Morphological diagnoses of higher taxa in Ophiuroidea (Echinodermata) in support of a new classification

O’Hara, Timothy D.; Stöhr, Sabine; Hugall, Andrew F.; Thuy, Ben; Martynov, Alexander

doi:10.5852/ejt.2018.416

Cited by 55 publications

(128 citation statements)

References 8 publications

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“…The photos were organized into plates for each species using Adobe Photoshop. The taxonomy follows the new classification of Ophiuroidea (O'Hara et al, 2018;Stöhr et al, 2019). The species were described in detail from images, previous notes and appropriate taxonomic resources (Tommasi, 1970;Borges et al, 2002;Borges & Amaral, 2005;Alitto et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

New diagnostic characters forAmphiodiaandOphiophragmus(Amphiuridae, Ophiuroidea, Echinodermata)

et al. 2020

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The genera Ophiophragmus and Amphiodia are amphiurids that are considered taxonomically difficult due to their great resemblance, few diagnostic characters and synonymy problems. Our aim is to redescribe the species using scanning electron microscopy and morphometry of diagnostic structures, and to provide new information for the identification of these Ophiuroidea. Five Amphiodia spp. and six Ophiophragmus spp. recorded in Brazil were rigorously redescribed. The descriptions include new diagnostic characters derived from external morphology, arm microstructures and morphometry. We also provided comparative analyses of species with shared characters such as Amphiodia riisei and Amphiodia trychna. The geographic and bathymetric distributions of the studied species were updated, and new records are provided. All the information presented may be used in taxonomic, ecological and phylogenetic studies, helping to fill gaps in the knowledge of the biodiversity, ecology and evolution of these Ophiuroidea. Conclusively, all the tools applied here assisted in the identification of genera and species and could be useful in other taxonomic studies of Echinodermata.

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Section: Methodsmentioning

confidence: 99%

New diagnostic characters forAmphiodiaandOphiophragmus(Amphiuridae, Ophiuroidea, Echinodermata)

et al. 2020

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“…This is surprising considering that there are over 7,500 species of echinoderms that live in a wide variety of habitats (Zhang 2011). Also striking is the fact that although Ophiuroidea is the largest class of echinoderms (about 2100 described species according to O'Hara et al (2018)) and are generally photonegative (Stöhr et al 2012;O'Hara et al 2018), only a few (39) species have been found in caves.…”

Section: Introductionmentioning

confidence: 99%

Troglomorphism in the brittle star Ophionereis commutabilis Bribiesca-Contreras et al., 2019 (Echinodermata, Ophiuroidea, Ophionereididae)

Márquez-Borrás¹,

Solís-Marín²,

Mejía-Ortíz³

2020

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Due to their peculiar and sometimes bizarre morphology, cave fauna (across invertebrates and vertebrates from both aquatic and terrestrial cave habitats) have fascinated researchers throughout history. Despite their success in colonizing most marine ecosystems, the adaptations of cave brittle stars (Ophiuroidea) to a stygobiotic lifestyle have been scarcely examined. Employing comparative methods on a data set of two species belonging to the genus Ophionereis, this study addresses whether a cave-dwelling species from Cozumel exhibited similar troglomorphic traits as those of other taxa inhabiting caves. Our work demonstrated that some characters representing potential morphological cave adaptations in O. commutabilis were: bigger sizes, elongation of arms and tube feet and the presence of traits potentially paedomorphic. In addition, an element of ophiuroid’s photoreceptor system, as well as pigmentation, was observed to be peculiar in this stygobiotic species, plausibly as a result of inhabiting a low light-energy environment. Finally, we add evidence to the statement that O. commutabilis is a cave endemic species, already supported by demography, distribution and origin of this species, and now by a typical array of troglomorphisms.

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“…Over the last two decades, internal morphological studies (Martynov 2010;Thuy & Stöhr 2011;Okanishi et al 2017) and molecular analyses (O'Hara et al 2017) have accumulated strong evidence suggesting that the previously accepted classification of ophiuroids does not reflect their true phylogenetic relationships. This has finally led to the proposal of a new phylogeny (O'Hara et al 2017), and as a result a new higher classification (O'Hara et al 2018), from class to family level.…”

Section: Introductionmentioning

confidence: 99%

“…The new classification scheme recognizes 33 families and six orders, a considerable increase on the 17 families and two orders recognized previously. However, this scheme still leaves many genera unplaced, due to a lack of both molecular and morphological data (O'Hara et al 2018). Recently, Wilkie & Brogger (2018) tested the phylogeny using an examination of peristomial plates, which have not been considered for their taxonomic information in over a century.…”

Section: Introductionmentioning

confidence: 99%

“…Combining molecular and morphological data should ensure a higher accuracy in phylogenetic reconstructions; however, the morphological dataset recently produced by Thuy & Stöhr (2016, 2018 is still too limited for such an approach (46 species, 130 characters). Nevertheless, morphological studies were instrumental in supporting the new classification (O'Hara et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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<p class="HeadingRunIn"><strong>Comparison of 2D SEM imaging with 3D micro-tomographic imaging for phylogenetic inference in brittle stars (Echinodermata: Ophiuroidea)</strong></p>

et al. 2019

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Recent efforts to reconstruct the phylogeny of brittle stars (ophiuroids) have shown the need for more objective and reproducible data collection methods than the traditional visual examination and verbal description of morphological characters. Complex skeletal structures may be better understood in three dimensions than in two dimensions obtained from techniques like scanning electron microscopy (SEM). We test this hypothesis using three types of three-dimensional tomographic imaging methods—lab-based micro-CT, X-ray microscopy and synchrotron-based tomography—to examine the morphology of ophiuroid arms, and compare them with two-dimensional data obtained from SEM. We describe the advantages and disadvantages of each instrument and set of parameters in terms of the ease and efficiency of data collection for morphometric analyses. We present new morphological observations obtained by digital sectioning of three-dimensional images that could not be achieved with SEM. Overall, our findings suggest that three-dimensional imaging has a high potential to address the gaps in knowledge of the internal ophiuroid skeleton, which will be pivotal to providing morphological characters that will aid in phylogenetic reconstructions.

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Morphological diagnoses of higher taxa in Ophiuroidea (Echinodermata) in support of a new classification

Cited by 55 publications

References 8 publications

New diagnostic characters forAmphiodiaandOphiophragmus(Amphiuridae, Ophiuroidea, Echinodermata)

New diagnostic characters forAmphiodiaandOphiophragmus(Amphiuridae, Ophiuroidea, Echinodermata)

Troglomorphism in the brittle star Ophionereis commutabilis Bribiesca-Contreras et al., 2019 (Echinodermata, Ophiuroidea, Ophionereididae)

<p class="HeadingRunIn"><strong>Comparison of 2D SEM imaging with 3D micro-tomographic imaging for phylogenetic inference in brittle stars (Echinodermata: Ophiuroidea)</strong></p>

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