Diaulota orientalis Tasaku, Ono & Maruyama, sp. n.

[Japanese name: Higashi-shiributo-umi-hanekakushi]

(Figs. 12 & 24)

Type material. Holotype. Male, “ NIPPON: Kanagawa-ken, / Jôgashima, 16 VI 2003, / Maruyama M. / Dzâ川県 µヶ島（潮®帯） ” (Fig. 12A) (KUM) . Paratypes. Japan: Honshû: Chiba-ken : 2 males, 5 females, Tateyama-shi, Okinoshima, 31. III. 2021, H. Ono (KUM) ; 2 males, 2 females, Tateyama-shi, Ito, 15. IV. 2008, H. Ono (KUM) . Tôkyô-to: 1 male, Izu-ôshima, Okada, Noda-hama, 15. VII. 2022, Y. Tasaku (cYT) ; 2 males, 1 female, ditto, 17. V. 2022, H. Ono (cHO); 1 male, ditto, 18. V. 2022, H. Ono (cHO) . Kanagawa-ken: 9 males, 13 females, Yokosuka-shi, Wada-nagahama (Nahama), 5. IV. 2007, I. Kawashima (KUM, OMNH, HIWA, cYT); 7 males, 9 females, ditto, 5. IV . 2007, M.Asano (KUM) ; 4 males, 4 females, Miura-shi, Misaki-machi, Koajiro, Aburatsubo, 29. V . 2018, H. Ono (cHO); 5 males, 11 females, same data as holotype, M. Maruyama (KUM, OMNH, cYT) . Shizuoka-ken: 1 male, 1 female, Shimoda-shi, Tarai-misaki, 21. IV . 2003, M. Moriguchi (KUM).

Diagnosis. This new species is very similar to D. uenoi and D. submarina but, can be distinguished by the combination of following characteristics: apex of median lobe truncate in ventral view; apical sclerite rounded in lateral view (Fig. 12E), narrow toward apical margin in ventral view (Fig. 12F); suspensonia spoon-shaped and broad in apical half (Fig. 12F); spermatheca twice curved (Fig. 12G).

Description. Body robust, flattened. Ground color reddish brown, abdominal segment VI black, mouth parts yellow (Fig. 12A & B). Head quadrate, broader than pronotum in males, as broad as pronotum in females; eyes relatively small; antennae shorter than head and pronotum combined; segment I longest; segment II as long as XI; segment III shorter than II, about 1.5 times longer than IV; segments IV–VIII as long as wide; segments IX and X slightly wider than long; segment XI about 1.5 times longer than wide. Labrum semicircular, with about 20 setae. Mandibles almost symmetric, with a small tooth. Maxillary palpi 4 segmented; segment I very short, as long as IV; segment II quadrate, 2 times longer than I; segment III oval, slightly longer than II; segment IV thin. Labium: prementum without medial seta; ligula unilobed, short; labial palpi 3 segmented, segment II as thin as I, shorter than twice length of I; segment III thin, shorter than I (Fig. 12C). Mentum almost trapezoidal (Fig. 12D), emarginated at apical margin, with 6 setae. Pronotum flattened, trapezoidal. Elytra shorter than wide. Hind wings absent. Abdomen oval. Tarsal formula 4-4-5.

Male; tergite VIII with apical margin truncate; sternite VIII with apical margin slightly prolonged posteriorly; apical lobe of median lobe short, slightly pointed in lateral view (Fig. 12E); internal structure of median lobe with apical sclerites rounded at apex (Fig. 12E); suspensonia spoon-shaped, broad in apical half in ventral view (Fig. 12F); apical lobe of paramere slender.

Female; tergite VIII apical margin truncate; sternite VIII apical margin rounded; spermatheca short, apical part circular, twice curved around base (Fig. 12G).

Measurements. Male (N = 7): BL, 2.55–2.80 mm; FBL, 1.18–1.31 mm; HW, 0.60–0.67 mm; PL, 0.47–0.54 mm; PW, 0.51–0.56 mm; EW, 0.51–0.56 mm; HW/PW, 1.13–1.21. Female (N = 7): BL, 2.29–2.75 mm; FBL, 1.11– 1.21. mm; HW, 0.45–0.48 mm; PL, 0.44–0.48 mm; PW, 0.46–0.48 mm; EW, 0.45–0.47 mm; HW/PW, 0.94–1.03.

Etymology. The Latin “ orientalis ” means eastern in referring to its eastern distribution of the Diaulota uenoi species-complex in Japan.

Habitat. This species is found from the crevices of rocks and occasionally inside of the dead barnacles ( Tetraclita japonica (Pilsbry)) on the intertidal zones. They usually occur lower than where R. koheii sp. n. are found, its habitat is exposed to strong waves.

Distribution. Japan: central Honshû (Pacific Ocean side) (Fig. 24).