The oldest synallactid sea cucumber (Echinodermata: Holothuroidea: Aspidochirotida)

Reich, Mike

doi:10.1007/s12542-010-0067-8

Cited by 16 publications

(8 citation statements)

References 23 publications

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“…The ancestor of Chiridota heheva diverged from the ancestors of two shallow-water holothurians ( A. japonicus and P. parvimensis ) approximately 429 Ma. As Apodida is the basal taxon in Holothuroidea, these results support the view that holothurians had evolved by the Early Ordovician (Reich, 2010). To better investigate the evolution of holothurians, we inferred the histories of ancestral population sizes of C. heheva and A. japonicus using PSMC ( Fig.…”

Section: Discussionsupporting

confidence: 83%

The genome of an apodid holothuroid (Chiridota heheva) provides insights into its adaptation to deep-sea reducing environment

Zhang

Tan

Gong

et al. 2021

Preprint

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Cold seeps and hydrothermal vents are deep-sea reducing environments that are characterized by a lack of oxygen, photosynthesis-derived nutrients and a high concentration of reducing chemicals. Apodida is an order of deep-sea echinoderms lacking tube feet and complex respiratory trees, which are commonly found in holothurians. Chiridota heheva Pawson & Vance, 2004 (Apodida: Chiridotidae) is one of the few echinoderms that resides in deep-sea reducing environments. Unlike most cold seep and hydrothermal vent-dwelling animals, C. heheva does not survive by maintaining an epi- or endosymbiotic relationship with chemosynthetic microorganisms. The species acquires nutrients by extracting organic components from sediment detritus and suspended material. Here, we report a high-quality genome of C. heheva as a genomic reference for echinoderm adaptation to reducing environments. Chiridota heheva likely colonized its current habitats in the early Miocene. The expansion of the aerolysin-like protein family in C. heheva compared with other echinoderms might be involved in the disintegration of microbes during digestion, which in turn facilitates the species' adaptation to cold seep environments. Moreover, several hypoxia-related genes were subject to positive selection in the genome of C. heheva, which contributes to their adaptation to hypoxic environments.

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Section: Discussionsupporting

confidence: 83%

The genome of an apodid holothuroid (Chiridota heheva) provides insights into its adaptation to deep-sea reducing environment

Zhang

Tan

Gong

et al. 2021

Preprint

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“…Smirnov (2012) published the most recent broad holothuroid taxonomic system ( Fig. 2O) after considering the views of Becher (1909,) Kerr and Kim (2001), and the results from previously published (Lacey et al, 2005;Smith, 1997) and unpublished (Solís-Marín, 2003) molecular phylogenetic and paleontological findings (Reich, 2010a;Reich, 2010c). Partially following Becher"s (1909) phylogeny, Smirnov (2012) proposed that one group (Synaptacea) include holothuroids with wheel-shaped ossicles and without respiratory trees, and that a second group (Holothuriacea + Elpidiacea) include holothuroids with both respiratory trees and secondarily-lost respiratory trees.…”

Section: Taxonomic Historymentioning

confidence: 98%

Molecular phylogeny of extant Holothuroidea (Echinodermata)

Miller

Kerr

Paulay

et al. 2017

Molecular Phylogenetics and Evolution

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146

115

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Sea cucumbers (Holothuroidea) are a morphologically diverse, ecologically important, and economically valued clade of echinoderms; however, the understanding of the overall systematics of the group remains controversial. Here, we present a phylogeny of extant Holothuroidea assessed with maximum parsimony, maximum likelihood, and Bayesian approaches using approximately 4.3kb of mt- (COI, 16S, 12S) and nDNA (H3, 18S, 28S) sequences from 82 holothuroid terminals representing 23 of the 27 widely-accepted family-ranked taxa. Currently five holothuroid taxa of ordinal rank are accepted. We find that three of the five orders are non-monophyletic, and we revise the taxonomy of the groups accordingly. Apodida is sister to the rest of Holothuroidea, here considered Actinopoda. Within Actinopoda, Elasipodida in part is sister to the remaining Actinopoda. This latter clade, comprising holothuroids with respiratory trees, is now called Pneumonophora. The traditional Aspidochirotida is paraphyletic, with representatives from three orders (Molpadida, Dendrochirotida, and Elasipodida in part) nested within. Therefore, we discontinue the use of Aspidochirotida and instead erect Holothuriida as the sister group to the remaining Pneumonophora, here termed Neoholothuriida. We found four well-supported major clades in Neoholothuriida: Dendrochirotida, Molpadida and two new clades, Synallactida and Persiculida. The mapping of traditionally-used morphological characters in holothuroid systematics onto the phylogeny revealed marked homoplasy in most characters demonstrating that further taxonomic revision of Holothuroidea is required. Two time-tree analyses, one based on calibrations for uncontroversial crown group dates for Eleutherozoa, Echinozoa and Holothuroidea and another using these calibrations plus four more from within Holothuroidea, showed major discrepancies, suggesting that fossils of Holothuroidea may need reassessment in terms of placing these forms with existing crown clades.

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“…Holothurians have an extremely poor fossil record because their skeleton is usually reduced to microscopic elements that rapidly disarticulate after death. These ossicles are not uncommon in the fossil record (Gilliland, 1993) and allow us to deduce that holothurians had evolved by the early Upper Ordovi-cian age (Reich, 2010b) and that crown-group divergence had occurred by the early/middle Silurian (Reich, 2010a). However, isolated ossicles provide little insight into how the holothurian body plan arose.…”

Section: Introductionmentioning

confidence: 93%

Tracing the evolution of the holothurian body plan through stem-group fossils

Smith

Reich²

2013

Biol J Linn Soc Lond

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The fossil echinoderm Palaeocucumaria, from the early Devonian Hunsrück Slate of southwestern Germany, has been studied using both traditional techniques and X‐ray microtomography, and its anatomy clarified. Phylogenetic analysis shows that it is a stem‐group holothurian with a combination of characters that help understand how the modern (crown‐group) holothurian body plan developed. Echinoids and holothurians have evolved along different paths, by differential growth of the larval‐ and rudment‐derived body regions. Palaeocucumaria shows that late stem‐group holothurians had a water vascular organization with a single external madreporite and calcified stone canal leading to the aboral end of the peripharyngeal coelom, and five primary radial water vessels that gave rise to tentacle‐like tube‐feet. This fossil data, in combination with a molecular phylogeny based on 18 s‐like rRNA gene sequence data, is used to order evolutionary steps in the making of the crown‐group holothurian body plan. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 670–681.

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The oldest synallactid sea cucumber (Echinodermata: Holothuroidea: Aspidochirotida)

Cited by 16 publications

References 23 publications

The genome of an apodid holothuroid (Chiridota heheva) provides insights into its adaptation to deep-sea reducing environment

The genome of an apodid holothuroid (Chiridota heheva) provides insights into its adaptation to deep-sea reducing environment

Molecular phylogeny of extant Holothuroidea (Echinodermata)

Tracing the evolution of the holothurian body plan through stem-group fossils

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