Soft substratecrinoids (Crinoidea: Comatulida) andtheir macrosymbionts in Halong Bay (North Vietnam) Author Es, Mekhova Author Ta, Britayev text Raffles Bulletin of Zoology 2015 2015-10-09 63 438 445 journal article 10.5281/zenodo.5385536 2345-7600 5385536 39EA82B2-4BF4-41AB-9B25-D51A3F0D1EC1 Comatula cf. solaris Lamark, 1816 ( Fig. 2a ) Comatula solaris Lamark 1816: 533 ; Clark AH, 1921: 233 pl.1 figs. 960–962; Clark & Rowe, 1971 : pp. 6–7, 14, pl. 1 figs. 7, 8; Rowe & Gate, 1995: 148; 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 – 15 specimens ; St. 3, 4–5 m depth , 1 May 2012 – 3 specimens ; St. 7, 0–3 m depth , 4 May 2012 – 3 specimens ; St. 8, 1–10 m depth , 6 May 2012 – 4 specimens . Table 1. List of sampling stations with geographical coordinates, sampling dates, substrate, and comatulids species collected.

Station No	Coordinates	Data	Depth (m)	Substrate	Crinoids (individuals number)
1	N 20º 46’ 02.5’’ E 107º 05’ 48.0’’	30 April 2012	1–4	muddy sand	Amphimetra tessellata (1) Comatula solaris (1)
2	N 20º 47’ 23.1’’ E 107º 06’ 31.9’’	30 April 2012	10–15	muddy sand with shell fragments	Amphimetra tessellata (2) Comatula solaris (15) Oligometra serripinna (3) Zygometra comata (1)
3	N 20º 47’ 05.4’’ E 107º 06’ 06.2’’	01 May 2012	4–5	dead coral reef, muddy sand with fragments of corals	Comatula solaris (3)
4	N 20º 44’ 29.8’’ E 107º 04’ 05.9’’	01 May 2012	4–6	dead corals	No comatulids
5	N 20º 47’ 22.7’’ E 107º 06’ 13.0’’	03 May 2012	1–5	octocorals on silty-sand (1–3 m), silt (3–5 m)	No comatulids
6	N 20º 45’ 26.7’’ E 107º 04’ 41.6’’	03 May 2012	1–6	scleractinian and octocorals	Oligometra serripinna (1)
7	N 20º 46’ 18.6’’ E 107º 07’ 42.0’’	04 May 2012	0–3	octocorals on the muddy sand, muddy sand	Comatula solaris (3)
8	N 20º 45’ 57.4’’ E 107º 07’ 43.3’’	06 May 2012	1-10	scleractinian and octocorals, muddy sand	Comatula solaris (4) Capillaster gracilicirrus (1) Oligometra serripinna (5)

Table 2. Species list of crinoids of the Gulf of Tonkin with notes on their dial activity and preferred substrates in the Gulf. D – diurnal species, N – nocturnal species, UN – activity and substrate is unknown in the Gulf. Species reported for the first time from the Gulf and the coast of Vietnam marked by bold and asterisk, respectively.

Crinoid species	Dial activity	Substrate	References
Amphimetra tessellata	D	muddy sand	This report
Capillaster gracilicirrus *	N?	muddy sand	This report
Cenometra bella	D	on gorgonians	Guryanova, 1972
Comaster schlegelii	UN	UN	Guryanova, 1972
Comatula solaris	UN	UN muddy sand	Guryanova, 1972 , this report
Metacrinus superbus	UN	UN	Guryanova, 1972
Metacrinus sp.	UN	UN	Guryanova, 1972
Oligometra serripinna *	D	on gorgonians	This report
Zygometra comata	D	muddy sand	Ho, 1994

Coloration. Uniformly brown with a pinkish tinge, red in alcohol. Measurements. Ten arms 80–120 mm in length: 9–16 cirri 7–12 mm in length. Taxonomic remarks. Genus Comatula consists of seven species with four having cirri ( Messing, 2015 ). Cirri arranged in one row around centrodorsal, numbers usually exceeding 10 ( Fig. 2 ). Number of cirrals usually less than 16. P1 and P2 have long combs with 20–26 confluent teethes. P3 and following pinnules without combs. Second and third basal segments of P2 with small ridge-like extensions on the aboral sides. Five of 10 arms without ambulacral grooves. These features are in accordance with diagnoses of C. solaris provided by Messing (2015) . Closely related species, C. pectinata and C. tenuicirra have less number of cirri on 1–2 interradial corners. Ecological notes. Common. Found both solitarily and in groups of three to seven individuals, on soft ground in burrows, recesses, or under dead bivalve shells; depth range 1–15 m . Probably nocturnal; during the day arms are usually folded. In some individuals arms were extended but did not form a filtration fan. Reported previously on soft substrate under a small rock ( Messing et al., 2006 ). RAFFLES BULLETIN OF ZOOLOGY 2015 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. Symbionts. Polychaetes Hololepidella cf. laingensis Britayev, Doignon & Eeckhaut, 1999 , Myzostoma cf. fissum Graff, 1884 ; ophiuroid Ophiomaza cacaotica Lyman, 1871 ; gastropod Eulimidae gen. sp.; Amphipoda gen. sp. Distribution. Vietnam , China , Singapore (Lane at al., 2000), North Australia , West India ( Clark & Rowe, 1971 ; Messing, 2014).