Rotundicephala koreana (Yoo & Ahn, 2021), comb. n.

[Japanese name: Sazare-umi-hanekakushi]

(Figs. 14C; 15C, D & H; 25A)

Diaulota koreana Yoo & Ahn, 2021: 551 (original description; type locality: Gyeongnam Prov.: Tongyeong-si, Sanyang-eup, Is. Mireukdo).

Material examined. Honshû: Hiroshima-ken: 1 male, 15 unsexed, Kure-shi, Kurahashi-chô, Kurahashi-jima (Umikoshi), 1. II. 2009, K. Nakano (KUM) ; Yamaguchi-ken: 5 unsexed, Kaminoseki-chô, Naga-shima, 1. V. 2008, M. Moriguchi (KUM) . Shikoku: Kagawa-ken: 1 male, 1 female, 8 unsexed, Higashikagawa-shi, Matsubara, Kaburagoshi-kaigan, 6. V. 2014, T. Taki (cYT) ; 1 unsexed, ditto, 23. V. 2016, T. Taki (cYT); 6 unsexed, ditto, 21. III. 2021, T. Taki (cYT); 1 male, Higashikagawa-shi, Koiso, Koura-kaigan, 27. V. 2017, T. Taki (cYT) ; 3 unsexed, Marugame-shi, Hon-jima, Kôshô, 30. IV. 2017, H. Fujimoto . Kyûshû: Ôita-ken: 1 male, Ôita-shi, Shûki, 5. IV. 2023, S. Akamine (KUM) ; Nagasaki-ken: Tsushima: 1 unsexed, Izuhara-machi, Azamo, 15. VI. 2022, H. Ono (cHO) ; 1 female, 3 unsexed, ditto, 18. VI. 2022, H. Ono (cHO); 1 male, 1 female, 4 unsexed, ditto, 19. VI. 2022, Y. Tasaku (cYT) .

Diagnosis. This species is similar to other species of Rotundicephala, but can be distinguished by the long antennae reaching to elytra (Figs. 14C; 15H).

Habitat. In our survey in Tsushima, unlike other species of this genus that occur in rock crevices, this species was collected from under pebbles on the intertidal zones of gravel beach (1.5–20 mm in diameter), together with the members of other intertidal aleocharine genus Bryothinusa Casey, 1904 . This habitat preference is an important piece of information other than morphological information to readily identify this species.

Distribution. Japan: Honshû, Shikoku, Kyûshû, Tsushima; South Korea (Fig. 25A). Newly recorded from Japan.