Diplopodes et autres myriapodes de Mayotte

Cet ouvrage, richement illustré, est le résultat d’un inventaire des myriapodes dressé à l’issue d’une campagne de terrain en novembre 2019 et du contenu des collections de myriapodes de Mayotte du Musée royal de l’Afrique centrale et du Muséum national d’Histoire naturelle de Paris. Les myriapodes, souvent appelés mille-pattes et scolopendres, restent très méconnus. Ils sont pourtant d’excellents bio-indicateurs de l’état écologique des écosystèmes terrestres. Ce guide a pour but de présenter un aperçu des espèces de diplopodes et autres myriapodes présents à Mayotte, mais aussi des techniques de récolte, d’inventaire et d’identification de ceux-ci.De façon surprenante et contrairement à ce que le lecteur pourrait s’imaginer, les individus les plus grands ne sont pas les mieux connus. À Mayotte, plusieurs espèces de grande taille se sont avérées nouvelles pour la science et endémiques de l’île. C’est le cas notamment de Sechelleptus arborivagus,une nouvelle espèce décrite à l’occasion de cet inventaire. Le projet a été cofinancé par le ministère de la Transition écologique et solidaire (MTES-France) et le Musée royal de l’Afrique centrale (MRAC-Belgique)

Handbook of best practice and standards for 2D+ and 3D imaging of natural history collections

peer reviewedDigitising a collection is key to make it last even after the physical objects are no longer available. Almost all of the techniques currently available to digitise a natural history collection in 2D+ and 3D are listed herein. The techniques are explained in a way that even one without any knowledge on the subject may understand their principle. The strong and weak points of the techniques are discussed, and an overview of suitable collections and specimens are given for each one of them. Also, plenty of examples already digitised with each technique are provided together with the links to visualise them in 3D. After explaining all the different digitisation options, the subsequent chapters provide information on how to improve the 2D+ and 3D digital twins of the specimens and techniques are compared to each other by means of test specimens. These give a fast overview of the capabilities of the digitisation techniques. Possible solutions to avoid digitisation errors are equally provided. Lastly, the dissemination of the results and the data management of the 3D models are briefly discussed in the final chapters. Also, a large chapter is provided with several workflows that can be followed to get the best possible results

Sechelleptus arborivagus Sp. Nov., a new arboreal spirostreptid millipede (diplopoda, spirostreptidae) endemic to Mayotte island (comoros archipelago), Indian Ocean

peer reviewedA new millipede species of the genus Sechelleptus Mauriès, 1980 is described and illustrated from Mayotte Island, Indian Ocean. This new species, S. arborivagus sp. nov., found on trees, looks particularly similar to the sympatric S. variabilis VandenSpiegel & Golovatch, 2007, but is much larger and has a very different ecological behavior. Phylogenetic analyses based on a concatenated dataset of the COI and 16S rRNA genes and including nine species of Spirostreptidae (including Sechelleptus, Doratogonus Attems, 1914, Bicoxidens Attems, 1928 and Spirostreptus Brandt, 1833), strongly support the monophyly of Sechelleptus. Despite the similarity of their genitalia, the molecular analyses also reveal a clear-cut genetic divergence between S. arborivagus sp. nov. and S. variabilis (22.55% for COI and 6.63% for 16SrRNA) and further suggest the presence of a higher diversity within the genus Sechelleptus on Mayotte

Sechelleptus arborivagus Sp. Nov., a new arboreal spirostreptid millipede (diplopoda, spirostreptidae) endemic to Mayotte island (comoros archipelago), Indian Ocean

peer reviewedA new millipede species of the genus Sechelleptus Mauriès, 1980 is described and illustrated from Mayotte Island, Indian Ocean. This new species, S. arborivagus sp. nov., found on trees, looks particularly similar to the sympatric S. variabilis VandenSpiegel & Golovatch, 2007, but is much larger and has a very different ecological behavior. Phylogenetic analyses based on a concatenated dataset of the COI and 16S rRNA genes and including nine species of Spirostreptidae (including Sechelleptus, Doratogonus Attems, 1914, Bicoxidens Attems, 1928 and Spirostreptus Brandt, 1833), strongly support the monophyly of Sechelleptus. Despite the similarity of their genitalia, the molecular analyses also reveal a clear-cut genetic divergence between S. arborivagus sp. nov. and S. variabilis (22.55% for COI and 6.63% for 16SrRNA) and further suggest the presence of a higher diversity within the genus Sechelleptus on Mayotte

Focus stacking: Comparing commercial top-end set-ups with a semi-automatic low budget approach. A possible solution for mass digitization of type specimens

peer reviewedIn this manuscript we present a focus stacking system, composed of commercial photographic equipment. The system is inexpensive compared to high-end commercial focus stacking solutions. We tested this system and compared the results with several different software packages (CombineZP, Auto-Montage, Helicon Focus and Zerene Stacker). We tested our final stacked picture with a picture obtained from two high-end focus stacking solutions: a Leica MZ16A with DFC500 and a Leica Z6APO with DFC290. Zerene Stacker and Helicon Focus both provided satisfactory results. However, Zerene Stacker gives the user more possibilities in terms of control of the software, batch processing and retouching. The outcome of the test on high-end solutions demonstrates that our approach performs better in several ways. The resolution of the tested extended focus pictures is much higher than those from the Leica systems. The flash lighting inside the Ikea closet creates an evenly illuminated picture, without struggling with filters, diffusers, etc. The largest benefit is the price of the set-up which is approximately € 3,000, which is 8 and 10 times less than the LeicaZ6APO and LeicaMZ16A set-up respectively. Overall, this enables institutions to purchase multiple solutions or to start digitising the type collection on a large scale even with a small budget

Classification of Multispectral Point Clouds applied to Archaeological Material

Over the past few years, the spectral classification gained major interest in the field of teledetection, urban landscape and some cultural heritage application in order to detect non straight visible features. On the other hand, 3D acquisition lead to the gathering of high resolution point clouds describing the geometric object’s features. Both approaches are rarely combined in the archaeological domain despite the fact that an increasing number of museums are digitizing their collection in 3D and perform two dimension multispectral analysis in conservation, analysis and restoration purposes. In this study, we propose to attach multispectral information to a point cloud representing archaeological objects. A multivalued classification can then be performed to the cloud. The approach shows two major interest: first, the three spatial dimensions of the point cloud can be considered in order to improve the classification; secondly, since the classification results are known in 3D, the classes can be easily represented in 3D which is a major issue for archaeological results interpretation. The artefacts digitization goes through a photogrammetric process. We produced objects images in multiple wavelengths ranging from ultraviolet, visible to near-infrared spectrum. From the 3D textured mesh (one per wavelength), we applied a data fusion to generate a unique point cloud containing the multispectral information as scalar fields. We tested several unsupervised and supervised classification processes dedicated to multispectral information or not of the point clouds such as K-means, Random Forests… The classification results allows to segment the point cloud and highlight the discovered parts of the artefact. Based on the training classification set, researchers can enhance the different features of an object (pigments, composite objects, restorations). The segmented data allow automatic surface repartition measurements and a better understanding of the creation process

Handbook of best practice and standards for 2D+ and 3D imaging of natural history collections

Digitising a collection is key to make it last even after the physical objects are no longer available. Almost all of the techniques currently available to digitise a natural history collection in 2D+ and 3D are listed herein. The techniques are explained in a way that even one without any knowledge on the subject may understand their principle. The strong and weak points of the techniques are discussed, and an overview of suitable collections and specimens are given for each one of them. Also, plenty of examples already digitised with each technique are provided together with the links to visualise them in 3D. After explaining all the different digitisation options, the subsequent chapters provide information on how to improve the 2D+ and 3D digital twins of the specimens and techniques are compared to each other by means of test specimens. These give a fast overview of the capabilities of the digitisation techniques. Possible solutions to avoid digitisation errors are equally provided. Lastly, the dissemination of the results and the data management of the 3D models are briefly discussed in the final chapters. Also, a large chapter is provided with several workflows that can be followed to get the best possible results

Identifying the challenges and solutions for 3D digitization of bioart

editorial reviewed"Arc-hive: Case Studies and Life as an Object" is a two-part publication offering fresh and valuable insights from numerous authors to the challenges of working with biomedia, with special focus on preservation, archiving and digitisation of biomedia practices.ArcHIV