https://repository.kopri.re.kr/handle/201206/15683 2026-04-08T06:12:46Z https://repository.kopri.re.kr/handle/201206/16605 Title: Early aculiferan diversification shaped by Ægir-Iapetus palaeogeography: Insights from North Greenland (Cambrian Series 2, Stage 4) Authors: Oh, Yeongju; Park, Tae-Yoon S.; Peel John S. Abstract: Aculifera, comprising Polyplacophora (chitons) and Aplacophora, is one of two major molluscan clades, characterised by a scleritome of mineralised sclerites or plates. Their early evolutionary history is poorly understood due to sparse fossil records bridging possible Terreneuvian (early Cambrian) stem-group taxa and Furongian (late Cambrian) chiton-like articulated representatives. Here, we describe seven species in five genera from the Aftenstjernes & oslash; Formation (Cambrian Series 2, Stage 4) of North Greenland, including a second species, Qaleruaqia bronlundensis sp. nov., of the oldest paleoloricate, Qaleruaqia sp.; the sachitid Hippopharangites groenlandicus, Hippopharangites? sp.; a possible intermediate plate of a chiton-like scleritome, Avannaplax midsommersoensis gen. et sp. nov.; and possible aculiferans Ocruranus? kangerluk and Xianfengella yatesi. Morphological comparisons of the North Greenland assemblage reveal strong affinities with Terreneuvian taxa, including maikhanellids and the Ocruranus-Eohalobia group, supporting their interpretation as stem-group aculiferans. A palaeobiogeographic analysis using 650 global occurrences of Cambro-Ordovician taxa shows that the AE gir Ocean as a principal dispersal corridor for early diversification of aculifera. During the Terreneuvian, aculiferans were widespread along AE gir margins but rare in Laurentia, likely due to isolation by the Iapetus Ocean. From Cambrian Series 2 onward, increased connectivity and expanded low-latitude carbonate platforms fostered diversification in eastern Laurentia, including North Greenland. This assemblage from North Greenland bridges a critical spatio-temporal and morphological gap between the earliest Cambrian taxa and Furongian paleoloricates, offering new insight into aculiferan diversification and palaeobiogeography. 2025-12-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16564 Title: An integrative description of a new species of marine water bear (Heterotardigrada: Echiniscoididae) from the tidal zone of the east coast of Korea Authors: Kim, Ji-Hoon; Piotr Gasiorek; Rho, H. S.; Lee, H.; Han, S.; Kim, J.; Kang, Pil-Mo; Choi, J.; Jung, W.; Park, Tae-Yoon S. Abstract: Tardigrades, or water bears, are microscopic invertebrates renowned for their extraordinary resilience and cryptic diversity. Their microscopic size, paucity of taxonomically distinctive morphological characters, and limited molecular data have caused significant taxonomic deflation. Echiniscoides, the most speciose genus in the family Echiniscoididae, also harbors multiple undescribed species. In this study, we describe a new marine tardigrade species, Echiniscoides testudolapis sp. nov., collected from barnacles inhabiting the intertidal zone of Uljin, Korea. The new species was characterized using an integrative taxonomic approach combining detailed morphological, morphometric, and molecular analyses, including DIC microscopy, SEM microscopy, and molecular phylogenetic reconstructions based on mitochondrial COI sequences. Morphologically, E. testudolapis sp. nov. is distinguished by its dorsal cuticular sculpturing in the form of circular discs with central punctations (weakly elevated processes), the presence of sensory organs on all legs (papilliform on legs I？II, IV, and spike-like on legs III), and a dominant claw formula of 9,9,9,8. Notably, our COI analyses revealed substantial intraspecific genetic variability, with 20 haplotypes identified among 28 individuals (p-distances = 0.1？2.8%). In contrast, the examined nuclear markers exhibited low to no genetic variation (p-distances are 0.05%, 0%, 0.2？0.5%, 0.2？0.4% for 18S, 28S, ITS1, and ITS2, respectively). Single nucleotide polymorphism (SNP) analyses indicated that the observed COI polymorphisms are likely functionally neutral. These findings highlight the value of an integrative taxonomic approach in revealing cryptic diversity and provide new insights into the evolutionary processes and biogeographic patterns shaping marine tardigrades diversity. 2025-11-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16008 Title: A fossilized ventral ganglion reveals a chaetognath affinity for Cambrian nectocaridids Authors: Vinther, Jakob; Parry, Luke A; Lee, Mirinae; Nielsen, Morten Lunde; Oh, Yeongju; Park, Changkun; Kim, Ji-Hoon; DeVivo Giacinto; Harper David A. T.; Nielsen Arne T.; Park, Tae-Yoon S. Abstract: Nectocaridids are enigmatic Palaeozoic animals with a controversial phylogenetic position. Previous hypotheses have placed them in their own phylum, chordates, molluscs (specifically cephalopods), or radiodont panarthropods. We describe here a nectocaridid, Nektognathus evasmithae gen. et sp. nov. from the early Cambrian (similar to 519 million years) Sirius Passet Lagerstatte of North Greenland. Key specimens preserve paired, phosphatized arcuate structures consistent with preservation of a ventral ganglion, a feature characteristic of extant and fossil chaetognaths, including the amiskwiid Timorebestia koprii also from Sirius Passet. Nektognathus shares a gnathostomulid-like jaw apparatus, lateral fins, subterminal anus, and large antennae with Timorebestia and Amiskwia, placing nectocaridids in the chaetognath stem lineage. The complex sensory anatomy of nectocaridids, which is partially shared with other extinct amiskwiids, highlights a more dynamic predatory lifestyle much higher in the trophic food chain during early chaetognath evolution. 2025-07-01T00:00:00Z