Integrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)

Abstract The taxonomy of many groups of meiofauna is challenging due to their low number of diagnostic morphological characters and their small body size. Therefore, with the advent of molecular techniques that provide a new source of traits, many cryptic species have started to be discovered. Tardi...

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Main Authors: Daniel Stec, Matteo Vecchi, Magdalena Dudziak, Paul J. Bartels, Sara Calhim, Łukasz Michalczyk
Format: Article
Language:English
Published: BMC 2021-05-01
Series:Zoological Letters
Subjects:
Online Access:https://doi.org/10.1186/s40851-021-00176-w
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author Daniel Stec
Matteo Vecchi
Magdalena Dudziak
Paul J. Bartels
Sara Calhim
Łukasz Michalczyk
author_facet Daniel Stec
Matteo Vecchi
Magdalena Dudziak
Paul J. Bartels
Sara Calhim
Łukasz Michalczyk
author_sort Daniel Stec
collection DOAJ
description Abstract The taxonomy of many groups of meiofauna is challenging due to their low number of diagnostic morphological characters and their small body size. Therefore, with the advent of molecular techniques that provide a new source of traits, many cryptic species have started to be discovered. Tardigrades are not an exception, and many once thought to be cosmopolitan taxa are being found to be complexes of phenotypically similar species. Macrobiotus pallarii Maucci, 1954 was originally described in South Italy and has been subsequently recorded in Europe, America, and Asia. This allegedly wide geographic range suggests that multiple species may be hidden under this name. Moreover, recently, genetic evidence to support this was put forward, and the Macrobiotus pallarii complex has been proposed to accommodate putative species related to M. pallarii. Here, we describe three new pseudocryptic species based on populations that would have been all classified as Macrobiotus pallarii if molecular methods were not employed. Using an integrative taxonomy approach, we analyzed animals and eggs from the topotypic population of Macrobiotus pallarii, together with four other populations of the complex. We recovered four distinct phylogenetic lineages that, despite the overlap of morphometric traits, can be separated phenotypically by subtle but discrete morphological characters. One lineage corresponds to Macrobiotus pallarii, whereas the other three are newly described as Macrobiotus margoae Stec, Vecchi & Bartels, sp. nov. from the USA, Macrobiotus ripperi Stec, Vecchi & Michalczyk, sp. nov. from Poland and Finland, and Macrobiotus pseudopallarii Stec, Vecchi & Michalczyk, sp. nov. from Montenegro. To facilitate species identification, we provide a dichotomous key for species of the M. pallarii complex. Delimitation of these pseudocryptic taxa highlights the need for an integrative approach to uncover the phylum’s diversity in full.
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spelling doaj.art-371a507dd69b4650a1f97bf77a1ea2542022-12-21T18:00:03ZengBMCZoological Letters2056-306X2021-05-017114510.1186/s40851-021-00176-wIntegrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)Daniel Stec0Matteo Vecchi1Magdalena Dudziak2Paul J. Bartels3Sara Calhim4Łukasz Michalczyk5Department of Invertebrate Evolution, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian UniversityDepartment of Biological and Environmental Science, University of JyväskyläDepartment of Invertebrate Evolution, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian UniversityDepartment of Biology, Warren Wilson CollegeDepartment of Biological and Environmental Science, University of JyväskyläDepartment of Invertebrate Evolution, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian UniversityAbstract The taxonomy of many groups of meiofauna is challenging due to their low number of diagnostic morphological characters and their small body size. Therefore, with the advent of molecular techniques that provide a new source of traits, many cryptic species have started to be discovered. Tardigrades are not an exception, and many once thought to be cosmopolitan taxa are being found to be complexes of phenotypically similar species. Macrobiotus pallarii Maucci, 1954 was originally described in South Italy and has been subsequently recorded in Europe, America, and Asia. This allegedly wide geographic range suggests that multiple species may be hidden under this name. Moreover, recently, genetic evidence to support this was put forward, and the Macrobiotus pallarii complex has been proposed to accommodate putative species related to M. pallarii. Here, we describe three new pseudocryptic species based on populations that would have been all classified as Macrobiotus pallarii if molecular methods were not employed. Using an integrative taxonomy approach, we analyzed animals and eggs from the topotypic population of Macrobiotus pallarii, together with four other populations of the complex. We recovered four distinct phylogenetic lineages that, despite the overlap of morphometric traits, can be separated phenotypically by subtle but discrete morphological characters. One lineage corresponds to Macrobiotus pallarii, whereas the other three are newly described as Macrobiotus margoae Stec, Vecchi & Bartels, sp. nov. from the USA, Macrobiotus ripperi Stec, Vecchi & Michalczyk, sp. nov. from Poland and Finland, and Macrobiotus pseudopallarii Stec, Vecchi & Michalczyk, sp. nov. from Montenegro. To facilitate species identification, we provide a dichotomous key for species of the M. pallarii complex. Delimitation of these pseudocryptic taxa highlights the need for an integrative approach to uncover the phylum’s diversity in full.https://doi.org/10.1186/s40851-021-00176-wcryptic taxaDNA barcodingegg ornamentationnew speciesspecies complexspecies delimitation
spellingShingle Daniel Stec
Matteo Vecchi
Magdalena Dudziak
Paul J. Bartels
Sara Calhim
Łukasz Michalczyk
Integrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)
Zoological Letters
cryptic taxa
DNA barcoding
egg ornamentation
new species
species complex
species delimitation
title Integrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)
title_full Integrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)
title_fullStr Integrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)
title_full_unstemmed Integrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)
title_short Integrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)
title_sort integrative taxonomy resolves species identities within the macrobiotus pallarii complex eutardigrada macrobiotidae
topic cryptic taxa
DNA barcoding
egg ornamentation
new species
species complex
species delimitation
url https://doi.org/10.1186/s40851-021-00176-w
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