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 :
https://onlinelibrary.wiley.com/doi/full/10.1111/jpy.12860?saml_referrer
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.
