Asymmetron lucayanum: How many species are valid?

Subirana, Lucie; Farstey, Viviana; Bertrand, Stéphanie; Escrivà, Héctor

doi:10.1371/journal.pone.0229119

Cited by 10 publications

(19 citation statements)

References 23 publications

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“…Due to this phylogenetic position and their slow evolutionary rate (Louis et al, 2012), lancelets are considered valuable proxies for the chordate ancestor, both at the anatomic and genomic levels (Bertrand and Escrivá, 2011;Holland, 2015). The subphylum Cephalochordata is subdivided into three genera: Branchiostoma, Epigonichthys, and Asymmetron (Poss and Boschung, 1996;Nishikawa, 2004;Zhang et al, 2006;Kon et al, 2007;Holland and Holland, 2010;Yue et al, 2014;Carvalho et al, 2017b;Subirana et al, 2020). Recent analyses of mitochondrial genomes suggested that the genus Asymmetron occupies the basal position and diverged from the Epigonichthys/Branchiostoma clade about 258-171 mya (million years ago) (Subirana et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

An Updated Staging System for Cephalochordate Development: One Table Suits Them All

Carvalho

Lahaye

Yong

et al. 2021

Front. Cell Dev. Biol.

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Chordates are divided into three subphyla: Vertebrata, Tunicata, and Cephalochordata. Phylogenetically, the Cephalochordata, more commonly known as lancelets or amphioxus, constitute the sister group of Vertebrata and Tunicata. Lancelets are small, benthic, marine filter feeders, and their roughly three dozen described species are divided into three genera: Branchiostoma, Epigonichthys, and Asymmetron. Due to their phylogenetic position and their stereotypical chordate morphology and genome architecture, lancelets are key models for understanding the evolutionary history of chordates. Lancelets have thus been studied by generations of scientists, with the first descriptions of adult anatomy and developmental morphology dating back to the 19th century. Today, several different lancelet species are used as laboratory models, predominantly for developmental, molecular and genomic studies. Surprisingly, however, a universal staging system and an unambiguous nomenclature for developing lancelets have not yet been adopted by the scientific community. In this work, we characterized the development of the European lancelet (Branchiostoma lanceolatum) using confocal microscopy and compiled a streamlined developmental staging system, from fertilization through larval life, including an unambiguous stage nomenclature. By tracing growth curves of the European lancelet reared at different temperatures, we were able to show that our staging system permitted an easy conversion of any developmental time into a specific stage name. Furthermore, comparisons of embryos and larvae from the European lancelet (B. lanceolatum), the Florida lancelet (Branchiostoma floridae), two Asian lancelets (Branchiostoma belcheri and Branchiostoma japonicum), and the Bahamas lancelet (Asymmetron lucayanum) demonstrated that our staging system could readily be applied to other lancelet species. Although the detailed staging description was carried out on developing B. lanceolatum, the comparisons with other lancelet species thus strongly suggested that both staging and nomenclature are applicable to all extant lancelets. We conclude that this description of embryonic and larval development will be of great use for the scientific community and that it should be adopted as the new standard for defining and naming developing lancelets. More generally, we anticipate that this work will facilitate future studies comparing representatives from different chordate lineages.

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Section: Introductionmentioning

confidence: 99%

An Updated Staging System for Cephalochordate Development: One Table Suits Them All

Carvalho

Lahaye

Yong

et al. 2021

Front. Cell Dev. Biol.

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“…Despite the general importance of Branchiostomatidae, little is known about much of this family. Several species were newly described, or their taxonomy has been clarified only recently [2,29,30], and species misidentification or cryptic diversity have been found using molecular approaches or integrative taxonomy [14,[31][32][33][34][35][36]. Moreover, new records of lancelet larvae or adults improved our assessment of species-specific geographical distribution and ecological traits at a range of scales [37][38][39][40][41][42][43][44][45][46].…”

Section: Introductionmentioning

confidence: 99%

Molecular taxonomy confirms that the northeastern Atlantic and Mediterranean Sea harbor a single lancelet, Branchiostoma lanceolatum (Pallas, 1774) (Cephalochordata: Leptocardii: Branchiostomatidae)

et al. 2021

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Branchiostomatidae (lancelets or amphioxus) comprises about 30 species, several of which are well-established models in evolutionary development. Our zoological and ecological knowledge of the family is nonetheless limited. Despite evident differences can be found among known populations, the taxonomy of Branchiostoma lanceolatum (type species of the genus Branchiostoma) has never been investigated with modern methods through its range in the northeastern Atlantic and Mediterranean Sea. We address this via a multilocus molecular approach and comparing specimens collected from different European populations. Results obtained here confirm the presence of a single species inhabiting the range between the topotypical localities of B. lanceolatum (Atlantic Ocean) and of its junior synonym B. lubricum (Mediterranean Sea), without evincing geographical structure between populations. This suggests that environment most likely drives the characteristics observed in different geographic areas. The long larval phase and the slow mutation rate in lancelets may have played a key role in the evolutionary history of this iconic species.

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“…Branchiostoma, Epigonichthys and Asymmetron [4][5][6][7][8][9][10][11]. Recent analyses of mitochondrial genomes suggested that the genus Asymmetron occupies the basal position and diverged from the Epigonichthys plus Branchiostoma clade about 42…”

Section: Introductionmentioning

confidence: 99%

“…The subphylum Cephalochordata is subdivided into three genera: Branchiostoma , Epigonichthys and Asymmetron (Poss and Boschung, 1996; Nishikawa, 2004; Zhang et al, 2006; Kon et al, 2007; Holland and Holland, 2010; Yue et al, 2014; Carvalho et al, 2017b; Subirana et al, 2020). Recent analyses of mitochondrial genomes suggested that the genus Asymmetron occupies the basal position and diverged from the Epigonichthys / Branchiostoma clade about 258-171 Mya (million years ago) (Subirana et al, 2020). It was further proposed that the split of the Epigonichthys and Branchiostoma lineages occurred about 182-120 Mya and that speciation within the genus Branchiostoma , between B. belcheri and B. japonicum versus B. floridae and B. lanceolatum , took place about 130-85 Mya (Subirana et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Recent analyses of mitochondrial genomes suggested that the genus Asymmetron occupies the basal position and diverged from the Epigonichthys / Branchiostoma clade about 258-171 Mya (million years ago) (Subirana et al, 2020). It was further proposed that the split of the Epigonichthys and Branchiostoma lineages occurred about 182-120 Mya and that speciation within the genus Branchiostoma , between B. belcheri and B. japonicum versus B. floridae and B. lanceolatum , took place about 130-85 Mya (Subirana et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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An updated staging system for cephalochordate development: one table suits them all

Carvalho

Lahaye

Yong

et al. 2020

Preprint

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Background:The chordates are divided into three subphyla: Vertebrata, Tunicata and Cephalochordata. Phylogenetically, the Cephalochordata, more commonly known as lancelets or amphioxus, constitute the sister group of Vertebrata plus Tunicata. Due to their phylogenetic position and their conserved morphology and genome architecture, lancelets are important models for understanding the evolutionary history of chordates. Lancelets are small, marine filter-feeders, and the few dozen species that have so far been described have been grouped into three genera: Branchiostoma, Epigonichthys and Asymmetron.Given their relevance for addressing questions about the evolutionary diversification of chordates, lancelets have been the subjects of study by generations of scientists, with the first descriptions of adult anatomy and developmental morphology dating back to the 19 th century. Today, several different lancelet species are used as laboratory models, predominantly for developmental, molecular and genomic studies. It is thus very surprising that there is currently no universal staging system and no unambiguous nomenclature for developing lancelets. Results:We illustrated the development of the European amphioxus (Branchiostoma lanceolatum) using confocal microscopy and compiled a streamlined developmental staging system, from fertilization through larval life, with an unambiguous stage nomenclature. By tracing growth curves of the European amphioxus reared at different temperatures, we were able to show that our staging system permits the easy conversion of any developmental time into a defined 3 stage name. Furthermore, comparisons of embryos and larvae from the European amphioxus (B. lanceolatum), the Florida amphioxus (B. floridae), the Chinese amphioxus (B. belcheri), the Japanese amphioxus (B. japonicum) and the Bahamas lancelet (Asymmetron lucayanum) demonstrated that our staging system can readily be applied to other lancelet species.Conclusions: Here, we propose an updated staging and nomenclature system for lancelets. Although the detailed staging description was carried out on developing B. lanceolatum, comparisons with other lancelet species strongly suggest that both staging and nomenclature are applicable to all extant lancelets.We thus believe that this description of embryonic and larval development can be of great use for the scientific community and hope that it will become the new standard for defining and naming developing lancelets. KeywordsAmphioxus, Asymmetron lucayanum, Branchiostoma belcheri, Branchiostoma floridae, Branchiostoma japonicum, Branchiostoma lanceolatum, Confocal Microscopy, Embryonic and Larval Development, Evolution and Development, Lancelet 4

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Asymmetron lucayanum: How many species are valid?

Cited by 10 publications

References 23 publications

An Updated Staging System for Cephalochordate Development: One Table Suits Them All

An Updated Staging System for Cephalochordate Development: One Table Suits Them All

Molecular taxonomy confirms that the northeastern Atlantic and Mediterranean Sea harbor a single lancelet, Branchiostoma lanceolatum (Pallas, 1774) (Cephalochordata: Leptocardii: Branchiostomatidae)

An updated staging system for cephalochordate development: one table suits them all

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