Homology of the head sensory structures between Heterotardigrada and Eutardigrada supported in a new species of water bear (Ramazzottiidae: Ramazzottius)
Abstract Phylum Tardigrada is represented by microscopic eight-legged panarthropods that inhabit terrestrial and marine environments. Although tardigrades are emerging model animals for areas of research including physiology, evolutionary biology, and astrobiology, knowledge of their external morpho...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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BMC
2023-11-01
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| Series: | Zoological Letters |
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| Online Access: | https://doi.org/10.1186/s40851-023-00221-w |
| _version_ | 1827602587448246272 |
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| author | Ji-Hoon Kihm Krzysztof Zawierucha Hyun Soo Rho Tae-Yoon S. Park |
| author_facet | Ji-Hoon Kihm Krzysztof Zawierucha Hyun Soo Rho Tae-Yoon S. Park |
| author_sort | Ji-Hoon Kihm |
| collection | DOAJ |
| description | Abstract Phylum Tardigrada is represented by microscopic eight-legged panarthropods that inhabit terrestrial and marine environments. Although tardigrades are emerging model animals for areas of research including physiology, evolutionary biology, and astrobiology, knowledge of their external morphology remains insufficient. For instance, homologies between marine and terrestrial relatives largely remain unexplored. In the present study we provide detailed pictures of the head sensory organs in a new tardigrade, Ramazzottius groenlandensis sp. nov. Specimens were collected from a mixed moss and lichen sample on Ella Island, East Greenland. The new species differs from congeneric species in the presence of polygonal sculpturing on the dorsal cuticle, which is accentuated in the posterior region of the body, a lateral papilla on leg IV, and distinctive egg morphology. A Bayesian phylogenetic analysis (18S rRNA + 28S rRNA + COI) places the new species within the genus Ramazzottius with high confidence. Interestingly, the new species shows a full set of well-developed cephalic organs, which correspond to all sensory fields found in eutardigrades. Details on the full set of head organs were present only for heterotardigrades. The surface of these organs is covered with small pores, which presumably play a sensory role. This discovery suggests the homology of head sensory structures between heterotardigrades and eutardigrades, implying that the distinctive arrangement and positioning of sensory organs on the head is a plesiomorphic feature of tardigrades. Moreover, we find that the Ramazzottius oberhaeuseri morphotype forms a morphogroup, not a monophyletic species complex. |
| first_indexed | 2024-03-09T05:22:35Z |
| format | Article |
| id | doaj.art-cebf11d22d6c432291b0bea51519de28 |
| institution | Directory Open Access Journal |
| issn | 2056-306X |
| language | English |
| last_indexed | 2024-03-09T05:22:35Z |
| publishDate | 2023-11-01 |
| publisher | BMC |
| record_format | Article |
| series | Zoological Letters |
| spelling | doaj.art-cebf11d22d6c432291b0bea51519de282023-12-03T12:40:01ZengBMCZoological Letters2056-306X2023-11-019111710.1186/s40851-023-00221-wHomology of the head sensory structures between Heterotardigrada and Eutardigrada supported in a new species of water bear (Ramazzottiidae: Ramazzottius)Ji-Hoon Kihm0Krzysztof Zawierucha1Hyun Soo Rho2Tae-Yoon S. Park3Division of Earth Sciences, Korea Polar Research InstituteDepartment of Animal Taxonomy and Ecology, Faculty of Biology, Adam Mickiewicz UniversityEast Sea Environmental Research Center, East Sea Research Institute, Korea Institute of Ocean Science & TechnologyDivision of Earth Sciences, Korea Polar Research InstituteAbstract Phylum Tardigrada is represented by microscopic eight-legged panarthropods that inhabit terrestrial and marine environments. Although tardigrades are emerging model animals for areas of research including physiology, evolutionary biology, and astrobiology, knowledge of their external morphology remains insufficient. For instance, homologies between marine and terrestrial relatives largely remain unexplored. In the present study we provide detailed pictures of the head sensory organs in a new tardigrade, Ramazzottius groenlandensis sp. nov. Specimens were collected from a mixed moss and lichen sample on Ella Island, East Greenland. The new species differs from congeneric species in the presence of polygonal sculpturing on the dorsal cuticle, which is accentuated in the posterior region of the body, a lateral papilla on leg IV, and distinctive egg morphology. A Bayesian phylogenetic analysis (18S rRNA + 28S rRNA + COI) places the new species within the genus Ramazzottius with high confidence. Interestingly, the new species shows a full set of well-developed cephalic organs, which correspond to all sensory fields found in eutardigrades. Details on the full set of head organs were present only for heterotardigrades. The surface of these organs is covered with small pores, which presumably play a sensory role. This discovery suggests the homology of head sensory structures between heterotardigrades and eutardigrades, implying that the distinctive arrangement and positioning of sensory organs on the head is a plesiomorphic feature of tardigrades. Moreover, we find that the Ramazzottius oberhaeuseri morphotype forms a morphogroup, not a monophyletic species complex.https://doi.org/10.1186/s40851-023-00221-wCephalic sensory structureArcticAncestral characterMorphogroupGreenland |
| spellingShingle | Ji-Hoon Kihm Krzysztof Zawierucha Hyun Soo Rho Tae-Yoon S. Park Homology of the head sensory structures between Heterotardigrada and Eutardigrada supported in a new species of water bear (Ramazzottiidae: Ramazzottius) Zoological Letters Cephalic sensory structure Arctic Ancestral character Morphogroup Greenland |
| title | Homology of the head sensory structures between Heterotardigrada and Eutardigrada supported in a new species of water bear (Ramazzottiidae: Ramazzottius) |
| title_full | Homology of the head sensory structures between Heterotardigrada and Eutardigrada supported in a new species of water bear (Ramazzottiidae: Ramazzottius) |
| title_fullStr | Homology of the head sensory structures between Heterotardigrada and Eutardigrada supported in a new species of water bear (Ramazzottiidae: Ramazzottius) |
| title_full_unstemmed | Homology of the head sensory structures between Heterotardigrada and Eutardigrada supported in a new species of water bear (Ramazzottiidae: Ramazzottius) |
| title_short | Homology of the head sensory structures between Heterotardigrada and Eutardigrada supported in a new species of water bear (Ramazzottiidae: Ramazzottius) |
| title_sort | homology of the head sensory structures between heterotardigrada and eutardigrada supported in a new species of water bear ramazzottiidae ramazzottius |
| topic | Cephalic sensory structure Arctic Ancestral character Morphogroup Greenland |
| url | https://doi.org/10.1186/s40851-023-00221-w |
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