TY - JOUR

T1 - The Macrobiotus ariekammensis species complex provides evidence for parallel evolution of claw elongation in macrobiotid tardigrades

AU - Stec, Daniel

AU - Voncina, Katarzyna

AU - Kristensen, Reinhardt Møbjerg

AU - Michalczyk, Łukasz

PY - 2022

Y1 - 2022

N2 - The recent integrative revision of the family Macrobiotidae demonstrated monophyly of the genus Macrobiotus and its complex, mosaic morphological evolution. Here, we analyse three Macrobiotus populations that exhibit extraordinary claw morphology characterized by elongated primary branches. Two of these populations, from the Arctic, were initially classified as Macrobiotus ariekammensis, but detailed integrative analyses resulted in splitting them into two subspecies: Macrobiotus ariekammensis ariekammensis and Macrobiotus ariekammensis groenlandicus subsp. nov.. The third population was Macrobiotus kirghizicus from Kyrgyzstan. Given the unusual phenotype of the above-mentioned taxa, we tested whether they constitute a distinct lineage in the family Macrobiotidae and could be delineated as a new genus. Although the phylogenetic investigation showed that the three taxa form a monophyletic group, the Glade is nested in the genus Macrobiotus. Therefore, despite their morphological distinctiveness, a new genus cannot be established and we group these taxa in the Macrobiotus ariekammensis species complex instead. The complex includes the three above-mentioned taxa and Macrobiotus ramoli, which is included based on morphological characters. Moreover, our results provide evidence for rapid parallel evolution of long claws in macrobiotid tardigrades inhabiting cold and icy environments. Finally, we discuss the validity of the recent suppression of the genus Xerobiotus, which gathers macrobiotids with reduced claws.

AB - The recent integrative revision of the family Macrobiotidae demonstrated monophyly of the genus Macrobiotus and its complex, mosaic morphological evolution. Here, we analyse three Macrobiotus populations that exhibit extraordinary claw morphology characterized by elongated primary branches. Two of these populations, from the Arctic, were initially classified as Macrobiotus ariekammensis, but detailed integrative analyses resulted in splitting them into two subspecies: Macrobiotus ariekammensis ariekammensis and Macrobiotus ariekammensis groenlandicus subsp. nov.. The third population was Macrobiotus kirghizicus from Kyrgyzstan. Given the unusual phenotype of the above-mentioned taxa, we tested whether they constitute a distinct lineage in the family Macrobiotidae and could be delineated as a new genus. Although the phylogenetic investigation showed that the three taxa form a monophyletic group, the Glade is nested in the genus Macrobiotus. Therefore, despite their morphological distinctiveness, a new genus cannot be established and we group these taxa in the Macrobiotus ariekammensis species complex instead. The complex includes the three above-mentioned taxa and Macrobiotus ramoli, which is included based on morphological characters. Moreover, our results provide evidence for rapid parallel evolution of long claws in macrobiotid tardigrades inhabiting cold and icy environments. Finally, we discuss the validity of the recent suppression of the genus Xerobiotus, which gathers macrobiotids with reduced claws.

KW - Arctic

KW - claws

KW - convergence

KW - integrative taxonomy

KW - Macrobiotus gretae comb. nov.

KW - Macrobiotus kirghizicus

KW - Macrobiotus ramoli

KW - Mesobiotus barabanovi

KW - molecular phylogeny

KW - parallel evolution

KW - Tardigrada

KW - water bears

KW - Xerobiotus

KW - INTEGRATIVE DESCRIPTION

KW - HUFELANDI GROUP

KW - SP-NOV

KW - PHYLOGENETIC ANALYSIS

KW - MOLECULAR-DATA

KW - SP. NOV.

KW - ET-AL.

KW - EUTARDIGRADA

KW - GENUS

KW - GENERA

U2 - 10.1093/zoolinnean/zlab101

DO - 10.1093/zoolinnean/zlab101

M3 - Journal article

VL - 195

SP - 1067

EP - 1099

JO - Zoological Journal of the Linnean Society

JF - Zoological Journal of the Linnean Society

SN - 0024-4082

IS - 4

ER -