"Flabellum knoxi Ralph and Squires, 1962
Flabellum knoxi Ralph and Squires, 1962, pp. 14, 15, pi. 7, figs. 1, 2.—Squires, 1964a, pp. 11, 12, 19, 20, pi. 1, figs. 4-6, pi. 2, fig. 7, pi. 3, figs. 3-5, pi. 4, figs. 1-4; 1969, p. 18, pi. 6, map 4.—Squires and Keyes, 1967, pp. 26, 27, pi. 5, figs. 1, 2.—Zibrowius, 1974b, p. 18.
Description. Corallum flabellate, compressed; angle of lateral edges typically 135°-180°, inclination of lateral faces 30°-35°. Lateral edges usually rounded, not carinate. Base of pedicel small, 2.5-3.0 mm in diameter; height about 5-10 mm. One of largest specimens (holotype) 112 x 55 mm in CD and 65 mm tall. Theca very thin and fragile, bearing thin, incised striae, one corresponding to each septum. Closely spaced, transverse growth lines form chevrons, peaking at each stria. Theca uniformly reddish-brown, entirely white, or bearing reddish-brown stripes corresponding to each septum, Darker, broader stripes corresponding to major septa. Calice entire, not lacerate, and strongly arched. Up to 348 thin, fragile septa per calice, arranged in three size groups. Largest septa (primaries) extending to columella and having very
sinuous lower inner edges. Between each primary a secondary, usually smaller (three fourths of a size of primary) but in larger specimens almost reaching columella. A much smaller tertiary septum, occurring between each primary and secondary, rarely extending more than halfway to pedicel. In larger specimens, rudimentary quaternaries present near calicular edge. Upper septal margins invariably broken, but septa do not appear to be exsert. Very small, pointed granules arranged in widely spaced rows parallel to septal margins. Columella long and slender (1.5-2.2 mm wide) but very sturdy, often remaining intact after surrounding septa have been broken away (Plate 13, fig. 7). Columella composed of loose fusion of convoluted lower inner edges of primary septa.
Remarks. The living coral appears to remain in the upright position, as is concluded from the presence of attached filter feeders on both lateral faces. Squires (1964a) suggested that it maintains this orientation by sinking its pedicel into soft mud in areas of low-velocity current. Coralla are rarely attached, but if they are, to sand or pebbles, which are usually incorporated into the pedicel. According to Squires (1974a), specimens that are accidentally knocked to the prone position will produce recurved (angle of lateral edges up to 250°) and reflexed coralla in an effort to right the upper half of the polyp relative to the substrate.
The variation in thecal striping and color of F. knoxi is similar to that found in F. pavoninum atlanticum Cairns, 1979. In general, the intensity of striping correlates with age (Squires and Keyes, 1967), the younger specimens having the more pronounced stripes.
Discussion. F. knoxi is extremely similar and may be identical to F. magnificum Marenzeller, 1904, from off Sumatra. The type of the latter species was not examined.
Material. Eltanin sta. 1398 (2), USNM 47496; sta. 1989 (7), USNM 47493. NZOI sta. A-898 (5), USNM 47495; sta. D-6 (2), USNM 47494; sta. D-175 (4), USNM 47492; sta. D-176 (15), USNM 53379; sta. D-177 (6), USNM 53378; sta. D-179 (2), USNM 53380; sta. D-207 (8), USNM 53376.
Types. The holotype is deposited at the Canter bury Museum, Christchurch, New Zealand. Type-locality: Chatham Rise; 402-512 m.
Distribution. Chatham Rise; Campbell Plateau; off Macquarie Island (Map 9). Depth range: 201- 914 m." Cairns 1982, pp. 42-44, Plate 13, figs. 4-7.
