Massinium bonapartum O’Loughlin, 2014

P. Mark O’Loughlin, Melanie Mackenzie & Didier Vandenspiegel, 2014, New dendrochirotid sea cucumbers from northern Australia (Echinodermata: Holothuroidea: Dendrochirotida), Memoirs of Museum Victoria 72, pp. 5-23 : 12-13

Massinium bonapartum O’Loughlin sp. nov.

Zoobank LSID. http://zoobank.org:act:C34C417F-9A65-4346-

8145-ED9E350D7E21

Figures 5 , 6 , key.

Material examined. Holotype. NW Australia, Joseph Bonaparte Gulf , Kimberley region, off King George River, 13.85°S 129.29°E, RV Solander, 45 m, J. Keesing, 6 Jun 2013, WAM Z27860 (KGR lot 23323; UF tissue lot MOLAF1457 ).

Paratype. Joseph Bonaparte Gulf , 11.54°S 129.83°E, RV Solander, 173 m, Geosciences Australia, 14 Sep 2009, NMV F202985 (1) (GA lot SOL4934 35BS24; UF tissue lot MOLAF1519 ).

Description. Form sub-spherical, slightly elongate, up to 43 mm long (preserved), mouth anterior dorsal, anus posterior dorsal, slightly developed oral and anal cones; firm leathery body wall; tube feet scattered over body, withdrawn, diameters about 0.2 mm, sparse dorsally, close cover ventrally and around mouth and anus; 20 dendritic tentacles, 5 pairs large in an outer ring, 5 pairs very small in an inner ring (proximal circumoral); calcareous ring long, tubular, composite; radial plates blunt anteriorly with 2 lateral shallow notches and deeper central notch, radial plates lacking median un-calcified section; inter-radial plates pointed anteriorly, large oval un-calcified posterior section closed distally by thin calcified link; 2 polian vesicles; short branched gonad tubules; respiratory trees extending the length of the coelom.

Ossicles in mid-body wall tables only, sparse dorsally, more numerous ventrally; table disc outlines irregularly round, typically 4 larger central and some small outer perforations, margin smooth or spinous, discs up to 112 µ m wide; spires with 2 frequently fused pillars, low or residual, few thick blunt apical spines. Oral disc with abundant tables with discs up to 112 µ m long, irregularly oval, many perforations, margins smooth; spires discrete, up to 70 µ m long, 2 partly fused pillars, rarely single, 1 to 3 median perforations, long apical spines typically widely splayed. Peri-anal body wall with abundant tables similar to those in the mid-body wall; some rods with distal perforations, rods up to 80 µ m long; small multi-layered anal scales about 200 µ m long. Tube feet with endplates, up to 320 µ m diameters, margin thick, lacking support ossicles; body wall type tables. Tentacles with abundant rods and rosette-like rod ossicles and some tables; rods up to 70 µ m long with ends widened with few perforations; rosette-like rods up to 88 µ m long with short rod widened distally with many small perforations created by dendritic branch fusing; few tables, similar to those in peri-oral disc.

Colour live off-white to pale yellow; colour preserved offwhite to pale brown, tube feet brown; tentacle dendritic branches black, trunks off-white to grey.

Distribution. NW Australia, Joseph Bonaparte Gulf, Kimberley region, off King George River, 45– 173 m.

Etymology. Named with reference to the Joseph Bonaparte Gulf from which the type specimens were collected.

Remarks. A distinctive character of Massinium bonapartum O’Loughlin sp. nov. is the widely splayed long apical spines frequently present on the tables. We observed the five pairs of small tentacles to be in an inner ring. Massinium bonapartum sp. nov. is distinguished from other species in the genus by the combination of morphological characters shown in the key.

Figures

Figure 5. Photos of live and preserved specimens of Massinium bonapartum O’Loughlin sp. nov. A, dorsal view of live holotype specimen (WAM Z27860); B, lateral view of preserved paratype (NMV F202985, 43 mm long); insert with photo of the calcareous ring of the paratype; C, dorsal view of preserved holotype (30 mm long); insert with sketch of the calcareous ring of the holotype; D, ventral view of the preserved holotype.

Figure 6. SEM images of ossicles from the holotype of Massinium bonapartum O’Loughlin sp. nov. (WAM Z27860). A, mid-dorsal body wall tables, spires short with fused pillars (scale bars 20 µm); B, peri-anal body wall scale fragment (bottom right, scale bar 50 µm), and irregular tables with 2 discrete or fused pillars (scale bars 20 µm); C, mid-ventral body wall tables (scale bars 20 µm), and fragment of endplate with thickened margin (scale bar 50 µm); D, tentacle rods and rosette-like rod (scale bars 10 µm); E, oral disc tables, table discs irregularly oval with many perforations, spires with 2 pillars partly fused and with long splayed distal spines (scale bars 20 µm).