Dendostrea crenulifera ( Sowerby, 1871 )

Lam, Katherine & Morton, Brian, 2004, The Oysters Of Hong Kong (Bivalvia: Ostreidae And Gryphaeidae), Raffles Bulletin of Zoology 52 (1), pp. 11-28 : 23-24

Dendostrea crenulifera ( Sowerby, 1871)

Common name: Crenulate oyster ( Figs. 5 D-F)

Ostraea crenulifera Sowerby, 1871: 67 , Pl. 27, Figs. 67a, b. Dendostrea crenulifera Torigoe, 1981: 338-339 , Pl. 28; Hayami,

2000: 926-927, Fig. 12.

Material examined. – Syntypes, two dry shells (largest 36.71 by 21.39 mm)( NHM 1879.2.26.242), ‘‘ Red Sea’ ’, coll. Lombe-Taylor, no date .

Description. – Shells are <30mm in dorso-ventral height and of variable form, depending on the substratum. Attachment area varies among individuals. Shell margins usually crenulated: hence the name ‘ crenulifera ’. Some individuals have deep and regular plications whereas others have poorlydeveloped ones along the margins. The right valve is usually heavily eroded such that the white, chalky calcareous shell layer is exposed. Thin, reddish brown radial lines on the right valves can be observed on uneroded specimens. The left valve is also white. Small, rounded chomata are present either along the posterior and anterior margins or along the entire shell margin. The hinge line is straight and short. Ligament area is short. The interior varies from lustrous white to pale green. The green-tinted interior of the shell is a particular character of this species. The adductor muscle scar is colourless, halfmoon shaped or reniform. It is positioned in the posterior ventral third of the pallial area.

Distribution. – Dendostrea crenulifera occurs on subtidal (> 7m) boulders or is associated with hard corals in the eastern waters of Hong Kong such as Hoi Ha Wan. It also attaches to the walls of the marine cave at Conic Island. This species is probably stenohaline since it is not recorded from the western side of Hong Kong where salinities are much lower. This species is distributed in the Red Sea and from Japan south into the Indo-West Pacific.

Remarks. – Some authors consider Dendostrea crenulifera to be a synonym of Saccostea mordax and Pustulostrea tuberculata Lamarck, 1804 . D. crenulifera , however, can be distinguished from these two species in having a green-tinted interior to the shell and occurring in subtidal waters.

Figures

Fig. 5. Dendostrea and Ostrea from Hong Kong showing external and internal views of the right valves and the internal views of left valves. A-C. D. folium (SBMNH 345717). D-F. D. crenulifera (NHM 20030493). G-I. O. denselamellosa (AM 108985). Scale bar = 20 mm.