Onychocella subsymmetrica Canu & Bassler, 1929

Yang, Ho Jin, Seo, Ji Eun & Gordon, Dennis P., 2018, Sixteen new generic records of Korean Bryozoa from southern coastal waters and Jeju Island, East China Sea: evidence of tropical affinities, Zootaxa 4422 (4), pp. 493-518 : 498-499

Onychocella subsymmetrica Canu & Bassler, 1929

(Figs 8, 9)

Onychocella angulosa: Harmer 1926: 256 , pl. 16, figs 8, 9 (cum syn.); Silén 1941: 61; Mawatari 1965: 603, fig. 59a, b. Non Cellepora angulosa Reuss, 1848 .

Onychocella subsymmetrica Canu & Bassler 1929: 124 ; Kataoka 1961: 233, pl. 28, fig. 3.

Material examined. Four colonies (NIBRIV0000805882, MBRBKW3–5), from off South Sea Islands (Soan, Hajo), 33–37 m, collected by Bum Sik Min, and at Munseom Island , Jeju, collected by Ho Jin Yang .

Description. Colony encrusting, multiserial, unilaminar, up to 17 mm across, color light brown to chestnut brown when dry. Autozooids roundly subhexagonal to subpentagonal, longer than wide. Cryptocyst granular, entirely sunken below level of zooidal rim, surrounding opesia on all sides but most extensive as shelf that occupies proximal half of zooid frontal skeleton. Opesia weakly campanuliform, as wide as long or a little wider, sides angled obliquely distad, proximal rim straight or weakly convex. Opercular sclerite inversely U-shaped, parallel-sided, with short lateral flanges. Gymnocyst absent, manifested in some zooids as small boss or knob-like tubercle at proximal end(s), or occurring as narrow smooth distal rim that can be enlarged to form conspicuous smooth eminence.

Avicularium vicarious, asymmetrical, rostrum elongate, acute, torqued towards adjacent autozooid; no protruding mandibular pivots but a pair of small slits in margin near widest point of avicularium; combined rostral foramen-opesia elongate, rounded distad, tapering proximad, completely surrounded by granular palatal shelf and cryptocyst. Mandible winged on outer side only, rachis triangular proximally, tapering as setiform axial sclerite.

Female zooid not identified with certainty, but a large zooid seen in one colony with dimorphic roundly triangular opesia and a distal structure that appeared to be an ooecium.

Measurements. ZL 263–434 (338) µm; ZW 192–295 (253) µm; OpL 68–112 (88) µm; OpW 99–149 (116) µm; AvL 228–352 (303) µm; AvW 153–181 (170) µm.

Remarks. Onychocella angulosa ( Reuss, 1848) , first described from the European Tertiary, has been accorded a very large geographical range (e.g. Harmer 1926). Hayward (1974) illustrated by SEM Recent material from the Aegean Sea that he attributed to this species and it certainly resembles what Harmer (1926) described from the Indo-Pacific. On the other hand, Canu & Bassler (1929) described from the Philippines a very similar species, O. subsymmetrica , which shows the type of dimorphic zooid that we have encountered. Of this morph, Canu & Bassler (1929) wrote: “As in all the species of this genus there are larger opesia [sic] (B) producing a false cellular dimorphism.” Given the suspiciously large temporal and geographic range of Reuss’s species, we accordingly attribute our material to O. subsymmetrica rather than to O. angulosa .

Distribution. NE Indonesia, Philippines, South China Sea, Japan. Depth range 16– 439 m. Korea: Seogwipo, Jeju Island, 20 m depth.