https://repository.kopri.re.kr/handle/201206/5448 2026-04-07T15:56:32Z 2026-04-07T15:56:32Z Park, Tae-Yoon S. https://repository.kopri.re.kr/handle/201206/11110 2022-03-24T07:15:37Z 2019-01-24T00:00:00Z

Title: Phylogenetic elucidation of tardigrades through paleontological comparative research Authors: Park, Tae-Yoon S.

2019-01-24T00:00:00Z Kim, Ji-Hoon Kim, Sanghee Park, Tae-Yoon S. https://repository.kopri.re.kr/handle/201206/12367 2022-03-24T07:15:42Z 2018-01-01T00:00:00Z

Title: The new species of Dactylobiotus (Parachela, Eutardigrada) from King George Island, Antarctica Authors: Kim, Ji-Hoon; Kim, Sanghee; Park, Tae-Yoon S. Abstract: Phylum Tardigrada is a minute, hydrophilous animal group with a five segmented body which consists of a head and four trunk segments. This phylum is famous for the ability to survive the severe conditions such as cold, dry, or high radiation environments. The limno-terrestrial tardigrades are one of the dominant animal groups in the terrestrial ecosystem of Antarctica. However, due to their limited morphological characteristics and restricted access to the habitats, taxonomic study on Antarctic tardigrades is difficult to carry out. KOPRI ecology team collected several species of tardigrades from King George Island, Antarctica during 2014-2015 season expedition. Among the collected tardigrades, one species shows a bucco-pharyngeal apparatus with 10 peribuccal papillae reminiscent of Macrobiotus-type and the cuticular connection between claws, which are characteristics of the genus Dactylobiotus. This species is large in size (600-700 μm) with smooth cuticle and no conical papillae between 3rd and 4th limbs. Key morphological characters of bucco-pharyngeal apparatus and claws are being measured, and pt ratio (the ratio of the length of a given structure to the length of the buccal tube) are compared to that of other Dactylobiotus speciesto see whether the species is a previously reported Dactylobiotus species documented in other regions around the world, or a new species.

2018-01-01T00:00:00Z Kim, Ji-Hoon JIANNI, LIU Kim, Sanghee Park, Tae-Yoon S. https://repository.kopri.re.kr/handle/201206/12692 2022-03-24T07:14:57Z 2018-01-01T00:00:00Z

Title: Comparative morphological study between Cambrian lobopodians and extant tardigrades Authors: Kim, Ji-Hoon; JIANNI, LIU; Kim, Sanghee; Park, Tae-Yoon S. Abstract: Background: Order Arthrotardigrada includes marine heterotardigrades which have been known to retain more plesiomorphic conditions than the Eutardigrada. Especially, Parastygarctus was considered as the most primitive genus, based on the morphological comparison with a Cambrian lobopodian, Aysheaia pedunculata from the Burgess Shale, Canada, which was one of the two known Cambrian lobopodian until the 1980’s. However, since the 90’s thirteen more Cambrian lobopodian species have been discovered from the Chengjiang, China, which have significantly promoted our knowledge on the Cambrian lobopodian morphology, necessitating novel morphological comparison between tardigrades and the Cambrian lobopodians. Results: We have compared morphological characters between tardigrades and the Cambrian lobopodians. Among several species of Cambrian lobopodians, Aysheaia pedunculata displays six peri-buccal papillae around the mouth opening, which are reminiscent of those of apochelan Milnesium tardigradum. Eutardigrades and the Cambrian lobopodians have terminally-opened mouth which is an important plesiomorphic character of panarthropods, whereas most heterotardigrade show a ventrally-opened mouth. The Cambrian lobopodians had claws at the end of their limbs, lacking digits or toes which are present in heterotardigrades. The Cambrian lobopodians and eutardigrades show lobe-like limbs, while heterotardigrades have telescopic limbs. Presence of circum-oral elements and pharyngeal teeth are plesiomorphic for Ecdysozoa, but only eutardigrades have these structures. In addition, the elongated pharyngeal bulb and parallel piercing stylets of apochelan tardigrade reminds the elongated pharynx and parallel rostral spines of Kerygmachela kierkegaardi respectively. Conclusions: Based on the morphological comparison with the Cambrian lobopodians, it is suggested that eutardigrades retain more plesiomorphic morphologies than heterotardigrades. Particularly, apochelans display many similarities with Cambrian lobopodians.

2018-01-01T00:00:00Z