This study introduces a newly discovered brittle star, Amphiophiura megapoma, from the mesophotic zone in the East Sea, Korea. It is the second species belonging to the genus Amphiophiura (which includes 57 species) to be recorded in Korean waters after A. sculpta. The specimen was discovered during a September 2022 survey, by SCUBA diving in the upper mesophotic zone of the East Sea, Korea. This study presents the morphological characteristics of A. megapoma, highlighting its differences from the related species within a comprehensive taxonomic description. It provides highresolution images of A. megapoma and a taxonomic key for Amphiophiura species in Korea.

Henricia specimen was collected from the East Sea of Korea using fishing nets. The specimen was identified as Henricia hayashii (Djakonov 1961), belonging to the family Echinasteridae of the order Spinulosida. This species can be distinguished from other Henricia species by slender arms (R/r=7.4), constricted arm base, six to thirtyfive slender spinelets, open-meshed, reticulated abactinal skeleton comprising semitriangular, rod-like form, and small ossicles present inside the papular areas. This species superficially resembles H. reniossa in terms of its body size but differs in the shape and arrangement of the abactinal and actinal plates. To date, two genera of Echinasteridae, Aleutihenricia and Henricia, including a total of 14 species, have been reported in Korea. Herein, the morphological characteristics of H. hayashii are described, and photographs are provided.

Henricia specimens were collected using fishing nets from the East Sea of Korea. The specimens were identified as Henricia oculata Pennant, 1777, belonging to the family Echinasteridae of the order Spinulosida. This species can be distinguished from other Henricia species by broad arms (R/r=4-4.1), rough skin, a thick arm base, three to nine minute delicate abactinal spines, and inferomarginal plates reniform in shape. This species superficially resembles H. pachyderma in its body size and wide papular areas but differs mainly in the number of papulae and abactinal spines, and the shape and arrangement of the inferomarginal plates. To date, two genera of Echinasteridae, Aleutihenricia and Henricia, with a total of 13 species, have been reported in Korea. The morphological characteristics of H. oculata are described, and photographs are provided.

Sea stars were collected from the adjacent waters of Jukbyeon and Jumunjin, Korea, using fishing nets at depths of 70-100 m. The specimens were identified as Henricia perforata (O.F. Müller, 1776) in the family Echinasteridae and order Spinulosida, with worldwide species distribution. H. perforata can be distinguished from some morphologically related Henricia species by its long, slender, and pointed adambulacral spines. The abactinal skeleton of H. perforata has wide papular areas resembling those of H. pachyderma, but the former has more papulae (two to seven). Previously, two genera of Echinasteridae, Aleutihenricia and Henricia, with a total of 12 echinasterid species, have been reported in Korea. The morphological characteristics of H. perforata are described and photographs are provided.

Asteroid specimens were collected using fishing nets from the East Sea, Korea. The specimens were identified as Solaster paxillatus Sladen, 1889, belonging to the family Solasteridae of the order Valvatida. This species can be distinguished from three other Korean Solaster species by having 10 arms; subambulacral spines comprising four or five near base of arm, six or seven in middle part, and five or six in distal part of arm; furrow spines comprising four or five near basal part and three or four in distal part of arm; and suboral spines comprising more than ten spinules. The morphological characteristics of this species were described with illustrations. Solaster paxillatus is first reported in marine fauna of Korea.

An asteroid specimen that belongs to the genus Henricia was collected from the waters near Ongpo harbor, Jeju Island using fishing net on 24 January 2017. The specimen was identified as Henricia anomala Hayashi, 1973, which belongs to the family Echinasteridae and order Spinulosida. Henricia anomala was first described by Hayashi, 1973, who captured it from Sagami Bay at a depth of 110-116 m. This species can be distinguished from other Henricia species by short arms (R/r=4), abactinal spines lining the abactinal plates and bearing about two to five spinelets, closely meshed abactinal skeleton, composed of small rod-like and subtriangular plates, a narrow papular area containing one or two papulae, and adambulacral armature composed of five to seven bluntly pointed spinelets. This is the first report of Henricia anomala in Korea.

Asteroid specimens of the genus Diplopteraster were collected by trawling nets at a depth of 93 m on 05 November 2016 from the Korea Strait (33°41′N, 127°26′E). The specimens were identified as Diplopteraster multipes (M. Sars, 1866), which belongs to the family Pterasteridae, order Velatida. This species is similar to other Diplopteraster species in its pentagonal stellate shape, but is distinguished by having each paxilla composed of a protruded spine, more than eight spiracles, and regularly reticulated muscular bands. It is not commonly found in shallow water. This is the first report of the genus Diplopteraster and D. multipes in Korea.

Some asteroid specimens were collected at a depth of 150 m near Moseulpo in Jeju Island, Korea using fishing nets on October 2014. The specimens were identified as Henricia pacifica Hayashi, 1940 belonging to the family Echinasteridae of order Spinulosida. In the Korean fauna, seven species of genus Henricia were reported of which two species, H. nipponica and H. ohshimai, were distributed in Jeju Island. The morphological characteristics of this species were re-described with illustrations.

Asteroid specimens were collected from Shinnam, Gangwondo in the East Sea of Korea with fishing nets on 12 September 2014. The specimens were identified as Henricia reticulata Hayashi, 1940, belonging to family Echinasteridea of order Spinulosida. This species can be distinguished by a larger disc and broader arms compared to those other Henricia species. The morphological characteristics of this species are re-described with illustrations. By previous work of this genus, six species have been reported in the Korean fauna.