Ophiolimna gyrei, O’Hara & Thuy, 2025

Ophiolimna gyrei sp. nov.

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Fig. 21a–f View FIGURE 21 , 22 View FIGURE 22

? Ophiolimna bairdii . — O’Hara & Thuy, 2022: 28, fig. 6g –h.

TYPE LOCALITY. Coral seamount, 41° 20.708´S, 42° 55.292´E GoogleMaps to 41° 20.99´S, 42° 55.12´E, 1300 m

TYPE MATERIAL. — JC066 : stn 4-2, Coral seamount, 41° 20.708´S, 42° 55.292´E to 41° 20.99´S, 42° 55.12´E, 1300 m, 12/11/2011, holotype: 1 ( NHMUK 2025.43 About NHMUK ); paratypes: 6 ( NHMUK 2025.44 About NHMUK ) ( DNA code= JC066-3438 ); paratype: 1 ( MV F321043 ) GoogleMaps .

OTHER STUDY MATERIAL. — JC066 : stn 4-9, Coral seamount, 41° 21.0283´S, 42° 55.145´E to 41° 21.7´S, 42° 54.8´E, 1100 m, 14/11/2011: 1 GoogleMaps ( NHMUK 2025.45 About NHMUK ) .

COMPARATIVE MATERIAL EXAMINED. Ophiolimna gyrei SS 01/2008/25, Huon seamounts, 44° 16.6296´S, 147° 15.9498´E, 900 m, 17/1/2008, MV F159772 ( DNA code=F159772). SS10/2005/44, Albany, 35° 26.046´S, 118° 21´E to 35° 26.244´S, 118° 21.06´E, 900–915 m, 25/11/2005, MV F112108 ( DNA code=F112108). TN228/J2-385-002, Z27 Seamount, Huon, 44° 14.623´S, 147° 7.339´E, 1184 m, 21/12/2008, MV F168122 ( DNA code=MVF168122). Ophiolimna antarctica ( Lyman, 1879) : CEAMARC/29EV59, Eastern Antarctica, 66° 0.478´S, 143° 18.915´E to 65° 58.594´S, 143° 23.255´E, 452–480 m, 24/12/2007, MNHN IE.2009.6359 ( DNA code=IE.2009.6359). IN2015_E02/021, Huon Commonwealth Marine Reserve, 44° 19.35´S, 147° 19´E to 44° 19.17´S, 147° 18.47´E, 2028 m, 11/4/2015, MV F227354 ( DNA code=F227354). Talud Continental 1/11, Mar del Plata Submarine Canyon, 37° 59.258´S, 54° 41.436´W, 854 m, 11/8/2012, CNP-INV ( DNA code=L11C2). Ophiolimna bairdi ( Lyman, 1883) : ME 85- 3/967, South Iceland, Iceland Basin, 60° 2.77´N, 21° 28.5396´W to 60° 2.78´N, 21° 30.0696´W, 2750 m, 29/8/2011, DZMB-HH 58721 ( DNA code=DZMB37562C). Ricker/TC2006-012, Cape Scott; West of Cape Scott, 50° 36.45´N, 129° 4.37´W to 50° 35.9´N, 129° 2.3´W, 1847–1867 m, 11/10/2006, RBCM 007-00030-002 ( DNA code=RBCM7-30-2). TAN0803/17, Seamount 1 Spastic Spider, Macquarie Ridge. New Zealand EEZ, 48° 32.93´S, 164° 57.75´E to 48° 32.66´S, 164° 58.04´E, 1318–1327 m, 30/3/2008, NIWA 43081 ( DNA code=TOH_0349). Ophiolimna perfida ( Koehler, 1904) : ATIMO VATAE/CP3595, Sud Pointe Barrow, 25° 35´S, 44° 15´E, 821–910 m, 12/5/2010, MNHN IE.2007.4348 ( DNA code=TOH274-IE.2007.4348). IN2022_V09/106, Gascoyne Marine Park. Site:031, 22° 11.766´S, 113° 38.9403´E to 22° 12.608´S, 113° 38.4044´E, 712–730 m, 7/12/2022, MV F309523 ( DNA code=F309523). Ophiolimna placentigera (Lyman, 1880) : KANADEEP2/CP5060, Slope, 22° 15.6432´S, 167° 37.5174´E, 2018–2065 m, 22/9/2019, MNHN IE.2019.3146 ( DNA code=IE.2019.3146). Ophiolimna sp. MoV.7379 BIOPAPUA/CP3672, Nord de Rabaul, 4° 4´S, 151° 50´E, 702–724 m, 24/9/2010, MNHN IE.2023.4067 ( DNA code=BP26).

Diagnosis. Disc covered in dense spherical to conical granules with a few longer spines in the centre of the disc, radial shields hidden. Disc granules present on oral frame, 4 oral papillae, distal papilla small and round, oral shields triangular. Five arms, DAPs triangular and separated, LAPs striated but arms not moniliform, VAPs axe-head shaped, separate, striated, 4 smooth hollow arm spines, upper to 2 segments in length, with a flattened ventral side, one oval tentacle scale.

Description. Holotype 4 mm dd, disc covered in very thin irregular scales which are in turn covered by dense round to conical granules, interspersed with taller sharp spines on the central part of the dorsal disc, 4x as high as wide, radial shields hidden by granules, 4x as long as wide, bar-like with slightly expanded distal section, separate; ventral granules smaller than dorsal, genital slits wide, extending from the oral shields to disc margin, disc granules also covering the oral frame except for a small naked patch in the centre of the oral shields; 4 round oral papillae, inner 2x higher than wide, some pointed, distal ones as high as wide, round, separate; 3 pointed teeth, upper two can be horizontally offset from each other, widest at mid-height, 2x as large as oral papillae, 2nd oral tentacle pore opening inside of slit between the distal two oral papillae.

Arms five, DAPs triangular, 2x as wide as long, widely separated, a few disc granules on the basal plate; LAPs with a notable spine flange, but arms not moniliform, vertically striated, widely contiguous dorsally and ventrally, ventral side constricted thus forming the proximal angle of the VAPs; first VAP obscured by granules, 2nd VAP roughly rhomboid, with wider straight to slightly convex distal edge, incised lateral sides (for pore) and with a very obtuse angle proximally, 3rd VAP axe-head shaped, wider than 2nd, all VAPs widely separate, transversely striated; 4 arm spines, hollow, semi-circular in cross section, with a tapering bluntly pointed apex, microscopically perforated and furrowed near tip, basal dorsalmost one to 2 segments in length, lower ones 1–1.5 segments long, distal arm spines not hooked; one oval tentacle scale, 2x as long as wide, just shorter than the VAP, thin and glassy, longitudinally striated, orientated distolaterally, becoming more pointed after the first few segments. Colour (preserved) pale brown, arm spines with dark patch near base.

Paratypes 2–4 mm dd, disc spines continue to near margin one some specimens, one paratype has 5 arm spines on 2nd free arm segment. Ventral granules were removed from one paratype which revealed triangular oral shields, as wide as long, roughly triangular adoral shields, expanded distally, meeting proximally at interradius, and small rhomboid first VAP, widest proximally at end of jaw slit. Other material: F112108 ( 5 mm dd) has 5 arm spines on the first 2 free segments, the upper one is thickened as well as longer; lacking tall disc spines, but having elongated granules, distal oral papilla can be a little widened but not scale-like.

Paratype ossicles, LAPs ( Fig. 22a–c View FIGURE 22 ) squarish in lateral view and curved over and under arm to meet centrally, with external vertical striations, often bordered by a row of minute thorns, wavy distal margin, more open stereom near arm spines, with large prominent ear-shaped arm spine articulations, with expanded curved distal lobe and smaller ridge-like ventral lobe, with large central muscle attachment and smaller distal nerve pore; vertebrae semi-circular in cross section ( Fig. 22h–i View FIGURE 22 ) with spindle-shaped ventral groove outlined by ridges, vertebrae wider proximally than distally, zygospondylous articulation, v-shaped processes on the dorsal surface; DAPs ( Fig. 22d View FIGURE 22 ) and VAPs ( Fig. 22e View FIGURE 22 ) with similar transverse striations to LAPs, arm spines semi-cylindrical with ventral side flattened perforated and grooved apically ( Fig. 22r View FIGURE 22 , left), and the curved side transversely striated ( Fig. 22r View FIGURE 22 , right), a few thorns apically; disc spines conical with thorny striations and relatively few perforations; oral plate complex 2x as long as tall; dental plate small and oblong, with 3 tooth articulations.

Distribution. S Australia ( 900–1184 m), Coral seamount ( 1100–1300 m)

Remarks. DNA evidence ( Fig. 2b View FIGURE 2 ) indicates the Coral seamount specimens are part of a lineage that is divergent from other Ophiolimna species known from the Southern Ocean including O. antarctica and O. bairdi . This new lineage also occurs off Southern Australia, and possibly around the Amsterdam and St Paul Islands ( O’Hara & Thuy 2022). The Coral seamount specimens appear to differ from O. antarctica and O. bairdi by having asymmetrical arm spines that have a flattened ventral edge, being more densely granulated on oral and adoral shields, and having small rounded distal oral papillae. Ophiolimna antarctica is further differentiated by lacking spines on the disc surface. Larger specimens (to 10 mm dd) of O. antarctica and O. bairdi can have up to 7 arm spines. Specimens from the tropical Indo-Pacific (e.g. BP26, and O’Hara & Stöhr 2006) are another undescribed species ( Ophiolimna sp. MoV.7379, see O’Hara & Thuy 2022).

Etymology. Named after the South Indian Gyre that transports ophiuroid larvae eastward across the Indian Ocean.