Ophiacantha metallacta H.L. Clark, 1915

Fig 16a–c, 19a–f

Ophiacantha vepratica . — Koehler, 1914: 94–95, pl. 13(6) [Non Ophiacantha vepratica Lyman T, 1878; see Clark, H.L., 1915].

Ophiacantha metallacta Clark, H.L., 1915: 202–203 . — Mortensen, 1933d: fig. 18b,d. — Paterson, 1985: 44, fig. 19.

STUDY MATERIAL. — JC066: stn 8-5, Atlantis Bank, 32° 42.862´S, 57° 14.666´E to 32° 43.3´S, 57° 15.2´E, 828–994 m, 10/12/2011: 1 (NHMUK 2025.32) (DNA code= JC066-3683); 1 (NHMUK 2025.33) .

COMPARATIVE MATERIAL EXAMINED. Ophiacantha metallacta H.L. Clark, 1915: BIOPAPUA/ DW3719, Vitiaz strait, 6° 3´S, 147° 36´E, 410 m, 7/10/2010 , MNHN IE.2023.4074 (DNA code=BP87). EX1806 / D07_01B, Richardson Ridge, 31° 46.2´N, 77° 21.6´W, 1753 m, 21/6/2018 , USNM 1490594 (DNA code= USNM 1490594). Kraken 2/2-2, 24° 14.3322´N, 80° 55.0169´W, 513 m, 29/11/2011 , MV F248413 (DNA code=F248413). SS05/2007/156, Northwestern Australia, Leveque L 27 transect, 14° 33.432´S, 121° 20.388´E to 14° 32.767´S, 121° 19.65´E, 1100 m, 3/7/2007, MV F167998 (DNA code= TOH _584). TAN1206/34, Site SM3 a, summit of Clark Seamount, Kermadec Ridge, 36° 26.832´S, 177° 50.31´E to 177° 50.508´N, 36° 26.982´W, 850–980 m, 18/4/2012, MV F188863 (DNA code=02WOZ) .

Description. Disc 6 mm dd, covered in small disc spines (Fig. 19e), typically 0.20 mm high, with a slightly waisted pedicel and a convex crown bearing short divergent points, 0.18 mm across, absent from the radial shields, becoming smaller and conical to spherical in shape ventrally, extend to the oral shields; oral shields 1.5x wider than long, widest proximally with a rounded distal lobe; 3 oral papillae along the jaw sides in addition to 3–8 suboral papillae that can also occur around the adoral shields, tapered apical teeth. Arms not moniliform, vertebrae (Fig. 19f) with a pronounced distal zygosphene and zygocondyles further back. DAPs wide and triangular, over 2x wider than long, widely separated. LAPs quadrangular in lateral view (Fig. 19a–b) with a notable vertical wavy ridge that separates the proximal part of the plate from the arm spine articulation area, arm spine articulations typical Ophiacantha in form. VAPs 1.5x as wide as long, contiguous, with a glassy striated convex distal margin and obtuse angle proximally (Fig 19c); to 9 finely-rugose arm spines forming a fan across the dorsal arm proximally, uppermost just over 2 segments in length (Fig. 19d); one oval tentacle scale, sometimes thorny at the tip, 1/3 the VAP in length.

Distribution. W Atlantic (305–1753 m), Indo-Pacific (410–1100 m), New Zealand (850–980 m), Atlantis Bank (828–994 m).

Remarks. The Atlantis Bank specimens differ from previous descriptions in having suboral as well as the 3 oral papillae. These are only rarely present on the other specimens examined. More specimens are required to determine whether this difference is significant or not. The DNA evidence (Fig. 2b), however, suggests that it is a widespread species complex occurring from Western Atlantic to northern New Zealand.