Ulva lactuca renamed

Ulva lactuca ; What’s in a name ?

Dejay’s alert that U lactuca ids on ispot have been ‘rolled over’ to U. fenestrata here : https://www.ispotnature.org/communities/uk-and-ireland/view/observation/792372/ulva-lactuca

was a suprise ; I blame the covid epidemic for my having failed to notice it……

However, now we know about it, are there any issues for iSpot observations (and for the world of marine algology in general) ?

First up :


Genetic analysis of the Linnaean Ulva lactuca (Ulvales, Chlorophyta) holotype and related type specimens reveals name misapplications, unexpected origins, and new synonymies

Jeffery R. Hughey, Christine A. Maggs, Frédéric Mineur, Charlie Jarvis, Kathy Ann Miller, Soha Hamdy Shabaka, Paul W. Gabrielson

First published: 25 March 2019

My notes.

They begin with « Currently, the genetic identity and origin of the holotype of U. lactuca remain unknown. ». And proceed to try to sort it out.

Linnaeus’s ( 1753) description of Ulva lactuca referred to earlier accounts by British and continental European authors, implying a European distribution. However,….

Our rbc L gene sequences show that the U. lactuca holotype is the species currently called U. fasciata in the subtropics and U. lobata in the eastern Pacific Ocean (Fig. 1). We hypothesize that the holotype specimen was collected in the Indo-Pacific by one of Linnaeus’s many colleagues and students who participated in early voyages of exploration and scientific discovery.

For two and a half centuries, its reported distribution, based on the morpho-anatomical characters of thallus shape, cell number and shape, and pyrenoid number … has expanded globally. However, identification is problematic because species of Ulva show a high degree of plasticity in these characters.

The current distribution of U. lactuca , confirmed by DNA sequences …. is the eastern (Australia) and northern (India) Indian Ocean, central (Hawai’i, USA) and temperate southeast (Chile, Peru), southwest (Australia), and northwest (South Korea, Japan) Pacific Ocean, warm temperate eastern (Azores) and western (Florida, USA) Atlantic Ocean and the eastern (Egypt, Israel) and western (Italy) Mediterranean Sea.

These data show that the oldest available name for the European “Ulva lactuca” is U. fenestrata and that U. stipitata is a heterotypic synonym.

And conclude with » Foliose Ulva species are morphologically very simple and show relatively few and subtle morphological differences … with overlaps between species morphologies, which raises questions about their genetic distinctness.

Without the support and assistance of herbarium curators who understand the value of sacrificing small amounts of type material to correctly apply names, we would just be making educated guesses. »

So I think we may proceed with the use of the name Ulva fenestrata for European specimens previously identified as U. lactuca.

However, in the identification of European specimens we should is still take account of those characters which formerly distinguished the different possibilities.

In algaebase Ulva fenestrata Postels & Ruprecht :: AlgaeBase

the entry for U. fenestrata gives this paper :

Fort, A., McHale, M., Cascella, K., Potin, P., Usadel, B., Guiry, M.D. & Sulpice, R. (2021). Foliose Ulva species show considerable inter-specific genetic diversity, low intra-specific genetic variation, and the rare occurrence of inter-specific hybrids in the wild. Journal of Phycology 57(1): 219-233.

This paper acknowledges U. fenestrata as the European species; however, the paper primarily explores molecular data. This comment “Foliose Ulva species are morphologically very simple and show relatively few and subtle morphological differences (Flagella et al. 2010, Lee et al. 2019), with overlaps between species morphologies, which raises questions about their genetic distinctness.” That gives me no comfort.

The description for U. lactuca, as it was then named, (Brodie J., Maggs C.A., John D.M. Green Seaweeds of Britain and Ireland 2007 British Phycological Society.) gives morphological characters which enable it to be differentiated from other species of Ulva.

I have found no similarly detailed description for U. fenestrata so, in the absence of a molecular kit, I assume we are continuing with that description for the time being.

This website has a very general description of Ulva fenestrata;

with “There are a number of other species of Ulva in our waters that form blades (exclusively or only in certain environments being tubes in other habitats) and confident identification requires molecular data.”

Suggesting that identification of foliose Ulva (and the monostromatic Ulvaria) species rests solely on molecular data. Not much help for us.

p.s. I apologise for the irregular formatting of latin genus and specific names in this post. I drafted this in WORD appropriately, but the forum didn’t use the underlinings in my format.

An earlier work on the subject, also paywalled. (Paywalled at JSTOR as well.)

Typification of Linnaean names relevant to algal nomenclature - Spencer - 2009 - TAXON - Wiley Online Library

(I was thinking that perhaps there would be a proposal to conserve Ulva lactuca, with a new type, but according to Google Scholar there’s nothing in Taxon on the subject.)

OK maybe I can blame Covid brain fog - or maybe just the late hour - hoping for a bottom line.
I have some observations from the Cape - should I be doing something?

It is only the European Ulva Lactuca that has been renamed. The distribution of the ‘ real’ U. lactuca is
The current distribution of U. lactuca , confirmed by DNA sequences …. is the eastern (Australia) and northern (India) Indian Ocean, central (Hawai’i, USA) and temperate southeast (Chile, Peru), southwest (Australia), and northwest (South Korea, Japan) Pacific Ocean, warm temperate eastern (Azores) and western (Florida, USA) Atlantic Ocean and the eastern (Egypt, Israel) and western (Italy) Mediterranean Sea.
SA is not mentioned but I would be surprised if SA was not an equivalent area to those mentioned.

I would suggest a look at:

The 2021 paper by Hughey et al, which seems to suggest to me that morphological identification of flat fronded Ulva is pretty much impossible.

Sea Lettuce has a nice history in iSpot
Here’s the earliest Observation, to which I added a comment in 2015 https://www.ispotnature.org/communities/uk-and-ireland/view/observation/1289/
And the latest, though not the last https://www.ispotnature.org/communities/uk-and-ireland/view/observation/857374/sea-lettuce
All the Ulva fenestrata (Explore Community (Filter))

It’s still OK to use the common name in Observations. We would like to see that it is green, a little floppy and broadleaved, rather like Sainsbury’s Round or a leaf from a Little Gem but not a Cos and certainly not Iceberg!
It needs to look a little like this https://img.freepik.com/premium-photo/salad-leaf-lettuce-isolated-white-with-clipping-path_9635-3077.jpg?w=2000 but maybe with natural holes (fenestral?)
We can use microscopy to add a little spice but beware many of the Ulvaceae structures look very similar.
Ulva WoRMS - World Register of Marine Species - Photogallery
Codium https://images.marinespecies.org/thumbs/15058_ulva-rigida.jpg?w=700
3 photos of the SAME Ulva (U.ohnoi) (Asia)
Occurrence Detail 4009873702
Please add the tag Marine Alga to any seaweed
There is a nice iSpotlight which rarely gets opened

As they would say in the Cape “Ja-well, no fine”
(South Africa) Variously expressing ridicule, irony, indifference, boggling, or ambivalence, possibly in combination, depending on tone and context.

ja well no fine - Wiktionary
https://en.wiktionary.org ›

I think I was told that nothing was simple and a firm ID possibly needed microscopy.
Maybe I should read The Tao of Pooh again-
“The author’s purpose in writing this book is to teach readers how to stay happy and calm under all circumstances. He warns the reader that if he or she tries too hard, they will miss the point of Taoism.”

I’m happy and remaining calm…
Green seaweeds of Britain & Ireland. Brodie, Maggs & John (2007).
At the end of the description of Ulva lactuca is this paragraph:

The nomenclature of the species currently known as Ulva lactuca requires evaluation. The margin of the thallus lacks the microscopic tooth-like protuberances that are common in Ulva rigida. However, the Holotype of Ulva lactuca in the Linnaean herbarium is “dentate with quite large teeth“ (Papenfuss 1960). This suggests that the specimen might not be U. lactuca as presently conceived, but could be Ulva rigida. Nevertheless, Bliding (1968) was of the opinion that Papenfuss’s description of the type material fits exactly the characters, cell shape and size of what he regarded as Ulva lactuca.

And so it came to pass.

This article, which as Lavateraguy notes is behind a pay wall, Spencer 2009. Typification of Linnaean names relevant to algal nomenclature, says “As part of continuing research by the Linnaean Plant Name Typification Project at the Natural History Museum, London, all Linnaean names relevant to algal nomenclature have been investigated.”

Ulva is one they cover in this article. However, it addresses the validity of names and type specimens they relate to; we have already been alerted to the problem with Linnaeus’ U. lactuca specimen. As far as I can see it does not address the identification issues of Ulva lactuca.

I searched iSpot for Ulva rigida. There are 17 from Southern Africa, none of which had any microscopic details; most had no details or comments. This one had a comment trail

It would seem U. lactuca was not recognised as a S A species by ispotters, possibly because U. lactuca was thought to be a European species. However I note it is currently in Southern African dropdown.

There is one B. Isles post (2013) with sufficient details based on morpho-anatomy to get agreements at that time & with a comment trail

Gulvain’s source (Jeffery R. Hughey, Paul W. Gabrielson, Christine A. Maggs &

Frédéric Mineur), which says “Since U. lacinulata is the oldest validly published name, it is the correct one to apply to the globally distributed species that was previously but incorrectly known as U. rigida.”

I am minded to Edit the U. rigida post with a link to this forum.

Gulvain’s recent post is very informative https://www.ispotnature.org/communities/uk-and-ireland/view/observation/856941/in-the-footsteps-of-lily-newton

To note dejay’s link, a doctoral theses: https://oceanrep.geomar.de/id/eprint/44963/1/Ulvales_diversity_in_northern_Germany.pdf

We here present a reassessment of the diversity of Ulva sensu lato at geographically separated coasts of the German state of Schleswig-Holstein, including sampling sites on Baltic Sea and North Sea coasts and on Helgoland. Our survey is based upon a combined approach of DNA barcoding and observation of classical morphological identification criteria. Mostly field collected specimens, but also some herbarium vouchers were examined, which allowed us to detect several cryptic or newly introduced species and to unravel some historical misinterpretations.

The results presented in this thesis clearly emphasize the segregation of two subclades among the entities representing the genus Ulva (Chapter I, figure 2) and thus do not indicate its monophyletic origin.

3.4 Phenotypic plasticity of Ulva sensu lato.(p. 205) does what is says in the title…

This doctoral thesis shows that the genetically evaluated species diversity of Ulva sensu lato in northern Germany strongly differs from previous surveys which relied only on the identification of species by morphological characters.

The thesis mentions clades; here’s some more on Ulva clades:


It is clear that the U. lactuca IDs on ispot which have been renamed U. fenestrata may not represent the current, DNA, description of Ulva fenestrata or Ulva lactuca. Indeed, if Ulva species are no longer able to be identified morphologically, then Ulva sensu lato seems an attractive possibility for us.

A search of Google Scholar shows that at least one paper has accepted the term:


I like it.

Another nice summary
The NHM dictionary has only these sensu entries
One is interesting, as it is in the Attribution

It would be nice if there were an Ulva sensu lato dictionary entry, it would seem reasonable to recognise the limits of morphological identification.
I don’t see any problem with not getting to species level. It would not cross my mind to try and do so for Eyebrights, for example. For some species it feels like equivalent of writing down all the decimal places your calculator produces, thus claiming far more precision that the data warrants.

Ulva sensu lato isn’t what you’d want - Ulva sensu lato includes the former Enteromorpha intestinalis (gutweed). Ulva lactuca agg. may be what you’re looking for.

Quoting from: https://doi.org/10.1080/09670262.2021.1914862

“These analyses and previously published genetic studies using type materials of Ulva convincingly demonstrate that traditional morpho-anatomical methods and barcode surveys using recently collected specimens have failed to correctly apply names to foliose species of Ulva. We think it highly likely that the same applies to tubular species of Ulva and that type specimens of these also need to be sequenced. It is time to refrain from making educated guesses by using either morpho-anatomy or matches to sequences in public databases when applying Ulva species names.”

I suppose a flat frond Ulva and tubular Ulva dictionary entry, is what I was thinking about. However, that presupposes that round and tubular forms are not different forms of the same or overlapping species.

It turns out that Ulva pseudocurvata and Enteromorpha compressa together are about as genetically diverse as Enteromorpha intestinalis alone.

Ulva olivascens has been separated out into Umbraulva olivascens. I wonder whether this is field-identifiable (from olive-green versus grass-green colour). It has a deepwater habitat, so perhaps it’s less likely to be encountered.

Even if you find it Umbraulva olivascens (P.J.L.Dangeard) E.H.Bae & I.K.Lee; but where it has become Umbraulva dangeardii anyway!
Umbraulva dangeardii from New Quay, Co. Clare, Ireland on April 01, 2014 at 01:00 PM by Svenja Heesch. Distinguishable from Ulva species by its olive green colour. ID confirmed by DNA sequence. · iNaturalist

This website ( D Fenwick who’s had it verified) says it’s a pontoon fouling species and also found washed up on shore. His specimen was 2.4 m ( metre) long.

This genus is distromatic, like Ulva, but the presence of the photosynthetic pigment siphonaxanthin, not found in Ulva is what separates it. Green Seaweeds book (as above). Not an easy field character.

A very interesting paper, which I have only read once so far.
My rather oversimplified interpretation is that Ulva and Enteromorpha are are closely related enough to be in one genus, which is now the case.
Some Ulva are tubular and some Entermorpha are flat.
It is probably possible to identify some tubular forms to the species level, however, for any serious research where the identity actually matters then DNA is the only reliable method.
Maybe I do mean Ulva sensu lato.

1 Like

Entermorpha is, of course, not in the current Dictionary
I find it interesting that the whole genus name was dropped (possibly in 2012) in favour of Linnaeus’ 1753 description
Oh dear I cannot find (Dr) LINK, where did he go? Anyone?

Probably considerably earlier that 2012. It would follow from the 1999 paper I link to above. I don’t see any relevant earlier work in its references, but it does mention a 1977 paper (paywalled) which indicates that the morphology is affected by environmental influences.


A further search finds that the transfers were made in 2002.

Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera: European Journal of Phycology: Vol 38, No 3 (tandfonline.com)

As for Herr Doktor Professor Link see Johann Heinrich Friedrich Link - Wikipedia

Production of reducing sugar from Enteromorpha intestinalis by hydrothermal and enzymatic hydrolysis - PubMed and there are plenty of ‘papers’ dated 2015.
There is an entry in our dictionary for Ulvales incertae sedis with no observations of course
I looked through a few old Observations, here’s an Enteromorpha reference
The first ID was obviously from the Dictionary but it may have been free-typed

It does take time for knowledge of taxonomic changes to percolate.