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Maroni PJ, Wilson NG. Multiple
Doris
“
kerguelenensis
” (Nudibranchia) species span the Antarctic Polar Front. Ecol Evol 2022; 12:e9333. [PMID: 36188511 PMCID: PMC9486823 DOI: 10.1002/ece3.9333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 08/25/2022] [Accepted: 08/30/2022] [Indexed: 11/27/2022] Open
Abstract
Despite strong historical biogeographical links between benthic faunal assemblages of the Magellan region of South America and the Antarctic Peninsula, very few studies have documented contemporary movement and gene flow in or out of the Southern Ocean, especially across the Antarctic Polar Front (APF). In fact, oceanographic barriers such as the APF and Antarctica's long geologic isolation have substantially separated the continents and facilitated the evolution of endemic marine taxa found within the Antarctic region. The Southern Ocean benthic sea slug complex, Doris “kerguelenensis,” are a group of direct‐developing, simultaneous hermaphrodites that lack a dispersive larval stage. To date, there are 59 highly divergent species known within this complex. Here, we provide evidence to show intraspecific genetic connectivity occurs across the APF for multiple species within the D. “kerguelenensis” nudibranch species complex. We addressed questions of genetic connectivity by examining the phylogeographic structure of the three best‐sampled D. “kerguelenensis” species and another three trans‐APF species using the protein coding mtDNA gene, cytochrome oxidase I. We also highlight alternative refugia uses among species with the same life history traits (i.e., benthic and direct developers) and for some species, extremely large distributions are established (e.g., circumpolarity). By improving our sampling of these nudibranchs, we gain better insight into the population structure and connectivity of the Antarctic region. This work also demonstrates how difficult it is to make generalizations across Antarctic marine species, even among ecologically‐similar, closely related species.
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Affiliation(s)
- Paige J. Maroni
- School of Biological Sciences (M092) University of Western Australia Crawley Western Australia Australia
- Western Australian Museum, Research & Collections Welshpool Western Australia Australia
| | - Nerida G. Wilson
- School of Biological Sciences (M092) University of Western Australia Crawley Western Australia Australia
- Western Australian Museum, Research & Collections Welshpool Western Australia Australia
- Securing Antarctica's Environmental Future Western Australian Museum Welshpool Western Australia Australia
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2
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Lucena RA, Lindsey Christoffersen M. Pycnogonida (Arthropoda) from Museu de Ciências Naturais, Rio Grande do Sul, Brazil. ZOOSYST EVOL 2022. [DOI: 10.3897/zse.98.83671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Five species were identified in the studied collection: Colossendeis megalonyx Hoek, 1881, first record for Uruguay, Ascorhynchus corderoi du Bois-Reymond Marcus, 1952 and Pallenopsis candidoi Mello-Leitão, 1949, with extended ranges, Pallenopsis patagonica (Hoek, 1881), a species complex recently analysed with molecular data and Ammothea tetrapoda, recorded previously for Uruguayan waters. Our study clarifies records based on morphology, provides new data on distributions and species ranges and correlates species with ecological conditions.
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3
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Puillandre N, Brouillet S, Achaz G. ASAP: assemble species by automatic partitioning. Mol Ecol Resour 2020; 21:609-620. [PMID: 33058550 DOI: 10.1111/1755-0998.13281] [Citation(s) in RCA: 351] [Impact Index Per Article: 87.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 11/27/2022]
Abstract
Here, we describe Assemble Species by Automatic Partitioning (ASAP), a new method to build species partitions from single locus sequence alignments (i.e., barcode data sets). ASAP is efficient enough to split data sets as large 104 sequences into putative species in several minutes. Although grounded in evolutionary theory, ASAP is the implementation of a hierarchical clustering algorithm that only uses pairwise genetic distances, avoiding the computational burden of phylogenetic reconstruction. Importantly, ASAP proposes species partitions ranked by a new scoring system that uses no biological prior insight of intraspecific diversity. ASAP is a stand-alone program that can be used either through a graphical web-interface or that can be downloaded and compiled for local usage. We have assessed its power along with three others programs (ABGD, PTP and GMYC) on 10 real COI barcode data sets representing various degrees of challenge (from small and easy cases to large and complicated data sets). We also used Monte-Carlo simulations of a multispecies coalescent framework to assess the strengths and weaknesses of ASAP and the other programs. Through these analyses, we demonstrate that ASAP has the potential to become a major tool for taxonomists as it proposes rapidly in a full graphical exploratory interface relevant species hypothesis as a first step of the integrative taxonomy process.
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Affiliation(s)
- Nicolas Puillandre
- Institut Systématique Evolution Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Paris, France
| | - Sophie Brouillet
- Institut Systématique Evolution Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Paris, France
| | - Guillaume Achaz
- Institut Systématique Evolution Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Paris, France.,SMILE Group, CIRB, UMR 7241, Collège de France, CNRS, INSERM, Paris, France.,Éco-anthropologie, Muséum National d'Histoire Naturelle, CNRS UMR 7206, Université de Paris, Paris, France
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4
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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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Brenneis G, Arango CP, Sharma PP, Schwentner M. The more the merrier: unparalleled sympatric species richness in a sea spider genus (Pycnogonida : Callipallenidae : Pallenella) from Tasmanian waters. INVERTEBR SYST 2020. [DOI: 10.1071/is20022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Southern Australian waters feature remarkably diverse assemblages of the sea spider family Callipallenidae Hilton, 1942. The most speciose of the three Australian-endemic genera currently recognised has been known as Meridionale Staples, 2014, but is here reinstated under the name Pallenella Schimkewitsch, 1909 based on its type species Pallenella laevis (Hoek, 1881). This genus includes several brightly coloured forms that occur in high abundance on arborescent bryozoans. However, considerable similarity of congeners and scarcity of diagnostic characters continue to render species delineation in this genus challenging. Using an integrative taxonomic approach, we combine detailed morphological investigation with analysis of two genetic markers (mitochondrial cytochrome c oxidase subunit I, and nuclear rDNA including internal transcribed spacers 1 and 2) to explore the extraordinary species richness of the genus Pallenella in south-east Tasmania. In agreement with our morphology-based segregation of different species and morphotypes, we recovered well-supported corresponding clades in the genetic analyses. Strong mito-nuclear concordance in the two markers supports the inference of sustained reproductive isolation between the sympatrically occurring forms. Based on these findings, we distinguish a total of 13 Tasmanian congeners, representing the most diverse assemblage of sympatric species in the same microhabitat reported for a single pycnogonid genus. Within this assemblage, we (1) record the type species P. laevis for the first time after almost 150 years, (2) delineate the two Tasmanian morphotypes of the provisional ‘variabilis’ complex, and (3) describe two species new to science (P. karenae, sp. nov., P. baroni, sp. nov.). Despite considerable genetic divergences between most congeners, only few and often subtle characters are found to be suitable for morphology-based delineation. Notably, colouration of living specimens is suggested to be informative in some cases. For morphology-based species identification of preserved specimens, a key relying on combinations of characters rather than single diagnostic features is proposed.
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6
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Moreau C, Danis B, Jossart Q, Eléaume M, Sands C, Achaz G, Agüera A, Saucède T. Is reproductive strategy a key factor in understanding the evolutionary history of Southern Ocean Asteroidea (Echinodermata)? Ecol Evol 2019; 9:8465-8478. [PMID: 31410254 PMCID: PMC6686340 DOI: 10.1002/ece3.5280] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 05/04/2019] [Indexed: 12/12/2022] Open
Abstract
Life traits such as reproductive strategy can be determining factors of species evolutionary history and explain the resulting diversity patterns. This can be investigated using phylogeographic analyses of genetic units. In this work, the genetic structure of five asteroid genera with contrasting reproductive strategies (brooding: Diplasterias, Notasterias and Lysasterias versus broadcasting: Psilaster and Bathybiaster) was investigated in the Southern Ocean. Over 1,400 mtDNA cytochrome C oxidase subunit I (COI) sequences were analysed using five species delineation methods (ABGD, ASAP, mPTP, sGMYC and mGMYC), two phylogenetic reconstructions (ML and BA), and molecular clock calibrations, in order to examine the weight of reproductive strategy in the observed differences among phylogeographic patterns. We hypothesised that brooding species would show higher levels of genetic diversity and species richness along with a clearer geographic structuring than broadcasting species. In contrast, genetic diversity and species richness were not found to be significantly different between brooders and broadcasters, but broadcasters are less spatially structured than brooders supporting our initial hypothesis and suggesting more complex evolutionary histories associated to this reproductive strategy. Broadcasters' phylogeography can be explained by different scenarios including deep-sea colonisation routes, bipolarity or cosmopolitanism, and sub-Antarctic emergence for the genus Bathybiaster; Antarctic- New Zealand faunal exchanges across the Polar Front for the genus Psilaster. Brooders' phylogeography could support the previously formulated hypothesis of a past trans-Antarctic seaway established between the Ross and the Weddell seas during the Plio-Pleistocene. Our results also show, for the first time, that the Weddell Sea is populated by a mixed asteroid fauna originating from both the East and West Antarctic.
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Affiliation(s)
- Camille Moreau
- Marine Biology LabUniversité Libre de Bruxelles (ULB)Belgium
- Biogéosciences, UMR 6282 CNRSUniversité Bourgogne Franche‐ComtéDijonFrance
| | - Bruno Danis
- Marine Biology LabUniversité Libre de Bruxelles (ULB)Belgium
| | - Quentin Jossart
- Marine Biology LabUniversité Libre de Bruxelles (ULB)Belgium
- Marine BiologyVrije Universiteit Brussel (VUB)BrusselsBelgium
| | - Marc Eléaume
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d'Histoire naturelle, CNRSSorbonne UniversitéParisFrance
| | - Chester Sands
- Natural Environment Research CouncilBritish Antarctic SurveyCambridgeUK
| | - Guillaume Achaz
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d'Histoire naturelle, CNRSSorbonne UniversitéParisFrance
- Centre Interdisciplinaire de Recherche en Biologie (CIRB), CNRSINSERM, Collège de FranceParisFrance
| | - Antonio Agüera
- Marine Biology LabUniversité Libre de Bruxelles (ULB)Belgium
| | - Thomas Saucède
- Biogéosciences, UMR 6282 CNRSUniversité Bourgogne Franche‐ComtéDijonFrance
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Phylogenomics of the longitarsal Colossendeidae: The evolutionary history of an Antarctic sea spider radiation. Mol Phylogenet Evol 2019; 136:206-214. [PMID: 31002869 DOI: 10.1016/j.ympev.2019.04.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 11/20/2022]
Abstract
Sea spiders (Pycnogonida) constitute a group of marine benthic arthropods that has a particularly high species diversity in the Southern Ocean. The "longitarsal" group of the sea spider family Colossendeidae is especially abundant in this region. However, this group also includes some representatives from other oceans, which raises the question where the group originates from. Therefore, we here investigated the phylogeny of the group with a hybrid enrichment approach that yielded a dataset of 1607 genes and over one million base pairs. We obtained a well-resolved phylogeny of the group, which is mostly consistent with morphological data. The data support an Antarctic origin of the longitarsal Colossendeidae and multiple dispersal events to other regions, which occurred at different timescales. This scenario is consistent with evidence found in other groups of marine invertebrates and highlights the role of the Southern Ocean as a source for non-Antarctic biota, especially of the deep sea. Our results suggest an initially slow rate of diversification followed by a more rapid radiation possibly correlated with the mid-Miocene cooling of Antarctica, similar to what is found in other taxa.
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8
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Brenneis G, Arango CP. First description of epimorphic development in Antarctic Pallenopsidae (Arthropoda, Pycnogonida) with insights into the evolution of the four-articled sea spider cheliphore. ZOOLOGICAL LETTERS 2019; 5:4. [PMID: 30656062 PMCID: PMC6330760 DOI: 10.1186/s40851-018-0118-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Accepted: 12/26/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Sea spiders (Pycnogonida) are an abundant faunal element of the Southern Ocean (SO). Several recent phylogeographical studies focused on the remarkably diverse SO pycnogonid fauna, resulting in the identification of new species in previously ill-defined species complexes, insights into their genetic population substructures, and hypotheses on glacial refugia and recolonization events after the last ice age. However, knowledge on the life history of many SO pycnogonids is fragmentary, and early ontogenetic stages often remain poorly documented. This impedes assessing the impact of different developmental pathways on pycnogonid dispersal and distributions and also hinders pycnogonid-wide comparison of developmental features from a phylogenetic-evolutionary angle. RESULTS Using scanning electron microscopy (SEM) and fluorescent nuclear staining, we studied embryonic stages and postembryonic instars of three SO representatives of the taxon Pallenopsidae (Pallenopsis villosa, P. hodgsoni, P. vanhoeffeni), the development of which being largely unknown. The eggs are large and yolk-rich, and the hatching stage is an advanced lecithotrophic instar that stays attached to the father for additional molts. The first free-living instar is deduced to possess at least three functional walking leg pairs. Despite gross morphological similarities between the congeners, each instar can be reliably assigned to a species based on body size, shape of ocular tubercle and proboscis, structure of the attachment gland processes, and seta patterns on cheliphore and walking legs. CONCLUSIONS We encourage combination of SEM with fluorescent markers in developmental studies on ethanol-preserved and/or long term-stored pycnogonid material, as this reveals internal differentiation processes in addition to external morphology. Using this approach, we describe the first known cases of pallenopsid development with epimorphic tendencies, which stand in contrast to the small hatching larvae in other Pallenopsidae. Evaluation against current phylogenetic hypotheses indicates multiple gains of epimorphic development within Pycnogonida. Further, we suggest that the type of development may impact pycnogonid distribution ranges, since free-living larvae potentially have a better dispersal capability than lecithotrophic attaching instars. Finally, we discuss the bearing of pycnogonid cheliphore development on the evolution of the raptorial first limb pair in Chelicerata and support a multi-articled adult limb as the plesiomorphic state of the chelicerate crown group, arising ontogenetically via postembryonic segmentation of a three-articled embryonic limb.
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Affiliation(s)
- Georg Brenneis
- Zoologisches Institut und Museum, Cytologie und Evolutionsbiologie, Universität Greifswald, Soldmannstraße 23, 17489 Greifswald, Germany
- Institut für Biologie, Vergleichende Zoologie, Humboldt-Universität zu Berlin, Philippstraße 13, Haus 2, 10115 Berlin, Germany
| | - Claudia P. Arango
- Queensland Museum, Biodiversity Program, PO Box 3300, South Brisbane, QLD 4101 Australia
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9
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Collins EE, Galaska MP, Halanych KM, Mahon AR. Population Genomics of Nymphon australe Hodgson, 1902 (Pycnogonida, Nymphonidae) in the Western Antarctic. THE BIOLOGICAL BULLETIN 2018; 234:180-191. [PMID: 29949435 DOI: 10.1086/698691] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Within the Southern Ocean, the Antarctic Circumpolar Current is hypothesized to facilitate a circumpolar distribution for many taxa, even though some, such as pycnogonids, are assumed to have limited ability to disperse, based on brooding life histories and adult ambulatory capabilities. With a number of contradictions to circumpolarity reported in the literature for other pycnogonids, alternative hypotheses have been explored, particularly for Nymphon australe, the most common species of Pycnogonida (sea spider) in the Southern Ocean. Glacial events have been hypothesized to impact the capacity of organisms to colonize suitable areas without ice coverage as refuge and without the eurybathic capacity to colonize deeper areas. In this study, we examine populations of one presumed circumpolar species, the pycnogonid N. australe, from throughout the Western Antarctic, using a 2b-RAD approach to detect genetic variation with single-nucleotide polymorphisms. Using this approach, we found that N. australe included two distinct groups from within >5000-km sampling region. By using a discriminant analysis of principle components, sparse nonnegative matrix factorization, and admixture coefficient analysis, two distinctive populations were revealed in the Western Antarctic: one covered distances greater than 5000 km (Weddell, Western Antarctic Peninsula, and Ross Sea), and the other shared limited connectivity entrained within the Amundsen Sea. Under further scrutiny of the 3086 single-nucleotide polymorphisms in the data set, only 78 loci had alignment stacks between the two populations. We propose that the populations analyzed are divergent enough to constitute two different species from within this common Antarctic genus known for its phenotypic plasticity.
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Key Words
- 2b-RAD, 2b restriction site-associated DNA genotyping
- ACC, Antarctic Circumpolar Current
- APF, Antarctic Polar Front
- COI, cytochrome c oxidase subunit I
- DAPC, discriminant analysis of principle components
- FST, fixation index
- K, number of populations
- LEA, Landscape and Ecological Associations
- Mb, megabases (unit of length for DNA fragments = 1 million nucleotides)
- RADseq, restriction site-associated DNA sequencing
- SNP, single-nucleotide polymorphism
- mya, million years ago; PCA, Principal Component Analysis
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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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Hübner J, Wagner P, Lehmann T, Melzer RR. Testing species delimitation with larval morphology: scanning electron microscopy analysis of protonymphon larvae of two closely related sea spiders, Pallenopsis patagonica (Hoek) and Pallenopsis yepayekae Weis. INVERTEBR SYST 2017. [DOI: 10.1071/is16050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We used scanning electron microscopy (SEM) to establish species-specific sets of characters for protonymphon larvae of two representatives of the ‘patagonica’ species group of Pallenopsis, P. patagonica and P. yepayekae. The larvae of both species are ‘typical’ protonymphon larvae sensu Bain (2003). Despite the close relationship of the two species, we observed numerous features that allow for differential diagnosis, e.g. general habitus, the number, arrangement and branching type of setules, the armature of the movable and immovable chelifore fingers, and the shape of the dactylus and setules of appendages II and III. SEM is particularly suitable for visualising these features. Our results further support the idea that protonymphon larvae can be identified to species level when adequate imaging techniques are used, as is also the case for larvae of other arthropods. Moreover, the status of the two studied species of Pallenopsis is fully supported by protonymphon larval morphology.
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