Holothuria (Metriatyla) keesingi O’Loughlin, 2016

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 : 9-14

Holothuria (Metriatyla) keesingi O’Loughlin sp. nov.

Zoobank LSID. http://zoobank.org/ urn:lsid:zoobank.org:act:

ED316CAC-695D-4EB7-97DD-8999F2CD33CF

Table 1 ; appendix 1; figures 2a, b, 3, 4

Material examined. Holotype. Northwest Western Australia, Kimberley Region, Camden Sound , WAMSI 1.1.1, RV Solander, sled, site no SOL_47, WAM station no 42, barcode 10002938, from -15.612805 124.073033 36 m to -15.612437 124.072883 35 m, 26 Mar 2015, WAM Z89006 .

Paratypes. Camden Sound , WAMSI 1.1.1, RV Solander, sled, site no SOL_107, WAM station no 1, barcode 10000043, from -15.514826 124.183111 46 m to -15.514503 124.183774 45 m, 14 Mar 2015, WAM Z89000 (1 specimen); RV Solander , sled, site no SOL_8, WAM station no 7, barcode 10000403, from -15.313929 124.112518 47 m to -15.313336 124.111992 48 m, 16 Mar 2015, WAM Z89001 (3) ; RV Solander , sled, site no LIN_36, WAM station no 17, barcode 10001168, from -15.220444 124.320894 50 m to -15.220159 124.320648 50 m, 18 Mar 2015, WAM Z89002 (2) ; RV Solander , sled, site no SOL_32, WAM station no 19, barcode 10001320, from -15.253592 124.203038 45 m to -15.253318 124.202302 45 m, 19 Mar 2015, WAM Z89003 (1) ; RV Solander , sled, site no SOL_24, WAM station no 23, barcode 10001821, from -15.40642783 124.1259284 42 m to -15.40693704 124.1253687 42 m, 20 Mar 2015, WAM Z89004 (2) ; RV Solander , sled, site no SOL_87, WAM station no 24, barcode 10001954, from -15.448727 124.153629 36 m to -15.44933 124.154105 36 m, 20 Mar 2015, WAM Z89005 (2) ; RV Solander , sled, site no SOL_47, WAM station no 42, barcode 10002963, from -15.612805 124.073033 36 m to -15.612437 124.072883 35 m, 26 Mar 2015, WAM Z89007 (1).

Description (preserved in 95% ethanol). Up to 60 mm long, 18 mm wide, 12 mm high; body surface finely nodulose; body arched dorsally, with rounded ventro-lateral margins, low convex ventrally; strongly tapered anteriorly and posteriorly; dorsal and lateral papillae irregularly distributed, conical, with tapered to pointed ends, of variable sizes, up to 3 mm long; about eight papillae across body transversely, longest on dorso-lateral radii, about 40 ventro-lateral papillae in close irregular series on each margin; tube feet digitiform, up to 2 mm long, scattered on ventrum but in recognizable irregular longitudinal series, paired irregular series latero-ventrally, paired irregular series on each side of bare mid-ventrum; mouth antero-ventral, with 20 tentacles, mouth surrounded by a ring of about 16 conical papillae, up to 1 mm long; calcareous ring solid, widths of radial and inter-radial plates sub-equal, inter-radials half the height of the radials, with undulating posterior edge, lacking posterior prolongations.

Body wall ossicles large tables and buttons, buttons more abundant than tables; table discs of variable size, shallow concave, irregularly round to rounded square to oval, margin smooth, discs 48–240 µm across, disc perforations from 8 to more than 50, perforations very small marginally; table spires of variable height, up to 176 µm long, 4 pillars, up to 8 cross bridges, spire rounded distally with cluster of small spinelets, sometimes spinelets extend along distal sides of spire; buttons predominantly elongate with up to about 7 irregularly paired perforations, some buttons with 1–3 pairs of perforations, button sizes 50–200 µm long, buttons smooth and variably knobbed. Dorsal papillae with tables, buttons and thick perforated rods; rods thick, mid-rod widened with perforations, distal ends widened with small perforations, rods up to 336 µm long. Ventral tube feet with endplates, thick endplate support rods, tables and buttons; endplates slightly convex, central perforations slightly larger, margin bluntly digitiform, endplate diameters about 300 µm; thick rods curved, widened and perforated mid-rod and distally, up to 264 µm long. Tentacles with minutely spinous, non-perforate, curved rods, rods up to 320 µm long.

Colour (preserved). Body pale mottled brown to off-white, dorsal and lateral irregular fine brown-black flecks and spots, about 4 dorso-lateral pairs of large irregular brown-black patches that are partly merged at the anterior end; tentacles and distal papillae and tube feet yellow. Live colour similar but the body base colour yellow.

Distribution. NW Western Australia, Kimberley Region, Camden Sound, mud, 35– 50 m.

Etymology. Named for John Keesing of the CSIRO Oceans and Atmosphere, and The Western Australian Marine Science Institution, with appreciation of his live colour photography of Camden Sound sea cucumbers used in this work, and his gracious collaboration with data.

Remarks. The morphology of Holothuria (Metriatyla) keesingi O’Loughlin sp. nov. satisfies the diagnosis of the Holothuria sub-genus Metriatyla Rowe, 1969:

1. 20 tentacles;

2. collar of papillae around the base of the tentacles;

3. large conical, irregularly arranged papillae dorsally, a lateral flange sometimes evident;

4. tube feet irregularly arranged on the ventrum;

5. body arched dorsally, flattened ventrally;

6. size small to large;

7. body wall thin to thick;

8. calcareous ring well developed;

9. table ossicles with smooth disc and spire of moderate height to high, terminating in a few to many small spines;

10. buttons simple, with moderate-sized irregularly arranged knobs and 3–10 pairs of relatively large holes.

We qualify the diagnostic characters of Rowe (1969) to include the possibility of species with a large body and thick body wall (as in Holothuria (Metriatyla) scabra Jaeger, 1833 ).

Table 1; appendix 1; figure 5

Rowe (in Rowe & Gates 1995) synonymised Holothuria bowensis Ludwig, 1875 (type from Bowen, NE Australia) and Holothuria subverta H. L. Clark, 1921 (type from Torres Strait, NE Australia) with Holothuria (Metriatyla) martensii Semper, 1868 (type from Amboina, Indonesia). Of the species referred to sub-genus Metriatyla, the new species resembles Holothuria (Metriatyla) martensii . However, the new species Holothuria (Metriatyla) keesingi O’Loughlin is significantly different in the following ways:

1. smaller species with numerous preserved specimens up to only 60 mm long;

2. preserved colour with yellow papilla and tube foot and tentacle ends, and dorsal body with four irregular longitudinal paired dark brown patches;

3. larger tables, with discs up to more than 200 µm across, disc perforations up to more than 40, spires up to more than 150 µm high;

4. larger smooth and knobbed buttons, predominantly about 7 irregular pairs of perforations, up to 200 µm long.

Théel (1886) referred two specimens to Holothuria (Metriatyla) martensii , one from Indonesia and one from the Philippines. Sizes were 150 mm and 85 mm long. Buttons were up to 140 µm long. Table disc perforations were fewer than 30. Colours are described with no reference to brown dorsal patches. These morphological characters of Holothuria (Metriatyla) martensii (sensu Théel 1886) are significantly different to those of Holothuria (Metriatyla) keesingi O’Loughlin sp. nov.

The buttons in H. (Metriatyla) horrida Massin, 1987 are similar to those in Holothuria (Metriatyla) keesingi O’Loughlin. And the high table spires of H. (Metriatyla) horrida are also similar but significantly shorter (up to 120 µm long). The table discs in H. (Metriatyla) horrida are significantly smaller (up to 140 µm across), the table disc perforations significantly fewer (up to 16), and the colour reported as grey.

Frank Rowe (pers. comm.) suggested that the size and form of the ossicles in the relatively small specimens appear somewhat paedomorphic. But the mature gonads that are present confirm that the specimens are adult.