Alexandrium Tamarense Species Complex”

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/328938370 A practical guide to new nomenclature for species within the “Alexandrium tamarense species complex” Article · October 2018 CITATIONS READS 0 186 10 authors, including: Richard Wayne Litaker Marina Montresor National Oceanic and Atmospheric Administration Stazione Zoologica Anton Dohrn 159 PUBLICATIONS 4,155 CITATIONS 220 PUBLICATIONS 5,451 CITATIONS SEE PROFILE SEE PROFILE Michael Brosnahan Shauna Murray Woods Hole Oceanographic Institution University of Technology Sydney 21 PUBLICATIONS 408 CITATIONS 233 PUBLICATIONS 2,924 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: LIFEHAB View project Ecological and evolutionary significance of seed banks for the expansion of harmful algae blooms in the Baltic Sea View project All content following this page was uploaded by Richard Wayne Litaker on 14 November 2018. The user has requested enhancement of the downloaded file. A practical guide to new nomenclature designation of the Group I ribotype as A. fundyense. for species within the “Alexandrium The controversy regarding the tamarense species complex” Group I designation centers on whether the cells used for the original A. catenella description were from Group I or IV, For several decades, the “Alexandrium ITS2 complementary base pair changes, given that populations of both species tamarense species complex” included saxitoxin production and the presence in the Pacific are known to exhibit the three morphologically defined spe- or absence of a key gene involved in classic “A. catenella” morphotype. Mo- cies, A. catenella, A. fundyense, and A. saxitoxin synthesis. These combined lecular analyses of “A. catenella” cells tamarense [1]. Worldwide, the group data fully support the conclusion that collected from the coast of California at is one of several responsible for para- the Group I–V ribotypes are distinct Redondo Beach [13] and Monterey Bay lytic shellfish poisoning, a potentially species. [14], south of the type location, indi- life-threatening syndrome that occurs Equally important, the morphologi- cated that these cells belonged to Group following the consumption of shellfish cal analysis by John et al. [8] showed I (Fig. 1). Further, there is no evidence contaminated with paralytic shellfish no single morphological trait, or that any species except Group I occurs toxins (saxitoxin and analogs). Mor- suite of traits, corroborated the in all of the Americas [5, 13-17]. Use phologically, Alexandrium catenella was original morphospecies descrip- of species-specific molecular assays in distinguished by rounded, slightly ante- tions, nor could any combination of other parts of the world, however, have rior-posteriorly compressed cells, chain morphological traits distinguish the shown Group I and IV cells matching formation, and a 1’ plate lacking a ven- ribotype groups from one another. the A. catenella morphotype co-occur tral pore [1, 2]. Alexandrium fundyense There was simply too much overlap in (see Fig. 1 and associated references). and A. tamarense shared the same Ko- the morphologies expressed by each of The lack of any extant type material for foidian plate tabulation as A. catenella, the ribotype groups for morphological molecular testing and the overlapping but typically exhibited less compressed characters to prove useful. For example, distributions of Group I and IV cells cellular morphologies [1, 3]. Alexan- Group I populations in the entire north exhibiting the “A. catenella” morphol- drium tamarense and A. fundyense were Atlantic and north Pacific including ogy in other regions creates uncertain- distinguished based on the presence of Alaska exhibit both “A. fundyense” and ty about which ribotype was described a ventral pore on the 1ʹ plate in A. tama- “A. tamarense” morphology. In contrast, originally. Based partially on this uncer- rense and its absence in A. fundyense [1]. those in the eastern Pacific from San tainty, John et al. [4] submitted a formal Field and culture studies over the Francisco Bay south to Chile, the south- proposal to Taxon for rejection of the past 20 years often described “A. tama- east Atlantic coast of South Africa and name Alexandrium catenella in favor of rense species complex” cells exhibit- many areas in the western Pacific from A. fundyense. ing intermediate morphologies when Australia to Japan, frequently form mul- A second reason for using the A. compared to the original descriptions ti-cell chains, a signature of the original fundyense name in lieu of A. catenella is of all three species (see John et al. [4] “A. catenella” morphological descrip- that a large volume of literature regard- for a summary). Phylogenetic studies tion. These latter Group I populations ing Group I blooms, especially from the of rDNA gene sequences obtained from also display the typical “A. catenella” Gulf of Maine, has been published using “A. tamarense complex” isolates fall into morphology and are indistinguishable the name A. fundyense. Continued use one of five distinct ribotype groups. from the Group IV populations found in of A. fundyense would cause less dis- These do not correlate with the original the Western Pacific (South Japan, Korea ruption to the existing documentation morphologically defined species and and China) and the Mediterranean Sea and serve the International Code of No- were initially designated as Groups I–V [5, 9, 10, 12]. menclature (ICN) Article 14.2 goal that [5-8]. The genetic distances among the Based on their analyses, John et al. states: “Conservation aims at retention ribotypes are typical of those separat- [8] assigned the following species des- of those names that best serve stability ing other dinoflagellate species. Togeth- ignations to each ribotype group: A. of nomenclature”. A third reason for re- er, these observations indicate that the fundyense (Group I), A. mediterraneum jecting A. catenella, and assigning Group original species descriptions depicted a (Group II), A. tamarense (Group III), A. I to A. fundyense and Group IV to A. pa- series of “morphotypes” shared by vari- pacificum (Group IV) and A. australiense cificum, was to provide the scientific ous species in the A. tamarense complex (Group V). John et al. [8] took further community a means of unambiguously rather than actual species. Consequent- steps to provide exhaustive morpho- distinguishing the Group I and IV cells ly, researchers set out to confirm that logical and genetic descriptions and exhibiting the same A. catenella mor- the five ribotypes represented separate submitted holotype and epitype mate- photype, especially in regions where species (e.g., [5, 8-11]). The most com- rial, as appropriate, to the Herbarium they are sympatric. prehensive of these efforts by John et al. Senckenbergianum (FR) in the Centre Based on the known distribution of [8] assembled diverse lines of evidence, of Excellence for Dinophyte Taxonomy Group I cells along the coast of North including detailed morphological analy- (Wilhelmshaven, Germany). Most of and South America, Fraga et al. [18] ses, rDNA phylogenies, mating incom- these nomenclatural reassignments submitted a counterproposal to Taxon patibility assessments, ITS1/5.8S/ITS2 raised minimal concerns among taxon- against rejecting the name A. catenella. rDNA uncorrected genetic distances, omists. The primary exception was the The authors argued that the Group I HARMFUL ALGAE NEWS NO. 61 / 2018 13 Fig. 1. Known locations where Group I A. catenella (red dots) and Group IV A. pacificum (yellow dots) cells have been collected and confirmed with molecular assays [6-8, 11, 12, 15-17, 20-37]. The yellow line and yellow arrow on the west coast of North America indicates the type locality for A. catenella. The white arrow shows the type locality for A. fundyense in the Bay of Fundy, Canada. The single report of A. catenella in the Mediterranean and A. pacificum in the Drake Passage between South America and Antarctica should be considered provisional until additional isolates were identified in both regions. No isolates of Alexandirum catenella have been obtained for the Mediterranean Sea despite extensive sampling and though Busch et al. [34] detected putative A. catenella sequences from environmental DNA samples collected from Fangar Bay (Catalan coast) using 454 pyrosequencing of LSU rDNA, the reads are so short they cannot be considered as definitive. If A. catenella does occur in the Mediterranean it may represent a recent introduction. distribution in the type locale was suf- to be aware of this nomenclatural 1. You work in a region where co-oc- ficiently established to conclude only change as it will affect reporting curring members of the “Alexandri- Group I cells were used for the original requirements, communication with um tamarense species complex” are A. catenella description (Fig. 1). If true, the public, and use of past literature present. Based on their morphology, the ICN rules of priority, in cases where when developing strategies for deal- you have assigned them the names the type material is not in question, ing with paralytic shellfish poison- A. catenella and A. tamarense. What clearly dictates retention of the name ing events and regulations. do you do? “A. catenella” for Group I because it was 3. This decision also places significant • You need to sequence barcoding published prior to the “A. fundyense” demands on future researchers as marker regions from the strains, Group I description [1, 2]. they investigate the literature. For specifically, ribosomal RNA genes Nomenclature change proposals example, with the exception of Chil- or use species-specific molecular such as those of John et al. [4] and Fraga ean and South African research, assays. Only then can you truly et al. [18] are adjudicated by The ICN most of the papers published on “A. determine the species present, Nomenclature Committee for Algae. catenella” before 2015 represent i.e. A. australiense, A. catenella, A. This committee met to consider the reports of the morphologically in- mediterraneum, A.

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