Mitogenome analysis of a green tide forming <i>Ulva</i> from California, USA confirms its identity as <i>Ulva expansa</i> (Ulvaceae, Chlorophyta)

Ulva (Ulvophyceae, Chlorophyta) is common in intertidal environments and can also be found in freshwater ecosystems. The difficulty to morphologically identify Ulva species due to cryptic diversity and morphological plasticity has caused a taxonomic conundrum. Fortunately, molecular data have begun to unravel a better understanding of its diversity. Here, we present a molecular analysis with 247 samples of Ulva from the Gulf of Mexico and Atlantic USA based on chloroplast (rbcL and tufA) and nuclear (ITS1‐5.8S‐ITS2) molecular markers. Twenty‐four Ulva taxa had previously been reported for this area based on morphology and earlier molecular studies mostly from Northeastern USA and Canada. In this study, sixteen Ulva clades were identified representing 13 named clades and putatively three undescribed species. Only nine of the 24 taxa previously reported for the Western Atlantic were confirmed. Four species were identified for the first time in the U.S. East and Gulf Coast (U. aragoënsis, U. californica, U. meridionalis, and U. tepida). This study provides a foundation for future research on Ulva in this area and reiterates the necessity of using molecular‐assisted identifications for this group.

“…A few studies have been successful in sequencing old type material of Ulva australis (Hanyuda and Kawai 2018), Ulva expansa (Hughey et al. 2018) and U. lactuca (Hughey et al. 2019).…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Diversity of the green macroalgal genus Ulva (Ulvophyceae, Chlorophyta) from the east and gulf coast of the United States based on molecular data

Melton

Lopez-Bautista

2021

“…2017; U. expansa, Hughey et al. 2018; U. flexuosa, Cai et al. 2018; U. compressa, NCBI reference sequence NC_043860; and U. mutabilis , NCBI accession MK069587).…”

Section: Discussionunclassified

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

Fort

McHale

Cascella

et al. 2020

Foliose Ulva spp. have become increasingly important worldwide for their environmental and financial impacts. A large number of such Ulva species have rapid reproduction and proliferation habits, which explains why they are responsible for Ulva blooms, known as “green tides”, having dramatic negative effects on coastal ecosystems, but also making them attractive for aquaculture applications. Despite the increasing interest in the genus Ulva, particularly on the larger foliose species for aquaculture, their inter‐ and intra‐specific genetic diversity is still poorly described. We compared the cytoplasmic genome (chloroplast and mitochondrion) of 110 strains of large distromatic foliose Ulva from Ireland, Brittany (France), the Netherlands and Portugal. We found six different species, with high levels of inter‐specific genetic diversity, despite highly similar or overlapping morphologies. Genetic variation was as high as 82 SNPs/kb between Ulva pseudorotundata and U. laetevirens, indicating considerable genetic diversity. On the other hand, intra‐specific genetic diversity was relatively low, with only 36 variant sites (0.03 SNPs/kb) in the mitochondrial genome of the 29 Ulva rigida individuals found in this study, despite different geographical origins. The use of next‐generation sequencing allowed for the detection of a single inter‐species hybrid between two genetically closely related species, U. laetevirens, and U. rigida, among the 110 strains analyzed in this study. Altogether, this study represents an important advance in our understanding of Ulva biology and provides genetic information for genomic selection of large foliose strains in aquaculture.

“…Specimens reported as “ U. lobata ” from the northeast Pacific (Hayden and Waaland , , Saunders and Kucera ) are U. expansa (Hughey et al. ). Based on rbc L and tuf A sequences, the current distribution of U. expansa is Vancouver Island, British Columbia, Canada, to San Simeon, California, USA.…”

mentioning

confidence: 99%

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

Hughey

Maggs

Mineur

et al. 2019

Self Cite

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.