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Genus Rhipidipathes Milne-Edwards & Haime, 1857 Diagnosis. Corallum flabellate; anastomosing among some branches; polypar spines acute or blunt, smooth or tuberculate; circumpolypar spines slightly larger than interpolypar spines; hypostomal spines often equal to the circumpolypar spines but may be reduced in size or absent on some portions of the corallum. Remarks. Although Rhipidipathes is currently in the Aphanipathidae, previous (Brugler et al. 2013; Bo et al. 2018; Terrana et al. 2021) and the present study indicate that the genus is more closely related to species in the Antipathidae. The present study suggests that Rhipidipathes shares a lineage with the genus Blastopathes Horowitz, 2020 (Fig 2). Both genera have distinct morphological differences. For example, Rhipidipathes consists of thin branches that can fuse to create flabellate “fan-like” colonies (Opresko 2004) and Blastopathes consists of thick, stem-like branches that do not fuse and possess branches that sprout from clusters to create “tree-like” colonies (Horowitz et al. 2020). Due to the differences between these “sister” genera, their family-level relationships need to be verified. Type Species: Rhipidipathes reticulata (Esper 1795) Type Locality: East Indian Ocean, Published as part of Horowitz, Jeremy, Opresko, Dennis, Molodtsova, Tina N., Beaman, Robin J., Cowman, Peter F. & Bridge, Tom C. L., 2022, Five new species of black coral (Anthozoa; Antipatharia) from the Great Barrier Reef and Coral Sea, Australia, pp. 1-35 in Zootaxa 5213 (1) on page 10, DOI: 10.11646/zootaxa.5213.1.1, http://zenodo.org/record/7350036, {"references":["Haime, J. & Milne-Edwards, H. (1857) Histoire naturelle des coralliaires, ou polypes proprement dits; par H. Milne-Edwards ... Histoire naturelle des coralliaires, ou polypes proprement dits. Roret, Paris, 326 pp.","Brugler, M. R., Opresko, D. M. & France, S. C. (2013) The evolutionary history of the order Antipatharia (Cnidaria: Anthozoa: Hexacorallia) as inferred from mitochondrial and nuclear DNA: implications for black coral taxonomy and systematics. Zoological Journal of the Linnean Society, 169, 312 - 361. https: // doi. org / 10.1111 / zoj. 12060","Bo, M., Barucca, M., Biscotti, M. A., Brugler, M. R., Canapa, A., Canese, S., lo Iacono, C. & Bavestrello, G. (2018) Phylogenetic relationships of Mediterranean black corals (Cnidaria: Anthozoa: Hexacorallia) and implications for classification within the order Antipatharia. Invertebrate Systematics, 32, 1102. https: // doi. org / 10.1071 / is 17043","Terrana, L., Flot, J. - F. & Eeckhaut, I. (2021) ITS 1 variation among Stichopathes cf. maldivensis (Hexacorallia: Antipatharia) whip black corals unveils conspecificity and population connectivity at local and global scales across the Indo-Pacific. Coral Reefs, 40, 521 - 533. https: // doi. org / 10.1007 / s 00338 - 020 - 02049 - 8","Horowitz, J., Brugler, M. R., Bridge, T. C. L. & Cowman, P. F. (2020) Morphological and molecular description of a new genus and species of black coral (Cnidaria: Anthozoa: Hexacorallia: Antipatharia: Antipathidae: Blastopathes) from Papua New Guinea. Zootaxa, 4821 (3), 553 - 569. https: // doi. org / 10.11646 / zootaxa. 4821.3.7","Opresko, D. M. (2004) Revision of the Antipatharia (Cnidaria: Anthozoa). Part IV. Establishment of a new family, Aphanipathidae. Zoologische Mededelingen, Leiden, 78, 1 - 15.","Esper, E. J. C. (1795) Die Pflanzenthiere in Abbildungen nach der Natur mit Farben erleuchtet nebst Beschreibungen. in der Raspischen Buchhandlung, Nurnberg, 303 pp."]}

Antipathes morrisi Horowitz sp. nov. (Figs. 1–3; Supplementary Tables 1–2) Material examined. Holotype, MTQ G80140, Australia, Great Barrier Reef, Orpheus Island, Pioneer Bay North, expedition Voyage of the Kalinda, collected on October 22, 2019, - 18.5998° S, 146.4888° E, 14 m depth, collector Jeremy Horowitz. Diagnosis. Flabellate corallum, up to ~ 1 cm thick; branches and terminal branchlets arranged bilaterally, or anterolaterally; overlapping, and branches anastomose. Terminal branchlets 4 to 10 mm in length, slightly curved distally, distal angles ~45 to almost 90°, 0.11 to 0.25 mm in basal diameter, spaced 2 to 5 mm apart: with a density of ~4 per cm including all rows. Spines smooth, conical, and laterally compressed, 0.085 to 0.19 mm tall. Some spines on branches possess up to four small, cone-shaped apical knobs. Four to five axial rows of spines counted in one view and four to seven spines counted in one cm in one row. Polyps 0.8 to 1 mm in transverse diameter, spaced ~ 0.2 mm apart, with eight to nine polyps per cm. Description of holotype. The entire colony was 60 cm tall by 60 cm wide and 1 cm thick (Fig. 3A), but only a 28 cm tall and 20 cm wide section (MTQ G80140) was collected. The colony is branched to the fourth and rarely fifth order and has branches and terminal branchlets that are mostly distally directed and form one distinct, ~ 1 cm thick flabellate plane with highly anastomosing branches (Fig. 3B). Branches bilaterally arranged projecting in one plane with the smaller branchlets occurring unilaterally or bilaterally in two lateral or rarely anterolateral rows. Branches range from ~0.3 to ~ 1 mm in diameter excluding spine heights. Terminal branchlets are mostly 4 to 10 mm in length, have basal diameters ranging from 0.11 to 0.25 mm, and are spaced 2 to 5 mm apart on one side of a branch resulting in about 8 to 10 terminal branchlets per cm, counting terminal branches on both sides of the branch. Branches and terminal branchlets form ~45 to almost 90° distal angles and can be almost straight or slightly curved upwards. Spines on terminal branchlets are smooth, conical, and laterally compressed. Spines are slightly distally inclined or perpendicular to the axis with convex proximal sides, and tips curved slightly upwards (Fig. 3C). On terminal branchlets with diameters from 0.11 to 0.25 mm, polypar spine heights range from 0.12 to 0.19 mm and abpolypar spine heights range from 0.085 to 0.11 mm (Fig. 3C). On lower order branches, spines are more conical and can possess two to four small conical knobs 0.01 to 0.03 mm tall, concentrated near their apexes that are directed in the same general direction as the spine. On a section of a branch 0.22 mm in diameter, polypar spines are 0.13 mm and abpolypar spines are 0.1 mm (Fig. 3D). Four to five axial rows of spines can be counted in one view of branches and terminal branchlets and four to seven spines can be counted in one cm, in one row. Polyps are yellow to brown in color, oblong in shape, and occur on one side of the colony, in one row. Polyps are 0.8 to 1 mm in transverse diameter and spaced ~ 0.2 mm apart resulting in about nine polyps per cm (Fig. 3E). Comparative diagnosis. Twenty-one out of 67 nominal species possess flabellate planar corallums with anastomoses. Of this number, Antipathes clathrata Pallas, 1766 and Antipathes tristis (Duchassaing, 1870) have very vague original descriptions that lack sufficient taxonomic information to clearly separate these two species. All other species can be distinguished from the new species. Antipathes delicatula Schultze, 1896 and Antipathes ceylonensis (Thomson & Simpson, 1905) are more loosely branched than the new species. Antipathes atlantica Gray, 1857, A. ceylonensis, Antipathes gracilis Gray, 1860, Antipathes indistincta (van Pesch, 1914) and Antipathes rhipidion Pax, 1916 form only rare occasional anastomoses, whereas the new species form a densely anastomosing fan. Antipathes craticulata Opresko, 2015, Antipathes dubia (Brook, 1889) and Antipathes plana Cooper, 1909 have uniserial arrangement of terminal branchlets throughout the corallum in contrast to new species, that demonstrate characteristic biserial arrangement (Fig. 3B). The new species is also different than A. craticulata by having less distinctly curved branches and terminal branchlets. Antipathes hypnoides (Brook, 1889), Antipathes minor (Brook, 1889), Antipathes sibogae (van Pesch, 1914), and Antipathes elegans (Thomson & Simpson, 1905) have polyps less than 0.5 mm in transverse diameter compared with 0.8 to 1.0 mm in the new species. The new species is also different than A. hypnoides by having much more regularly spaced terminal branchlets and a lower density of terminal branchlets (4 per cm vs> 9 per cm). Antipathes assimilis (Brook, 1889), Antipathes flabellum Pallas, 1776 (sensu Terrano et al., 2021), Antipathes irregularis (Thomson and Simpson, 1905), Antipathes ternatensis Schultze, 1896, Antipathes zoothallus Pax, 1932 and Antipathes speciosa (Brook, 1889) have rather small spine heights 0.09 mm and less, whereas the new species has polypar spines 0.12-0.19 mm and abpolypar spines 0.008 5 to 0.11 mm. The new species is also different than A. flabellum by having branches projecting perpendicular to the colony plane, narrower distal angles (45° vs 79°), and spines that are more perpendicular. The new species has some similarities with Antipathes aculeata (Brook, 1889) including fused branches and short spines with sharp and sometimes forked tips. However, the new species differs from A. aculeata regarding the colony thickness where the new species is only 1 cm thick because branches and terminal branchlets are arranged bilaterally forming a distinct fan-shape while A. aculeata forms a dense mass of branches resembling a bush. Also, the new species has a smaller terminal branchlet basal diameter compared to A. aculeata (0.11 to 0.25 mm vs 0.3 mm). The new species also has some features similar with Arachnopathes ericoides (Pallas, 1776) like fused branches and short branchlets slightly curved upwards; however, as with A. aculeata, the new species forms a fan while Ar. ericoides forms a thick and dense mass, like A. aculeata. Additionally, Ar. ericoides has spines that can be forked and inclined in different directions, including downwards, and can lack longitudinal rows (Terrana et al. 2020) while the new species has spines that are not forked but can be slightly multi-knobbed, not proximally directed, and form distinct longitudinal rows along branches and terminal branchlets. This new species is phylogenetically similar to A. falkorae sp. nov. and Ar. ericoides; however, A. morrisi sp. nov. and Ar. ericoides have fused branches while A. falkorae sp. nov. does not contain any fused branches (see description below). A. falkorae sp. nov. also contains longer and straighter branches that form fronds rather than the single fan characteristic of A. morrisi sp. nov. The morphological differences are sufficient to separate the species and the phylogenetic comparison does not include holotype or topotype specimens for most species being compared with the new species in the Antipathidae, which should be done in future studies that are devoted to species delimitations. Etymology. In recognition of the Morris Family Foundation that funds research at the Orpheus Island Research Station where the new species was first found and collected. Distribution. Known only from the Great Barrier Reef at 14 m depth., Published as part of Horowitz, Jeremy, Opresko, Dennis, Molodtsova, Tina N., Beaman, Robin J., Cowman, Peter F. & Bridge, Tom C. L., 2022, Five new species of black coral (Anthozoa; Antipatharia) from the Great Barrier Reef and Coral Sea, Australia, pp. 1-35 in Zootaxa 5213 (1) on pages 4-5, DOI: 10.11646/zootaxa.5213.1.1, http://zenodo.org/record/7350036, {"references":["Pallas, P. (1766) s. n. In: Elenchus zoophytorum sistens generum adumbrationes generaliores et specierum cognitarum succintas descriptiones, cum selectis auctorum synonymis. Apud Petrum van Cleef, IIagae-Comitum the Hagae, pp. 451 - 451.","Duchassaing, de F. (1870) s. n. In: Revue des zoophytes des spongiaires des Antilles. V. Masson, Paris, pp. 23 - 24.","Schultze, L. (1896) Beitrag Zur Systematik Der Antipatharien. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft, 23, 1 - 40.","Thomson, J. & Simpson, J. J. (1905) Report on the Antipatharia collected by Prof. Herdman at Ceylon in 1902. Supplemental Report No. XXV to the Report to the Government of Ceylon on the Pearl Oyster Fisheries of the Gulf of Manaar, Part 4, 93 - 106.","Gray, J. E. (1857) Synopsis of the families and genera of axiferous zoophytes or barked corals. Proceedings of the Zoological Society of London, 25, 278 - 294. https: // doi. org / 10.1111 / j. 1096 - 3642.1857. tb 01242. x","Gray, J. E. (1860) Notice of some new corals from Madeira discovered by JY Johnson, Esq. The Annals and magazine of natural history; zoology, botany, and geology being a continuation of the Annals combined with Loudon and Charlesworth's Magazine of Natural History, 6, 311.","Pesch, A. J. van (1914) The Antipatharia of the Siboga Expedition. Siboga-Expeditie, 17, 1 - 258.","Pax, F. (1916) Eine neue Antipathes-Art aus Westindien. Zoologische Jahrbucher, Supplement 11, 433 - 436.","Opresko, D. M. (2015) New species of black corals (Cnidaria: Anthozoa: Antipatharia) from New Zealand and adjacent regions. New Zealand Journal of Zoology, 42, 145 - 164. https: // doi. org / 10.1080 / 03014223.2015.1051550","Brook, G. (1889) Report on the Antipatharia. Report on the scientific results of the voyage of H. M. S. Challenger, 32, 1 - 222.","Cooper, C. F. (1909) Antipatharia. Reports of the Percy Sladen Trust Expedition to the Indian Ocean. In: Transactions of the Linnean Society of London, Zoology Series 2, 12, 301 - 323.","Pax, F. (1932) Beitrag zur Kenntnis der japanischen Dornchenkorallen. Zoologische Jahrbucher, 63, 407 - 450.","Terrana, L., Bo, M., Opresko, D. M. & Eeckhaut, I. (2020) Shallow-water black corals (Cnidaria: Anthozoa: Hexacorallia: Antipatharia) from SW Madagascar. Zootaxa, 4826, 1 - 62. https: // doi. org / 10.11646 / zootaxa. 4826.1.1"]}

Rhipidipathes helae Horowitz sp. nov. (Figs. 1–2 and 5; Tables 1 and Supplementary Table 1) Material examined: MTQ G80117, Australia, Great Barrier Reef, Bowl Slide, Schmidt Ocean Institute R / V Falkor Northern Depths of the Great Barrier Reef expedition FK200930, ROV SuBastian dive S0394, collected on October 5, 2020, 18.3865° S, 147.6705° E, 119 m depth, collector Jeremy Horowitz. Diagnosis: Corallum flabellate, branched; branches and branchlets extensively anastomosing. Terminal branchlets 0.5 to 1 cm in length and 0.08 mm in diameter, arranged bilaterally, are irregularly alternate, opposite, or subopposite, and slightly protrude from the colony plane. Spines on branches perpendicular or distally inclined. Circumpolypar spines 0.23 to 0.29 mm tall and hypostomal and interpolypar spines maximum of 0.11 mm tall. Spines on terminal branchlets are distinctly curved apically and rarely basally. Five to six axial rows of spines can be counted in one view. Surface of spines extensively tuberculated, especially from about the midpoint to the apex. Polyps roundish, 0.8 mm in transverse diameter. Interpolypar space 0.1 to 0.2 mm, with 10 polyps per cm. Description of holotype: Colony flabellate and about 20 cm wide and 20 cm high based on estimations from in situ images (Figs. 5A–B). Collected sample about 7 cm wide and 9 cm tall. Longest branches are ~ 8 cm in length and have 0.1 cm basal diameter. Terminal branchlets are 0.5 to 1 cm in length, arranged bilaterally, and are either irregularly alternate, opposite, or subopposite. Branchlets often not strictly bilateral but slightly protrude from the general plane of the colony forming ~120° interior angles. Most terminal branchlets form ~80° distal angles and are slightly curved distally (Fig. 5B). There is extensive fusing among branches and terminal branchlets (Fig. 5C). Four anastomosing branches/branchlets can be counted in a 5 cm 2 fragment of a colony. Terminal branchlet basal diameter is 0.08 mm, distance between neighboring terminal branchlets ranges from 1 to 3 mm, and about 10 branchlets can be counted per cm of a branch, counting branches in both rows. On a branch 0.2 mm thick, polypar spines are anisomorphic with circumpolypar spines ranging from 0.23 to 0.29 mm tall and hypostomal and interpolypar spines reduced to 0.11 mm. Abpolypar spines are uniform in height, ranging from 0.13 to 0.15 mm (Fig. 5D). Polypar spines on branches are positioned mostly perpendicular to the axis or slightly distally inclined and abpolypar spines are more distally directed than polypar spines, creating ~45° distal angles (Figs. 5D–E). Six to 10 conical and apically directed tubercles can be counted in lateral view of the polypar spines, including those on the edges (Fig. 5E) and three to six tubercles can be counted in lateral view of abpolypar spines, with the proximal surface of all spines being mostly smooth (Figs. 5C–D). Tubercles become elongated and strongly appressed to the surface of the spine as they increase in size, reaching a maximum size of 0.03 mm (measuring the distance from the base of the tubercle to the apex of the tubercle). Tip of largest tubercles up to 0.004 mm above the spine surface (Fig. 5E). On thin branchlets (0.08 to 0.095 mm in diameter), circumpolypar spines are 0.13 mm tall, oriented perpendicular to the axis, and are distinctly curved upward (Fig. 5D, right image). On thin branchlets abpolypar spines are 0.11 mm tall, distally directed and are curved upward. On thin branchlets, a maximum of three tubercles can be counted in one lateral view of the surface of polypar and abpolypar spines, with the proximal surface of all spines being mostly smooth. On branches and terminal branchlets, five to six uneven axial rows of spines can be counted in one view. Polyps are pink, roundish with equally developed tentacles, and sagittal tentacles positioned slightly lower than lateral tentacles (Fig. 5B). On terminal branchlets and branches, polyps occur in one row; however, polyps can be arranged in several rows along thicker branches near the base of the colony. Polyps are ~ 0.8 mm in the transverse diameter and spaced 0.1 to 0.2 mm apart, resulting in 10 polyps per cm. Tentacles are approximated from in situ images to be 0.15 mm in length, when extended. Comparative diagnosis. This is the third nominal species in the genus Rhipidipathes. Rhipidipathes reticulata (Esper 1795) and Rhipidipathes colombiana (Opresko & Sánchez 1997) are similar in most features (See Table 1 for comparison of three species); however, R. colombiana has limited anastomosing branchlets, hypostomal spines that are only minimally reduced in size, and spines with almost no tubercles while R. reticulata has greater anastomosing branchlets, reduced hypostomal spines, and possesses tubercles on polypar spines. The new species is morphologically and phylogenetically most similar to R. reticulata by having highly anastomosing branchlets and terminal branches, reduced hypostomal spines and clear presence of tubercles on spines. The new species is different from R. reticulata by having thinner terminal branchlets (0.08 vs 0.22 mm in the type) and has spines on terminal branchlets that are distinctly curved, mostly upward but sometimes downward, not found in R. reticulata. See comparison of spines on a terminal branchlet between R. helae sp. nov. (Fig. 5D, right image) that possesses upward curved spines and R. reticulata holotype (Fig. 5F) that possesses straight spines. Additionally, the new species has a greater number of tubercules on polypar and abpolypar spines than R. reticulata (six to 10 vs three to seven tubercles in one view of a polypar spine, and three to six vs zero to three tubercles in one view of an abpolypar spine). Etymology: From the Norse, “hel”, goddess of death, who is depicted wearing a headdress of curved deer antlers that resemble the distinctively curved spines of the new species. Distribution. Known only from the Great Barrier Reef at 119 m depth., Published as part of Horowitz, Jeremy, Opresko, Dennis, Molodtsova, Tina N., Beaman, Robin J., Cowman, Peter F. & Bridge, Tom C. L., 2022, Five new species of black coral (Anthozoa; Antipatharia) from the Great Barrier Reef and Coral Sea, Australia, pp. 1-35 in Zootaxa 5213 (1) on pages 10-13, DOI: 10.11646/zootaxa.5213.1.1, http://zenodo.org/record/7350036, {"references":["Opresko, D. M. & Sanchez, J. A. (1997) A new species of antipatharian coral (Cnidaria: Anthozoa) from the Caribbean Coast of Colombia. Caribbean Journal of Science, 33, 75 - 81.","Esper, E. J. C. (1795) Die Pflanzenthiere in Abbildungen nach der Natur mit Farben erleuchtet nebst Beschreibungen. in der Raspischen Buchhandlung, Nurnberg, 303 pp.","Opresko, D. M. & Baron-Szabo, R. C. (2001) Re-descriptions of the antipatharian corals described by E. J. C. Esper with selected English translations of the original German text. Senckenbergiana biologica, 81, 1 - 21."]}

Hexapathes bikofskii Horowitz sp. nov. (Figs. 1–2 and 7; Supplementary Table 1 and Table 2) Material examined: Holotype. MTQ G80122, Australia, Great Barrier Reef, Noddy Reef, expedition Schmidt Ocean Institute R / V Falkor Seamounts, Canyons, and Reefs of the Coral Sea expedition 200802, ROV Subastian dive S0398, collected on October 15, 2020, 13.5174° S, 144.1012° E, 789 m depth, collector Jeremy Horowitz. Paratype. MTQ G80024, Australia, Coral Sea, Herald Cays, expedition Schmidt Ocean Institute R / V Falkor Seamounts, Canyons, and Reefs of the Coral Sea expedition 200802, ROV SuBastian dive S0376, collected on August 08, 2020, - 16.9095° S, 149.1601° E, 638 m depth, collector Jeremy Horowitz. Diagnosis: Colony monopodial, unbranched, and pinnulate. Pinnules arranged in two lateral rows and one anterior row. Basal-most pair of lateral pinnules subopposite, other lateral pinnules alternating. Striatum present from 1 cm above basal plate to first anterior pinnules. Lateral pinnules simple, up to 12 cm long, densities of six to 10 per 3 cm counting both rows. Anterior pinnules simple, 0.8 to 1.2 cm in length, densities of 11 to 15 per 3 cm. Polyps 4 to 6 mm in transverse diameter. Description of holotype (G80122): Colony is monopodial and pinnulate with a slight sickle shape curvature of the stem (Fig. 7A). Grooves and ridges on the stem are present from 1 cm from the basal plate to the first anterior pinnule. Colony is 23 cm tall and 17 cm wide. Unpinnulated section of the stem is 4 cm and the pinnulated section of the stem is 19 cm (Fig. 7A). The specimen has two rows of lateral pinnules where the bottom pair of pinnules are subopposite and positioned perpendicular to the stem. Above the bottom pair of pinnules, pinnules are arranged alternately with distal angles ranging from ~80° at the bottom of the pinnulated section to ~20° at the top; with most pinnules having 45° distal angles. Lateral pinnules are curved forward and then backward so that the pinnule tips face in the opposite direction from the anterior pinnules. Lateral pinnules increase in length from the lowest pair of pinnules, which are ~ 8.5 cm, to midway up the pinnulated section where the longest pinnules are 12 cm, and then decrease towards the apex where the most distal pinnules are ~ 3 cm. Lateral pinnules are ~ 0.5 mm in diameter near the attachment point, and distances between pinnules in each row range from 5 to 10 mm (increasing in distance distally), resulting in 10 lateral pinnules counted near the bottom of the pinnulated section of the stem and six pinnules counted near the top of the pinnulated section, per 3 cm counting lateral pinnules in both rows. Anterior pinnules are simple, in one row and range from 0.8 to 1.5 cm in height, with most up to 1 cm in height. Distance between anterior pinnules range from 2 to 3 mm, resulting in 11 to 13 anterior pinnules counted per 3 cm. Spines on lateral pinnules are 0.025 to 0.1 mm in height, smooth, triangular, and distally directed (Fig. 7B). Lateral pinnule spines are spaced 0.45 to 0.7 mm apart in each row, and two spines can be counted per mm in one row. Four axial rows of spines can be counted in lateral view (Fig. 7B). Spines on anterior pinnules are smooth, triangular to conical, and distally directed. Spine heights are variable, ranging from 0.04 to 0.08 mm, and the distance between spines in one row is about 0.25 mm. Three to four axial rows of spines can be counted in one view of anterior pinnules. Polyps are ~ 4 to 6 mm in the transverse diameter and 6 to 8 polyps counted per three cm. Description of paratype (G80024): The colony is monopodial and pinnulate with a slight sickle shape curvature of the stem (Fig. 7C) and has two rows of distally directed lateral pinnules. Grooves and ridges are present along the stem from 1 cm above basal plate to the first anterior pinnule. Colony is 13 cm tall and 13 cm wide. The unpinnulated section of the stem is 4 cm and the pinnulated section is 9 cm in height. The lowest pair of pinnules are suboppositely arranged and are positioned almost perpendicular to the axis. All other pinnules are alternating and have distal angles ranging from ~20 degrees proximally to ~80 degrees distally. Lateral pinnules increase in length from the lowest pair of pinnules, which are 4 cm, to midway up the pinnulated section where the longest pinnules range from 6. 5 to 8 cm, and then decreasing towards the apex where the highest pair of pinnules are ~ 3 cm (Fig. 7C). Distances between pinnules range from 5 to 9 mm (increasing in distance distally), resulting in eight pinnules (near the top of the pinnulated section of stem) to 10 pinnules (near the bottom of the pinnulated section of stem) per 3 cm, counting lateral pinnules in both rows. Lateral pinnules are 0.3 mm in diameter near the attachment point. Anterior pinnules are simple, in one row with lengths ranging from 0.5 to 1 cm, with most pinnules being close to 1 cm (Fig. 7D). Anterior pinnules begin from the same height on the stem as the second lowest lateral pinnules, and extend to 5 mm above the most distal lateral pinnule. Anterior pinnules are 0.18 mm in diameter near the attachment point, and distances between pinnules range from 2 to 4 mm, resulting in 13 to 15 pinnules per 3 cm. Spines on lateral pinnules 0.05 mm in height and are smooth and triangular (Fig. 7E). Lateral pinnule spines have distances between spines in one row from 0.48 to 0.7 mm and two to three spines can be counted in one mm in one row. Five axial rows of spines can be counted in one view. Spines on anterior pinnules are smooth, triangular to conical, and distally directed (Fig. 7F). Spine heights are variable, and range from 0.02 to 0.07 mm and distances between spines in one row range from 0.32 to 0.45 mm. Three to four axial rows of spines can be counted in one view of anterior pinnules. Polyps are in a poor state of preservation and estimated based on in-situ images to be reddish in color and 6 mm in the transverse diameter. Comparative diagnosis. H. bikofskii sp. nov. is different than other species in Hexapathes by having only one row of simple (unpinnulated) and short (maximum of 1 cm in the new species vs maximum of 6 to 11 cm in currently described Hexapathes spp.) and straight anterior pinnules. See Table 2 for comparison of species in the genus. The new species is like H. australiensis Opresko, 2003 and H. alis Molodtsova, 2006 by having just one row of anterior pinnules; however, the anterior pinnules of both species are subpinnulated while the new species has simple anterior pinnules. The new species is like H. hivaensis Molodtsova, 2006 and H. heterosticha Kinoshita, 1910 by lacking anterior subpinnules; however, both species have two or more rows of anterior pinnules while the new species only has one row of anterior pinnules. Another difference between the new species and currently described species in the genus is the length of the unpinnulated section of the stem (ranging from 2 to 2.5 cm in described species vs 4 cm in the new species). The new species shares other features with H. australiensis for the following morphometrics: 1) distance between lateral pinnules on one side of the stem (0.5 to 1 cm vs 0.4 to 1.1 cm in H. australiensis), both of which have spaces greater than the other three described species, and 2) the basal diameter of lateral pinnules is 0.3 to 0.5 mm in the new species and 0.5 mm in H. australiensis), both of which are smaller than the other three described species. The two specimens representing the new species form a clade sister to H. heterosticha; however, the other species in the genus have yet to be sequenced. Specimens representing species in the genus Hexapathes should be sequenced to further investigate morphological boundaries between species. Etymology: In recognition of lead author’s grandfather, Morton Isaiah Bikofsky, a high school teacher whose passion for science fuelled JH’s interest in research. Distribution. Known only from the Great Barrier Reef and Coral Sea from 638 to 789 m depth.

Antipathes falkorae Horowitz sp. nov. (Figs. 1–2 and 4; Supplementary Table 1) Material examined. Holotype, MTQ G80067, Australia, Great Barrier Reef, Ribbon Reef Canyons, Schmidt Ocean Institute R / V Falkor, Seamounts, Canyons, and Reefs of the Coral Sea expedition FK200802, ROV SuBastian dive S0385, collected on August 18, 2020, - 15.3968° S, 145.7934° E, 111 m depth, collector Jeremy Horowitz. Diagnosis. Colony fan-like, with unilateral and sparse branching mostly to the second and third order; terminal branchlets 3 to 5 cm long and curved proximally forming 45° distal branch angles. Spines conical, mostly smooth with distinct apical knobs, secondary knobs, and some papillae on the apical section of spines 0.15 to 0.17 mm tall. Four to five axial rows of spines counted in one view. Polyps 0.8 to 1 cm in transverse diameter and eight polyps per cm. Description of holotype. Specimen is fan-like and 21 cm in height (lowermost 5 cm or more of the stem and the holdfast not collected); branched mostly to the second and rarely to the third or fourth order, with stiff and straight or slightly curved vertically directed branches (Figs. 4A–B). Distal branch angles are mostly 45°. Branching is sparse and in one plane, with mostly one and sometimes two or three branches occurring on a given lower order branch. Branching is unilateral with successive orders of branches often arising on the same side as the lower order branches. The five most basal branches are disposed on one side of the stem with subsequent branches disposed on the same side as lower order branches, while the four most apical branches occur on the opposite side of the stem and have higher order branches disposed on the same side as their direct lower order branches (Fig. 4B). The one branch between the five most basal and four most apical branches is disposed on the same side as the basal branches but has secondary branches occurring on both sides of the branch. Terminal branchlets are 3 to 5 cm in length and 0.19 to 0.2 mm in diameter near the base (Fig. 4B). The lowest portion of the stem is 0.9 mm in diameter. Spines on a branch 0.2 mm thick or greater have polypar spines 0.15 to 0.17 mm tall and abpolypar spines 0.1 to 0.15 mm tall (Fig. 4C). On branches 0.20 mm in diameter, spines are about 0.14 mm tall (Fig. 4D), and on terminal branchlets 0.2 mm or less in diameter, spines are at most 0.13 mm tall (Fig. 4E). Spines on large (about 0.2 mm or thicker) branches have extensive apical knobbing with knobs reaching maximum heights of 0.04 mm (Fig. 4F). Where knobbing is most pronounced, spine tips flare outward (at right angles to the direction of the branch axis) and become vertically compressed with small secondary knobs occurring on primary knobs (Fig. 4G). Faint papillae can be seen on and in between well-developed knobs (Fig. 4G). Spines on terminal branchlets less than 0.2 mm in diameter have few or no apical knobs, and are smooth, triangular, slightly distally directed, laterally compressed. Four to five axial rows of spines can be counted in one view; 3.5 to 4 spines can be counted in one mm; and distances between axial rows range from ~0.3 to 0.4 mm. Polyps are yellow to white in color, 0.8 to 1 mm in the transverse diameter with about 0.5 mm space between polyps resulting in about eight polyps in one cm (Fig. 4H). Comparative diagnosis. A. falkorae sp. nov. is most like Antipathes coronata Opresko, 2019 by having straight and vertically directed branches, unilateral branching, slightly larger polypar than abpolypar spines, and apical knobs on the spines. However, the new species has more extensive apical knobbing where on a spine ~ 0.14 mm tall, the new species has five to six primary knobs compared to A. coronata, which has three knobs. The new species also has small protrusions that could be considered secondary knobs on top of primary knobs that are absent on A. coronata. The new species has on average a smaller terminal branchlet diameter than A. coronata (0.2 vs 0.3 mm); however, both species have ~5 axial spine rows visible in a lateral view. The new species also has slightly wider distal branch angles that create more of a fan shape compared to A. coronata. Lastly, the new species has very faint papillae on and in between primary and secondary knobs, which differs from A. coronata that has smooth knobs. Antipathes elegans Thomson & Simpson 1905 and A. gallensis Thomson & Simpson 1905 are also morphologically like A. falkorae sp. nov. where both have apical knobbing on the spines and faint papillae on the surface of the spines; however, the new species is different from both species by having more extensive knobbing (about six knobs per spine vs three to four in A. elegans and A. gallensis) and a presence of secondary knobs that are lacking in these other species. This new species is phylogenetically similar to Ar. ericoides and A. aculeata (Supplementary Table 3); however, the new species does not possess fused branches while Ar. ericoides and A. aculeata have high levels of fused branches. Additionally, the specimens representing A. aculeata are not holotype or topotype specimens, which explains why they do not form a monophyletic relationship. The new species also has a low phylogenetic distance with A. morrisi sp. nov. and a feature that unites the two new species is a presence of apical knobs on the spines. However, A. morrisi sp. nov. has fused branches, unlike A. falkorae sp. nov. Etymology. In recognition of the Schmidt Ocean Institute R/V Falkor, onboard which this and many other black coral species were collected from the Great Barrier Reef and Coral Sea. Distribution. Known only from the Great Barrier Reef at 111 m depth.

Genus Antipathes Pallas, 1766 Diagnosis (after Opresko 2019). Corallum sparsely to densely branched. Branching bushy, bramble-like, broomlike, or fan-shaped. Terminal branchlets of varying length; arranged irregularly, or bilaterally. Spines triangular or cone-shaped in lateral view; smooth or papillose; apex of spines simple or with one or more lobes or bifurcations. Polyps less than 1 mm in transverse diameter. Type Species. Antipathes dichotoma Pallas, 1766 Type Locality. Mediterranean Sea Remarks. Antipathes dichotoma is the type species of the Antipathidae; however, molecular studies (Bo et al. 2018; Brugler et al. 2013), including this study (Fig. 2), have found that the species is more closely related to species in the Aphanipathidae than the Antipathidae. A formal review with integrated morphological and molecular data of all species in each family is required to resolve this taxonomic issue., Published as part of Horowitz, Jeremy, Opresko, Dennis, Molodtsova, Tina N., Beaman, Robin J., Cowman, Peter F. & Bridge, Tom C. L., 2022, Five new species of black coral (Anthozoa; Antipatharia) from the Great Barrier Reef and Coral Sea, Australia, pp. 1-35 in Zootaxa 5213 (1) on page 4, DOI: 10.11646/zootaxa.5213.1.1, http://zenodo.org/record/7350036, {"references":["Pallas, P. (1766) s. n. In: Elenchus zoophytorum sistens generum adumbrationes generaliores et specierum cognitarum succintas descriptiones, cum selectis auctorum synonymis. Apud Petrum van Cleef, IIagae-Comitum the Hagae, pp. 451 - 451.","Opresko, D. M. (2019) New species of black corals (Cnidaria: Anthozoa: Antipatharia) from the New Zealand region, part 2. New Zealand Journal of Zoology, 47, 149 - 186. https: // doi. org / 10.1080 / 03014223.2019.1650783","Bo, M., Barucca, M., Biscotti, M. A., Brugler, M. R., Canapa, A., Canese, S., lo Iacono, C. & Bavestrello, G. (2018) Phylogenetic relationships of Mediterranean black corals (Cnidaria: Anthozoa: Hexacorallia) and implications for classification within the order Antipatharia. Invertebrate Systematics, 32, 1102. https: // doi. org / 10.1071 / is 17043","Brugler, M. R., Opresko, D. M. & France, S. C. (2013) The evolutionary history of the order Antipatharia (Cnidaria: Anthozoa: Hexacorallia) as inferred from mitochondrial and nuclear DNA: implications for black coral taxonomy and systematics. Zoological Journal of the Linnean Society, 169, 312 - 361. https: // doi. org / 10.1111 / zoj. 12060"]}

Genus Aphanipathes Brook, 1889 Diagnosis. Colony sparsely to densely, irregularly branched, bushy, sometimes broom-like, with short to long, straight or curved, often ascending branches. Spines with tall and pronounced tubercles. Type Species. Aphanipathes sarothamnoides Brook, 1889 Type Locality. Vanuatu, Published as part of Horowitz, Jeremy, Opresko, Dennis, Molodtsova, Tina N., Beaman, Robin J., Cowman, Peter F. & Bridge, Tom C. L., 2022, Five new species of black coral (Anthozoa; Antipatharia) from the Great Barrier Reef and Coral Sea, Australia, pp. 1-35 in Zootaxa 5213 (1) on page 13, DOI: 10.11646/zootaxa.5213.1.1, http://zenodo.org/record/7350036, {"references":["Brook, G. (1889) Report on the Antipatharia. Report on the scientific results of the voyage of H. M. S. Challenger, 32, 1 - 222."]}

Horowitz, Jeremy, Opresko, Dennis, Molodtsova, Tina N., Beaman, Robin J., Cowman, Peter F., Bridge, Tom C.L. (2022): Five new species of black coral (Anthozoa; Antipatharia) from the Great Barrier Reef and Coral Sea, Australia. Zootaxa 5213 (1): 1-35, DOI: https://doi.org/10.11646/zootaxa.5213.1.1

Alternatipathes Molodtsova and Opresko, 2017 (emended) Alternatipathes Molodtsova & Opresko, 2017: 358 (see synonymy therein). Diagnosis. Corallum attached to substrate; monopodial, unbranched or with a few basal branches, and pinnulate. When present, pinnate branches of first order develop from lowermost pinnules of stem. Pinnules simple, arranged alternately (including lowermost pair) in two lateral rows. Length of pinnules on stem and branches decreasing in a distal direction, forming a triangularly shaped outline. Striatum absent. Spines conical, smooth, simple (or rarely forked), with acute to slightly rounded apex and flared base. Spines larger on polypar side of pinnule. Polyps 2–7 mm in transverse diameter. Type species. Umbellapathes bipinnata Opresko, 2005. Remarks. The diagnosis of the genus has been emended to account for the larger polyps found in the new species described below. The genus Alternatipathes was established by Molodtsova and Opresko (2017) based on corallum morphology (alternating pinnules and stem lacking a fluted region referred to as a striatum) and the results of mt DNA sequencing studies using cox3-cox1 (Brugler et al. 2013), which indicated that Umbellapathes bipinnata Opresko, 2005, and an undescribed Umbellapathes species (USNM 1204042, see Brugler et al. 2013, figures 2 and 3) were genetically distant from both Bathypathes and Schizopathes. More recent DNA sequencing studies using the mt gene regions, cox3-cox1 and nad5-nad1 (Chery et al. 2018) support the separation of A. bipinnata from Schizopathes; however, several unbranched specimens morphologically similar to Alternatipathes grouped with Schizopathes. Further study is needed to determine the parameters that separate Alternatipathes from Schizopathes. Species assigned to the genus. Umbellapathes bipinnata Opresko, 2005, Bathypathes alternata Brook, 1889, Alternatipathes venusta Opresko & Wagner, 2020, and Alternatipathes mirabilis n. sp. Distribution. The genus occurs in the Pacific, Indian, Atlantic and Southern Oceans at depths usually exceeding 2500 m and often greater than 4000 m. Information regarding occurrences in the Southern Ocean (mostly Bellingshausen/Amundsen Abyssal plains) are based on unpublished R/V Eltanin records at the NMNH [e.g., USNM 1114499 (R/V Eltanin sta. 673); USNM 78806 and USNM 83545 (R/V Eltanin sta. 1140); and USNM 78811 (R/V Eltanin sta. 1640)]., Published as part of Opresko, Dennis M. & Molodtsova, Tina N., 2021, New species of deep-sea Antipatharians from the North Pacific (Cnidaria: Anthozoa: Antipatharia), Part 2, pp. 401-422 in Zootaxa 4999 (5) on page 403, DOI: 10.11646/zootaxa.4999.5.1, http://zenodo.org/record/5119429, {"references":["Molodtsova, T. N. & Opresko, D. M. (2017) Black corals (Anthozoa: Antipatharia) of the Clarion-Clipperton Fracture Zone. Marine Biodiversity, 47 (2), 349 - 365. https: // doi. org / 10.1007 / s 12526 - 017 - 0659 - 6","Opresko, D. M. (2005) New genera and species of antipatharian corals (Cnidaria: Anthozoa) from the North Pacific. Zoologische Mededelingen, Leiden, 79, 129 - 165.","Brugler, M. R., Opresko, D. M. & France, S. C. (2013) The evolutionary history of the order Antipatharia (Cnidaria: Anthozoa: Hexacorallia) as inferred from mitochondrial and nuclear DNA: implications for black coral taxonomy and systematics. Zoological Journal of the Linnean Society, 169, 312 - 361. https: // doi. org / 10.1111 / zoj. 12060","Chery, N., Parra, K., Evankow, A., Stein, D., Distel, D., Appiah-Madson, H., Ross, R., Sanon, E., Alomari, N., Johnson, R., Vasovic, A., Horowitz, A., Popa, H., Short, B., Kourehjan, D., Vasquez, D. M., Rodriguez, E., Opresko, D. M. & Brugler, M. R. (2018) Partnering with the Ocean Genome Legacy to advance our understanding of black corals (Order Antipatharia). 15 th Deep-Sea Biology Symposium, Monterey, California, 9 - 14 September 2018. poster presentation. [preprint available from M. Brugler at https: // tidalmarshtaskforce. wixsite. com / uscb / publications]","Brook, G. (1889) Report on the Antipatharia. Report on the Scientific Results of the Voyage of the HMS Challenger during the years 1873 - 1876, Zoology, 32, 1 - 222.","Opresko, D. M. & Wagner, D. (2020) New species of black corals (Cnidaria: Anthozoa: Antipatharia) from deepsea seamounts and ridges in the North Pacific. Zootaxa, 4868 (4), 543 - 559. https: // doi. org / 10.11646 / zootaxa. 4868.4.5"]}

Parantipathes pluma n. sp. (Figs 6–8) urn:lsid:zoobank.org:act: 7E0195DB-65A4-4DD9-9320-C013B125012A Parantipathes sp. Brugler et al. 2013: fig. 7A, 7D. Material examined. Holotype: USNM 1093058 (SEM stub 503), N. Pacific, central Aleutian Islands, S. of Amlia Island, ROV Jason II, Dive 95 (Field Identification Number: J 2095-2-7-4), 51.8116°N, 173.8328°W, 843 m, coll. R. Stone, 25 July 2004 (specimen dry). Paratype: USNM 1498742 (SEM stub 510), N. Pacific, Bering Sea, Zhemchug Canyon, F / V Cape Flattery, 58.5395°N, 175.0640°W, 977 m, coll. J. Hoff, 10 Jul 2016. Other Material: USNM 1093061, N. Pacific, central Aleutian Islands, Bobrof Island Pass, ROV Jason II, Dive 106 (Field Identification Number: J 2106-7-1), 51.8924°N, 177.2863°W, 936 m, coll. R. Stone, 7 Aug 2004; USNM 1482130, N. Pacific, central Aleutian Islands, SW of Adak Island, F/ V Ocean Olympic, 51.5270°N, 177.0170°W, 329 m, coll. G. Nightengale, Oct 2004. Diagnosis. Tall colonies, monopodial, unbranched or sparsely branched to the second order. Stem and branches pinnulate. Pinnules mostly simple, up to 13 cm long, arranged bilaterally along the stem, and, in varying degrees of regularity within and between colonies, with two to three rows on each side of axis, and in alternating semispiral groups typically consisting of two or three, and very rarely four pinnules. Pinnular density very variable depending on specimen, location on corallum, number of pinnules per group, and spacing of pinnules within and between groups; commonly 13–16 total per cm, but ranging from about 10 to 19 per cm. Pinnular spines usually simple (rarely with apical lobes), smooth, perpendicular to the axis, with 4–5 spines per mm; polypar spines mostly 0.06–0.08 mm tall (maximum about 0.09 mm); abpolypar spines 0.04–0.06 mm. Polyps on pinnules estimated to be 2.8–3.2 mm in transverse diameter with 2.5–3 polyps per cm. Description of holotype. Holotype (USNM 1093058, Fig. 6A) monopodial, without branches, but pinnulate with simple pinnules in multiple rows along the axis. Holdfast and lower unpinnulated section of stem missing; stumps of pinnules present to bottom of remaining part of stem. Apical section of corallum retained. Remaining section of stem 104 cm long (in three broken pieces). Stem diameter 5.7 mm at broken off basal end. Pinnules (Fig 6B) simple, elongate, arranged bilaterally with two or three rows on each side of the axis, and also in groups of two or three pinnules, one from each row. Spacing of pinnules within each group very irregular both along the axis and around it; therefore, the groups of pinnules are often not in clearly defined semispirals. Pinnules within a group mostly 1–2 mm apart, and a clearly defined semispiral group of three pinnules covers an axial distance of about 3.5 mm. Pinnules are 11–13 cm long and 0.4–0.6 mm in diameter near the base, and inclined distally (distal angle 40–60°). Pinnules subequal in length in all rows. Pinnular density very variable, but commonly 11–13 total per cm (range 9–16 per cm). Pinnules in only 4 rows at bottom of stem, with 10 pinnules total per cm. Pinnular spines (Fig. 7) are smooth, triangular in lateral view, mostly standing nearly perpendicular to the axis, but with some inclined distally and a few inclined basally (relative to the direction of the pinnule). The apex can be acute or rounded. On sections of pinnules where the axis is 0.31–0.37 mm in diameter (excluding spines), the polypar spines are typically 0.07–0.08 mm tall (maximum about 0.09 mm), and the abpolypar spines are usually 0.04–0.06 mm tall (maximum about 0.07 mm). On sections of pinnules where the axis is 0.20–0.23 mm in diameter (excluding spines) and the spines are more compressed laterally, the polypar spines are mostly 0.06 mm tall and the abpolypar spines are only slightly smaller. The spines are arranged in axial rows, six or seven of which can be seen in lateral view, and within the rows there are 4–5 spines per mm. On some sections of the pinnules the rows of polypar spines often appear very crowded together when compared to the rows of abpolypar spines. Often the base of the spines extends out along the axis distally and basally forming axial ridges. The polyps are in a very poor state of preservation (colony dry). They are uniserially arranged on the pinnules, often on the upper or lower side such that those on adjacent pinnules on the same side of the corallum tend to face towards each other. The transverse diameter of the polyps is estimated to range from 2.8 to 3.2 mm, but is mostly close to 3 mm, with 2.5 to 3 polyps per centimeter. Description of paratypes and other material. The specimen selected as a paratype of Parantipathes pluma (USNM 1498742) is an almost complete monopodial colony, without branches, but is only half the size of the holotype (Fig. 8A). The stem is 55 cm long (in four broken pieces) and has a basal diameter of 3 by 3.4 mm just above the holdfast. Pinnulation begins about 2.5 cm above the holdfast. As in the holotype, the pinnules are arranged bilaterally, with three rows on each side of the stem, and they are subequal in length in all rows. The longest pinnules are 11 cm long and have a basal diameter of about 0.4 mm. Pinnules (Fig. 8C) are mostly in alternating semispiral groups of three on each side of the axis (very rarely four per group). The pinnular density along most of the stem is about five groups of three pinnules per cm, but because of varying interpinnular distances and the overlap of pinnules on each side of the axis, the total number of pinnules per cm ranges from 14 to 19 per cm, compared to a typical range of 11–13 per cm in the holotype. The semispiral groups of three pinnules cover a distance of 2 to 2.5 mm. The pinnules on lowest part of stem are in groups of two. In places along the stem the pinnular arrangement in rows and semispiral groups becomes very distorted as in the holotype. The pinnules in all rows are inclined distally such that the distal angle they form with the stem is close to 45°, but nearer the top of the stem this increases to about 60°. The interior angle formed between the two posterior rows of pinnules is about 180°; that of lateral and anterior rows is around 120°. The pinnular spines (Fig. 8B) are similar to those in the holotype in being triangular in lateral view, standing nearly perpendicular to the axis. They have an acute to rounded apex. On sections of pinnules 0.2 to 0.32 mm in diameter, the polypar spines are 0.07 to 0.086 mm tall, and slightly larger than the abpolypar spines (0.04 to 0.07 mm). Four or five rows of spines are visible in lateral view, and there are 4–5 spines per mm in each row. On the lower part of some pinnules (5–10 mm above base) the sclerenchyme becomes thickened and the spines on one side of the axis have multiple (usually 2–4) conically-shaped, apical lobes (Fig. 8D). On the lower part of the stem, the spines are up to about 0.09 mm tall and appear to be in clusters, although these spines may have originated as single spines with multiple apical lobes as those on the lower sections of some of the pinnules. Polyps are too poorly preserved to estimate their size or density. The other two specimens assigned to this species (USNM 1093061 and USNM 1482130) are similar to the type in having pinnules up to 13 cm; pinnules in semispiral groups of mainly two or three; and with spines 0.05–0.07 mm tall. In situ photos of USNM 1093061 (Brugler et al. 2013: 7 A) indicate that the colony was very sparsely branched to the second order; however, only a single branch was collected. Genetic data. GenBank Acc. Nos.: USNM 1093058, holotype [KF054491 (igrW), KF054637 (igrN), and KF054384 (cox3-cox1)]; USNM 1093061 [KF054490 (igrW), KF054644 (igrN), and KF054384 (cox3-cox1)]. DNA sequencing studies using the mt gene regions listed above (Brugler et al. 2013), as well as those using nad5-nad1 (Chery et al. 2018), revealed that all haplotypes of the holotype of P. pluma (USNM 1093058) were identical to those of other Pacific Parantipathes specimens, and to Pacific specimens of Lillipathes and Dendrobathypathes Opresko, 2002. Atlantic species of Parantipathes, including P. larix (Esper, 1790), however, fell into a separate subclade. These results suggest either a polyphyletic origin of the Parantipathes morphotype, or a relatively high degree of genetic change and possibly interchange following the isolation of the populations in separate oceanic basins. Comparisons. Parantipathes pluma n. sp. differs from most of the hitherto known species of the genus by its very long pinnules which are typically more than 10 cm long. The new species is superficially similar to the Atlantic species Parantipathes larix in the maximum length of the pinnules (11–13 cm vs. 6–13 cm in P. larix), number of rows of pinnules (4–6), and in the size of the polypar spines on the pinnules (up to 0.09 mm vs. up to 0.11 mm in P. larix), but differs in the larger size of the polyps (2.8–3.2 mm vs. 1.6–2.2 mm) and in the lower density of the pinnules (mostly 11–13 per cm vs. 21 per cm). In addition, the distal angle of the pinnules is 80–90° in P. larix and much less in P. pluma, (40–60°), the number of rows of spines seen in lateral view is greater (6–7 vs. 3–4), and the spines can be distinctly curved distally in P. larix but are more at right angles to the axis in P. pluma. As noted above, P. pluma is genetically distinct from P. larix. The one other species of Parantipathes found in the northern Pacific, P. euantha (see Molodtsova & Pasternak 2005 for redescription), which was described from a relatively small colony, differs from Parantipathes pluma in having shorter pinnules (up to 3.8 cm) and smaller polyps (1.9–2.7 mm). The type specimen of P. euantha was preserved in Bouin fixative, so it is not available for genetic studies. Etymology. Species name " pluma " is derived from the Latin " pluma ", meaning "feather", in reference to the general shape of the corallum. Distribution. Known only from the North Pacific at depths ranging from 329 to 977 m., Published as part of Opresko, Dennis M. & Molodtsova, Tina N., 2021, New species of deep-sea Antipatharians from the North Pacific (Cnidaria: Anthozoa: Antipatharia), Part 2, pp. 401-422 in Zootaxa 4999 (5) on pages 416-420, DOI: 10.11646/zootaxa.4999.5.1, http://zenodo.org/record/5119429, {"references":["Brugler, M. R., Opresko, D. M. & France, S. C. (2013) The evolutionary history of the order Antipatharia (Cnidaria: Anthozoa: Hexacorallia) as inferred from mitochondrial and nuclear DNA: implications for black coral taxonomy and systematics. Zoological Journal of the Linnean Society, 169, 312 - 361. https: // doi. org / 10.1111 / zoj. 12060","Chery, N., Parra, K., Evankow, A., Stein, D., Distel, D., Appiah-Madson, H., Ross, R., Sanon, E., Alomari, N., Johnson, R., Vasovic, A., Horowitz, A., Popa, H., Short, B., Kourehjan, D., Vasquez, D. M., Rodriguez, E., Opresko, D. M. & Brugler, M. R. (2018) Partnering with the Ocean Genome Legacy to advance our understanding of black corals (Order Antipatharia). 15 th Deep-Sea Biology Symposium, Monterey, California, 9 - 14 September 2018. poster presentation. [preprint available from M. Brugler at https: // tidalmarshtaskforce. wixsite. com / uscb / publications]","Opresko, D. M. (2002) Revision of the Antipatharia (Cnidaria: Anthozoa), Part II, Schizopathidae. Zoologische Mededelingen, Leiden, 76, 411 - 442.","Esper, E. J. C. (1790) Die Pflanzenthiere in Abbildungen nach der Natur mit Farben erleuchtet nebst Beschreibungen, Pflanzenthiere 1, Lieferung 5, Raspe, Nurnberg, pl. 4. [see also 1792, Pflanzenthiere 2, p. 147] https: // doi. org / 10.5962 / bhl. title. 118730","Molodtsova, T. N. & Pasternak, F. A. (2005) Redescription of Parantipathes euantha (Pasternak, 1958) (Anthozoa: Antipatharia) from Kurile-Kamchatka Trench. Invertebrate Zoology, 2 (2), 169 - 179."]}