Amphimetra tessellata ( Müller, 1841 )

Es, Mekhova & Ta, Britayev, 2015, Soft substratecrinoids (Crinoidea: Comatulida) andtheir macrosymbionts in Halong Bay (North Vietnam), Raffles Bulletin of Zoology 63, pp. 438-445 : 442

Amphimetra tessellata ( Müller, 1841)

( Fig. 2c )

Alecto tessellata Müller, 1841: 179–189

Amphimetra tessellata discoidea Clark AH, 1909 :

Amphimetra discoidea Clark AH, 1911: 435–467

Amphimetra tessellata Clark AH, 1921: 128 ; Mekhova & Britayev, 2012: 461–462; Messing, 2015.

Material. South China Sea , Halong Bay, Katba Is, St. 1, 1–4 m depth, 30 April 2012 – 1 specimen ; St. 2, 10–15 m depth, 30 April 2012 – 2 specimens.

Coloration. White, becoming purple in alcohol. It differs from our specimens from Nhatrang Bay having bright-brown coloration ( Mekhova & Britayev, 2012).

Mesurements. Ten arms 70–140 mm in length, 21–30 cirri 23–31 mm in length.

Taxonomic remarks. Morphology of this specimen is in accordance with the diagnoses of A. tessellata provided by Messing (2015). It differs by a small synarthrial tubercle on IBr2 from closely related species, A. ensifer ( Clark AH, 1909) having a synarthrial tubercle on IBr2 developed as a tall conical process ( Messing, 2015). Our specimens slightly smaller than that found in Nhatrang Bay ( Mekhova & Britayev, 2012).

Ecological notes. Rare. Found solitary, 4–15 m depth, on muddy sand. Diurnal, during the day fully exposed with the arms arranged in a parabolic filtration fan. Reported earlier clinging to algae, rocks and boulders ( Messing et al., 2006; Mekhova & Britayev, 2012).

Symbionts. Polychaetes Hololepidella cf. laingensis , Myzostoma cf. fissum; ophiuroid Ophiomaza cacaotica ; Amphipoda fam. et gen. sp.

Distribution. Japan, China, Vietnam, Philippines, Indonesia, Thailand, Australia, Fiji, India. ( Clark & Rowe, 1971; Lane et al., 2000; Mekhova & Britayev, 2012; Messing, 2015). First record from the Tonkin Gulf.

Figures

Fig. 2. Proximal ray articulations, branching patterns and arrangement of cirri: a, Comatula purpurea; b, Capillaster gracilicirrus; c, Amphimetra tessellata. IIBr and IIIBr division series. Scale bar = 1 cm.