Calloporina hayamiae Arakawa, 1995

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 : 507

Calloporina hayamiae Arakawa, 1995

(Figs 26, 27)

Calloporina sculpta: Nishizawa 1990: 119 , pl. 4, fig. 3. Non Calloporina sculpta Canu & Bassler, 1929 .

Calloporina hayamiae Arakawa, 1995: 98 , fig. 9A.

Material examined. Unique colony (NIBRIV00000805890), from Hajo Island, South Sea, 30 July 2016, 33 m, on oyster shell, collected by grab from RV Kuklipgongwon-yeoungu 1.

Description. Colony encrusting, multiserial, unilaminar, large, up to 77 mm across. Autozooids fairly regularly rhomboidal, rounded distally and proximally, more acute laterally, a little longer than wide. Lepralioid frontal shield with 12–17 conspicuous areolar-septular pores around margin, with slight ribbing between pores that converges to low frontal-shield ridges of irregular disposition. Orifice high-arched; weakly concave proximal margin with low, sloping condyles in corners. Oral spines 5–6, stout. Ascopore at some distance from orifice, incised, semi-lunate, very thin, lacking denticles.

Avicularia mostly single, on left or right sides of autozooids, less often paired, rarely absent; rostrum moderately long, acute, directed mostly obliquely distolaterally, tip often projecting just beyond lateral margin, crossbar well developed; half rostral length with palatal shelf, no opesial cryptocyst.

Developing ooecium with extensive membranous area of proximofrontal ectooecium that is calcified around periphery and has apical transverse rimmed cap; endooecium skeletally complex, initially with transverse creases proximofrontally and honeycomb of calcification frontally; as development proceeds, lateral calcification of ectooecium covers most of endooecium, leaving bean-shaped or bifenestrate window showing endooecial pits, distal of which is rimmed ectooecial cap, itself sometimes etched.

Well-developed basal pore-chambers at colony margin, two distolateral, one distal, each subdivided into paired chambers. Ancestrula not seen.

Measurements. ZL 388–524 (432) µm; ZW 295–551 (378) µm; OrL 87–108 (99) µm; OrW 91–110 (100) µm; AvL 101–158 (138) µm; AvW 39–67 (55) µm; OoL 137–166 (156) µm; OoW 153–186 (172) µm.

Remarks. Calloporina hayamiae was previously known only as a Pleistocene fossil from the Boso Peninsula, on the east coast of central Honshu, Japan. The characters of our material are identical to that described by Arakawa (1995), especially the distinctive semi-lunate ‘smile-like’ ascopore incised within sloping margins, and the form of the mature ooecium. Arakawa (1995) noted a range of 4–6 oral-spine bases. Calloporina hayamiae has not yet been reported from modern Japanese waters but it is highly likely that it will be discovered.

Distribution. Japan: Pleistocene, east-central Honshu. Korea: Jeju Island, 20 m depth.