Copidozoum rhoae

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: 496-497

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Copidozoum rhoae

n. sp.

Copidozoum rhoae  n. sp.

(Figs 2–5)

Etymology. Honorific for Emeritus Professor Boon Jo Rho, in recognition of her valuable contribution to Korean bryozoology.

Material examined. Holotype: NIBRIV0000805880, unique colony found at Munseom Island, Seogwipo , Jeju Island, 24 December 2016, 20 m, on oyster shell, collected by Ho Jin Yang. 

Description. Colony encrusting, multiserial, unilaminar, white in dried state, small, up to 7 mm across. Autozooids suboval to inversely subpyriform, longer than wide, generally widest in proximal third. Gymnocyst smooth, fairly well developed in proximal third, rapidly tapering along lateral margins, typically not visible frontally in distal third of zooid. Opesia oval, broader in proximal half, bordered by moderate-sized smooth cryptocystal shelf proximally, this narrow around rest of opesia, rising to form distal rim of orifice. Periopesial spines 11–15, distal two pairs flanking orifice shortly bifid, angled obliquely frontalwards but not reaching zooidal midline, distalmost pair smaller than second pair; remaining periopesial spines arching across opesia and interdigitating above midline.

Avicularia subvicarious, broadly scimitar-shaped, rounded rostral tip curving toward adjacent ooecium, rim raised, sloping obliquely away to interzooidal furrow on each side; fairly extensive palatal shelf, mandibular pivots stout, backcurved, palatal-opesial foramina unequal on either side of mandibular pivots, larger on rostral side.

Ooecium prominent, not closed by autozooidal operculum, ectooecium membranous except for very narrow distobasal rim of calcification, endooecium granular-tubercular, often with rounded distal peak.

Mid-distal and distolateral pore-chambers present. Ancestrula not seen.

Measurements. ZL 151–292 (230) µm; ZW 141–178 (158) µm; OrL 114–151 (138) µm; OrW 78–110 (97) µm; AvL 143–182 (159) µm; AvW 57–91 (67) µm; OoL 98–136 (115) µm; OoW 111–144 (125) µm.

Remarks. Copidozoum rhoae  n. sp. resembles Pleistocene Copidozoum kikaijimense Kataoka, 1961  from Kikaijima, an island in the Ryukyu Archipelago, but has a shorter avicularium.

One other Copidozoum  species is known from Korea. It was first described from the Pleistocene of eastern Honshu as Amphiblestrum canui Sakakura, 1935a  , rediscovered alive from western Honshu ( Sakakura 1935b) and later transferred to Ellisina  ( Silén 1938, 1941). It clearly does not belong to either of these genera owing to the form of the ooecium (globular, with a wholly granular-tubercular ectooecium and only a very narrow basal rim of calcified ectooecium) and the avicularium (large, curved and interzooidal). Rho & Seo (1986) previously reported it from Korea’s South Sea. Here, we reassign it as Copidozoum canui  n. comb. It differs from C. rhoae  n. sp. in having a more roundly triangular opesia and a tapering avicularian rostrum.

Distribution. Korea: Jeju Island, 20 m depth.