Ophiacantha exilis (Koehler, 1922)

Ophiacantha exilis (Koehler, 1922) View in CoL

Fig 16d–g View FIGURE 16

Ophiomitrella exilis Koehler, 1922a: 110–111 View in CoL , pl. 22(9,10).

Ophiacantha exilis View in CoL . — O’Hara & Stöhr, 2006: 49, 89. — O’Hara, 2024b: 39, fig. 39.

STUDY MATERIAL. — MD208 : stn CP4915, Walters shoal, Plaine Sud, 33° 56.85´S, 44° 0.07´E to 33° 58.8´S, 43° 55.3999´E, 1865–2058 m, 12/5/2017: 1 ( MNHN IE.2016.1370) ( DNA code= IE.2016.1370) GoogleMaps .

COMPARATIVE MATERIAL EXAMINED. Ophiacantha exilis ( Koehler, 1922a) : IN2015_E02/021, Huon Commonwealth Marine Reserve , 44° 19.35´S, 147° 19´E GoogleMaps to 44° 19.17´S, 147° 18.47´E, 2028 m, 11/4/2015, MV F227369 ( DNA code=F227369). IN2017 _ V03 /069, Hunter CMR, 32° 28.74´S, 152° 59.64´E GoogleMaps to 32° 30.42´S, 152° 59.46´E, 1006–1036 m, 3/6/2017, MV F239929 ( DNA code=F239929). IN2021 _ V04 /40, Shcherbakov Seamount, 10° 55.475´S, 104° 36.687´E GoogleMaps to 10° 55.441´S, 104° 38.0688´E, 1608–1663 m, 14/7/2021, identified by O’Hara (2024b), MV F305548 ( DNA code=F305548). TN228/RD2, A1 Seamount, Huon, 44° 19.667´S, 147° 16.48458´E, 1253–1273 m, 20/12/2008 GoogleMaps , MV F168108 . Ophiacantha richeri O’Hara & Stöhr, 2006 : TAN1402/31, Forde

Seamount, Stratum 1, 35° 19.01´S, 170° 27.09´W to 35° 18.48´S, 170° 27.53´W, 1205–1600 m, 11/2/2014, NIWA 95821 ( DNA code= NIWA 95821).

Distribution. E Indo-W Pacific ( 1280–1663 m), S Australia ( 1006–2518 m), Walters Shoal ( 1865–2058 m).

Remarks. The single MD 208 specimen measures 2 mm dd. It has the characters of O. exilis including a petaloid disc that is indented interradially; moniliform arms that curl under the disc; small slender disc spinelets, pedicel with 3–5 terminal thorns, sometimes smaller thorns on major ones; thorny arm spines that are short except the uppermost one near the arm base; one tentacle scale that is acute and thorny, to half the VAP in length; 3 oral papillae, the outer one pointed; and adoral shields that extend around the lateral tip of the oral shields. It differs a little from the type and specimens reported by O’Hara (2024b) in having lozenge-shaped oral shields that are only a little extended proximally. On specimens from Australia, the oral shields have a long pointed proximal extension that can separate the adoral shields, and the oral papillae are more spiniform. DNA evidence indicates that this species ranges across the Indian Ocean to SE Australia.