragrant aubergine, gon bao mushrooms, smacked cucumber.