Suhius rubescentis (Liu in Liu, Yin & Ma, 2001 )

Min, Bum Sik, Seo, Ji Eun, Grischenko, Andrei V. & Gordon, Dennis P., 2017, Intertidal Bryozoa from Korea — new additions to the fauna and a new genus of Bitectiporidae (Cheilostomata) from Baengnyeong Island, Yellow Sea, Zootaxa 4226 (4), pp. 451-470 : 465

Suhius rubescentis (Liu in Liu, Yin & Ma, 2001)

( Figs 27–30 )

Hippoporella hippopus: Androsova 1959: 64 , pl. 2, fig. 11; Huang 1994: 616. (Non Smitt, 1868b). Hippothyris rubescentis Liu in Liu, Yin & Ma, 2001: 579 , pl. 44, figs 3, 4.

Material examined. MBRBKSP030—Jinchon-ri, Baengnyeong Island. Other material: Woosuk University collection—Baengnyeong Island: Hwadong (2 colonies), Junghwadong (54 colonies), Dumujin (7 colonies), Jinchon-ri (69 colonies), Gobongpo (10 colonies), Yeonhwa-ri (53 colonies); mostly on rocky substrata, but also on crustose coralline algae ( Clathromorphum ).

Description. Colony encrusting, unilaminar, up to 80 mm in maximum breadth, beige to orange in life. Autozooids more or less elongate-rectangular and somewhat parallel-sided to weakly elongate-pentagonal, arranged regularly in quincunx with distinct slightly raised margins. Orifice hoof-shaped, parallel-sided or nearly so, tending to be slightly wider proximad, the two parts of the orifice delimited by a pair of stout articular condyles that are slightly curved in a proximal direction. No oral spines. Frontal shield centrally imperforate, 6–10 areolar septular pores along each lateral margin, developing weak ribbing between the pores; this ribbing extending onto the frontal shield, converging near its center at one or more short tubercles or umbones that develop concurrently as loci of secondary calcification. Multiporous mural septula present in lateral walls. Ooecium relatively large and prominent, acleithral; the ectooecium initially smooth with 4–6 scattered pores, its surface rapidly becoming encroached upon by a thin layer of secondary calcification contributed by adjacent zooids, the boundaries between the contributions marked by thin raised lines; further calcification results in short tubercles and other irregularities. Avicularia adventitious, varying in shape, size and orientation. Autozooids in the zone of astogenetic repetition may lack avicularia or a lateral-oral avicularium may develop on one side of the orifice; this expands laterally away from the orifice to a thin, rounded rostral rim, the palatal foramen separated from the avicularian opesia by a very thin crossbar. In some zooids this avicularium may be replaced by a larger avicularium subjacent to the orifice; its rostrum is directed obliquely frontally and is acutely triangular with a slightly elevated tip; the crossbar is thin. In the zone of reproductive zooids, larger such avicularia develop on the frontal shield, proximal or centrally, and vary in orientation.

Measurements. ZL, 398–496 (448) µm; ZW, 221–342 (276) µm; OrL, 115–130 (124) µm; OrW, 121–139 (128) µm; AvL, 59–69 (64) µm/ AvW, 64–66 (65) µm (small rounded avicularium); AvL, 81–108 (95) µm/ AvW, 62–85 (76) µm (larger acute avicularium); OoL, 202–214 (209) µm; OoW, 249–267 (275) µm.

Remarks. Liu et al. (2001) described the ancestrula and early astogeny. The ancestrula is tatiform, with a subcircular opesia occupying two-thirds of the frontal area and surrounded by 10 marginal spines. Periancestrular zooids have 4–5 oral spines.

Hippoporidra daedala Gontar, 1982 from the Kurile Islands has features that may ally it with Suhius n. gen. Her line drawing of the species shows a similar office, frontal shield and placement of avicularia, but no fully formed ooecia. What she described as ‘triangular structures on the proximal surface’ (one illustrated) are apparently incipient ooecia in the process of forming.

Distribution. Liu et al. (2001) recorded this species from the coastal waters of China south of the city of Huangdao, north to the northern Yellow Sea ( Korea Bay), from at least 5 m to 60 m depth. [One of their datum points seems to be in error as the coordinates, well within Korean waters, do not coincide with the stated depth of 4 m.] Androsova (1959) reported it (as Hippoporella hippopus ) from the Qingdao area. It is not surprising that it should be found at Baengnyeong Island, where it is common intertidally.

Figures

FIGURES 27 – 30. Suhius rubescentis (Liu in Liu, Yin & Ma, 2001), n. gen., Junghwadong. 27, Differentiating zooids in linear series; scale bar, 400 µm. 28, Two different kinds of lateral-oral avicularia; scale bar, 200 µm. 29, Ovicellate ephebic zooids with well-developed secondary calcification; scale bar, 200 µm. 30, Newly formed ooecia showing the smooth pseudoporous ectooecium with encroaching secondary calcification from adjacent zooids; scale bar, 200 µm.