KOREASCHOLAR

A study of intertidal habitats on Jejudo Island, Korea led to the identification of two new species, Desmoscolex (Desmoscolex) jejuensis sp. nov. and Desmoscolex (Desmoscolex) longispiculatus sp. nov., belonging to the subgenus Desmoscolex. Desmoscolex (D.) jejuensis sp. nov. is distinguished by the presence of 18 main rings, with males missing the 8th, 10th, and 14th subventral setae with the 2nd and 15th setae shifted laterally. In females, the 6th, 8th, 10th, and 14th subventral setae are absent. Conversely, D. (D.) longispiculatus sp. nov. exhibits 17 main rings with a typical somatic setae arrangement along with notably elongated spicules and the 14th and 15th subventral setae shifted laterally or slightly subdorsally. Both species are characterized by relatively long and slender cephalic setae. Detailed illustrations and high-magnification micrographs were produced using differential interference contrast (DIC) microscopy and scanning electron microscopy (SEM) to facilitate morphological comparisons between these new species and related taxa. Furthermore, a comparative trait table and a pictorial key are provided to clearly differentiate these new species from morphologically similar taxa. These findings contribute to the understanding of nematode biodiversity and contribute to the broader knowledge of Desmoscolex diversity in Korean coastal ecosystems.

Abstract
1.INTRODUCTION
2. MATERIALS AND METHODS
3. SYSTEMATIC ACCOUNTS
    3.1. Desmoscolex (Desmoscolex) jejuensis sp. nov.(Figs. 1-5, 10; Table 1)
    3.2. Desmoscolex (Desmoscolex) longispiculatussp. nov. (Figs. 6-10; Table 1)
4. DISCUSSION
http://www.koseb.org 539Two new Desmoscolex species from Koreahighlight the ecological and evolutionary significanceof morphological adaptations in marine nematodesand underscore the value of detailed taxonomic studiesin revealing biodiversity.5. CONCLUSIONS
CRediT authorship contribution statement
Declaration of Competing Interest
ACKNOWLEDGEMENTS
REFERENCES

• Wooin Jung(East Sea Environment Research Center, Korea Institute of Ocean Science and Technology (KIOST), Uljin 36315, Republic of Korea, Ocean Science, University of Science and Technology (UST), Daejeon 34113, Republic of Korea)
• Hyun Soo Rho(East Sea Environment Research Center, Korea Institute of Ocean Science and Technology (KIOST), Uljin 36315, Republic of Korea, Ocean Science, University of Science and Technology (UST), Daejeon 34113, Republic of Korea) Corresponding author