Plate 1, Figs. A–D, F–G
Cyathoceras rubescens Mosely, 1881: 157, pl. 2, figs. 8a–c. — Marenzeller, 1888: 21–22. — Yabe and Eguchi, 1942: 117. — Wells, 1964: 112. — Cairns, 1982: 22. — Cairns, 1984: 5, 15.
Cyathoceras tydemani Alcock, 1902a: 93–94; 1902 b: 14, pl. 1, figs. 7, 7a. — Faustino, 1927: 65, pl. 9, figs. 5–6. — Cairns, 1982: 22.
Cyathoceras diomedeae Vaughan, 1907: 77–78, pl. 7, figs. 1–2. — Vaughan, 1919: 1917, pl. XIII, figs. 2, 2a. — Yabe and Eguchi, 1942: 116–117, pl. 9, fig. 8. — Vaughan and Wells, 1943: 333, pl. 41, figs. 14, 14a. — Wells, 1964: 112. — Cairns, 1982: 22.
Crispatotrochus rubescens — Cairns, 1991: 15; — Cairns, 1994: 22, 51, pl. 22, figs. g–h. — Cairns and Zibrowius, 1997: 103–104, figs. 10a–c. —Cairns, 1999: 76–77. — Cairns et al. 1999: 21. — Cairns, 2004: 265, 279–280.
Material examined. Bathus 3 station CP 833, 2 (MNHN-Scl.2008-0041 [1], USNM 1115428 [1]).
Description. Corallum ceratoid, elongate, slightly curved, and flared distally. Pedicel robust ranging from 4.2 to 5.5 mm in diameter (PD:GCD = 0.26–0.31), expanding to a thin encrusting base. Largest specimen examined (USNM 1115428) 21 x 16.8 mm in CD and 37.2 mm in height. Costae more prominent (as low ridges) near calicular edge, fading to pedicel. Theca granular. Corallum white.
Septa hexamerally arranged in five complete cycles according to formula S1–2>S3>S4>S5, but largest specimen displays some rudimentary S6. S1–2 highly exsert, with sinuous vertical axial edges that fuse to columella. S3 four fifths width of S1–2 with slightly less sinuous inner edges. S4 three fourths width of S3, with less sinuous axial edges. S5 half width of S4. S6, if present, rudimentary and present only at calicular margin. Fossa of moderate depth, containing an elongate columella consisting of 4–9 slender, twisted elements.
Remarks. Among the species of Crispatotrochus that have 5 complete hexamerally arranged septal cycles (C. rubescens, C. foxi, and C. niinoi), all of which occur in temperate Pacific, C. rubescens is distinguished by having sinuous axial septal edges for S1 and S2, and costate theca at least near the calicular margin. One new record reported herein of C. rubescens (USNM 1115428) has 96 rudmentary S6, present only near calicular edge.
Type locality. Kai Islands, Banda Sea (5º49’15’’S, 132º14’15’’E), 236 m.
Type specimens. According to Cairns (1984) the holotype is lost.
Distribution. New Caledonia: 23º02.85’S, 166º58.23’E, 441– 444 m. Elsewhere: Wallis and Futuna; Vanuatu – Tanna; Australia – off Queensland; Philippines –Lubang Island, south of Negros (Bohol Sea), Sulu Archipelago (Sulu Sea); Indonesia – Kai Islands (Banda Sea), south of Tanimbar Islands (Arafura Sea), Sumba (Savu Sea); China – southern Formosa Strait (south China Sea); Japan – Sagami Bay and off Kushimoto (Honshu), Shikoku, and off Koshiki (Kyushu); Hawaii – Maui, Moloka‘i, O‘ahu, and Kaua‘i, and Nihoa, Blank, and Brooks Banks; Christmas Islands; 110– 634 m.