Colochirus quadrangularis Troschel, 1846

O’Loughlin, P. Mark, Harding 1, Caroline & Paulay, Gustav, 2016, The sea cucumbers of Camden Sound in northwest Australia, including four new species (Echinodermata: Holothuroidea), Memoirs of Museum Victoria 75, pp. 7-52 : 18-22

Colochirus quadrangularis Troschel, 1846

Table 1 ; appendices 1, 2; figures 1, 7, 8, 9

Colochirus quadrangularis Troschel, 1846: 64–66 (non Holothuria quadrangularis Lesson, 1830: 90–91 , pl. 31 fig. 1).— Théel, 1886: 81–82, 120–121, pl. 6 fig. 7, pl. 14 figs 7, 8.— Erwe, 1913: 353–355, fig. 2a–g.— Ekman, 1918: 21–26, pl. 1 figs 7–10, pl. 3 figs 13–15.— Panning, 1949: 446–447, figs 46, 47.— Liao & Clark, 1995: 474–475, fig. 286.—Rowe (in Rowe & Gates), 1995: 272–273.

Colochirus coeruleus Semper, 1867: 59 , pl. 11 fig. 1, pl. 13 fig. 18 (synonymy by H. L. Clark 1946).

Colochirus jagorii Semper, 1867: 60 .— Panning, 1971: 42 (type locality Singapore; synonymy by Rowe (in Rowe & Gates) 1995).

Colochirus tristis Ludwig, 1875: 87–88 (type locality Zanzibar; synonym of Colochirus jagorii by Panning 1971).

Pentacta quadrangularis .—H. L. Clark, 1946: 391.— Cannon & Silver, 1986: 30.

Pentacta coerulea .—H. L. Clark, 1932: 227.—H. L. Clark, 1938: 449–450, pl. 16 fig. 4.

Pentacta jagorii .—H. L. Clark, 1932: 228–229.—H. L. Clark, 1946: 391–392.

Pentacta coerulea var, rubra H. L. Clark, 1938: 451, pl. 16 fig. 5 (single specimen from Broome, NW Australia)

Type locality. Coast of Malacca (southern region of the Malay Peninsula, near Singapore) .

Material examined. Singapore, Johor Strait , dredge, channel between Beting Bronok and Chek Jawa channel, 1.41 103.98 1.5–2.4 m, mud, coll. Tan Koh Siang et al., 29 Jun 2011, NMV F210388 (1) (former registration ZRC.ECH.0208; donated to Museum Victoria); west end of Jurong island (composite new island), 1.22 103.67 23.1–24.4 m, dredge, rock, sand and mud, coll. Lim Swee Cheng et al., 19 Dec 2013, NMV F210389 (1) (former registration SEA –3046; donated to Museum Victoria) .

Northwest Western Australia, Kimberley Region , Camden Sound, WAMSI 1.1 .1, RV Solander , sled, site no SOL_107, WAM station no 1, barcode 10000001, from -15.514826 124.183111 46 m to -15.514503 124.183774 45 m, 14 Mar 2015, WAM Z89014 (1) ; RV Solander , sled, site no SOL_60, WAM station no 9, barcode 10000582, from -15.311436 124.162869 42 m to -15.311705 124.162473 42 m, 16 Mar 2015, WAM Z89015 (1) ; RV Solander , sled, site no SOL_60, WAM station no 9, barcode 10000647, from -15.311436 124.162869 42 m to -15.311705 124.162473 42 m, 16 Mar 2015, WAM Z89016 (1) ; RV Solander , sled, site no LIN_36, WAM station no 17, barcode 10001114, from -15.220444 124.320894 50 m to -15.220159 124.320648 50 m, 18 Mar 2015, WAM Z89017 (5) ; RV Solander , sled, site no SOL_32, WAM station no 19, barcode 10001331, from -15.253592 124.203038 45 m to -15.253318 124.202302 45 m, 19 Mar 2015, WAM Z89018 (6) ; RV Solander , sled, site no SOL_56, WAM station no 20, barcode 10001420, from -15.376537 124.192773 35 m to -15.376196 124.192071 35 m, 19 Mar 2015, WAM Z89019 (1) ; RV Solander , sled, site no SOL_84, WAM station no 21, barcode 10001560, from -15.414697 124.059193 36 m to -15.415001 124.059918 36 m, 20 Mar 2015, WAM Z89020 (1) ; RV Solander , sled, site no SOL_24, WAM station no 23, barcode 10001767, from -15.406428 124.125928 42 m to -15.406937 124.125369 42 m, 20 Mar 2015, WAM Z89021 (1) ; RV Solander , sled, site no SOL_160, WAM station no 25, barcode 10001971, from -15.428534 124.273164 17 m to -15.428908 124.273525 17 m, 21 Mar 2015, WAM Z89022 (2) ; RV Solander , sled, site no SOL_109a, WAM station no 33, barcode 10002500, from -15.711677 124.2303 25 m to -15.711054 124.229793 25 m, 23 Mar 2015, WAM Z89023 (1) ; RV Solander , sled, site no SOL_73, WAM station no 38, barcode 10002692, from -15.945442 124.366373 29 m to -15.945268 124.367171 28 m, 25 Mar 2015, WAM Z89024 (1) ; RV Solander , sled, site no SOL_69, WAM station no 41, barcode 10002871, from -15.747648 124.146502 43 m to -15.747285 124.14634 43 m, 26 Mar 2015, WAM Z89025 (1).

Joseph Bonaparte Gulf , cruise SOL 4934, station 33, sample 29024, -11.65 129.83 24 m, NMV F201791 (11) (tissue code MOL AF 1516 ); NMV F173258; NMV F173259; NMV F173260; NMV F173261; NMV F201781; NMV F201782; NMV F201788; NMV F201789; NMV F201790; NMV F201792; NMV F203004

Other Northern Australia, NMV F95253 ; NMV F95254 ; NMV F95255 ; NMV F95256 ; NMV F112191; NMV F112192; NMV F113573; NMV F113574; NMV F113575; NMV F113576; NMVF113577; NMVF113578; NMV F113579; NMV F113580; NMV F113581; NMV F149742.

Great Australian Bight, NMV F113582; NMV F199464.

Description. Body quadrangular in section, slightly tapered towards oral and anal ends, anal end slightly upturned, preserved body (excluding tentacles) up to 98 mm long, body surface with tessellated appearance or smooth; body and papillae firm, densely packed with ossicles; dorsal and ventro-lateral radii slightly raised, each with about 12 conical papillae in irregular zig-zag rows, papilla lengths variable up to about 10 mm long, papillae variably straight to curved, surmounted by tube feet ventro-laterally and sometimes dorsally, anterior and posterior ventral radii all with papillae; dorsal and lateral inter-radii slightly depressed, variably with or lacking scattered short conical or wart-like protuberances, lacking tube feet; 5 anterior oral valves, each with a terminal papilla and sometimes 1 or 2 additional papillae; 5 inner anal scales, some small peri-anal papillae, 5 longer proximal anal radial papillae; 10 dendritic tentacles, ventral 2 smaller; calcareous ring plates not forked posteriorly and lacking posterior prolongations; tube feet in discrete bands on ventral radii, each band about 4 wide, discrete inter-radii usually lacking tube feet, ventral inter-radii similar in width to the radial bands of tube feet.

Intergrading ossicle forms of dorsal mid-body wall (from NMV F210388):

1. on body wall surface, irregular oval to rounded-rectangular shallow bowls, long margins sometimes indented, four large central perforations, usually four small corner perforations, sometimes additional smaller marginal perforations, rim variably smooth or with fine knobs or fine blunt spines, bowls with or lacking bridges across rim, bowls up to rarely 56 µm long;

2. outer body wall, abundant rounded-rectangular to oval to irregular shallow bowls, four large central perforations, smaller peripheral perforations, one short or long margin prominently spinous, bowls variably partly bridged or not, up to 80 µm long;

3. inner body wall, some rounded-rectangular to oval shallow bowls, 4 large central perforations, smaller peripheral perforations, margin smooth, up to 96 µm long, sometimes partly bridged;

4. inner body wall, shallow bowls bridged on one side to create smooth, hollow irregular ellipsoids, up to 88 µm long;

5. inner body wall, shallow bowls, frequently thick-walled, bridged to create an upper surface and hollow ellipsoid, and inner-bridged irregular ellipsoids, not hollow, typically up to 88 µm long, rarely up to 136 µm long, some becoming enlarged and inter-grading with multi-layered scales;

6. underlying, multi-layered plates (scales), irregularly round to oval, up to at least 1.6 mm across/long.

Tentacle ossicles (from NMV F210388) elongate, thick, smooth, perforated rod-plates, curved and bent, up to 440 µm long; fine distally perforate rods; rosettes, up to 96 µm long.

Tube feet ossicles (from NMV F210389) endplates, uniform slightly irregular perforations, 400 µm diameter; endplate support rod-plates, narrow to elongate oval, to rounded triangular, smooth or knobbed, curved and bent, up to 272 µm long; spinous-edge bowls, variably bridged, as in dorsal body wall; shallow small bowls, variably knobbed, as in dorsal body wall; shallow larger bowls, margin and surface knobbed, two large and two smaller central perforations, smaller peripheral perforations, up to 88 µm long; hollow and inner-layered irregular ellipsoids as in dorsal body wall.

Live colour: radii and papillae variably red; dorsal and lateral inter-radii variably greenish; ventral inter-radii pale green; dendritic tentacles ends red; tentacle trunks greenish yellow with dark brown to black flecking; ventral tube feet red. Preserved colour: pale to dark grey.

Distribution. Through the tropical Indo-West-Pacific, from Zanzibar to Malaysia and Australia; 0–115 m (depth from Rowe & Gates 1995).

Remarks. We have observed specimens from Singapore waters that we judge to be Colochirus quadrangularis . Because of the proximal continuity of Singapore waters with those of the Straits of Malacca, we judge that the Singapore specimens are conspecific with those of the type locality. The live colour photos of Colochirus quadrangularis from Singapore waters that we have included here were provided for our work by our colleagues Wong Pei San Helen and Joo Yong Ong ( NUS TMSI). The specimens studied here were donated to Museum Victoria by the Lee Kong Chian Natural History Museum in Singapore, the donation facilitated by our colleagues Wong Pei San Helen and Joo Yong Ong. The description above incorporates observations by these colleagues of 139 specimens of this species in the Lee Kong Chian Natural History Museum.

The conspicuous and distinctive ossicle form in the upper body wall of Colochirus quadrangularis is the irregular shallow sub-rectangular bowl with one strongly spinous edge.