Ophiuroidea (Echinodermata): Systematics and Japanese Fauna

Okanishi, Masanori

doi:10.1007/978-4-431-56432-4_25

Cited by 9 publications

(10 citation statements)

References 34 publications

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“…Both specimens were deposited in the National Museum of Nature and Science (NSMT). Morphological terminology used in this study follows Stöhr et al (2012), Okanishi andFujita (2018b), andHendler (2018). Terminologies of oral papillae were used as sensu lato (hereafter s.l.)…”

Section: Methodsmentioning

confidence: 99%

“…Faunistic studies in this area are important for gaining a better understanding of the marine biodiversity, as it lies within the northernmost region of tropical marine ecosystem in Japan. Ophiuroids (Echinodermata) contain the largest number of species within the phylum Echinodermata and they inhabit nearly all marine habitats (Stöhr et al 2012;Okanishi 2016). Although some ophiuroid species have been reported from offshore areas of the Amami-oshima island group (e.g., Okanishi and Fujita 2009), the subtidal zone has been barely explored.…”

Section: Introductionmentioning

confidence: 99%

“…Of these, only O. pantherina Koehler, 1898 andO. squamifera Murakami, 1963 have been reported from Japanese waters (Okanishi 2016). Recently, Okanishi et al (2019) described O. xmasilluminans Okanishi, Oba, and Fujita, 2019 from a submarine cave in northwestern Australia, with notes on its bioluminescence and its sand-burrowing behavior.…”

Section: Introductionmentioning

confidence: 99%

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A New Record of Brittle Star Ophiopsila cf. polyacantha (Echinodermata: Ophiuroidea) from Southwestern Japan, with Notes on its Bioluminescence

Okanishi

Fujii

2020

Spec.Div.

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Two specimens of Ophiopsila cf. polyacantha H. L. Clark, 1915 are described from approximately 15 m water depth at Kakeromajima island, Amami Islands in southwestern Japan. The species occurs on sandy bottoms with the disc buried and the arms extended above the substratum. Bioluminescence and burrowing behavior are described. The specimens are clearly morphologically different from the two species of Ophiopsila Forbes, 1843 previously recorded from Japan. The new Japanese name "Kin-habu-toranoo-kumohitode" is proposed.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A New Record of Brittle Star Ophiopsila cf. polyacantha (Echinodermata: Ophiuroidea) from Southwestern Japan, with Notes on its Bioluminescence

Okanishi

Fujii

2020

Spec.Div.

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“…Morphological and behavioral specializations in ophiuroids, which are mainly represented by their flexible arms, enable them to live in a wide range of habitats: under rocks; in interstices within sponges and hard corals; on muddy bottoms, where some species can be found in aggregates; infaunally buried in sediments, with arms extended out of the bottom for filter feeding; and on the surface of various animals such as octocorals and hydrocorals (e.g. Okanishi 2016). Therefore, they are very useful as target organisms for marine environmental metabarcoding because the DNA of brittle stars, which have large populations and inhabit various environments, is likely to remain in marine environmental waters.…”

Section: Introductionmentioning

confidence: 99%

Development of two new sets of PCR primers for eDNA metabarcoding of brittle stars (Echinodermata, Ophiuroidea)

Okanishi¹,

Kohtsuka²,

Wu³

et al. 2023

MBMG

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Brittle stars (class Ophiuroidea) are marine invertebrates comprising approximately 2,100 extant species, and are considered to constitute the most diverse taxon of the phylum Echinodermata. As a non-invasive method for monitoring biodiversity, we developed two new sets of PCR primers for metabarcoding environmental DNA (eDNA) from brittle stars. The new primer sets were designed to amplify 2 short regions of the mitochondrial 16S rRNA gene, comprising a conserved region (111–115 bp, 112 bp on average; named “16SOph1”) and a hyper-variable region (180–195 bp, 185 bp on average; named “16SOph2”) displaying interspecific variation. The performance of the primers was tested using eDNA obtained from two sources: a) rearing water of an 2.5 or 170 L aquarium tanks containing 15 brittle star species and b) from natural seawater collected around Misaki, the Pacific coast of central Japan, at depths ranging from shallow (2 m) to deep (> 200 m) sea. To build a reference library, we obtained 16S rRNA sequences of brittle star specimens collected from around Misaki and from similar depths in Japan, and sequences registered in International Nucleotide Sequence Database Collaboration. As a result of comparison of the obtained eDNA sequences with the reference library 37 (including cryptic species) and 26 brittle star species were detected with certain identities by 16SOph1 and 16SOph2 analyses, respectively. In shallow water, the number of species and reads other than the brittle stars detected with 16SOph1 was less than 10% of the total number. On the other hand, the number of brittle star species and reads detected with 16SOph2 was less than half of the total number, and the number of detected non-brittle star metazoan species ranged from 20 to 46 species across 6 to 8 phyla (only the reads at the “Tank” were less than 0.001%). The number of non-brittle star species and reads at 80 m was less than 10% with both of the primer sets. These findings suggest that 16SOph1 is specific to the brittle star and 16SOph2 is suitable for a variety of marine metazoans. It appears, however, that further optimization of primer sequences would still be necessary to avoid possible PCR dropouts from eDNA extracts. Moreover, a detailed elucidation of the brittle star fauna in the examined area, and the accurate identification of brittle star species in the current DNA databank is required.

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“…Recent molecular phylogenetic studies showed that basket stars are polyphyletic in the order Euryalida (Euryophiurida) and belong to Gorgonocephalidae and Euryalidae among five known families of this order (O'Hara, Hugall, Thuy, Stöhr, & Martynov, 2017; Okanishi & Fujita, 2013). Approximately 80 species have been recorded from over the world and 20 species were recently reported from Japanese waters (Okanishi & Fujita, 2018; Okanishi, 2016b; Okanishi & Fujita, 2013).…”

Section: Introductionmentioning

confidence: 99%

Morphogenesis and histogenesis during the arm regeneration in a basket star Astrocladus dofleini (Euryalida, Ophiuroidea, Echinodermata)

Okanishi

Kohtsuka

Miura

2020

Journal of Morphology

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Basket stars, that is, Ophiuroidea in Echinodermata, exhibit distinctive morphological characteristics with their complicatedly branched arms that can regenerate immediately after mutilation. Although, in brittle stars, that is, ophiuroids with nonbranched arms, the arm regeneration process following accidental trauma or autotomy have been morphologically and histologically observed in several species, few studies have so far been carried out on the regeneration of branched arms in basket stars. In this study, the developmental and morphological features of arm regeneration in Astrocladus dofleini (Gorgonocephalidae, Euryalida, Euryophiurida), one of the most common basket star species in Japanese waters, was anatomically and histologically investigated. Results clearly showed the following phases during the arm regeneration: (a) repair phase, (b) early regenerative phase, (c) intermediate regenerative phase, (d) advanced regenerative Phase I, and (e) advanced regenerative Phase II. The morphogenetic process during the arm regeneration in the basket star showed similar patterns to those of nonbranched arms observed in other ophiuroids. However, differences were also seen between the two ophiuroid types, that is, there were some developmental features specific to the basket star. In the early regenerative phase, branching of coelomic cavities was observed prior to the formation of other tissues, probably inducing the later morphogenesis of branched arms. In addition, hard skeletal ossicles form rapidly at the advanced regenerative Phase II. These developmental features may have led the evolution of bizarre morphologies seen in basket stars, probably contributing to the adaptation to shallow waters from deep‐sea habitats.

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Ophiuroidea (Echinodermata): Systematics and Japanese Fauna

Cited by 9 publications

References 34 publications

A New Record of Brittle Star <i>Ophiopsila</i> cf. <i>polyacantha</i> (Echinodermata: Ophiuroidea) from Southwestern Japan, with Notes on its Bioluminescence

A New Record of Brittle Star <i>Ophiopsila</i> cf. <i>polyacantha</i> (Echinodermata: Ophiuroidea) from Southwestern Japan, with Notes on its Bioluminescence

Development of two new sets of PCR primers for eDNA metabarcoding of brittle stars (Echinodermata, Ophiuroidea)

Morphogenesis and histogenesis during the arm regeneration in a basket star Astrocladus dofleini (Euryalida, Ophiuroidea, Echinodermata)

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Ophiuroidea (Echinodermata): Systematics and Japanese Fauna

Cited by 9 publications

References 34 publications

A New Record of Brittle Star <i>Ophiopsila</i> cf. <i>polyacantha</i> (Echinodermata: Ophiuroidea) from Southwestern Japan, with Notes on its Bioluminescence

A New Record of Brittle Star <i>Ophiopsila</i> cf. <i>polyacantha</i> (Echinodermata: Ophiuroidea) from Southwestern Japan, with Notes on its Bioluminescence

﻿Development of two new sets of PCR primers for eDNA metabarcoding of brittle stars (Echinodermata, Ophiuroidea)

Morphogenesis and histogenesis during the arm regeneration in a basket star Astrocladus dofleini (Euryalida, Ophiuroidea, Echinodermata)

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Development of two new sets of PCR primers for eDNA metabarcoding of brittle stars (Echinodermata, Ophiuroidea)