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

Abstract

Current usage of the name Ulva lactuca, the generitype of Ulva, remains uncertain. Genetic analyses were performed on the U. lactuca Linnaean holotype, the U. fasciata epitype, the U. fenestrata holotype, the U. lobata lectotype, and the U. stipitata lectotype. The U. lactuca holotype is nearly identical in rbcL sequence to the epitype of U. fasciata, a warm temperate to tropical species, rather than the cold temperate species to which the name U. lactuca has generally been applied. We hypothesize that the holotype specimen of U. lactuca came from the Indo‐Pacific rather than northern Europe. Our analyses indicate that U. fasciata and U. lobata are heterotypic synonyms of U. lactuca. Ulva fenestrata is the earliest name for northern hemisphere, cold temperate Atlantic and Pacific species, with U. stipitata a junior synonym. DNA sequencing of type specimens provides an unequivocal method for applying names to Ulva species.

Taxonomy of <italic>Ulva</italic> causing blooms from Jeju Island, Korea with new species, <italic>U. pseudo-ohnoi</italic> sp. nov. (Ulvales, Chlorophyta)

“…U. lactuca was described on the basis of the epitype of U. fasciata (UC2050475) that supports the lectotype (PC0119343) from New Port, Alexandria, Egypt by Delile including the holotype of U. fenestrata from Kamchatka, Russia by Postels and Ruprech (Hughey et al 2019). Although it is one of the most cosmopolitan species found in all temperature conditions (Hughey et al 2019), the true taxonomic position of U. lactuca was only recently revealed through advanced analysis of the lectotype specimen for variations of tufA and rbcL. That analysis indicated that the type specimen of U. fasciata Delile first reported from Alexandria, Egypt and specimens recognized as U. fasciata collected worldwide are all U. lactuca, while numerous specimens recognized to date in width ( Fig.…”

“…S1). On the other hand, U. ohnoi was composed of the center (n = 41) from two (Hughey et al 2019). In the Ulva bloom areas of Jeju, this species is always the predominant species in conjunction with U. ohnoi, U. australis, U. laetevirens, and U. pseudo-ohnoi sp.…”

“…Distribution. Korea (Bae 2010, Kim et al 2013); Japan, Australia, Hawaii, Indo-Pacific region, The Mediterranean Sea, Central Atlantic (Hughey et al 2019).…”

Cellulose from the green macroalgae Ulva lactuca: isolation, characterization, optotracing, and production of cellulose nanofibrils

“…In addition, we apply optotracing as a novel method for carbohydrate analysis with the aim to shed new light on the carbohydrate composition of the extracted cellulose and the produced CNF. Even though Hughey et al (2019) suggested that the oldest available name for the northern hemisphere 'Ulva lactuca' is Ulva fenestrata, we will refer to the species used in our study as Ulva lactuca for reasons of general understanding. In the cellulose extraction process, we will try to replace sodium hypochlorite and methanol with hydrogen peroxide and ethanol in an attempt to apply greener extraction conditions than those reported in previous studies.…”

Schizymenia jonssonii sp. nov. (Nemastomatales, Rhodophyta): a relict or an introduction into the North Atlantic after the last glacial maximum?

“…In the summer, the crusts were overgrown by the red and green algae Cystoclonium purpureum , Ceramium virgatum , and Ulva fenestrata (cf Hughey et al. ) and difficult to spot. Crusts were up to 7 cm in diameter.…”