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Krol L, Dunker FH, LaDouceur E, Biswell E, Dilly GF, Delbeek JC, Albright R, López-Nandam EH, Reinbold N, Igel A, Larkin L, Hill J. MILBEMYCIN OXIME (INTERCEPTOR) TREATMENT OF PYCNOGONID SEA SPIDER INFESTATION IN THREE SPECIES OF CORALS. J Zoo Wildl Med 2023; 54:292-300. [PMID: 37428691 DOI: 10.1638/2022-0028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2023] [Indexed: 07/12/2023] Open
Abstract
A coral reef system at the Steinhart Aquarium in San Francisco, CA, USA experienced a population explosion of pycnogonid sea spiders (Arthropoda: Class Pycnogonida) with subsequent deleterious health effects on the corals in the system. Sixteen coral colonies across three species (Stylophora pistillata, Pocillopora damicornis, and Acropora tenuis) were chosen from this system for milbemycin oxime immersion therapy trials, with the goal of decreasing or eradicating the sea spider population with minimal detrimental effect to the corals. Corals underwent two milbemycin immersion treatments, administered 1 wk apart, at the previously published aquatic invertebrate dose of 0.016 parts per million (ppm; mg/L), but therapy did not reduce the number of sea spiders. Doubling the dose to 0.032 ppm milbemycin and repeating this immersion therapy 1/wk for three treatments successfully reduced the sea spiders. Histopathology was used to assess the health of the corals and tolerance to therapy, and posttreatment biopsies confirmed that there were no adverse effects to any of the three species of coral. Repeated 1/ wk treatments of milbemycin oxime immersion therapy at 0.032 ppm appears to be both safe and effective for reducing the numbers of pycnogonid sea spiders in the stony corals S. pistillata, P. damicornis, and A. tenuis.
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Affiliation(s)
- Lana Krol
- Steinhart Aquarium, California Academy of Sciences, San Francisco, CA 94118, USA,
| | - Freeland H Dunker
- Steinhart Aquarium, California Academy of Sciences, San Francisco, CA 94118, USA
| | - Elise LaDouceur
- Joint Pathology Center, Silver Spring, MD 20910, USA
- Zoetis Reference Laboratories, Louisville, KY 40213, USA
| | - Ethan Biswell
- Zoetis Reference Laboratories, Louisville, KY 40213, USA
| | - Geoffrey F Dilly
- Department of Biology, California State University Channel Islands, Camarillo, CA 93012, USA
| | - J Charles Delbeek
- Steinhart Aquarium, California Academy of Sciences, San Francisco, CA 94118, USA
| | - Rebecca Albright
- Steinhart Aquarium, California Academy of Sciences, San Francisco, CA 94118, USA
| | - Elora H López-Nandam
- Steinhart Aquarium, California Academy of Sciences, San Francisco, CA 94118, USA
| | - Nicholas Reinbold
- Department of Biology, California State University Channel Islands, Camarillo, CA 93012, USA
| | - Anthony Igel
- Department of Biology, California State University Channel Islands, Camarillo, CA 93012, USA
| | - Lisa Larkin
- Steinhart Aquarium, California Academy of Sciences, San Francisco, CA 94118, USA
| | - Jessica Hill
- Steinhart Aquarium, California Academy of Sciences, San Francisco, CA 94118, USA
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Sabroux R, Corbari L, Hassanin A. Phylogeny of sea spiders (Arthropoda: Pycnogonida) inferred from mitochondrial genome and 18S ribosomal RNA gene sequences. Mol Phylogenet Evol 2023; 182:107726. [PMID: 36754337 DOI: 10.1016/j.ympev.2023.107726] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/20/2023] [Accepted: 02/03/2023] [Indexed: 02/10/2023]
Abstract
The phylogeny of sea spiders has been debated for more than a century. Despite several molecular studies in the last twenty years, interfamilial relationships remain uncertain. In the present study, relationships within Pycnogonida are examined in the light of a new dataset composed of 160 mitochondrial genomes (including 152 new sequences) and 130 18S rRNA gene sequences (including 120 new sequences), from 141 sea spider morphospecies representing 26 genera and 9 families. Node congruence between mitochondrial and nuclear markers was analysed to identify the most reliable relationships. We also reanalysed a multilocus dataset previously published and showed that the high percentages of missing data make phylogenetic conclusions difficult and uncertain. Our results support the monophyly of most families currently accepted, except Callipallenidae and Nymphonidae, the monophyly of the superfamilies Ammotheoidea (Ammotheidae + Pallenopsidae), Nymphonoidea (Nymphonidae + Callipallenidae), Phoxichilidioidea (Phoxichilidiidae + Endeidae) and Colossendeoidea (Colossendeidae + Pycnogonidae + Rhynchothoracidae), and the sister-group relationship between Ammotheoidea and Phoxichilidioidea. We discuss the morphological evolution of sea spiders, identifying homoplastic characters and possible synapomorphies. We also discuss the palaeontological and phylogenetic arguments supporting either a radiation of sea spiders prior to Jurassic or a progressive diversification from Ordovician or Cambrian.
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Affiliation(s)
- Romain Sabroux
- Institut Systématique Evolution Biodiversité (ISYEB), Sorbonne Université, MNHN, CNRS, EPHE, UA, 57 rue Cuvier, CP 51, 75005 Paris, France
| | - Laure Corbari
- Institut Systématique Evolution Biodiversité (ISYEB), Sorbonne Université, MNHN, CNRS, EPHE, UA, 57 rue Cuvier, CP 51, 75005 Paris, France
| | - Alexandre Hassanin
- Institut Systématique Evolution Biodiversité (ISYEB), Sorbonne Université, MNHN, CNRS, EPHE, UA, 57 rue Cuvier, CP 51, 75005 Paris, France.
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Lamsdell JC. The Chelicerae of Slimonia (Eurypterida; Pterygotoidea). BULLETIN OF THE PEABODY MUSEUM OF NATURAL HISTORY 2022. [DOI: 10.3374/014.063.0102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- James C. Lamsdell
- Department of Geology and Geography, West Virginia University, Morgantown, WV 26506 USA—
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Brenneis G. The visual pathway in sea spiders (Pycnogonida) displays a simple serial layout with similarities to the median eye pathway in horseshoe crabs. BMC Biol 2022; 20:27. [PMID: 35086529 PMCID: PMC8796508 DOI: 10.1186/s12915-021-01212-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/14/2021] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Phylogenomic studies over the past two decades have consolidated the major branches of the arthropod tree of life. However, especially within the Chelicerata (spiders, scorpions, and kin), interrelationships of the constituent taxa remain controversial. While sea spiders (Pycnogonida) are firmly established as sister group of all other extant representatives (Euchelicerata), euchelicerate phylogeny itself is still contested. One key issue concerns the marine horseshoe crabs (Xiphosura), which recent studies recover either as sister group of terrestrial Arachnida or nested within the latter, with significant impact on postulated terrestrialization scenarios and long-standing paradigms of ancestral chelicerate traits. In potential support of a nested placement, previous neuroanatomical studies highlighted similarities in the visual pathway of xiphosurans and some arachnopulmonates (scorpions, whip scorpions, whip spiders). However, contradictory descriptions of the pycnogonid visual system hamper outgroup comparison and thus character polarization. RESULTS To advance the understanding of the pycnogonid brain and its sense organs with the aim of elucidating chelicerate visual system evolution, a wide range of families were studied using a combination of micro-computed X-ray tomography, histology, dye tracing, and immunolabeling of tubulin, the neuropil marker synapsin, and several neuroactive substances (including histamine, serotonin, tyrosine hydroxylase, and orcokinin). Contrary to previous descriptions, the visual system displays a serial layout with only one first-order visual neuropil connected to a bilayered arcuate body by catecholaminergic interneurons. Fluorescent dye tracing reveals a previously reported second visual neuropil as the target of axons from the lateral sense organ instead of the eyes. CONCLUSIONS Ground pattern reconstruction reveals remarkable neuroanatomical stasis in the pycnogonid visual system since the Ordovician or even earlier. Its conserved layout exhibits similarities to the median eye pathway in euchelicerates, especially in xiphosurans, with which pycnogonids share two median eye pairs that differentiate consecutively during development and target one visual neuropil upstream of the arcuate body. Given multiple losses of median and/or lateral eyes in chelicerates, and the tightly linked reduction of visual processing centers, interconnections between median and lateral visual neuropils in xiphosurans and arachnopulmonates are critically discussed, representing a plausible ancestral condition of taxa that have retained both eye types.
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Affiliation(s)
- Georg Brenneis
- Universität Greifswald, Zoologisches Institut und Museum, AG Cytologie und Evolutionsbiologie, Soldmannstraße 23, 17489, Greifswald, Germany.
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Schack CR, Gordon DP, Ryan KG. Community assembly in a modular organism: the impact of environmental filtering on bryozoan colony form and polymorphism. Ecology 2020; 101:e03106. [DOI: 10.1002/ecy.3106] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 04/02/2020] [Accepted: 04/14/2020] [Indexed: 11/10/2022]
Affiliation(s)
- Carolann R. Schack
- School of Biological Sciences Victoria University of Wellington Kelburn Wellington 6012 New Zealand
- New Zealand Institute of Marine and Atmospheric Science 301 Evans Bay Parade Hataitai Wellington 6021 New Zealand
| | - Dennis P. Gordon
- New Zealand Institute of Marine and Atmospheric Science 301 Evans Bay Parade Hataitai Wellington 6021 New Zealand
| | - Ken G. Ryan
- School of Biological Sciences Victoria University of Wellington Kelburn Wellington 6012 New Zealand
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Analyzing drivers of speciation in the Southern Ocean using the sea spider species complex Colossendeis megalonyx as a test case. Polar Biol 2020. [DOI: 10.1007/s00300-020-02636-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
AbstractColossendeis megalonyx Hoek, 1881 has the broadest distribution of all sea spiders in the Southern Ocean. Previous studies have detected several evolutionarily young lineages within this taxon and interpreted them as a result of allopatric speciation in a few shelf refuges during glacial maxima. However, alternative scenarios such as ecological speciation in sympatry have rarely been considered or tested. Here, we generated the most extensive genomic and morphometric data set on the C. megalonyx species complex to (i) comprehensively describe species diversity, (ii) explore intraspecific connectivity between populations located around Antarctica, and (iii) systematically test for positive selection indicative of adaptive speciation. We successfully applied a target hybrid enrichment approach and recovered all 1607 genes targeted. Phylogenomic analysis was consistent with previous findings and, moreover, increased the resolution of branching within lineages. We found specimens of phylogenetically well-separated lineages occurring in sympatry to be genetically distinct from each other and gene flow between geographically separated populations of the same lineages to be restricted. Evidence for positive selection was found for four genes associated with structural and neuronal functions. Hence, there is an indication for positive selection in the C. megalonyx species complex, yet its specific contribution to the speciation process remains to be explored further. Finally, morphometric analyses revealed multiple significant differences between lineages, but a clear separation proved difficult. Our study highlights the relevance of positive selection as a potential driver for speciation in the Southern Ocean.
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Dömel JS, Macher TH, Dietz L, Duncan S, Mayer C, Rozenberg A, Wolcott K, Leese F, Melzer RR. Combining morphological and genomic evidence to resolve species diversity and study speciation processes of the Pallenopsis patagonica (Pycnogonida) species complex. Front Zool 2019; 16:36. [PMID: 31516540 PMCID: PMC6728986 DOI: 10.1186/s12983-019-0316-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 05/06/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pallenopsis patagonica (Hoek, 1881) is a morphologically and genetically variable sea spider species whose taxonomic classification is challenging. Currently, it is considered as a species complex including several genetic lineages, many of which have not been formally described as species. Members of this species complex occur on the Patagonian and Antarctic continental shelves as well as around sub-Antarctic islands. These habitats have been strongly influenced by historical large-scale glaciations and previous studies suggested that communities were limited to very few refugia during glacial maxima. Therefore, allopatric speciation in these independent refugia is regarded as a common mechanism leading to high biodiversity of marine benthic taxa in the high-latitude Southern Hemisphere. However, other mechanisms such as ecological speciation have rarely been considered or tested. Therefore, we conducted an integrative morphological and genetic study on the P. patagonica species complex to i) resolve species diversity using a target hybrid enrichment approach to obtain multiple genomic markers, ii) find morphological characters and analyze morphometric measurements to distinguish species, and iii) investigate the speciation processes that led to multiple lineages within the species complex. RESULTS Phylogenomic results support most of the previously reported lineages within the P. patagonica species complex and morphological data show that several lineages are distinct species with diagnostic characters. Two lineages are proposed as new species, P. aulaeturcarum sp. nov. Dömel & Melzer, 2019 and P. obstaculumsuperavit sp. nov. Dömel, 2019, respectively. However, not all lineages could be distinguished morphologically and thus likely represent cryptic species that can only be identified with genetic tools. Further, morphometric data of 135 measurements showed a high amount of variability within and between species without clear support of adaptive divergence in sympatry. CONCLUSIONS We generated an unprecedented molecular data set for members of the P. patagonica sea spider species complex with a target hybrid enrichment approach, which we combined with extensive morphological and morphometric analyses to investigate the taxonomy, phylogeny and biogeography of this group. The extensive data set enabled us to delineate species boundaries, on the basis of which we formally described two new species. No consistent evidence for positive selection was found, rendering speciation in allopatric glacial refugia as the most likely model of speciation.
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Affiliation(s)
- Jana S. Dömel
- Aquatic Ecosystem Research, Faculty of Biology, University of Duisburg-Essen, Universitaetsstr. 5, 45141 Essen, Germany
| | - Till-Hendrik Macher
- Aquatic Ecosystem Research, Faculty of Biology, University of Duisburg-Essen, Universitaetsstr. 5, 45141 Essen, Germany
| | - Lars Dietz
- Zoological Research Museum Alexander Koenig, Statistical Phylogenetics and Phylogenomics, Adenauerallee 160, 53113 Bonn, Germany
| | - Sabrina Duncan
- Bavarian State Collection of Zoology – SNSB, Muenchhausenstr. 21, 81247 Munich, Germany
| | - Christoph Mayer
- Zoological Research Museum Alexander Koenig, Statistical Phylogenetics and Phylogenomics, Adenauerallee 160, 53113 Bonn, Germany
| | - Andrey Rozenberg
- Faculty of Biology, Technion – Israel Institute of Technology, 3200003 Haifa, Israel
| | - Katherine Wolcott
- Bavarian State Collection of Zoology – SNSB, Muenchhausenstr. 21, 81247 Munich, Germany
| | - Florian Leese
- Aquatic Ecosystem Research, Faculty of Biology, University of Duisburg-Essen, Universitaetsstr. 5, 45141 Essen, Germany
- Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitaetsstr. 2, 45141 Essen, Germany
| | - Roland R. Melzer
- Bavarian State Collection of Zoology – SNSB, Muenchhausenstr. 21, 81247 Munich, Germany
- Department Biologie II, LMU Munich, Großhaderner Str. 2, 82152 Planegg-Martinsried, Germany
- GeoBioCenter, LMU Munich, Richard-Wagner-Str. 10, 80333 Munich, Germany
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