Project description:In the hot debate on arthropod relationships, Crustaceans and the morphology of their appendages play a pivotal role. To gain new insights into how arthropod appendages evolved, developmental biologists recently have begun to examine the expression and function of Drosophila appendage genes in Crustaceans. However, cellular aspects of Crustacean limb development such as myogenesis are poorly understood in Crustaceans so that the interpretative context in which to analyse gene functions is still fragmentary. The goal of the present project was to analyse muscle development in Crustacean appendages, and to that end, monoclonal antibodies against arthropod muscle proteins were generated. One of these antibodies recognises certain isoforms of myosin heavy chain and strongly binds to muscle precursor cells in malacostracan Crustacea. We used this antibody to study myogenesis in two isopods, Porcellio scaber and Idotea balthica (Crustacea, Malacostraca, Peracarida), by immunohistochemistry. In these animals, muscles in the limbs originate from single muscle precursor cells, which subsequently grow to form multinucleated muscle precursors. The pattern of primordial muscles in the thoracic limbs was mapped, and results compared to muscle development in other Crustaceans and in insects.
Project description:BACKGROUND:Isopoda are the most diverse Crustacea. In order to encourage the study of isopod crustaceans and their use in biodiversity studies, systematics, ecology, physiology and more, one needs to know who the isopods are and where to find them. NEW INFORMATION:This is a short "how to" guide focusing on the free-living marine and freshwater isopods: where they live and how to collect and preserve them. The tools and techniques described here are simple, but invaluable in accessing the natural history of these remarkable creatures.
Project description:Four new isopods, Amakusanthura intermedia sp. nov., Apanthura laevipedata sp. nov., Idarcturus trispinosus sp. nov., and Neastacilla paralongipectus sp. nov., are reported from the sublittoral zones in Korean waters. Amakusanthura intermedia sp. nov. differs from its congeners by the following features: the uropodal exopod is sinuous distally and with pointed apex; the maxillipedal endite is present and reaching to the distal end of fused palp articles I and II; and the propodal palm of pereopod I is stepped. Apanthura laevipedata sp. nov. can be distinguishable from its related species by the following characteristics: the eye is lacking; the propodal palm of pereopod I is not stepped; and the uropodal exopod is not sinuous. Idarcturus trispinosus sp. nov. is diagnosed by the following features: the cephalon has three dorsal spines and a pair of lateral spines; pereonite IV has two pairs of small dorsolateral spines, four pairs of dorsal spines, and one posterior spine; and the pleotelson has three pairs of wings laterally. Neastacilla paralongipectus sp. nov. can be distinguished by the following characteristics: the body is smooth and lacking dorsal spines or tubercles; pereonite IV is approximately 5.4× longer than pereonites II and III together; and the pleotelson has two pairs of lateral wings. In this paper, detailed descriptions and illustrations of the four species are presented. A key to the genera of the family Arcturidae and keys to the species of the four genera are also provided.
Project description:This paper utilizes Critical Slowing Down (CSD; instability) indicators developed by statistical physics to analyse economic growth rate variability and secular stagnation in historical GDP data. Understanding these phenomena is vital, particularly in advanced economies faced with declining growth rates. Two novel indicators - the autocorrelation (AR1) and the variance - are found particularly useful in providing insight into inter-decadal GDP variability over this period. These indicators are first applied to the Maddison-Project historical dataset, which includes almost a century of data for some 80 countries and almost two centuries of data for 9 countries. They are additionally applied to ~50 years of recent annual data for around 130 countries from the World Bank dataset as well as ~60 years of recent quarterly data for around 20 countries from the OECD dataset. Analysis reveals inter-decadal variability in growth cycles (the recession cycle), highlighting periods of large slow growth cycles and periods of small fast growth cycles. The most commonly occurring pattern is characterised by an increase in CSD from the 1900s to 1940s, a decline in CSD between the 1930s and the 1970s, then a further increase in CSD from the 1960s to 2010. This pattern is significant in ~70% of the advanced economies. CSD indicators may then provide invaluable insights into specific aspects of inter-decadal GDP variability, such as on the nature of the business cycle, secular stagnation and the implicit "restoring forces" of the economy.
Project description:BackgroundCumaceans mostly inhabit marine environments, where they play a crucial role in marine food webs and actively participate in the transfer between benthic and pelagic systems. Scientific interest in these crustaceans has been increasing, but is limited to certain geographic areas, which do not include extreme environments such as hydrothermal vents.New informationTherefore, this study aimed to report the distribution of cumaceans in shallow-water hydrothermal vents at Banderas Bay and to identify the specimens present. Three sites were selected (20°44'54.7"N, 105°28'40.6"W; 20°44'54.8"N, 105°28'40.4"W; 20°44'54.9"N, 105°28'38.4"W) and each site was divided into three zones, based on sediment temperature. Through SCUBA diving, 27 sediment cores were collected. The samples were processed and identified in the laboratory. The families Bodotriidae T. Scott, 1901; Pseudocumatidae Sars, 1878; and Diastylidae Bate, 1856; were recorded and six morphospecies were identified. This work leaves a preliminary frame of reference for future studies related to the biodiversity of cumacean in Hydrothermal vents environments.
Project description:A new sphyrapodid tanaidacean, Sphyrapus caribensis sp. nov. is described and a new record of Kudinopasternakia siegi is reported for the Colombian Caribbean based on samples collected during cruises in 2014-2015. The new species appears to be most closely related to the northeast Atlantic species, Sphyrapus malleolus. Sphyrapus caribensis can be distinguished from Sphyrapus malleolus by a combination of characters, including the maxillipedal basis without long distal seta, the number of setae on the distoventral margin of pereopods 1 and 2, and the number of plumose seta on the pleopod basis. A key for the separation of Sphyrapus species is presented.
Project description:Thirty-eight species of Isopoda, belonging to 13 families and 29 genera, are listed from Kuwait based on previous literature records (of 17 species) and collections carried out along Kuwait's coastal and subtidal zones during the present study. The majority of species belongs to the suborder Cymothoida (23), followed by Sphaeromatidea (9), Oniscidea (3), Valvifera (2), and Asellota (1). In total, 25 species were collected and identified from 12 families and 22 genera from Kuwaiti coastal and subtidal areas. These include eight families, 15 genera, and 21 species recorded for the first time from Kuwait. Isopod diversity was highest in the sandy rock areas, including southern Kuwait, particularly in Al-Khiran and Al-Nuwaiseeb, and in mixed habitat (muddy, rocky, and sandy) intertidal transects such as in Failaka Island. The species number increased from the subtidal and lowest zones into the high tidal zone. Isopods were found in sandy substrata, among shells, cobbles, rocks, dead corals, and algae.
Project description:During monthly sampling of benthic invertebrates at 13 stations in the Maryland Coastal Bays (MCBs) from March to December 2012, a total of 29 individuals of Ianiropsis cf. serricaudis were collected. This species is being reported for the first time in MCBs. A detailed illustration and description of an adult male of I. cf. serricaudis from MCBs is presented. An illustrated key of males of Ianiropsis species belonging to the palpalis-group is also presented. The size of the largest male was 3.0 mm and that of the largest female was 2.5 mm. It is possible that I. cf. serricaudis was present in the MCBs, but overlooked during previous surveys of marine benthic invertebrates in the area because of its small body size and lack of taxonomic expertise.
Project description:The marsupium, a brood pouch in peracarid crustaceans (Crustacea, Malacostraca) has evolved in terrestrial environment for providing nutrition and optimal conditions for embryogenesis. In the present study we give details on the histology and ultrastructure of its constituting elements such as oostegites and cotyledons. Marsupia of two different eco-morphological types of woodlice, namely the non-conglobating species Trachelipusrathkii Brandt, 1833 and the conglobating species Cylisticusconvexus De Geer, 1778 were investigated. Light microscopic (LM) studies showed some differences in the main structure of the two species' brood pouch: in Trachelipusrathkii, a 'clinger' type woodlice, the oostegites bend outwards during brood incubation as growing offspring require more space, while in Cylisticusconvexus, a 'roller' type isopod, the sternites arch into the body cavity to ensure space for developing offspring and still allowing conglobation of the gravid females. The quantitative analysis of the oostegites' cuticle proved that the outer part is about 2.5 - 3 times thicker compared to the inner part in both species. Electron microscopic (TEM) examinations show only small histological differences in the oostegites and cotyledon structure of the two species. Cellular elements and moderately electron dense fleecy precipitate are found in the hemolymph space between the two cuticles of oostegites. The cells contain PAS positive polysaccharide areas. TEM studies revealed some differences in the cotyledon ultrastructure of the two species. Cotyledons of Trachelipusrathkii consist of cells with cristate mitochondria and granular endoplasmic reticulum with cisterns. Cotyledons of Cylisticusconvexus consist of cells with densely cristate mitochondria and ribosomes attached to vesicular membrane structures. In both species cells with electron dense bodies were observed. We conclude that - besides the differences in marsupial shapes - the fine structure of the oostegites and cotyledons is hardly affected by the eco-morphological type, specifically the conglobating or non-conglobating character of the studied species.
Project description:Until now, Hargeria was considered a monospecific leptocheliid genus, with the species Hargeria rapax considered a taxon with a wide distribution, from the Northwestern Atlantic to the Mexican Caribbean. Herein, after a detailed revision of type and topotype materials and specimens collected from the Mexican Caribbean, a new species H. chetumalensis sp. nov. is described, and the redescription of H. rapax is provided. Also, we found a significant genetic divergence between the two species based on the nucleotide sequences of cytochrome oxidase subunit I, which support the morphological data. The morphological features used to recognize both species are also adequate to link males, females, and juvenile stages, although these species have a high intraspecific polymorphism.