A review of the genus Narcissia Gray, 1840 (Echinodermata: Asteroidea: Ophidiasteridae)

Since the taxonomic revision of the Ophidiasteridae by H.L. Clark (1921), in which 20 genera were recognized as valid, several new genera and species were included in this family, and the boundaries between some of them became largely arbitrary. This also applies to Narcissia Gray, 1840, whose morphology and taxonomy are still very poorly understood today. The main goals of this research were: review the taxonomy of the genus Narcissia, from morphological studies; redescribe N. trigonaria Sladen, 1889s. str.; characterize N. canariensis (d'Orbigny, 1839) and N. gracilis A.H. Clark, 1916, the two valid species most similar to N. trigonaria; review the validity of N. ahearnae Pawson, 2007 and N. trigonaria var. helenae Mortensen, 1933; review the validity of N. gracilis malpeloensis Downey, 1975. Altogether 370 specimens were analysed. All morphological structures of taxonomic importance have been illustrated, and, for the first time, the internal characters of this group were studied, from electron microscopy and microtomography. A new diagnosis for the genus Narcissia was constructed. Narcissia trigonaria was redescribed from a large specimen, from the type locality (Bahia, Brazil). Narcissia ahearnae is considered a valid species, and N. canariensis and N. trigonaria distinct entities. Narcissia trigonaria var. helenae is placed in the synonymy of N. trigonaria, and N. gracilis malpeloensis into the synonymy of N. gracilis. The dataset obtained in this work is by far the most complete acquired for the genus Narcissia.

Towards non-blind optical tweezing by finding 3D refractive index changes through off-focus interferometric tracking

In modern 3D microscopy, holding and orienting arbitrary biological objects with optical forces instead of using coverslips and gel cylinders is still a vision. Although optical trapping forces are strong enough and related photodamage is acceptable, the precise (re-) orientation of large specimen with multiple optical traps is difficult, since they grab blindly at the object and often slip off. Here, we present an approach to localize and track regions with increased refractive index using several holographic optical traps with a single camera in an off-focus position. We estimate the 3D grabbing positions around several trapping foci in parallel through analysis of the beam deformations, which are continuously measured by defocused camera images of cellular structures inside cell clusters. Although non-blind optical trapping is still a vision, this is an important step towards fully computer-controlled orientation and feature-optimized laser scanning of sub-mm sized biological specimen for future 3D light microscopy.

Modern high strength steels under high strain-rate regimes

In order to properly design critical infrastructures and buildings in steel (bridges, high-rise building, off-shore, cranes, etc.), certain requirements concerning to mechanical resistance and robustness under exceptional actions have to be carefully fulfilled. An acceptable level of safety must be assured to avoid human loss, environmental pollution and material damage. These structures can be subjected to severe accidental loading such as blast or impact. In this context it is fundamental to adequately know the behaviour of structural steel under high strain rate. Modern high strength steels are quenched and selftempered steels. These steels have several layers with differentiated microstructures (martensitic in the cortical part and ferritic in the core). The behaviour of the single layer at high strain rate regimes have to be accurately studied. The paper collects and discusses the tensile results at high strain rate obtained on samples of homogeneous layers of S690QL and S960QL steels. Finally, the characterisation of the single layers has been used in order to analyse the results obtained in large specimen obtained from slabs 12mm thick.

Tests of bond between concrete and steel bars – literature background and program of own research

This article deals with the issue of the bond between concrete and reinforcement. The bond is crucial for reinforced concrete elements because it is possible to transfer forces (stresses) from concrete to the reinforcement. Basic information related to the cooperation of concrete and rebars was recalled in the article. Selected issues concerning theoretical and numerical analysis as well as experiments of the bond phenomenon were presented. The article also proposes its own concept of experimental studies on the bond on two types of specimens: so-called short specimen and large specimen that will be subjected to pull-out tests. The described concept is ultimately to form the basis for creating a numerical model, enabling the simulation of bond in various reinforced concrete elements, calibrated based on the results of experimental studies.

Taxonomy and functional morphology of the Urasterellidae (Paleozoic Asteroidea, Echinodermata)

Family-level taxonomic concepts for Paleozoic Asteroidea are problematic; data availability for the family Urasterellidae, however, is judged sufficient for familial reappraisal. The survey cannot be fully comprehensive because certain available names are founded on very limited material, with specimens widely scattered among collections. Recognized urasterellid genera include Urasterella Schuchert, 1914; Anthroosasterias Blake, 2017; Meturaster Blake, Guensburg, and Lefebvre, 2016; Salteraster Stürtz, 1893; Staurasterias Blake, 2017; Ulrichaster Spencer, 1950; and Pegoasterella pompom n. gen. n. sp. Other available generic names are held in abeyance. The name Urasterella has approached form-genus status, an outcome exacerbated by incomplete understanding of the type species. Urasterella huxleyi (Billings, 1865) is reassigned to Anthroosasterias. Relatively large specimen suites for Anthroosasterias huxleyi (Billings, 1865) and Salteraster grandis (Meek, 1872) enable some interpretation of urasterellid intrataxon variation, ontogenetic change, and life mode. Morphologic changes accompanying ontogeny of A. huxleyi are argued as favoring a shift from substrate surface feeding to feeding through extension of arms into the water column in a manner comparable to that seen among extant Forcipulatida and ophiurans.UUID: http://zoobank.org/82d2eca7-55e0-42ed-a164-c666652e3972

Male identification, generic classification and sexual dimorphism of Micronychus pardus (Kazantsev, 2018) comb. nov. (Coleoptera: Lycidae: Calochrominae)

Almost all net-winged beetles are members of Müllerian complexes and their similarity due to phenotypic coevolution sometimes complicates species identification and generic placement. Therefore, large specimen series, detailed exhaustive examination of morphological characters and molecular data are needed to clarify the taxonomic placement. Using mitochondrial DNA sequences, I investigated the sexual dimorphism and generic placement of the recently described species Calochromus pardus Kazantsev, 2018. I found that the species does not belong in Calochromus Guérin-Méneville, 1833 and all morphological characters and molecular analyses point to its placement in Micronychus Motschulsky, 1861. Therefore, Micronychus pardus (Kazantsev, 2018), comb. nov. is proposed. Additionally, the male is described here for the first time showing the sexual dimorphism in the species. Unlike the females, the males do not superficially resemble members of Xylobanus Waterhouse, 1879 with bright coloured elytral costae and black background, but mimics the sympatrically occurring yellow and black lycids in the genus Cautires Waterhouse, 1879.