taxonID	type	description	language	source
EB7A87EBA76F4C7132BFF99B43686CE8.taxon	materials_examined	Material examined. Holotype: Y 30046, attached on stones, collected on 16 December 2014 from FX-Dive 17 (137 ° 49.90 ′ E, 9 ° 0.82 ′ N), 1980 m, foraminiferal ooze bottom. Paratypes: Y 30051, two specimens, embraced sponge spicules, collected on 16 December 2014 from FX-Dive 17 (137 ° 49.81 ′ E, 8 ° 59.80 ′ N), 1928 m, foraminiferal ooze bottom. Body and Size. Pedal disc attached to stone or grasping sponge spicules. Column covered with brown cuticle, darker proximally than distally (Fig. 2). In preservation, column sub-cylindrical, height 13 – 70 mm (70 mm in holotype), diameter of pedal disc 27 – 89 mm (70 mm in holotype), larger than that of proximal column (18 – 55 mm; 45 mm in holotype), greatest diameter of distal column 17 – 74 mm (74 mm in holotype) (Fig. 2 B, C). Column divisible into scapus and scapulus: former provided with layer of cuticle and larger tubercles; latter short, without cuticle, longitudinally furrowed, with smaller tubercles (Fig. 2). Tubercles mainly in distal column, typically conical in holotype and rounded in smaller specimens, of different sizes, diameters of base to 7 mm and height to 9 mm, irregularly arranged. Mesogloea of column thick, to 3 mm between tubercles and about same thickness along column. Oral Disc and Tentacles. Oral disc pink, elliptical, long axis diameter 6 – 54 mm (54 mm in holotype). Actinopharynx well developed, length to 25 mm, occupying about 1 / 3 of column length in holotype. Tentacles marginal, retractile, smooth, tapered, and without mesogloeal thickenings on aboral side (Figs. 2 A). Length to 30 mm in life, to 10 mm long and 3 mm wide in preservation. Tentacles hexamerously arranged in six cycles, inner ones wider and longer than outer ones, 181 in holotype (12 cut off with margin for histological sections), 191 in larger paratype (15 cut off with margin for histological sections), and 92 in smaller paratype; full complement of large individuals likely 192 (6 + 6 + 12 + 24 + 48 + 96). Internal Anatomy. Two symmetrical siphonoglyphs well developed, each attached to pair of directive mesenteries. Mesenteries not divisible into macrocnemes and microcnemes. Equal number of mesenteries at margin and limbus. In large specimens (holotype and larger paratype), 96 pairs hexamerously arranged in five cycles. In holotype, six pairs of mesenteries of first cycle and one mesentery of second cycle perfect and sterile (mesentery pairing with perfect one of second cycle fertile). In larger paratype, mesenteries of first cycle except for one perfect and sterile (imperfect mesentery also sterile). Mesenteries of second-fourth cycle fertile (except for perfect mesentery in holotype), with oocytes larger than 250 Μm in diameter. Mesenteries of fifth cycle sterile. In smaller paratype, 48 pairs of mesenteries regularly arranged in four cycles: first cycle perfect and sterile, second and third cycles fertile, fourth cycle sterile. No cinclides. Larger mesenteries bear acontia proximally. Sphincter mesogloeal, alveolar, not very strong (Fig. 3 A). Longitudinal muscles of tentacles ectodermal. Radial muscles of oral disc meso-ectodermal, and mesogloea much thicker in parts corresponding to stronger endocoels than in exocoels (Fig. 3 B). Parietobasilar muscles weak (Fig. 3 C). Longitudinal retractor muscles diffuse, weak (Fig. 3 C). Cnidom. Spirocysts, basitrichs, microbasic p - mastigophores (Fig. 4). See Table 1 for size and distribution.	en	Li, Yang, Xu, Kuidong (2016): Paraphelliactis tangi n. sp. and Phelliactis yapensis n. sp., two new deep-sea species of Hormathiidae (Cnidaria: Anthozoa: Actiniaria) from a seamount in the tropical Western Pacific. Zootaxa 4072 (3): 358-372, DOI: 10.11646/zootaxa.4072.3.5
EB7A87EBA76F4C7132BFF99B43686CE8.taxon	distribution	Distribution and Habitat. Paraphelliactis tangi n. sp. has been found only from a seamount near the Yap Trench in the tropical Western Pacific, where the water depth ranged from 1,928 m to 1,980 m and the sediment was foraminiferal ooze. Some other individuals were also observed by ROV nearby, and the holotype attached on a stone and the paratypes embraced sponge spicules with pedal disc. Tissue Cnida type N n Range, in µm Tentacle Robust spirocysts (A) 3 / 3 65 (21.5) 25.5 – 75.0 × 3.2 – 9.0 Gracile spirocysts (B) 3 / 3 45 25.0 – 49.0 × 3.0 – 4.0 Basitrichs (C) 3 / 3 52 26.0 – 52.0 (56.0) × 2.5 – 4.0 Basitrichs (D) 2 / 3 7 16.0 – 21.0 × 1.5 – 3.0 Middle column Basitrichs (E) 3 / 3 40 14.0 – 24.0 × 2.0 – 4.0 Basitrichs (F) 3 / 3 33 9.5 – 14.0 × 1.5 – 2.0 Microbasic p - mastigophores (G) 1 / 3 18 18.2 – 21.0 × 3.0 – 4.0 Actinopharynx Basitrichs (H) 3 / 3 61 25.5 – 55.0 × 2.9 – 4.0 Basitrichs (I) 3 / 3 25 17.5 – 24.5 × 2.0 Microbasic p - mastigophores (J) 3 / 3 46 25.0 – 41.0 (50.0) × 4.0 – 4.9 Mesenterial filament Basitrichs (K) 3 / 3 35 35.0 – 60.0 × 3.0 – 4.0 (5.0) Basitrichs (L) 3 / 3 43 16.0 – 26.0 × 1.5 – 3.0 Microbasic p - mastigophores (M) 3 / 3 24 24.0 – 37.0 × 3.0 – 5.5 Acontia Basitrichs (N) 2 / 2 * 65 49.0 – 62.0 × 3.0 – 4.1 Basitrichs (O) 2 / 2 16 17.0 – 27.0 × 2.0 Etymology. Named in honor of the late Chinese marine biologist, Prof. Zhican TANG, for his great contribution to the taxonomy of Cnidaria in China.	en	Li, Yang, Xu, Kuidong (2016): Paraphelliactis tangi n. sp. and Phelliactis yapensis n. sp., two new deep-sea species of Hormathiidae (Cnidaria: Anthozoa: Actiniaria) from a seamount in the tropical Western Pacific. Zootaxa 4072 (3): 358-372, DOI: 10.11646/zootaxa.4072.3.5
EB7A87EBA76F4C7132BFF99B43686CE8.taxon	discussion	Remarks. The genus Paraphelliactis was established by Carlgren (1928 a) for Pa. spinosa based on its resemblance of appearance and structure with Phelliactis Simon, 1892. Subsequently a second species, Pa. michaelsarsi Carlgren, 1934, was described. Carlgren (1942, 1949) distinguished Paraphelliactis from Phelliactis mainly by the different arrangement of the radial muscles of the oral disc and the (probably) greater number of mesenteries at the margin than at the limbus. Riemann-Zürneck (1973) suggested the radial muscles of the oral disc used to separate Paraphelliactis and Phelliactis were variable and thus synonymized Paraphelliactis with Phelliactis. Later, Dunn (1982) described the third species of Paraphelliactis, Pa. pabista. Sanamyan & Sanamyan (2007) regarded Paraphelliactis as a valid genus after discussing the relation of the number of mesenteries at the margin to that at the limbus in Paraphelliactis and Phelliactis, where Ph. hertwigi Simon, 1892 (the type species) and many other species of Phelliactis have fewer mesenteries at the margin than at the limbus, while species of Paraphelliactis have more mesenteries at the margin than at the limbus. Molodtsova et al. (2008) reported a specimen, which has almost the equal number of mesenteries at the margin and at the limbus, and identified it as Phelliactis michaelsarsi (Carlgren, 1934). The new species Paraphelliactis tangi n. sp. has two unusual features: a complete fifth cycle of mesenteries and an equal number of mesenteries throughout the column. The former feature is absent in all three known species of Paraphelliactis, but exists in three of 20 known species of Phelliactis (Ph. americana Widersten, 1976, Ph. callicyclus Riemann-Zürneck, 1973 and Ph. lophohelia Riemann-Zürneck, 1973). The latter feature probably exists also in the three known species of Phelliactis and in the specimen identified by Molodtsova et al. (2008) as Ph. michaelsarsi. In addition, Pa. tangi n. sp. has another feature not observed in other Paraphelliactis or Phelliactis, viz., tentacles without mesogloeal thickenings on the aboral side. Nonetheless, the new species is covered with a thick cuticle, a typical feature of the genus Paraphelliactis, while in the species of Phelliactis the cuticle is usually thin and is easily stripped off. Thus, we assigned the new species to the genus Paraphelliactis rather than Phelliactis. We extend the generic diagnosis of Paraphelliactis as follows to include the new species by stating that the number of tentacles can be equal to that of mesenteries at the limbus and the fifth cycle of mesenteries may be complete. Improved diagnosis of Paraphelliactis Carlgren, 1928 (adapted from Carlgren 1949). Hormathiidae with well developed pedal disc. Column divisible into scapus and scapulus, the former strongly tuberculated and provided with a thick cuticle. Sphincter mesogloeal, alveolar. Tentacles arranged in more than five cycles, more than or almost equal to mesenteries at the limbus, with or without mesogloeal thickenings on the aboral side. Longitudinal muscles of tentacles ectodermal, radial muscles of oral disc ectodermal or more or less mesogloeal. Two well developed siphonoglyphs. Mesenteries hexamerously arranged in five cycles, usually six pairs perfect and sterile, and the last cycle incomplete or complete. Retractors of mesenteries diffuse and weak. Parietobasilar muscles weak. Acontia well developed. No cinclides. Cnidom: Robust and gracile spirocysts, basitrichs and microbasic p - mastigophores.	en	Li, Yang, Xu, Kuidong (2016): Paraphelliactis tangi n. sp. and Phelliactis yapensis n. sp., two new deep-sea species of Hormathiidae (Cnidaria: Anthozoa: Actiniaria) from a seamount in the tropical Western Pacific. Zootaxa 4072 (3): 358-372, DOI: 10.11646/zootaxa.4072.3.5
EB7A87EBA76F4C7132BFF99B43686CE8.taxon	distribution	Distribution W Pacific N Atlantic N Atlantic NE Pacific References Present study Carlgren 1928 a, 1942, 1949; Dunn Carlgren 1949; Dunn 1982; Dunn 1982; Sanamyan & Sanamyan 1982; Sanamyan & Sanamyan 2007 Riemann-Zürneck 1986; Sanamyan & 2007; Eash-Loucks & & Fautin 2012 Sanamyan 2007; Molodtsova et al. 2008 height 70 mm and width 74 mm vs. height up to 140 mm and width over 100 mm), the sub-cylindrical body shape (vs. cup shaped with pedal disc narrower than column), the solid mesogloea of column (vs. spongy), distinct scapulus (vs. indistinct), and stronger sphincter. Paraphelliactis tangi n. sp. differs from Pa. pabista Dunn, 1982 by the sub-cylindrical body shape (vs. cup shaped with pedal disc narrower than column), the irregularly arranged tubercles (vs. regularly arranged), the stronger sphincter, and the larger basitrichs of mesenterial filaments (length 35 – 60 Μm vs. 23 – 34 Μm) (Table 2, and references therein). So far, Pa. tangi n. sp. is the fourth species of the genus and the first known in the Western Pacific.	en	Li, Yang, Xu, Kuidong (2016): Paraphelliactis tangi n. sp. and Phelliactis yapensis n. sp., two new deep-sea species of Hormathiidae (Cnidaria: Anthozoa: Actiniaria) from a seamount in the tropical Western Pacific. Zootaxa 4072 (3): 358-372, DOI: 10.11646/zootaxa.4072.3.5
EB7A87EBA76A4C7D32BFFB6745D66F26.taxon	materials_examined	(Figs. 1, 5 – 7; Tables 3, 4) Material examined. Holotype: Y 30039, grasped sponge spicules, collected on 15 December 2014 from FX-Dive 16 (137 ° 44.84 ′ E, 8 ° 51.90 ′ N), 855 m, foraminiferal ooze bottom. Paratypes: Y 30040, one specimen, collected together with the holotype and attached to sponges; Y 30064, one specimen, attached to sponges, collected on 18 December 2014 from FX-Dive 18 (137 ° 48.00 ′ E, 8 ° 53.98 ′ N), 879 m, foraminiferal ooze associated with manganese nodules. Body and Size. Individuals usually grasping or attached to sponges (Fig. 5 A, C, D). In preservation, column sub-cylindrical, height 27 – 104 mm (104 mm in holotype), greatest diameter of pedal disc 18 – 98 mm (98 mm in holotype), greatest diameter of column 22 – 78 mm (78 mm in holotype), greatest diameter of oral disc 11 – 50 mm (50 mm in holotype). Column divisible into scapus and scapulus. Scapus with thin layer of cuticle, and irregularly arranged tubercles in distal column; tubercles hemispherical, diameter of base to 6 mm. Scapulus without cuticle, but with tubercles smaller than those of scapus; tubercles of varying shapes and sizes, irregularly arranged (Fig. 5 B). Ectoderm of column very thin, mostly stripped off. Mesogloea thick, about 1.5 mm in distal column between tubercles, and about 2.5 mm in margin and proximal column of holotype. Oral disc and Tentacles. Oral disc red, bilobed and asymmetric in holotype, larger part possesses 90 tentacles and 46 pairs of mesenteries, smaller part possesses 75 tentacles and 37 pairs of mesenteries (Fig. 5 B – D). Mouth ovoid, elevated in center of oral disc, same color as oral disc. Actinopharynx well developed, length to 33 mm, occupying near 1 / 3 of column length. Tentacles marginal, smooth, tapered, with mesogloeal thickenings on aboral side (Fig. 6 A); length to 10 mm, diameter of base to 6 mm in preservation. Tentacles alternately arranged in two cycles, with inner and outer ones subequal. Number 165 in holotype (six of them cut off with margin for histological sections), 82 in paratype Y 30040, and 91 in Y 30064. Internal Anatomy. Two elongate, symmetrical siphonoglyphs; each attached to pair of directive mesenteries. Mesenteries not divisible into macrocnemes and microcnemes, arranged in five cycles (Fig. 6 D). Mesenteries more numerous at limbus than margin: holotype has 176 mesenteries at limbus, 168 at middle column, and 166 at margin; paratype Y 30040 has 128 mesenteries at limbus and 114 at margin; paratype Y 30064 has 106 mesenteries at limbus, and 96 at margin. In holotype, mesenteries of first cycle perfect and sterile; those of second cycle rarely with gametogenic tissue, and two pairs of them perfect and sterile; those of third and fourth cycles fertile, with oocytes larger than 180 Μm in diameter; those of fifth cycle incomplete, some fertile, and one excrescent pair (Fig. 6 D). Mesentery arrangement undeterminable in paratypes as their damage in course of dissection and counting number of mesenteries. Longitudinal retractor muscles diffuse, weak (Fig. 6 C). No cinclides. Acontia well developed, not coiled, usually one acontium arises from each larger mesentery proximally. Sphincter mesogloeal, alveolar, and moderately strong (Fig. 6 B). Longitudinal muscles of tentacles and radial muscles of oral disc ectodermal (Fig. 6 A, E). Radial muscles of oral disc weaker and mesoglea thicker over endocoels than over exocoels (Fig. 6 E). Parietobasilar muscles weak (Fig. 6 C). Cnidom. Spirocysts, large basitrichs, small basitrichs, microbasic p - mastigophores (Fig. 7). See Table 3 for distribution and size.	en	Li, Yang, Xu, Kuidong (2016): Paraphelliactis tangi n. sp. and Phelliactis yapensis n. sp., two new deep-sea species of Hormathiidae (Cnidaria: Anthozoa: Actiniaria) from a seamount in the tropical Western Pacific. Zootaxa 4072 (3): 358-372, DOI: 10.11646/zootaxa.4072.3.5
EB7A87EBA76A4C7D32BFFB6745D66F26.taxon	distribution	Distribution and Habitat. Phelliactis yapensis n. sp. has been found only from a seamount near the Yap Trench in the tropical Western Pacific, where the water depth ranged from 855 m to 879 m and the sediment was foraminiferal ooze sometimes associated with manganese nodules. The holotype grasped sponge spicules with pedal disc and the paratypes attached to sponges.	en	Li, Yang, Xu, Kuidong (2016): Paraphelliactis tangi n. sp. and Phelliactis yapensis n. sp., two new deep-sea species of Hormathiidae (Cnidaria: Anthozoa: Actiniaria) from a seamount in the tropical Western Pacific. Zootaxa 4072 (3): 358-372, DOI: 10.11646/zootaxa.4072.3.5
EB7A87EBA76A4C7D32BFFB6745D66F26.taxon	etymology	Etymology. Named after the seamount / location (near the Yap Trench) where the species was discovered.	en	Li, Yang, Xu, Kuidong (2016): Paraphelliactis tangi n. sp. and Phelliactis yapensis n. sp., two new deep-sea species of Hormathiidae (Cnidaria: Anthozoa: Actiniaria) from a seamount in the tropical Western Pacific. Zootaxa 4072 (3): 358-372, DOI: 10.11646/zootaxa.4072.3.5
EB7A87EBA76A4C7D32BFFB6745D66F26.taxon	discussion	Remarks. Phelliactis yapensis n. sp. matches well with the definition of Phelliactis Simon, 1892 in Carlgren (1949). It differs from all congeners by the combination of body size, column structure, the arrangement of mesenteries and tentacles, and the size of cnidae (Table 4). Phelliactis yapensis n. sp. possesses characteristic, very large basitrichs of mesenterial filaments (Fig. 7 J; Table 3), a basitrich type not observed in the known species of Phelliactis. Among the 20 Phelliactis species recognized by Fautin (2013), only three were described by Wassilieff (1908) from the eastern sea area of Japan in the Western Pacific: Ph. crassa, Ph. japonica, and Ph. magna (Table 4). Phelliactis yapensis n. sp. is the first species found from the tropical Western Pacific Ocean (Fig. 1). It differs from the three known species by the distinct scapulus above the scapus (vs. no clear differentiation between the scapus and capitulum) (Stephenson 1918, 1920). In addition, Ph. yapensis n. sp. differs from Ph. crassa by its larger body size (up to 104 mm high and 98 mm wide vs. 50 mm high and 25 mm wide); from Ph. japonica by the stronger sphincter (vs. weak); and from Ph. magna by the strongly asymmetric oral disc (vs. slightly asymmetric), stronger sphincter (vs. weak), fewer tentacles (maximum 165 in 2 cycles vs. 192 in 6 cycles), and the higher number of perfect mesenteries (8 pairs vs. 6 pairs and 2 unpaired). According to Riemann-Zürneck (1973), the species of Phelliactis can be classified into three groups. Phelliactis yapensis n. sp. has six pairs of perfect mesenteries in the first cycle and two additional pairs in the second cycle, and thus belongs to the Phelliactis hertwigi group - together with its ten congeners Ph. algoaensis Carlgren, 1928; Ph. capensis Carlgren, 1938; Ph. capricornis Riemann-Zürneck, 1973; Ph. coccinea (Stephenson, 1918); Ph. hertwigii Simon, 1892; Ph. incerta Carlgren, 1934; Ph. magna (Wassilieff, 1908); Ph. pelophila Riemann-Zürneck, 1973; Ph. pulchra (Stephenson, 1918); and Ph. siberutiensis Carlgren, 1928 (Table 4). By contrast, the seven species of Phelliactis that have only six pairs of perfect mesenteries belong to the Phelliactis robusta group: Ph. callicyclus Riemann-Zürneck, 1973; Ph. carlgreni Doumenc, 1975; Ph. crassa (Wassilieff, 1908); Ph. hydrothermala Sanamyan & Sanamyan, 2007; Ph. japonica (Wassilieff, 1908); Ph. robusta Carlgren, 1928; and Ph. somaliensis Carlgren, 1928. The remaining three species have 12 pairs of perfect mesenteries: Ph. americana Widersten, 1976; Ph. gigantea (Carlgren, 1941); and Ph. lophohelia Riemann-Zürneck, 1973 (Table 4; and references therein). Our holotype has also an excrescent pair of mesenteries in the fifth mesentery cycle. Such a pattern is likely a minor irregularity in the arrangement of mesenteries. Similar case was also observed in Ph. americana Widersten, 1976. TABLE 4. Cοmparisοn οf Phelliactis yapensis n. sp. with knοwn species οf Phelliactis Simοn, 1892. −, Data nοt available.	en	Li, Yang, Xu, Kuidong (2016): Paraphelliactis tangi n. sp. and Phelliactis yapensis n. sp., two new deep-sea species of Hormathiidae (Cnidaria: Anthozoa: Actiniaria) from a seamount in the tropical Western Pacific. Zootaxa 4072 (3): 358-372, DOI: 10.11646/zootaxa.4072.3.5
