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Alexeeva N, Tamberg Y. Ultrastructure of the female pedal gonad in Phoxichilidium femoratum (Chelicerata, Pycnogonida). ARTHROPOD STRUCTURE & DEVELOPMENT 2023; 76:101295. [PMID: 37722770 DOI: 10.1016/j.asd.2023.101295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 07/19/2023] [Accepted: 07/21/2023] [Indexed: 09/20/2023]
Abstract
Phoxichilidium femoratum is a common species of sea spiders - a small and unique group of chelicerates with unusual adult anatomy. In particular, substantial parts of the reproductive system in pycnogonids (unlike euchelicerates) are located in the appendages. Existing studies of pycnogonid gonads are often limited to light-microscopic level, cover a small range of species, and focus on the contents of the gonad diverticula. Ultrastructural data are rare and contradictory, and the organisation of the gonad wall and the gonoducts is unknown. Here we present a detailed light and transmission electron microscopy-based examination of the pedal portion of the adult female reproductive system in Phoxichilidium femoratum Rathke, 1799. We describe its gross anatomy and the ultrastructure of the gonad diverticulum, oviduct and gonopore, as well as development of the oocytes. Each gonad diverticulum is enclosed in the extracellular matrix of the horizontal septum and bears some internal cellular lining. However, neither the gonad lining, nor the septum sheath cells, ever form a continuous epithelial layer. Oocytes, which undergo maturation in the diverticulum, remain, until very late in the process, attached to the gonad wall though specialised stalk cells. Interestingly, stalk cells do not participate in egg envelope or yolk formation: both are synthesized endogenously in the oocytes. The oviduct is supplied with musculature, which assists in egg transport to the gonopore, whereas the gonopore itself is surrounded by specialised glands.
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Affiliation(s)
- Nina Alexeeva
- White Sea Biological Station, Zoological Institute, Russian Academy of Sciences, Saint-Petersburg, Universitetskaya Nab. 1, St. Petersburg, 199034, Russian Federation.
| | - Yuta Tamberg
- National Public Health Service - Southern, 369 Taieri Road, 9010, Dunedin, New Zealand.
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2
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Frankowski K, Miyazaki K, Brenneis G. A microCT-based atlas of the central nervous system and midgut in sea spiders (Pycnogonida) sheds first light on evolutionary trends at the family level. Front Zool 2022; 19:14. [PMID: 35361245 PMCID: PMC8973786 DOI: 10.1186/s12983-022-00459-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 03/18/2022] [Indexed: 11/18/2022] Open
Abstract
Background Pycnogonida (sea spiders) is the sister group of all other extant chelicerates (spiders, scorpions and relatives) and thus represents an important taxon to inform early chelicerate evolution. Notably, phylogenetic analyses have challenged traditional hypotheses on the relationships of the major pycnogonid lineages (families), indicating external morphological traits previously used to deduce inter-familial affinities to be highly homoplastic. This erodes some of the support for phylogenetic information content in external morphology and calls for the study of additional data classes to test and underpin in-group relationships advocated in molecular analyses. In this regard, pycnogonid internal anatomy remains largely unexplored and taxon coverage in the studies available is limited. Results Based on micro-computed X-ray tomography and 3D reconstruction, we created a comprehensive atlas of in-situ representations of the central nervous system and midgut layout in all pycnogonid families. Beyond that, immunolabeling for tubulin and synapsin was used to reveal selected details of ganglionic architecture. The ventral nerve cord consistently features an array of separate ganglia, but some lineages exhibit extended composite ganglia, due to neuromere fusion. Further, inter-ganglionic distances and ganglion positions relative to segment borders vary, with an anterior shift in several families. Intersegmental nerves target longitudinal muscles and are lacking if the latter are reduced. Across families, the midgut displays linear leg diverticula. In Pycnogonidae, however, complex multi-branching diverticula occur, which may be evolutionarily correlated with a reduction of the heart. Conclusions Several gross neuroanatomical features are linked to external morphology, including intersegmental nerve reduction in concert with trunk segment fusion, or antero-posterior ganglion shifts in partial correlation to trunk elongation/compaction. Mapping on a recent phylogenomic phylogeny shows disjunct distributions of these traits. Other characters show no such dependency and help to underpin closer affinities in sub-branches of the pycnogonid tree, as exemplified by the tripartite subesophageal ganglion of Pycnogonidae and Rhynchothoracidae. Building on this gross anatomical atlas, future studies should now aim to leverage the full potential of neuroanatomy for phylogenetic interrogation by deciphering pycnogonid nervous system architecture in more detail, given that pioneering work on neuron subsets revealed complex character sets with unequivocal homologies across some families. Supplementary Information The online version contains supplementary material available at 10.1186/s12983-022-00459-8.
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Affiliation(s)
- Karina Frankowski
- Zoologisches Institut und Museum, AG Cytologie und Evolutionsbiologie, Universität Greifswald, Soldmannstraße 23, 17489, Greifswald, Germany
| | - Katsumi Miyazaki
- Department of Environmental Science, Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Niigata, 950-2181, Japan
| | - Georg Brenneis
- Zoologisches Institut und Museum, AG Cytologie und Evolutionsbiologie, Universität Greifswald, Soldmannstraße 23, 17489, Greifswald, Germany.
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Moritz L, Borisova E, Hammel JU, Blanke A, Wesener T. A previously unknown feeding mode in millipedes and the convergence of fluid feeding across arthropods. SCIENCE ADVANCES 2022; 8:eabm0577. [PMID: 35171667 PMCID: PMC8849289 DOI: 10.1126/sciadv.abm0577] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We report fluid feeding with a sucking pump in the arthropod class Diplopoda, using a combination of synchrotron tomography, histology, electron microscopy, and three-dimensional reconstructions. Within the head of nine species of the enigmatic Colobognatha, we found a pumping chamber, which acts as positive displacement pump and is notably similar to that of insects, showing even fine structural convergences. The sucking pump of these millipedes works together with protractible mouthparts and externally secreted saliva for the acquisition of liquid food. Fluid feeding is one of the great evolutionary innovations of terrestrial arthropods, and our study suggests that it evolved with similar biomechanical solutions convergent across all major arthropod taxa. While fluid-feeding insects are megadiverse today, it remains unclear why other lineages, such as Colobognatha, are comparably species poor.
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Affiliation(s)
- Leif Moritz
- Zoological Research Museum Alexander Koenig, Leibniz Institute for the Analysis of Biodiversity Change, Section Myriapoda, Adenauerallee 160, 53113 Bonn, Germany
- Institute of Evolutionary Biology and Animal Ecology, University of Bonn, An der Immenburg 1, 53121 Bonn, Germany
- Corresponding author.
| | - Elena Borisova
- Swiss Light Source, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Jörg U. Hammel
- Institute of Materials Physics, Helmholtz-Zentrum Hereon, Max-Planck-Str. 1, 21502 Geesthacht, Germany
| | - Alexander Blanke
- Institute of Evolutionary Biology and Animal Ecology, University of Bonn, An der Immenburg 1, 53121 Bonn, Germany
| | - Thomas Wesener
- Zoological Research Museum Alexander Koenig, Leibniz Institute for the Analysis of Biodiversity Change, Section Myriapoda, Adenauerallee 160, 53113 Bonn, Germany
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Histological characterization of the gastrointestinal tract of the adult horseshoe crab (Limulus polyphemus) with special reference to the stomach. Cell Tissue Res 2021; 383:949-957. [PMID: 33439346 DOI: 10.1007/s00441-020-03404-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 12/15/2020] [Indexed: 10/22/2022]
Abstract
The American horseshoe crab (Limulus polyphemus) is one of four extant species in the Order Xiphosura, subphylum Chelicerata, and are evolutionarily more closely related to scorpions and spiders, than crabs. The basic structure, function, and physiology of these invertebrates and their internal organs are not well documented in the literature. In this study, the gastrointestinal system, with a focus on the stomach, of adult L. polyphemus were assessed by gross and histologic methods to further characterize the pyloric valve, the lining of the ventricular lumen, and the muscular tunics of the stomach. Determination of normal anatomical structure of this organ system, along with characterization of the esophagus and intestinal tract, will set a standard against which tissue abnormalities, such as those seen with disease or pathology were to arise, would allow for better interpretation.
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Alexeeva N, Tamberg Y. Anatomical changes in postembryonic development of Pycnogonum litorale. J Morphol 2020; 282:329-354. [PMID: 33368492 DOI: 10.1002/jmor.21308] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 11/28/2020] [Accepted: 12/05/2020] [Indexed: 11/08/2022]
Abstract
Sea spiders (Pycnogonida) are a small group of arthropods, sister to other chelicerates. They have an unusual adult bauplan, oligosegmented larvae, and a protracted postembryonic development. Pycnogonum litorale (Strøm, 1762) is an uncommonly long-lived sea spider with a distinctive protonymphon and adult anatomy. Although it was described ~250 years ago, little is known about its internal organization and development. We examined the anamorphic and early epimorphic development of this species using histology, light microscopy, and SEM, and provide the first comprehensive anatomical study of its many instars. Postembryonic development of P. litorale includes transformations typical of pycnogonids: reorganization of the larval organs (digestive, nervous, secretory), formation of the abdomen, trunk segments (+ appendages), primary body cavity and reproductive system. Specific traits include the accelerated articulation of the walking legs, formation of the subesophageal and posterior synganglia, and the system of twin midgut diverticula. In addition, P. litorale simultaneously lose the spinning apparatus and all larval appendages. We found that developmental changes occur in synchrony with changes in ecology and food sources. The transition from the anamorphic to the epimorphic period in particular is marked by considerable anatomical and lifestyle shifts. HIGHLIGHTS: Postembryonic development of P. litorale includes numerous anamorphic and epimorphic stages. The instars acquire abdomen, trunk segments, body cavity, and gonads, while losing all larval appendages. Developmental changes are synchronized with changes in lifestyle and food sources.
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Affiliation(s)
- Nina Alexeeva
- White Sea Biological Station, Zoological Institute, Russian Academy of Sciences, Universitetskaya quay 1, Saint-Petersburg, Russian Federation
| | - Yuta Tamberg
- Department of Marine Science, University of Otago, Dunedin, New Zealand
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Haug C. The evolution of feeding within Euchelicerata: data from the fossil groups Eurypterida and Trigonotarbida illustrate possible evolutionary pathways. PeerJ 2020. [DOI: 10.7717/peerj.9696] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When the evolution of Euarthropoda is discussed, often the lineage of Chelicerata s. str. is assumed to be the more ‘primitive’ or ‘basal’ part of the tree, especially when compared to the other major lineage, Mandibulata. This claimed primitiveness is (at least partly) based on the assumption that different morphological structures are still in an ancestral state and did not evolve any further. One of these sets of structures is the feeding apparatus, which has been stated to be highly advanced in Mandibulata, but not ‘properly’ developed, or at least not to such a high degree, within Chelicerata s. str. In this study, I reinvestigate the feeding apparatus of different ingroups of Euchelicerata, with a focus on assumed ‘primitive’ groups such as Eurypterida and Trigonotarbida. The basis of this study is a large amount of material from different museum collections, with fossils with the entire feeding apparatuses being exceptionally well preserved. Based on high-resolution micro-photography and three-dimensional imaging, it is possible to resolve fine details of the feeding apparatuses. The results make clear that the feeding apparatuses of different ingroups of Euchelicerata are highly specialised and often possess morphological structures comparable to those of the feeding apparatuses of representatives of Mandibulata, apparently convergently evolved. Though the reconstruction of the evolution of the feeding apparatus within Euchelicerata is to a certain degree hampered by unclear phylogenetic relationships, there was clearly a shortening of the feeding apparatus from posterior (i.e. only the anterior appendages being involved in the feeding apparatus), probably linked to the colonisation of land in Arachnida.
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Affiliation(s)
- Carolin Haug
- Department of Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- GeoBio-Center, Ludwig-Maximilians-Universität München, Munich, Germany
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7
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Steinmetz PRH. A non-bilaterian perspective on the development and evolution of animal digestive systems. Cell Tissue Res 2019; 377:321-339. [PMID: 31388768 PMCID: PMC6733828 DOI: 10.1007/s00441-019-03075-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 07/08/2019] [Indexed: 12/14/2022]
Abstract
Digestive systems and extracellular digestion are key animal features, but their emergence during early animal evolution is currently poorly understood. As the last common ancestor of non-bilaterian animal groups (sponges, ctenophores, placozoans and cnidarians) dates back to the beginning of animal life, their study and comparison provides important insights into the early evolution of digestive systems and functions. Here, I have compiled an overview of the development and cell biology of digestive tissues in non-bilaterian animals. I will highlight the fundamental differences between extracellular and intracellular digestive processes, and how these are distributed among animals. Cnidarians (e.g. sea anemones, corals, jellyfish), the phylogenetic outgroup of bilaterians (e.g. vertebrates, flies, annelids), occupy a key position to reconstruct the evolution of bilaterian gut evolution. A major focus will therefore lie on the development and cell biology of digestive tissues in cnidarians, especially sea anemones, and how they compare to bilaterian gut tissues. In that context, I will also review how a recent study on the gastrula fate map of the sea anemone Nematostella vectensis challenges our long-standing conceptions on the evolution of cnidarian and bilaterian germ layers and guts.
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Affiliation(s)
- Patrick R H Steinmetz
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt. 55, 5006, Bergen, Norway.
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Alexeeva N, Tamberg Y, Shunatova N. The (not very) typical protonymphons of
Pycnogonum litorale. J Morphol 2019; 280:1370-1392. [DOI: 10.1002/jmor.21038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 06/12/2019] [Accepted: 06/16/2019] [Indexed: 01/09/2023]
Affiliation(s)
- Nina Alexeeva
- Department of Invertebrate ZoologySt. Petersburg State University St. Petersburg Russian Federation
| | - Yuta Tamberg
- Department of Marine ScienceUniversity of Otago Dunedin New Zealand
| | - Natalia Shunatova
- Department of Invertebrate ZoologySt. Petersburg State University St. Petersburg Russian Federation
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9
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Alexeeva N, Tamberg Y, Shunatova N. Postembryonic development of pycnogonids: A deeper look inside. ARTHROPOD STRUCTURE & DEVELOPMENT 2018. [PMID: 29524544 DOI: 10.1016/j.asd.2018.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Sea spiders form a small, enigmatic group of recent chelicerates, with an unusual bodyplan, oligosegmented larvae and a postembryonic development that is punctuated by many moults. To date, only a few papers examined the anatomical and ultrastructural modifications of the larvae and various instars. Here we traced both internal and external events of the whole postembryonic development in Nymphon brevirostre HODGE 1863 using histology, SEM, TEM and confocal microscopy. During postembryonic development, larvae of this species undergo massive reorganization: spinning apparatus and chelar glands disappear; larval legs redifferentiate; three new segments and the abdomen are formed with their corresponding internal organs and appendages; circulatory and reproductive systems develop anew and the digestive and the nervous systems change dramatically. The body cavity remains schizocoelic throughout development, and no traces of even transitory coeloms were found in any instar. In Nymphon brevirostre, just like in Artemia salina LINNAEUS 1758 the heart arises through differentiation of the already existing schizocoel, and thus the circulatory systems of arthropods and annelids are not homologous. We found that classical chelicerate tagmata, prosoma and opisthosoma, are inapplicable to adult pycnogonids, with the most striking difference being the fate and structure of the seventh appendage-bearing segment.
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Affiliation(s)
- Nina Alexeeva
- Department of Invertebrate Zoology, St. Petersburg State University, Universitetskaya nab. 7/9, St. Petersburg, 199034, Russian Federation.
| | - Yuta Tamberg
- Department of Marine Science, University of Otago, 310 Castle Street, Dunedin, 9016, New Zealand
| | - Natalia Shunatova
- Department of Invertebrate Zoology, St. Petersburg State University, Universitetskaya nab. 7/9, St. Petersburg, 199034, Russian Federation
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10
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Dietz L, Dömel JS, Leese F, Lehmann T, Melzer RR. Feeding ecology in sea spiders (Arthropoda: Pycnogonida): what do we know? Front Zool 2018; 15:7. [PMID: 29568315 PMCID: PMC5856303 DOI: 10.1186/s12983-018-0250-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 01/24/2018] [Indexed: 11/10/2022] Open
Abstract
Sea spiders (Pycnogonida) are a widespread and phylogenetically important group of marine arthropods. However, their biology remains understudied, and detailed information about their feeding ecology is difficult to find. Observations on pycnogonid feeding are scattered in the literature, often in older sources written in various languages, and have never been comprehensively summarized. Here we provide an overview of all information on feeding in pycnogonids that we have been able to find and review what is known on feeding specializations and preferences in the various pycnogonid taxa. We deduce general findings where possible and outline future steps necessary to gain a better understanding of the feeding ecology of one of the world's most bizarre animal taxa.
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Affiliation(s)
- Lars Dietz
- Zoological Research Museum Alexander Koenig, Statistical Phylogenetics and Phylogenomics, Adenauerallee 160, D-53113 Bonn, Germany.,2Faculty of Mathematics and Natural Sciences, University of Bonn, D-53012 Bonn, Germany
| | - Jana S Dömel
- 3Aquatic Ecosystem Research, Faculty of Biology, University Duisburg-Essen, Universitätsstr. 5, D-45141 Essen, Germany
| | - Florian Leese
- 3Aquatic Ecosystem Research, Faculty of Biology, University Duisburg-Essen, Universitätsstr. 5, D-45141 Essen, Germany
| | - Tobias Lehmann
- Bavarian State Collection of Zoology - SNSB, Münchhausenstraße 21, 81247 Munich, Germany.,5Department Biologie II, Ludwig-Maximilians-Universität München, Großhaderner Straße 2, 82152 Planegg-Martinsried, Germany
| | - Roland R Melzer
- Bavarian State Collection of Zoology - SNSB, Münchhausenstraße 21, 81247 Munich, Germany.,5Department Biologie II, Ludwig-Maximilians-Universität München, Großhaderner Straße 2, 82152 Planegg-Martinsried, Germany.,6GeoBioCenter LMU, Richard -Wagner-Str. 10, 80333 Munich, Germany
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11
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Alexeeva N, Bogomolova E, Tamberg Y, Shunatova N. Oligomeric larvae of the pycnogonids revisited. J Morphol 2017; 278:1284-1304. [DOI: 10.1002/jmor.20713] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 05/05/2017] [Accepted: 05/08/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Nina Alexeeva
- Department of Invertebrate Zoology; St. Petersburg State University; Universitetskaja nab. 7/9 St. Petersburg 199034 Russian Federation
| | - Ekaterina Bogomolova
- Department of Invertebrate Zoology; Moscow State University; Leninskie gory, 1, 12 Moscow 119234 Russian Federation
| | - Yuta Tamberg
- Department of Invertebrate Zoology; St. Petersburg State University; Universitetskaja nab. 7/9 St. Petersburg 199034 Russian Federation
| | - Natalia Shunatova
- Department of Invertebrate Zoology; St. Petersburg State University; Universitetskaja nab. 7/9 St. Petersburg 199034 Russian Federation
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12
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13
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Bogomolova EV, Malakhov VV. Ciliary cells in the epidermis, gut, and gonads of sea spiders (Pycnogonida). DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2014; 454:50-2. [PMID: 24659288 DOI: 10.1134/s001249661401013x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Indexed: 11/23/2022]
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14
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Lerosey-Aubril R, Hegna TA, Kier C, Bonino E, Habersetzer J, Carré M. Controls on gut phosphatisation: the trilobites from the Weeks Formation Lagerstätte (Cambrian; Utah). PLoS One 2012; 7:e32934. [PMID: 22431989 PMCID: PMC3303877 DOI: 10.1371/journal.pone.0032934] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 02/01/2012] [Indexed: 11/29/2022] Open
Abstract
Despite being internal organs, digestive structures are frequently preserved in Cambrian Lagerstätten. However, the reasons for their fossilisation and their biological implications remain to be thoroughly explored. This is particularly true with arthropods – typically the most diverse fossilised organisms in Cambrian ecosystems – where digestive structures represent an as-yet underexploited alternative to appendage morphology for inferences on their biology. Here we describe the phosphatised digestive structures of three trilobite species from the Cambrian Weeks Formation Lagerstätte (Utah). Their exquisite, three-dimensional preservation reveals unique details on trilobite internal anatomy, such as the position of the mouth and the absence of a differentiated crop. In addition, the presence of paired pygidial organs of an unknown function is reported for the first time. This exceptional material enables exploration of the relationships between gut phosphatisation and the biology of organisms. Indeed, soft-tissue preservation is unusual in these fossils as it is restricted to the digestive structures, which indicates that the gut played a central role in its own phosphatisation. We hypothesize that the gut provided a microenvironment where special conditions could develop and harboured a source of phosphorus. The fact that gut phosphatization has almost exclusively been observed in arthropods could be explained by their uncommon ability to store ions (including phosphorous) in their digestive tissues. However, in some specimens from the Weeks Formation, the phosphatisation extends to the entire digestive system, suggesting that trilobites might have had some biological particularities not observed in modern arthropods. We speculate that one of them might have been an increased capacity for ion storage in the gut tissues, related to the moulting of their heavily-mineralised carapace.
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Affiliation(s)
- Rudy Lerosey-Aubril
- Department of Palaeontology and Historical Geology, Senckenberg Research Institute, Frankfurt am Main, Germany
- * E-mail:
| | - Thomas A. Hegna
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut, United States of America
- Department of Geology, Western Illinois University, Macomb, Illinois, United States of America
| | - Carlo Kier
- Back to the Past Museum, Puerto Morelos, Quintana Roo, Mexico
| | - Enrico Bonino
- Back to the Past Museum, Puerto Morelos, Quintana Roo, Mexico
| | - Jörg Habersetzer
- Department of Palaeoanthropology and Messel Research, Senckenberg Research Institute, Frankfurt am Main, Germany
| | - Matthieu Carré
- Institute of Evolutionary Sciences, University Montpellier II, Montpellier, France
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15
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Morphogenesis of Pseudopallene sp. (Pycnogonida, Callipallenidae) I: embryonic development. Dev Genes Evol 2011; 221:309-28. [DOI: 10.1007/s00427-011-0382-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 11/08/2011] [Indexed: 12/20/2022]
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16
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Machner J, Scholtz G. A scanning electron microscopy study of the embryonic development of Pycnogonum litorale (Arthropoda, Pycnogonida). J Morphol 2010; 271:1306-18. [DOI: 10.1002/jmor.10871] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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17
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Edgecombe GD. Arthropod phylogeny: an overview from the perspectives of morphology, molecular data and the fossil record. ARTHROPOD STRUCTURE & DEVELOPMENT 2010; 39:74-87. [PMID: 19854297 DOI: 10.1016/j.asd.2009.10.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 10/12/2009] [Accepted: 10/14/2009] [Indexed: 05/03/2023]
Abstract
Monophyly of Arthropoda is emphatically supported from both morphological and molecular perspectives. Recent work finds Onychophora rather than Tardigrada to be the closest relatives of arthropods. The status of tardigrades as panarthropods (rather than cycloneuralians) is contentious from the perspective of phylogenomic data. A grade of Cambrian taxa in the arthropod stem group includes gilled lobopodians, dinocaridids (e.g., anomalocaridids), fuxianhuiids and canadaspidids that inform on character acquisition between Onychophora and the arthropod crown group. A sister group relationship between Crustacea (itself likely paraphyletic) and Hexapoda is retrieved by diverse kinds of molecular data and is well supported by neuroanatomy. This clade, Tetraconata, can be dated to the early Cambrian by crown group-type mandibles. The rival Atelocerata hypothesis (Myriapoda+Hexapoda) has no molecular support. The basal node in the arthropod crown group is embroiled in a controversy over whether myriapods unite with chelicerates (Paradoxopoda or Myriochelata) or with crustaceans and hexapods (Mandibulata). Both groups find some molecular and morphological support, though Mandibulata is presently the stronger morphological hypothesis. Either hypothesis forces an unsampled ghost lineage for Myriapoda from the Cambrian to the mid Silurian.
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Affiliation(s)
- Gregory D Edgecombe
- Department of Palaeontology, Natural History Museum, Cromwell Road, London, UK.
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Nephridial development and body cavity formation in Artemia salina (Crustacea: Branchiopoda): no evidence for any transitory coelom. ZOOMORPHOLOGY 2009. [DOI: 10.1007/s00435-008-0082-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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BARRETO FELIPES, AVISE JOHNC. Polygynandry and sexual size dimorphism in the sea spiderAmmothea hilgendorfi(Pycnogonida: Ammotheidae), a marine arthropod with brood-carrying males. Mol Ecol 2008; 17:4164-75. [DOI: 10.1111/j.1365-294x.2008.03895.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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