Alcyonidium pulposum, Seo & Chae & Winston & Zágoršek & Gordon, 2018

Seo, Ji-Eun, Chae, Hyun Sook, Winston, Judith E., Zágoršek, Kamil & Gordon, Dennis P., 2018, Korean ctenostome bryozoans-observations on living colonies, new records, five new species, and an updated checklist, Zootaxa 4486 (3), pp. 251-283 : 258

Alcyonidium pulposum n. sp.

( Fig. 4 )

Etymology. Latin pulposu s, fleshy, alluding to the fleshy form of the colony.

Material examined. Holotype: MBRBKH5, Yeonhwa-ri , Baengnyeong Island, 37.9461° N, 124.6267° E, intertidal, 18 May 2017 . Paratype: MBRBKP5, same data as holotype .

Description. Colony forming large, rubbery gelatinous creamy-yellow-brown masses that develop bulbous lobes of varied breadth and projecting irregular branches from encrusting base on algal stems or other cylindrical substrata ( Fig. 3A ); growth extending up to 14–15 cm long along stem. Zooids erect, irregular in size and shape, oval to hexagonal, frontal surface flat to slightly convex, with small round orifice that forms a little papilla when closed; zooid wall somewhat translucent, so that whitish shape of polypide can be discerned in deep body of cystid ( Fig. 4B, C, E ). Beneath outer layer of autozooids is firm gelatinous core that resists being cut ( Fig. 4F ). Zooid length, mean 0.363 mm (range 0.306–0.393, N = 6); zooid width, mean 0.258 mm (range 0.216–0.306, N = 6), orifice diameter, mean 0.087 mm (range, 0.072–0.208 mm, N = 6)). Kenozooids abundant ( Fig. 4B–D ). Some zooids contained clusters of yellow eggs or embryos ( Fig. 4B, C ).

Remarks. None of the colonies collected expanded while observed, so that polypide characters could not be noted. The species is similar to Alcyonidium bullitum n. sp. in the presence of abundant kenozooids, but these are larger relative to zooid size than in A. bullitum This species shows similarities to Alcyonidium diaphanum ( Hudson, 1778) from the Northeast Atlantic, but the lobes of the Korean species are larger and more rounded. Its closest relative may be Alcyonidium diaphanum alcilobatum d’Hondt & Mawatari, 1986 from Japanese Pacific localities and considered by them to be a new subspecies because of its geographic isolation from European populations. Its lobes are thinner and more leaf-like than those of A. pulposum n. sp., as shown in their paratype and holotype specimens (d’Hondt & Mawatari 1986, pl. 1, figs 1, 2). Colonies of A. pulposum n. sp. also lacked the small projecting bumps of incipient lobes seen in mature Belgian colonies of A. diaphanum illustrated by De Blauwe (2009, p. 43, figs 15, 16).

Distribution. Yellow Sea: Yeonhwa-ri, Baengnyeong Island, where subtidal colonies were washing up in the surf zone.

Figures

FIGURE 3. Alcyonidium bullitum n. sp., Junghwadong, Baengnyeong Island. A. Very young colony encrusting sea grass with tentacle crowns expanded (MBRBKP4). B. Large multilayered colony enveloping a crab from deeper water, including its eye (BKF1). C. Another view of seagrass colony in A. D. Preserved rock-encrusting colony showing position of retracted polypides (BKF1). E. SEM image of dried surface of colony from enveloped crab, showing area with protruding orifices and tips of tentacle sheaths of many autozooids (BKF1). F. Part of crab-encrusting colony surface with mostly kenozooids, some still with bubble-like frontal membranes, others collapsed (BKF1). Scale bars: A, C = 0.50 mm; D = 0.60 mm; E, F = 0.10 mm.

FIGURE 4. Alcyonidium pulposum n. sp., Yeonhwa-ri, Baengnyeong Island (MBRBKH5). A. Whole live colony. B. Close-up of branch tip showing thick side walls of zooids and yellow clusters of embryos. C. View of a larger bulbous area of the colony, again showing zooids and embryo clusters. D–F. Compound-microscope images. D. Part of colony surface showing very thick lateral walls and small oral papillae. E. Several more zooids showing thick lateral walls, small orifices. F. Two zooids at higher magnification to show very thick wall structure. Scale bars: B, C = 1 mm; D, E = 0.36 mm; F = 0.25 mm.