Pleuromucrum granulatum (Liu in Liu, Yin & Ma, 2001 )

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 : 510-512

Pleuromucrum granulatum (Liu in Liu, Yin & Ma, 2001)

( Figs 35, 36)

Allorhynchozoon granulatum Liu in Liu, Yin & Ma, 2001: 709 , 822, pl. 80, figs 4–6.

Pleuromucrum granulatum: Di Martino & Taylor 2017: 793 .

Material examined. Unique colony (NIBRIV0000805894), from Munseom Island , Seogwipo, Jeju Island, on oyster shell collected by Ho Jin Yang.

Description. Colony encrusting, multiserial, small, up to 5.4 mm across, unilaminar, but with some frontal budding in older, mature colonies. Autozooids lacking clear boundaries except at growing edge, generally as wide as long, but variable. Lepralioid frontal shield porcellanous, with only 1–3 small areolar-septular pores visible in each zooid; pointed or ridge-like suboral umbo. Orifice hoof-shaped, widest proximally; semicircular anter with smooth rim, delimited by stout angular condyles from broad, shallow poster. Six long oral spines.

Avicularia adventitious, paired, latero-oral, directed distolaterally; rostrum and mandible acute, with palatal shelf occupying half rostrum length, tapering past sides of roundly triangular rostral foramen; crossbar thin, opesial foramen semicircular, with very narrow smooth cryptocystal rim. Two or three additional such avicularia typically also develop on frontal shield, directed laterally and proximolaterally.

Ooecium prominent, glabrous, with broad, high opening, allowing mid-distal pair of spine bases to be seen; apex smooth, sometimes with small point; rarely an adventitious avicularium associated with ooecium.

Interzooidal communications via mural septula. Ancestrula not seen.

Measurements. ZL 199–275 (237) µm; ZW 176–298 (227) µm; OrL 64–78 (71) µm; OrW 51–69 (61) µm; AvL 36–59 (49) µm; AvW 19–31 (23) µm; OoL 77–132 (96) µm; OoW 112–188 (152) µm.

Remarks. Di Martino & Taylor (2017) have shown that Pleuromucrum Vigneaux, 1949 is a senior subjective synonym of Lifuella Gordon & d’Hondt, 1997 and Allorhynchozoon Liu in Liu, Yin & Ma, 2001 . Originally described from Hong Kong, Pleuromucrum granulatum is highly distinctive when it has the full complement of avicularia on the zooids. It is similar to Pleuromucrum lepralielloidum Liu in Liu, Yin & Ma, 2001 , but that species has a much shallower poster.

Distribution. China: Hong Kong, 4 m depth. Korea: Jeju Island, 20 m depth.

Figures

FIGURES 33, 34. Stephanollona boreopacifica n. sp., holotype, Munseom Island. 33, ovicellate orifice; 34, five-spined orifice. FIGURES 35, 36. Pleuromucrum granulatum (Liu in Liu, Yin & Ma, 2001), Munseom Island. 35, zooids, mostly ovicellate, near colony margin; 36, ooecia and avicularia. Scale bars: 33, 36, 100 µm; 34, 50 µm; 35, 500 µm.