Amathia cf. gracilis ( Leidy, 1855 )

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 : 275

Amathia cf. gracilis ( Leidy, 1855)

( Fig. 17 )

Bowerbankia gracilis: Seo 2011: 33 , fig. 11 (cum syn., part).

Material examined. MBRBK 1707 . Seongsan port, Jeju Island. 33.4690° N, 126.9260° E, intertidal rocks, 8 May 2017.

Description. Colonies in this species group consist of a network of stolons with erect, tubular and distally and proximally tapering zooids budded from them at intervals ( Fig. 17A, C ). Thriving colonies often grow into tangled masses, clumps and tufts. Zooids elongate-oval sacs, rounded at base and distally, with squared to puckered round orifice when polypide retracted. Retracted and preserved zooids c. 0.400 mm long, 0.060 mm wide, attached singly or in clusters on narrow creeping stolon. Internal organs and musculature seen through transparent walls of freshly budded zooids, but older zooids often fouled by algae or sediment particles. Polypide with conspicuous rounded gizzard and tentacle crown of 8 evenly spaced tentacles ( Fig. 17A, B ). No reproduction noted in colonies collected in this study.

Remarks. Bowerbankia gracilis was originally described by Joseph Leidy (1855) from Rhode Island, USA, on the Western Atlantic seaboard where it is tolerant of reduced salinities and variations in temperature, occurring in estuaries and harbors and among fouling communities. It has been reported from many localities around the world, but some records may refer to other similar species. It has been reported from China (e.g. Liu et al. 2001), Japan, and Korea ( Seo 2011).

Distribution. Members of species group found almost worldwide in fouling and shallow water communities.

Figures

FIGURE 17. Amathia cf. gracilis (Leidy, 1855), Seongsan port, Jeju Island (MBRBK1707). A. Two expanded 8-tentacled tentacle crowns and introverts of zooids attached to the sides of a hole bored in an intertidal stone. B. Zooids of another colony, the one inside hole is flicking tentacle crown tentacles to capture food particles. C. Zooids of A. gracilis to lower right of small crisiid in upper left of image.