Phonicosia crena n. sp.

(Figs 17, 18)

Material examined. Holotype: NIBRIV0000325936, RV Kuklipgongwon-yeoungu 1 station I2, 34.2721° N, 126.7920° E, 30 July 2016, 27 m, southeast of Wan Island (Wando) . Paratype: NIBRIV0000711265, Kuklipgongwon-yeoungu 1 station I3, 34.1585° N, 126.7689° E, 29 July 2016, 42 m, west of Cheongsan Island (Cheongsando).

Etymology. Latin, crena, f., notch, rounded projection (Brown 1956), alluding to the notched suboral umbo; used as a noun in apposition.

Description. Colony encrusting, unilaminar, up to 17 mm diameter. Autozooids more or less elongatehexagonal, narrowing distally and proximally, generally widest about midlength. Frontal shield smooth, with a conspicuous arcuate prominence just distal of the midpoint of the shield. A continuous line of closed pseudopores around the entire margin of the zooid except mid-distally, with additional such pseudopores from each corner of the orifice to near the widest point of the zooid, c. 30 pseudopores in total. Orifice high-arched, curving proximal with lateral margins becoming parallel. ‘Shoulders’ of orifice horizontal, bearing a long, narrow condyle, proximal to which is a parallel edge of minute denticulations on the oral rim; sinus small, U-shaped. 6 stout oral spines. Avicularia not seen. Ooecium hyperstomial, globular, acleithral, occupying most of the proximal half of the distal zooid; the ectooecium wholly membranous, the calcified endooecium with numerous minute pits everywhere except apically; 4 oral spines retained in ovicellate zooids. Basal pore-chambers present, one on each distolateral angle and one mid-distally.

Measurements. ZL 332–469 (380) µm, ZW 232–347 (281) µm; OL 73–86 (81) µm, OW 69–78 (74) µm; OoL 163 µm, OoW 202 µm.

Remarks. Phonicosia circinata (MacGillivray, 1869) from Australia has a frontal prominence but its sides continue to the corners of the orifice, creating a shallow concave bowl-like area; pseudopores are fewer (c. 20) and proportionally larger, and occasional frontal avicularia are present. Putative P. circinata from Japan (Hirose 2010) lacks the frontal-shield prominence, has supplementary pseudopores distributed more proximally, its spine bases are more widely separated, with an intervening pseudopore behind each pair, and the sinus is longer; it represents an undescribed species.

Distribution. Korea: South Sea coasts; 27–42 m on hard substrata.