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A proposed new Ordovician asterozoan genus and species, Cantabrigiaster fezouataensis , has been recently described and assigned to the class Somasteroidea. An accompanying phylogenetic analysis treated twenty-two asterozoans and sixteen early non-asterozoans, one of the latter providing the outgroup. The phylogenetic hypothesis focused on derivation of the subphylum Asterozoa and emphasized the Crinoidea; Cantabrigiaster fezouataensis was interpreted as documenting a critical transition stage in the origin of the Asterozoa. The diagnosis for the proposed new generic name posits absence of ambital framework ossicles as the single character expression that distinguishes Cantabrigiaster among somasteroid genera. Ambital framework ossicular presence is documented here in the holotype and other members of type suite; Cantabrigiaster is synonymized with Villebrunaster Spencer and V. fezouataensis nov. comb. is redescribed. The data matrix for the former Cantabrigiaster phylogenetic analysis relies on an earlier study treating overall echinoderm construction. Expressions outlined in the earlier study are not amenable to transfer to a data matrix without evaluation of level of universality of each cited expression; such evaluations were not provided thereby leading to flawed phylogenetic conclusions that are rejected. An alternative hypothesis for the early history of the Asterozoa supported by aspects of the fossil record, that subphylum diversification preceded the origin of readily preserved skeletons, and therefore potentially no tenable pre-asterozoan outgroup candidate survives in the fossil record, has not been falsified. [ABSTRACT FROM AUTHOR]

The first phylogenetic and phylogeographic studies of the cosmopolitan deep-sea species, Asteronyx loveni Müller and Troschel, 1842, were conducted, based on specimens collected from off the Pacific coast of Japan. Partial sequences of mitochondrial 16S (68 specimens) and COI (24 specimens) genes were analyzed. Phylogenetic trees and network analyses revealed three lineages and five sub-lineages of A. loveni . Genetic distance and AMOVA (analysis of molecular variance) analyses suggested that the lineages should be considered three cryptic species. Skin on the aboral disc is partly thickened and forms a mesh-like pattern, which has never been reported in previous descriptions of Asteronyx ; this is provided as a new taxonomic character. Based on absence/presence of mesh-like skin, one of the three lineages was assigned to A. loveni and another was described as Asteronyx reticulata new species. This new species can be distinguished from congeners by having mesh-like skin and small genital slits at the innermost position on the interradial oral disc. [ABSTRACT FROM AUTHOR]

The Mg/Ca and Sr/Ca ratios in echinoderm skeletal calcite are used as a proxy for Phanerozoic seawater changes, since the skeletal concentrations are, to some extent, controlled by environmental factors. However, it remains unclear how the influence of environmental factors is modified by vital effects, especially in polar waters. Therefore, the goal of this study was to compare the ratios of Mg/Ca and Sr/Ca among the skeletal parts of 10 common Arctic echinoderm species belonging to three classes Echinoidea, Asteroidea and Ophiuroidea that contribute substantially to the carbon cycle in the Arctic benthic system. Significant differences were recorded in echinoid skeletal element concentrations among specific skeletal parts. The lowest Mg/Ca and Sr/Ca ratios were detected in the spines (mean Mg/Ca 37.5 ± 8.8 SD; Sr/Ca 1.8 ± 0.1). The components of the Aristotle's lantern (epiphyses, pyramids and rotulas) were characterised by the highest Mg levels (Mg/Ca 79.9 ± 6.0; 75.2 ± 9.1; 60.1 ± 3.8, respectively). It is likely that mouth parts experience greater mechanical pressure compared to other body parts, and the higher content of Mg in the Aristotle's lantern contributes to its robustness. We did not find any distinctive trends in the distribution of skeletal elements in the asteroid and ophiuroid skeletal parts. The heterogeneous concentrations of Mg and Sr in different skeleton parts of the echinoids suggest possible physiological regulation of the chemical composition rather than the composition only being influenced by the environment. We cannot recommend echinoderm skeletons as reliable indicators in palaeoenvironmental reconstructions due to the possible biological control of skeletal chemistry, which may interfere with the effect of environmental variables. [ABSTRACT FROM AUTHOR]

The reproduction of the brittle star Astrotoma agassizii was studied from deep waters of the South Atlantic Ocean, based on samples collected in August 2012, and May and September 2013. Ten samples from 800 to 1400 m depths off Mar del Plata Canyon were studied. The species was found to be a brooding simultaneous hermaphrodite. Hermaphroditic gonads contained testis and ovaries inside the same sacs. Both, ovary and testis contained different stages of gametogenesis development simultaneously. Gonads contained several stages of oocytes in different stages of gametogenesis. The largest oocyte recorded was 800 µm diameter. Free spermatozoa were observed in the lumen of the testis, together with spermatogenic columns. Five individuals, from a total of 30 examined, resulted brooding, and most contained mature ovotestis at the same time. Incubation occurs in five of the ten bursal sacs, containing 15–20 young juveniles each. Maximum disc diameter recorded for a brood was 1100 µm. Herein we hypothesize that Astrotoma agassizii could be continuous breeder species in the deep-sea. [ABSTRACT FROM AUTHOR]

Abstract: The lipid, fatty acid (FA), and sterol composition of two ophiuroids and four holothurians from the abyssal eastern North Pacific were analysed to assess their feeding habits and to ascertain their composition for use in a larger study to examine food web dynamics and trophic ecology. Holothurians were rich in phytosterols and algal derived FA such as docosahexaenoic acid and eicosapentaenoic suggesting tight trophic coupling to phytodetritus. Large proportions of stanols were found, probably a result of enteric bacteria but they may come from sterol metabolism in the holothurians themselves. Oneirophanta mutabilis was distinct with much higher levels of stanols and bacterially derived FA suggesting specific selection of bacteria rich detrital particles or the activity of enteric and integumental bacteria. The ophiuroids sterol and FA compositions differed greatly from the holothurians and reflected consumption of animal material in addition to phytodetritus. Large proportions of energy storage lipids suggested a sporadic food supply. Several unusual fatty acids were found in these abyssal echinoderms. Tetracosahexaenoic acid, 24:6ω3, in ophiuroids and 23:1 in holothurians may be good biomarkers for food web studies. We report the first occurrence of αOH 24:1 in holothurians with none detected in ophiuroids. Its function is presently unknown. [Copyright &y& Elsevier]

Abstract: A worldwide stratigraphical survey of Late Palaeozoic and Early Mesozoic ophiuroids (Echinodermata) reveals unique extinction and recovery patterns during and after the end-Permian mass extinction event. The Ophiuroidea suffered the loss of all Palaeozoic genera. However, this clade profited greatly from the event by undergoing a significant increase in species number in the postextinction oceans. Although both sampling and taphonomic biases may have affected ophiuroid diversity changeover patterns across the Permian/Triassic (P/Tr) transition to some extent, both biases cannot explain adequately the abrupt increase in species numbers and geographically wide distributions of ophiuroids in the Early Triassic oceans. The Ophiuroidea recovery follows Erwin''s model of “a logistic increase in diversity beginning immediately after the end of the mass extinction” without the survival interval. Morphological innovation (i.e., emergence of advanced canal systems), diversification of life habitats and biogeographical dispersal over the Palaeotethyan and Gondwanan regions enabled the Ophiuroidea to occupy efficiently vacant ecospace created by the end-Permian extinction, enabling the clade to recover and radiate in the Early Triassic oceans. Previously reported ophiuroids from the Upper Permian to Lower Triassic of China are also taxonomically revised. These, Ophiaulaxoides bijieensis (Feng), Huangzhishania gulinensis (Feng), “Ophiolepis”? shanxiensis Yang and “Ophioderma”? schistovertebrata Yang, were described from the Lower Triassic; while Aganaster? qingchangensis (Feng) and Syntomospina? kaiyangensis Feng came from the Upper Permian. [Copyright &y& Elsevier]

Lateral arm plates and vertebrae of the ophiuroid Ophiosmilax? alternatus Kutscher et Jagt in Jagt, 2000, are described from the Lower Turonian of the Czech Republic and the Middle Turonian of Tunisia. This species has so far been recorded only from the Upper Campanian and Lower Maastrichtian of Germany, Denmark and Belgium. The vertebrae are morpho-functionally unique, and new descriptive terms, i.e., transspondylous vertebra and transspondylous vertebral type, are herein proposed. Ophiosmilax? alternatus appears to be an evolutionarily conservative lineage of wide palaeogeographical and stratigraphical ranges, existing for more than 20 or 25 million years. However, in comparison to other ophiuroid species, it was very rare in the benthic communities. In available collections of lateral arm plates and vertebrae from the Bohemian Cretaceous Basin, less than 1% of specimens belong to O.? alternatus. [Copyright &y& Elsevier]

Ophiophragmus filograneus is a unique echinoderm as it occurs in estuaries at reduced salinities and not in the open sea. The question is whether this distribution is because it is adapted to reduced salinities or whether some other factor is responsible. If it is adapted, it should function better at reduced salinities. To ascertain if this is true, O. filograneus were collected from Tampa Bay at 22‰ salinity and respiration, excretion, regeneration and production measured at 16‰, 22‰ and 30‰ salinity. Individuals in 16‰ salinity respired at a lower rate, excreted at a higher rate, and regenerated less than those in 22‰ or 30‰ salinity. O. filograneus was stressed in 16‰ salinity as production (increase in organic material) was less than in 22‰ and 30‰. Because O. filograneus functions better at higher salinities, its restriction to estuaries is probably due to other factors such as food resources, sediment type, competition and/or predation. [Copyright &y& Elsevier]

While Late Cretaceous ophiuroids are relatively well known in Europe, these faunas have been much less studied in North Africa. With the exception of some Tunisian assemblages preliminary described at the turn of the 21st century, nothing is known about the Cretaceous brittle stars of the southwestern Tethyan margin. The present paper seeks to bring the first data about hitherto unknown ophiuroids recently found in the early upper Cenomanian succession of the eastern side of the Preafrican trough (Menaguir section, Algeria). This "community" of brittle stars comprises at least eight species. Most of them are probably new, but have not been formally named here. These are representatives of the families Hemieuryalidae, Amphiuridae, Ophiodermatidae, Ophiacanthidae, Ophiopezidae and probably also Ophiomyxidae and Ophiobyrsidae. Almost all vertebrae are zygospondylous; no streptospondylous vertebrae indicate the absence of the order Euryalida here. Most of the ophiuroids belong to the orders Amphilepidida and Ophiacanthida. Ophiotitanos serrata , Ophiomyxa ? aff. jekerica , Ophiojagtus ? sp. and some other taxa resembling ophiuroid assemblages from the Late Cretaceous of central, western and northern Europe. With respect to the late Cenomanian age, the depth of the sea and the taxonomic composition, there are some similarities with ophiuroids of the Bohemian Cretaceous Basin. The mid-ramp subtidal facies suggests that brittle stars lived here in a warm, euphotic and probably shallow sea. [ABSTRACT FROM AUTHOR]

For a long time, as the asterozoan studies were rare among Devonian invertebrates of the Paraná Basin, the knowledge about the taxonomy, taphonomy, and palaeoecology of this regional group remained extremely limited. Therefore, this research focuses for the first time on the detailed identification and classification of fossil asteroids and ophiuroids from the Jaguariaíva and São Domingos members of the Ponta Grossa Formation. As a result, four species are described herein, Paranaster crucis nov. gen., nov. sp., Magnasterella darwini (Clarke, 1913) nov. gen., Encrinaster pontis (Clarke, 1913), and Marginix notatus nov. sp. In addition, the Paranasteridae nov. fam. is also proposed. On the other hand, the taphonomic analysis of this asterozoans, together with the interpretation of sedimentary matrix and associated fossil assemblages, reveals important palaeoenvironment details from the Devonian of the Paraná Basin. These echinoderms lived in a marine platform governed by a polar climate and low sedimentation rates. But the commonly articulated asterozoans also support important events of rapid burial. Finally, this research expands the diversity of malvinokaffric echinoderms, contributing to the palaeoecological reconstruction of the Ponta Grossa Formation. Image 1 • This manuscript is a review of the Brazilian Devonian asterozoan fauna. • A new family, two new genera, and two new species described. • Two new Malvinokaffric asterozoans: Paranaster crucis and Marginix notatus. [ABSTRACT FROM AUTHOR]