European Journal of Taxonomy 218: 1-52 http://dx.doi.org/10.5852/ejt.2016.218 www. europeanj ournaloftaxonomy. eu 2016 • Galea H R. ISSN 2118-9773 This work is licensed under a Creative Commons Attribution 3.0 License. Monograph urn:lsid:zoobank.org:pub:A4D7AA38-D18F-4604-A5E0-D965637BD9F8 Notes on some sertulariid hydroids (Cnidaria: Hydrozoa) from the tropical western Pacific, with descriptions of nine new species Horia R. GALEA Hydrozoan Research Laboratory, 405 Chemin des Gatiers, 83170 Tourves, France. E-mail: horia.galea.@gmall .com urn:lsid:zoobank.org:author:DE5AC672-0243-46F2-A910-AFF4E91A4C5D Abstract. Forty-three species of sertulariid hydroids (Cnidaria: Hydrozoa: Sertulariidae), collected from the tropical western Pacific (Taiwan, Philippines, New Caledonia, French Polynesia, Vanuatu, Fiji, Tonga, Solomon Islands) during various expeditions of the French Tropical Deep-Sea Benthos program, are discussed. Of these, nine are new to science: Gonaxia nova sp. nov., G. plumularioides sp. nov., Sertularella folliformis sp. nov., Se. plicata sp. nov., Se. pseudocatena sp. nov., Se. splendida sp. nov., Se. tronconica sp. nov., Se. tubulosa sp. nov., and Symplectoscyphus paucicatillus sp. nov. The subspecies Symplectoscyphus johnstoni (Gray, 1843) tropicus Vervoort, 1993 is raised to species but, in order to avoid the secondary homonymy with Sy. tropicus (Hartlaub, 1901), the replacement name, Sy fasciculatus nom. nov., is introduced. The male and female gonothecae of Diphasia cristata Billard, 1920, the male gonothecae of Gonaxia elegans Vervoort, 1993, as well as the female gonothecae of Salacia macer Vervoort & Watson, 2003, are described for the first time. Additional notes on the morphology of several other species are provided. All taxa are illustrated, in most cases using figures drawn at the same scale, so as to highlight the differences between related species. Key words. Deep water, new species, thecate hydroids, Sertulariidae. Galea H.R. 2016. Notes on some sertulariid hydroids (Cnidaria: Hydrozoa) from the tropical western Pacific, with descriptions of nine new species. European Journal of Taxonomy 218: 1-52. http://dx.doi.org/10.5852/eit.2016.218 Introduction The present report is a continuation of an earlier study dealing with some new sertulariid and syntheciid hydroids (Galea 2015 a), and completes a series of previous reports dealing with members of the families Sertulariidae Lamouroux, 1812 (Vervoort 1993), Halopterididae Millard, 1962 (AnsinAgis et al. 2009), Lafoeidae Hincks, 1868 (specifically, the genus Acryptolaria Norman, 1875) (Pena Cantero & Vervoort 2010), and Kirchenpaueriidae Stechow, 1921 (AnsinAgis et al. 2014) from the tropical western Pacific, obtained during numerous expeditions undertaken conjointly by the Institut de Recherche pour le Developpement (IRD, formerly ORSTOM) and the Museum national d'Histoire naturelle (MNHN) of Paris (Bouchet et al. 2008). The sertulariid hydroids dealt with herein belong to the following ten genera: Caminothujaria von Campenhausen, 1896, Diphasia L. Agassiz, 1862, Dynamena Lamouroux, 1812, Geminella Billard, 1925b, Gonaxia Vervoort, 1993, Idiellana Cotton & Godfrey, 1942, Salacia Lamouroux, 1816, 1 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Sertularella Gray, 1848, Sertularia Linnaeus, 1758 and Symplectoscyphus Marktanner-Turneretscher, 1890. Although most species have already been dealt with by Vervoort (1993), additional notes on them are provided, along with new data on the morphology of other taxa, including descriptions of nine new hy droids. Material and methods The methods of study were described in detail by Galea (2007, 2008). The list of stations is given in Table 1. Station numbers, as indicated in the text, are preceded by a two-letter prefix referring to the sampling gear used to secure the material, either a Charcot dredge (CC), a beam trawl (CP), a rocky- bottom dredge (DR) or a Warren dredge (DW). The material is deposited in the collections of MNHN. The species dealt with herein are listed according to their morphological similarities, notably the shape of their hydrothecae. Most figures, representing portions of colonies, hydro- and gonothecae, are drawn to the same scale and grouped onto the same plates, so as to facilitate comparisons between related species. Results Phylum Cnidaria Verrill, 1865 Class Hydrozoa Owen, 1843 Subclass Hydroidolina Collins & Marques, 2004 Order Leptothecata Cornelius, 1992 Family Sertulariidae Lamouroux, 1812 Genus Caminothujaria von Campenhausen, 1896 Caminothujaria molukkana von Campenhausen, 1896 Fig. 1A-B Caminothujaria molukkana von Campenhausen, 1896: 103. Caminothujaria molukkana - Schuchert 2015: 338, fig. 12. Material examined MUSORSTOM 3: Stn. DR117, numerous sterile fragments from an originally large colony (size undeterminable) (MNHN-IK-2012-16500); Stn. CP121, a 2.3 cm high, sterile colony (MNHN- IK-2012-16501); Stn. DR126, an originally 11.5 cm high colony, now broken into two parts, one gonotheca (MNHN-IK-2012-16502). MUSORSTOM 8: Stn. CP 1001, several stems and fragments up to 5.3 cm high, all sterile (MNHN- IK-2012-16503); Stn. DW1021, numerous sterile stems and fragments, 3-10.5 cm high, all sterile (MNHN-IK-2012-16504); Stn. CPI 104, an originally large but sterile colony, now fragmented, largest fragment ca 8 cm high (MNHN-IK-2012-16505). BORDAU2: Stn. CP 1582, ca 4 cm high, fertile colony composed of three stems (MNHN-IK-2012-16506). SALOMON 1: Stn. DW1756, three sterile stems 2.5-5 cm high (MNHN-IK-2012-16507); Stn. DW1767, a ca 12 cm high, sterile colony (MNHN-IK-2012-16508). Remarks A list of synonyms is provided by Schuchert (2015) and, for a re description, see Hirohito (1995). 2 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Table 1 . List of stations. Campaign DR117 CP121 DR126 CP134 CP34 DW37 DW38 DW66 CP69 DW46 CC174 DW205 DW221 DW423 DW40 DW48 DW55 DW57 DW39 DW127 DW716 CP737 CP804 CP806 DW809 DW810 CP813 CP814 CP821 CP823 DW829 DW830 DW902 CP906 DW914 DW923 CP1001 DW1019 DW1021 CP1083 CP1084 CP1104 CP 1131 DW1204 CP1265 CP 1447 CP1448 DW13 DW1513 1 Jun. 2000 CP1582 13 Jun. 2000 DW1595 16 Jun. 2000 DW1 27 Jul. 2000 DW1659 20Jun. 2001 DW1666 20Jun. 2001 DW1667 21 Jun. 2001 DW1699 24Jun. 2001 DW1704 25Jun. 2001 DW1712 26Jun. 2001 CP1719 26Jun. 2001 DW1722 26Jun. 2011 DW118 31 Jul. 2001 DW1741 23 Sep. 2001 DW1756 26 Sep. 2001 DW1767 28 Sep. 2001 DW1854 7 Oct. 2001 92-97 12°31' S 120°39' E 73-84 12°08' S 121°17'E 266 11°49' S 121°22'E 92-95 i2°or s 121 °57' E 710 23°11.88' S 167° 11.30' E 350 22°59.99' S 167°15.65 , E 360 22°59.74' S 167°15.31' E 505-515 24°55.43' S 168°21.67' E 1220-1225 23°51.38' S 167°58.68’E 570-610 22°53.05' S 167°17.08'E 385 19°00.30' S 163°18.50' E 160 22°38.50' S 167°06.80' E 535-560 22°58.60' S 167°36.80' E 280 20°25.85 f S 166°40.50'E 260 24°46.20' S 168°08.70'E 245 24°46.20 f S 168°08.70'E 260 23 o 21.40 , S 168°04.50' E 210 23°21.00' S 168°21.00' S 305 22°20.50' S 168°43.50'E 205-215 19°06' S 163°22'E 290-308 22°40' S 167°12'E 357-400 23°03.42' S 166°59.97' E 244-278 23°41.40' S 168°00.42'E 308-312 23°42.31' S 168°00.52'E 650-730 23°39.39 f S 167°58.94'E 850-900 23°40.45' S 167°58.83'E 410-415 23°45.23' S 168°16.57' E 444-530 23°47.60' S 168°17.10 , E 864-880 23°19.16' S 167°58.63'E 980-1000 23°22.76' S 167°51.60' E 386-390 23°21.37 f S 168°01.84' E 361-365 23°19.75' S 168°01.45'E 341-351 19°00.84 f S 163°14.83'E 339-350 19°01.07' S 163°14.5EE 600-616 18°48.79' S 163°15.23'E 502-470 18°51.51' S 163°24.17’ E 150-250 18°48.97' S 168°59.83' E 397-430 17°38.25' S 168°33.9E E 124-130 17°42.75' S 168°37.00' E 397-439 15°51.91' S 167°19.82'E 207-280 15°50.29' S 167°17.88'E 125-129 15°03.83' S 167 o 06.96'E 140-175 15°38.41' S 167°03.52'E 60-62 9°52.6' S 139°03.2' W 90-92 9°20.4' S 140°07.3' W 420-513 16°45.23' S 179°59.13'E 410-500 16°45.04' S 179°58.97'E 400 23°45’ S 168° 17' E 190-221 21°19' S 175°0E w 79-82 18°41' S 174°03' W 523-806 19°03'S 174°19 f W 98 23°38. F N 119°50.9'E 467-449 23°38 f S 167°42'E 469-860 23°42'S 167°43'E 237-250 23°41' S 168°0E E 581-600 24°40' S 168°39'E 420-400 23°47' S 168°17'E 180-250 23°22' S 168°03'E 391-407 23°21' S 168°02'E 540 23°16' S 168°01’E 128-136 24°56.3'N 122°01.5' E 557-655 11 °29 r S 159°57' E 497-511 08°52'S 159°50'E 98-200 08°19' S 160°40 f E 229-260 09°46' S 160°53 f E Station Date Depth (m) Latitude Longitude 3 Jun. 1985 3 Jun. 1985 4 Jun. 1985 5 Jun. 1985 29 Aug. 1985 30 Aug. 1985 30 Aug. 1985 3 Sep. 1985 3 Sep. 1985 30 Aug. 1985 17 Sep. 1985 27 Sep. 1985 29 Sep. 1985 16 Feb. 1989 7 Mar. 1989 8 Mar. 1989 9 Mar. 1989 9 Mar. 1989 8 Jun. 1989 4 Mar. 1990 10 May 1993 13 May 1993 27 Nov. 1993 27 Nov. 1993 27 Nov. 1993 27 Nov. 1993 28 Nov. 1993 28 Nov. 1993 29 Nov. 1993 29 Nov. 1993 29 Nov. 1993 29 Nov. 1993 4 Aug. 1994 4 Aug. 1994 5 Aug. 1994 6 Aug. 1994 25 Sep. 1994 28 Sep. 1994 28 Sep. 1994 5 Oct. 1994 5 Oct. 1994 7 Oct. 1994 11 Oct. 1994 28 Aug. 1997 3 Sep. 1997 4 Mar. 1999 4 Mar. 1999 12 Aug. 1999 MUSORSTOM 3 BIOCAL MUSORSTOM 4 MUSORSTOM 6 SMIB4 VOLSMAR SMIB6 BATHUS 2 BATHUS 3 BATHUS 4 MUSORSTOM 8 MUSORSTOM 9 BORDAU1 LITHIST BORDAU 2 TAIWAN 1 NORFOLK 1 TAIWAN 2 SALOMON 1 3 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Geographical distribution The known area of distribution ranges from Indonesia and Tuvalu in the south, through Japan in the north, and encompasses the Philippines and the South China Sea (Schuchert 2015). Genus Diphasia L. Agassiz, 1862 Diphasia cristata Billard, 1920 Fig. 1C-J Diphasia cristata Billard, 1920: 147, fig. If. Diphasia cristata - Billard 1925b: 218, fig. 57, pi. 3 fig. 32. — Hirohito 1983: 38, fig. 15; 1995: 161, fig. 51a-c. Material examined SMIB 4: Stn. DW57, several sterile stems and fragments, up to 2.5 cm high (MNHN-IK-2012-16509). SMIB 6: Stn. DW127, a female colony composed of several stems up to 4 cm high, epizoic on Gonaxia sp. (MNHN-IK-2012-16510). MUSORSTOM 8: Stn. DW1021, small female colony composed of a few stems, up to 2 cm high, epizoic on Caminothujana molukkana (MNHN-IK-2012-16511). BORDAU 1: Stn. CP 1447, small female colony composed of several stems up to 2.4 cm high (MNHN- IK-2012-16512); Stn. CP 1448, dense, fertile colony (or colonies?), up to 4 cm high, on dead antipatharian (MNHN-IK-2012-16513). BORDAU 2: Stn. DW1513, male and female colonies with stems up to 1.5 cm high, on antipatharian and aglaopheniid hydroid (MNHN-IK-2012-16514). Remarks This species is immediately recognizable through the presence of five prominent, longitudinal, perisarcal crests running over the whole body of hydrothecae, as well as of an additional one found on the dorsal side of the intemodes. For the most recent description, see Hirohito (1995). It should be noted that the oblique node demarcating the junction between the basal, ahydrothecate part and the main, distal, hydrothecate part of the stems and side branches is not always present in the material examined here. The gonothecae of this species, hitherto unknown, are described from the present material. Male and female gonothecae present, each sex borne on different stems, but, due to their high density and the numerous branches and anastomoses of the stolon, it is impossible to determine if it is a single colony or whether several colonies are represented. The male gonothecae (Fig. II—J) are 1505-1580 pm long, ovoid (480-530 pm wide in middle), and provided with numerous upturned spines (width including the spines 1000-1170 pm). The aperture occurs on the apex of a short neck region and is surrounded by a few, short spines. The female gonothecae (Fig. 1F-H) are comparatively larger (2985-3160 pm long), have a rhomboidal cross-section (940-1010 pm wide), forming four crests at each angle; each one is provided with a succession of moderately long, upturned spines (width of gonotheca including the spines ca 1300 pm). A central, piriform chamber is attached to the walls of the gonotheca through four perisarcal connections, whose position alternates with that of the crests. The aperture is situated apically, and is small and quadrangular. 4 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Geographical distribution Previously known from the Philippines (Billard 1920, 1925b) and Japan (Hirohito 1983, 1995). The present material originates from New Caledonia, Vanuatu, Fiji, and Tonga. Dipltasia orientalis Billard, 1920 Fig. IK Diphasia orientalis Billard, 1920: 146, fig. Id. Diphasia orientalis -Billard 1925b: 212, figs 52-53. — Gibbons & Ryland 1989: 407, fig. 26. Fig. 1. — A-B. Caminothujaria molukkana von Campenhausen, 1896 (BORDAU 2, Stn. CP 1582). A. Fragment of internode with verticil of hydrothecae. B. Gonotheca. — C-J. Diphasia cristata Billard, 1920 (BORDAU 1, Stn. CP1448). C. Pair of hydrothecae, frontal view. D. Same, dorsal view. E. Cross section through basal part of hydrothecal pair, showing perisarcal crests. F. Female gonotheca. G. Same, apical view. H. Same, cross section. I. Male gonotheca. J. Same, apical view. — K. Diphasia orientalis Billard, 1920 (MUSORSTOM 3, Stn. DR117), internode with pair of hydrothecae. — L-O. Dynamena heterodonta (Jarvis, 1922) (MUSORSTOM 9). L. Pair of hydrothecae in material from Stn. DW1204. M. Same sample, hydrothecal aperture, showing internal, submarginal cusps. N-O. Isolated (N) or stacked (O) pairs of hydrothecae in material from Stn. CP 1265. — P. Geminella ceramensis Billard, 1925a (MUSORSTOM 8, Stn. CP 1084), internode with pair of hydrothecae. Scale bars: A-D, K-L, N-P = 500 pm; E = 400 pm; F-J = 1 mm ; M = 100 pm. 5 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Material examined MUSORSTOM 3: Stn. DR117, two infertile, unbranched stems, 9 and 12 mm high, detached from substrate (MNHN-IK-2012-16515); Stn. CP121, two infertile, unbranched stems, 13 and 22 mm high, detached from substrate (MNHN-IK-2012-16516). Remarks For a thorough description of this species, see Billard (1925b). Geographical distribution Indonesia (Billard 1925b), Fiji (Gibbons & Ryland 1989), Philippines (present report). Genus Dynamena Lamouroux, 1812 Dynamena heterodonta (Jarvis, 1922) Fig. 1L-0 Pasythea heterodonta Jarvis, 1922: 344, pi. 24, figs 11-12. Dynamena heterodonta -Billard 1925b: 198, fig. 44. — Redier 1966: 86. — Vervoort & Vasseur 1977: 36, figs 16-17. Sertularia gracilis - Billard 1905: 334 (not Sertularia gracilis FI assail, 1848: 2223). non Dynamena quadridentata f. heterodonta - Vannucci 1951a: 83; 1951b: 108, 112, 114 [= D. quadri- dentata (Ellis & Solander, 1786)]. Material examined MUSORSTOM 9: Stn. DW1204, small colony composed of four infertile stems, 6-12 cm high, detached from substrate (MNHN-IK-2012-16517); Stn. DW1265, sterile colony with stems up to 2.6 cm high, epizoic on Synthecium sp. (MNHN-IK-2012-16518). Remarks The sterile, unbranched stems, divided here and there by oblique nodes, each of which comprises a varied number of isolated hydrothecal pairs, occasionally forming apically stacked groups of two, the lack of evidence of an abcauline caecum in retracted hydranths, the two-cusped hydrothecae with a pleated adcauline flap and a semicircular abcauline flap, and the inconstant presence of internal, submarginal cusps in the hydrothecae suggest that they belong, with little doubt, to Jarvis’ (1922) species. Vervoort & Vasseur (1977) provided a reexamination of the type material, as well as a discussion regarding its differences with/), quadridentata (Ellis & Solander, 1786). Geographical distribution St. Brandon (Cargados Carajos) (Jarvis 1922), Indonesia (Billard 1925b), New Caledonia (Redier 1966), French Polynesia [Billard (1905), as Sertularia gracilis Hassall, 1848; Vervoort & Vasseur (1977); present study]. 6 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Genus Geminella Billard, 1925b Geminella ceramensis (Billard, 1925a) Fig. IP Sertularella ceramensis Billard, 1925a: 649. Geminella ceramensis - Schuchert 2003: 174, fig. 31. Material examined MUSORSTOM 8: Stn. CP 1084, small, sterile colony, less than 1 cm high, with tangled stems fixed on calcareous substrate (MNHN-IK-2012-16519); Stn. CPI 131, two sterile stems 0.5 cm high, detached from substrate (MNHN-IK-2012-16520). Remarks For a redescription of this distinctive species, see Schuchert (2003), who also provided a synonymy. Geographical distribution Indonesia, Philippines, New Caledonia (Schuchert 2003), and Vanuatu (present study). Genus Gonaxia Vervoort, 1993 Gonaxia amphorifera Vervoort, 1993 Figs 2A, 3A-B Gonaxia amphorifera Vervoort, 1993: 117, figs 3f, 4, 5, 6a-b, 8a. Material examined SMIB 6: Stn. DW127, two colonies, one unbranched and 4.5 cm high, the other forked twice and 9 cm high, both bear male gonothecae (MNHN-IK-2012-16521). Remarks The difficulty of distinguishing G. amphorifera from G. ampullacea Vervoort, 1993 without their female gonothecae is notorious. Since the present material bears only male gonothecae, attention was focused on the hydrothecal features, in an attempt to separate them specifically. Although Vervoort (1993) emphasized several distinguishing characters, the distinction was still laborious and, eventually, two features proved useful. It was found that in the present species the free, distal part of the hydrocladial hydrothecae was constantly set at about 90° with the axis of the cladia, regardless the position of the thecae (Fig. 2A) while, in the following species, that angle varied considerably (Fig. 2B) between the proximal hydrothecae (where it was of 80-90°) and the distalmost ones (usually reaching 45°). The size of the hydrothecae was comparatively smaller in the present material (Fig. 3 A) than in that assigned to G. ampullacea Vervoort, 1993 (Fig. 3C). I believe that the lack of a distinct inflation of the hydrothecae invoked by Vervoort is misleading. Some hydrothecae exhibit incipient lateral diverticuli (Fig. 3A). Their structure is discussed under G. aff. similis Vervoort, 1993. Geographical distribution New Caledonia (Vervoort 1993; present study). 7 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Gonaxia ampullacea Vervoort, 1993 Figs 2B, 3C-D Gonaxia ampullacea Vervoort, 1993: 121, figs 6c, 7a-c, 9. Material examined BATHUS 4: DW914, a 3.5 cm high colony with unbranched stem, bearing male gonothecae (MNHN- IK-2012-16522). Fig. 2. — A. Gonaxia amphorifera Vervoort, 1993 (SMIB 6, Stn. DW127), portion of stem with cladium. — B. Gonaxia ampullacea Vervoort, 1993 (BATHUS 4, Stn. DW914), portion of stem with cladia. — C. Gonaxia compacta Vervoort, 1993 (BATHUS 4, Stn. DW923), portion of stem with cladium. — D. Gonaxia intermedia Vervoort, 1993 (BATHUS 4, Stn. CP906), portion of stem with cladium. — E. Gonaxia sinuosa Vervoort, 1993 (SMIB 4, Stn. DW40), portion of stem with cladia. Scale bar: A-E = 1 mm. 8 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Remarks As stated above, the larger size and the more acute angle formed by the free part of the hydrocladial hydrothecae with the axis of cladia were used to assign this material to G. ampullacea. As in G. amphorifera , some hydrothecae exhibit incipient lateral diverticuli (Fig. 3C). Geographical distribution New Caledonia (Vervoort 1993; present study). Gonaxia comp acta Vervoort, 1993 Figs 2C, 3E-F Gonaxia compacta Vervoort, 1993: 135, figs 8c, 14a-b, 15a. Material examined BATHUS 4: Stn. DW923, a single, 6 cm high colony bearing an abortive gonotheca, as well as a row of incipient gonothecae, highly obscured by the accessory tubes of the stem (MNHN-IK-2012-16523). Remarks As already stated by Vervoort (1993), the hydrothecae of this species bear an obvious resemblance to those of G. amphorifera , G. ampullacea , and G. sinuosa , but it could be readily distinguished from them on the account of the absence of a pit formed by the free adaxial wall with the internode (Fig. 3E). Only an abortive gonotheca, arising from within the first hydrotheca of a cladium (Fig. 3F), was found. Several successive, elongate masses among the accessory tubes of the stem suggest the imminent fonnation of normal gonothecae. Geographical distribution New Caledonia (Vervoort 1993; present study). Gonaxia intermedia Vervoort, 1993 Figs 2D, 3G-K Gonaxia intermedia Vervoort, 1993: 157, figs 23e, 24d, 25a-c, 26a. Material examined BATHUS 4: Stn. DW902, several colonies and fragments, up to 9.5 cm high, mostly fertile, bearing male gonothecae (MNHN-IK-2012-16524); Stn. CP906, a total of twelve fertile colonies (10 male and 2 female), 4-6 cm high (MNHN-IK-2012-16525). Remarks In some colonies, the length of cladia reaches as much as 2.8 cm, and each may bear up to 116 hydrothecae. Aberrant secondary cladia, as those occurring in specimens from Stn. DW902, are given off from either within some cladial hydrothecae (Fig. 3J), or from short, auxiliary cladial tubes running parallel to the proximal parts of the axes of cladia. Both male and female colonies are present in the material in hand. As stated by Vervoort (1993), the gonothecae of this species resemble those of G. amphorifera and G. ampullacea through their general shape and nearly fully adnate condition. They seem to originate from below the axillar hydrothecae. The distal part of a gonotheca overlaps the proximal part of the following one, though their bodies never fuse with each other. Their apertures (50-65 pm wide in males, and 250-290 pm wide in females) 9 European Journal of Taxonomy 218 : 1-52 ( 2016 ) are mounted on raised cones situated near the distal ends of their bodies. In the male colonies, the gonothecae are so obscured by the numerous auxiliary tubes running parallel to the stem, that only the tips of their neck regions protrude from the strongly fascicled mass which composes the stems. In one male specimen (from Stn. CP906) with otherwise normal gonothecae, an elongate, abortive gonotheca, with two distal apertures, is given off from the lumen of a cladial hydrotheca The occurrence of such Fig. 3. — A-B Gonaxia amphorifera Vervoort, 1993 (SMIB6, Stn. DW127). A. Two successive cladial internodes with their hydrothecae. B. Portion of stem with male gonothecae. — C-D. Gonaxia ampullacea Vervoort, 1993 (BATHUS 4, Stn. DW914). C. Two successive cladial internodes with their hydrothecae. D. Portion of stem with male gonothecae. — E-F. Gonaxia compacta Vervoort, 1993 (BATHUS 4, Stn. DW923). E. Two successive cladial internodes with their hydrothecae. F. Abortive gonotheca (of undetermined sex) originating from within a hydrotheca. — G-K. Gonaxia intermedia Vervoort, 1993 (BATHUS 4). G. Two successive cladial internodes with their hydrothecae (Stn. CP906). H. Portion of stem with male gonothecae (Stn. CP906). I. Portion of stem with female gonothecae (Stn. CP906). J-K. Abortive gonothecae arising from hydrothecal lumina (Stn. DW902). — L-N. Gonaxia sinuosa Vervoort, 1993 (SMIB 4, DW40). L. Two successive cladial intemodes with their hydrothecae. M-N. Two female gonothecae. Scale bars: A, C, E, G, T = 300 pm; B, D, F, H-K, M-N = 1 mm. 10 GALEA H.R., Sertulariid hydroids from the tropical western Pacific gonothecae is considerable in the material from Stn. DW902, and specimens with one (Fig. 3K), two (Fig. 3J), or exceptionally three apertures could be seen. These so called abortive gonothecae may prove fully functional, as they are provided with apertures. However, their lumina are empty in the specimens in hand, and this assumption could not be checked at this stage. Geographical distribution New Caledonia (Vervoort 1993; present study). Gonaxia sinuosa Vervoort, 1993 Figs 2E, 3F-N Gonaxia sinuosa Vervoort, 1993: 179, figs 31c-e, 35b, 37a-b, 38a. Material examined SMIB 4: Stn. DW40, an originally 8 cm high colony with simple stem, now broken into two parts, bearing male gonothecae (MNHN-IK-2012-16526); Stn. DW48, an originally 5.5 cm high, sterile colony with simple stem, now broken into two unequal parts (MNHN-IK-2012-16527). BATHUS 2: Stn. DW716, six colonies and fragments, 2.3-9.1 cm high, with simple or branched stems, two of which are sterile, two others bear male gonothecae, and the remaining two carry female gonothecae (MNHN-IK-2012-16528). BATHUS 3: Stn. CP804, eleven colonies and fragments, 1.5—4.9 cm high, all with simple stems, of which four are sterile, three bear male gonothecae, and the remaining four bear female gonothecae (MNHN-IK-2012-16529); Stn. DW829, two colonies with simple stems, 3.8 and 2.4 cm high, the latter devoid of its basal part, and bearing three incipient gonothecae (MNHN-IK-2012-16530). Remarks The shape of the hydrothecae (Fig. 3F), as well as the condition and morphology of the gonothecae (Fig. 3M-N) are characteristic. One stem from BATHUS 2, Stn. DW716 is fully fertile (male) and bears its gonothecae in two parallel rows, each one originating from below the base of an axillar hydrotheca. The female stems examined here bear a lesser number of gonothecae. Geographical distribution New Caledonia (Vervoort 1993; present study), Norfolk Ridge (Vervoort 1993). Gonaxia crassicaulis Vervoort, 1993 Fig. 4A Gonaxia crassicaulis Vervoort, 1993: 145, figs 18c-d, 19a-b. Material examined MUSORSTOM 4: Stn. DW205, a cladium, 2.5 cm long (MNHN-IK-2012-16531). NORFOFK 1: Stn. DW1712, an infertile colony, 3.8 cm high (MNHN-IK-2012-16532). Remarks According to Vervoort (1993), G. crassicaulis is easily recognizable through the characteristic development of the perisarc, forming thick, internal, longitudinal ridges, connecting the adnate adaxial walls of the hydrothecae in each row (Fig. 4A). 11 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Fig. 4. - A Gonaxia crassicaulis Vervoort, 1993 (MUSORSTOM 4, Stn. DW205), portion of cladium. — B-D. Gonaxia elegans Vervoort, 1993 (BATHUS 3, Stn. DW809). B. Portion of stem and basal part of a cladium. C. Two consecutive internodes with their hydrothecae. D. Portion of stem with male gonothecae. — E-F. Gonaxia cf. errans Vervoort, 1993 (BATHUS 2, Stn. CP737). E. Distalmost portion of stem with basal parts of four hydrocladia. F. Two consecutive cladial intemodes with their hydrothecae. — G-J. Gonaxia plumularioides sp. nov. (BIOCAL, Stn. CP34). G. Distalmost part of a stem, showing the structure of internodes. H. Two consecutive cladial internodes with their hydrothecae. I. Stem hydrotheca. J. Axillar hydrotheca. Scale bars: A-B, D-E, G = 1 mm; C, F, H-J = 300 pm. 12 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Also characteristic is the presence of large, internal, semi-circular “thickenings” of the perisarc (Fig. 4A), arching over the basal foramina, when the hydrothecae are seen laterally. These structures, one situated in the “frontal” aspect of the hydrothecae, the other on their “dorsal” side, correspond in fact to the attachment points of the hydrothecal bases to the lateral walls of the thecae which, in this species, are raised above the level of the foramina. When the hydrothecae are seen facing their apertures, the hydrothecal bases appear U-shaped, the foramina being situated at the bottom of this concavity. Geographical distribution New Caledonia (present study), Norfolk Ridge (Vervoort 1993). Gonaxia elegans Vervoort, 1993 Fig. 4B-D Gonaxia elegans Vervoort, 1993: 153, figs 19c, 21b-c, 22. Material examined BATHUS 3: Stn. DW809, a 4.4 cm high colony devoid of hydrorhiza and bearing female gonothecae, as well as an originally 5.4 cm high colony (now broken into two parts) bearing male gonothecae and several broken cladia originating from both colonies (MNHN-IK-2012-16533). Remarks This species is immediately recognizable through the characteristic position and shape of its hydrothecae. The 5.4 cm high colony is evidently male when compared to the smaller one, which bears gonothecae possessing much wider apertures. Only the female gonothecae were described by Vervoort (1993) but, upon a careful inspection of the present material, it should be stated that they do not arise from the accessory tubes on the hydrocaulus, but from the main tube itself, as this is indisputably seen in the monosiphonic part of the stem. In addition, in this colony at least, nearly all accessory tubes are found on the “dorsal” aspect of the stem, while the row of gonothecae is situated on its “front”. The male gonothecae, observed here for the first time, are similar in shape to the female ones, and also arise from the main tube of the stem, but in both the frontal and dorsal aspects of the colony. They are given off closely and in a single row (Fig. 4D), are about half adnate, and their free parts are shifted alternately left and right; their bases are obscured by the numerous accessory tubes running up the stem. They are long (1.5-2 mm), tubular (480-520 pm wide), with small, circular apertures (100-120 pm wide) mounted on the summit of a conical, distal neck region. Geographical distribution New Caledonia (Vervoort 1993; present study), Norfolk Ridge (Vervoort 1993). Gonaxia cf. errans Vervoort, 1993 Fig. 4E-F Gonaxia errans Vervoort, 1993: 154, figs 23a-d, 24a-c. Material examined BATHUS 2: Stn. CP737, two stem fragments, 13 and 9 mm high, the former corresponding to the middle part of a colony, while the latter is likely the distalmost end of (another?) colony; both are sterile; several broken cladia are also present (MNHN-IK-2012-16534). 13 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Remarks The pattern of cladial arrangement on the stem in this scarce material seems to follow a rather peculiar sequence: each equivalent of internode (the nodes are inconspicuous) has a proximal apophysis with its associated axillar hydrotheca, two alternate hydrothecae above, as well as a second, distal apophysis (on the side opposite to the former) with its associated axillar hydrotheca; the same sequence is repeated on the following “internode” but, there, it is the opposite image of the preceding one. In the distalmost part of one of the available colony fragments, two successive cladia occur on the same side, and are separated on the opposite side by a single stem hydrotheca. According to Vervoort (1993), the cladial arrangement is varied, with “zero to three hydrothecae between two successive apophyses”, which is apparently the case in the present material. The shape of the hydrothecae also fits the original description of G. errans , though they are comparatively shorter in the material in hand (free adaxial side 335-365 pm, adnate adaxial side 280-300 pm, abaxial side 490-510 pm), but seem to have almost the same width (maximum width 205-220 pm, diameter at aperture 165-175 pm) as in Vervoort’s samples. Consequently, the present material is provisionally assigned to G. errans. Geographical distribution New Caledonia (present study), Norfolk Ridge (Vervoort 1993). Gonaxia plumularioides sp. nov. um:lsid:zoobank.org:act:6A07FF84-EAA6-4AE6-8755-B450B17A28EB Fig. 4G-J; Table 2 Diagnosis Gonaxia with slender, fascicled, branched or unbranched stems; cladia monosiphonic. Equivalents of internodes composed of a proximal hydrocladial apophysis and its associated axillary hydrotheca, two alternate hydrothecae above, and a second, distal hydrocladial apophysis and its associated hydrotheca. Hydrothecae tubular, slightly curved up- and outwards, comparatively slender and more immersed on stem than on cladia. Gonothecae unknown. Etymology From the Latin pluma , meaning feather, and the Greek eiSog, meaning likeness, with reference to their plumose appearance, recalling the branching pattern displayed by some hydroids belonging to the superfamily Plumularioidea. Material examined Holotype BIOCAL: Stn. CP34, a 2.8 cm high, distal fragment of a branch or a stem, itself branched twice, sterile (MNHN-IK-2012-16535). Paratype BIOCAL: Stn. CP34, a 7.7 cm high, unbranched colony devoid of its hydrorhiza, as well as a 1 cm high fragment corresponding to the distalmost part of a colony; both are sterile (MNHN-IK-2012-16536). Description Colonies attaining at least 8 cm high, composed of either simple or ramified stems of slender appearance, despite being fascicled; accessory tubes on both “frontal” and “dorsal” sides of stems; the latter uniformly grading to monosiphonic distally. Side branches, when present, arising only in 14 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Table 2. Measurements (in pm) of hydrothecae of Gonaxia plumularioides sp. nov. and G. nova sp. nov. G. plumularioides sp. nov. G. nova sp. nov. Caulinar hydrotheca Axillar hydrotheca Cladial hydrotheca Caulinar hydrotheca Axillar hydrotheca Cladial hydro theca Free adaxial side 85-125 75-140 180-210 555-575 565-630 580-615 Adnate adaxial side 355-380 360-440 315-350 220-245 175-220 175-205 Abaxial side 315-345 195-245 395M40 600-630 505-575 620-665 Maximum width 110-125 125-145 195-205 260-270 270-290 250-260 Diameter at rim 80-90 80-95 160-170 160-165 150-185 165-175 “frontal” aspect of the stem or higher order branches; up to 2 nd order branching observed. Division into internodes indistinct, but equivalents of internodes composed of the regular sequence: a first, basal apophysis (60-90 pm long) and its associated axillar hydrotheca, two additional, alternate hydrothecae above, and a second axillar apophysis with its associated hydrotheca. Following internode with same sequence, but its proximal apophysis on side opposite to the distal apophysis of preceding internode. Cladia leaving axis at 75-80° from upper part of stem or branches; two successive cladia on same side of stem are distant of 2200-2310 pm; strictly monosiphonic, alternate, up to 1 cm long, comprising a succession of up to 23 alternate hydrothecae. Division into internodes indistinct; equivalent of first cladial internode comparatively longer (580-705 pm) than subsequent ones (480-515 pm); intemodes short, accommodating a single hydrotheca distally. Hydrothecae widely spaced on stem (570-740 pm), less so on cladia (470-530 pm); tubular, slightly curving up- and outwards, free part angled at 50° to the axis of internode; stem hydrothecae slightly shifted on frontally; the two rows of cladial hydrothecae coplanar; less than half adnate on cladia, but considerably immersed into the stem internodes; free adaxial side nearly straight, adnate counterpart curved, ending basally in perisarc peg; abaxial side convex, with inflexion point in middle; aperture with three low cusps separated by shallow embayments; opercular apparatus lost. Gonothecae unknown. Remarks The branching pattern of the stems of G. plumularioides sp. nov. resembles that seen in some plumularioid hy droids that build three-dimensional colonies (e.g., Macrorhynchia philippina Kirchenpauer, 1872, M. allmani (Nutting, 1900), Plumularia spiralis Billard, 1911, etc.), and is consequently different from that observed in its congeners (e.g., G. amphorifera, G. sinuosa , G. nova sp. nov., see description below), which generally build planar colonies. The regular structure of the stem internodes is also peculiar, and is only occasionally observed in the material assigned herein to G. errans, a species known for its inconstant structure of the stem (Vervoort 1993). The shape of the hydrocladial hydrothecae resembles that of other congeners: 1) G. complexa Vervoort, 1993, but in this species the hydrothecae have an exceedingly long part free from internode; 2) G. elegans , but its hydrothecae have a conspicuously straight axis instead of being convex (compare Fig. 4C and 4H); 3) G. errans , whose hydrothecae have, however, a much longer free part (compare Fig. 4F with Fig. 4H); 4) G. intercalata Vervoort & Watson, 2003, but its hydrothecae are huge compared to those of the new species; 5) G. stricta Vervoort, 1993, but here the hydrothecae have a much longer free part, and the cladial internodes are marked by internal, oblique perisarcal thickenings (Vervoort 1993); 6) G. tasmanica Watson & Vervoort, 2001, but its hydrothecae are comparatively larger. Geographical distribution New Caledonia. 15 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Gonaxici nova sp. nov. um:lsid:zoobank.org:act:6C6AA611-2E5C-40B9-9502-31888388A7E9 Figs 5A-B, 6A-E; Table 2 Diagnosis Gonaxia with either branched or unbranched, rigid, fascicled stems arising from disc-shaped hydrorhiza. Intemodes slightly geniculate, comprising a latero-distal cladial apophysis with its associated hydrotheca, and two alternate hydrothecae below. Cladia alternate, composed of moderately long, geniculate internodes. Hydrothecae arranged at a wide angle to the stem; long, tubular, slightly arcuate, tumid proximally, distally tubular, adnate for % their length. Gonothecae originating on both sides of the stem from below axillar hydrothecae; adnate for about half their length; erect portion tubular, ending in rather long neck region bearing the aperture distally. Etymology From the Latin novus , -a, -um (and the Grek vsof), meaning new, indicating that we are dealing with a new, undescribed species. Material examined Holotype MUSORSTOM 8: Stn. CP 1083, a 4.2 cm high, unbranched colony bearing male gonothecae (MNHN- IK-2012-16537). Paratypes MUSORSTOM 8: Stn. CP1083, eight colonies or fragments with branched or unbranched stems, of which four bear female gonothecae and range between 2.6 and 5.0 cm in height, while the remaining four bear male gonothecae and range between 2.8 and 3.9 cm in height (MNHN-IK-2012-16538). Description Colonies composed ofbranched or unbranched, thick, rigid, fascicled stems arising from rhizoid hydrorhiza firmly attached to substrate. Nodes inconspicuous, even in the monosiphonic parts, but equivalents of internodes 1580-2000 pm long, slightly geniculate, composed of a latero-distal hydrocladial apophysis with its associated hydrotheca, and two additional, alternate hydrothecae below. Hydrocladia strictly monosiphonic, arranged at approximately right angles to the stem; up to 1.2 cm long, nodes indistinct (60-70 pm wide); equivalents of internodes moderately long, geniculate, each carrying a hydrotheca distally; first internode comparatively longer (1020-1240 pm) than subsequent ones (590-760 pm); up to 20 hydrothecae per cladium. Hydrothecae long, tubular, facing outwards at nearly right angles to their corresponding internodes; slightly tumid basally, walls parallel distally; adnate for about % th their length; free adaxial side slightly convex proximally, then straight; abaxial wall with noticeable convexity in middle; aperture triangular in frontal view; margin with three conspicuous cusps (two latero-adaxial and one abaxial) separated by rather deep embayments; operculum composed of three triangular flaps forming a low roof. Gonothecae on both sides of the stem, originating from below axillar hydrothecae; about half adnate, strongly appressed proximally to the stem; distal half erect, tubular, ending in moderately long, tronconical collar, bearing the aperture distally (small in male, Fig. 6E; comparatively larger in female, Fig. 6D); perisarc of abaxial wall of fused part finely and densely striated (Fig. 6E-F); individual gonothecae either solitary (towards apex of stem) or fused together through auxiliary tubes given off from one or both ends of their adnate parts; in highly polysiphonic parts of stem, adnate parts of gonothecae obscured by apposition of auxiliary tubes; length of adnate part 1250-1340 pm (S) and 1720-1970 pm (§), and of free part 1540-1910 pm (c?) and 1640-1720 pm (§); width of free part 16 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Fig. 5. — A-B Gonaxia nova sp. nov. (MUSORSTOM 8, Stn. CP 1083). A. Distalmost, monosiphonic part of a colony. B. Portion of stem with basal part of a cladium. — C-G. Gonaxia scalariformis Vervoort, 1993, portions of stems and basal parts of cladia from BIOCAL, Stn. DW46 (C = colony #1; D = colony #2; E = colony #3), Stn. DW66 (F), and NORFOLK 1, Stn. DW1699 (G), showing discrete differences in shape and size. — H. Gonaxia aff. similis Vervoort, 1993 (MUSORSTOM 6, Stn. DW423), portion of stem with cladium. Scale bars: A = 1 mm; B-H = 500 pm. 17 European Journal of Taxonomy 218 : 1-52 ( 2016 ) 18 GALEA H.R., Sertulariid hydroids from the tropical western Pacific 565-590 pm (c?) and 620-690 pm (§); length of neck region 260-365 pm (c?) and 165-245 p ($); diameter at aperture 90-105 pm (c?) and 245-260 pm (5). Remarks The hydrothecae of this species resemble those of several congeners: 1) G. bulbifera Vervoort, 1993, but this species has proportionally smaller hydro- and gonothecae (about two times smaller), its hydrothecal axes are straight instead of being curved, its caulinar apophyses are conspicuously inflated, and its cladial internodes are collinear instead of being slightly geniculate; 2) G. elegans , but in this species the hydrothecae are much more closely-set, and the cladial internodes are strictly collinear (compare Fig. 5B with Fig. 4B); 3) G. perplexa Vervoort, 1993, but in this species the hydrothecae are more approximated and have straight axes, and the gonothecae are nearly fully adnate, their bodies being likely fused to each other, and their apertures are characteristically shifted outward from the stem; 4-7) G. complexa Vervoort, 1993, G. persimilis Vervoort, 1993, G. similis, and G. scalariformis, but these species are immediately distinguished through their free gonothecae, originating perpendicularly to the stems; 8) G. stricta Vervoort, 1993, but in this species the hydrothecae have straight axes and they are more approximated on cladia. Geographical distribution Vanuatu. Gonaxia scalariformis Vervoort, 1993 Figs 5C-G, 6F-R Gonaxia scalariformis Vervoort, 1993: 173, figs 31b, 32, 33c-d, 35a. Material examined BIOCAF: Stn. DW46, three colonies (#1-3) slightly differing in the size of their hydrothecae: colony #1 is 3.5 cm high, devoid of its hydrorhiza, and bears two female gonothecae (MNHN-IK-2012-16539), colony #2 is 2.8 cm high, devoid of its hydrorhiza, and bears three female gonothecae (MNHN- IK-2012-16540), and colony #3 is 2.2 cm high and broken in two parts, the basal one e xhi biting re mn ants of hydrorhiza; both parts bear five male gonothecae each (MNHN-IK-2012-16541); Stn. DW66, a 1.6 cm high colony devoid of both its hydrorhiza and apical part, with two abortive gonothecae (MNHN- IK-2012-16542); Stn. CP69, a 1.4 cm high colony devoid of its distalmost part, with a single female gonotheca (MNHN-IK-2012-16543). NORFOFK 1: Stn. DW1699, a 1.7 cm high colony devoid of both its hydrorhiza and upper part, bearing two female gonothecae (MNHN-IK-2012-16544). Fig. 6. (previous page) — A-E. Gonaxia nova sp. nov. (MUSORSTOM 8, Stn. CP 1083). A. Axillar hydrotheca. B. Caulinar hydrotheca. C. Cladial hydrotheca. D. Female gonothecae, lateral view. E. Male gonotheca, slightly oblique view. — F-R. Gonaxia scalariformis Vervoort, 1993. F. Axillar hydrotheca (BIOCAF, Stn. DW46, colony # 1). G. Cladial hydrotheca (BIOCAF, Stn. DW46, colony # 1). H. Caulinar and axillar hydrothecae (BIOCAF, Stn. DW66). I-M. Normal gonothecae from BIOCAF, Stn. DW46 (I = colony #1; J-K = colony #2; F-M = colony #3). N-O. Abortive gonotheca from BIOCAF, Stn. DW66. P-R. Normal gonothecae from BIOCAF, Stn. CP69 (P) and NORFOFK 1, Stn. DW1699 (Q- R). — S-X. Gonaxia aft similis Vervoort, 1993 (MUSORSTOM 6, Stn. DW423). S. Cauline hydrotheca. T. Axillar hydrotheca. U. Cladial hydrotheca. V. Fateral view of a hydrotheca, showing diverticulum. W. Same hydrotheca viewed from above, showing minute foramen for the passage of coenosarc, and lateral diverticuli. X. Same hydrotheca in apical view, showing lateral diverticuli and basal foramen. Scale bars: A-C, F-H, S-U = 300 pm; D-E, I-R = 1 mm; V-X = 200 pm. 19 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Remarks All available specimens have lightly fascicled stems basally, and none is ramified. Although the arrangement and general shape of the hydrothecae perfectly match the description of the holotype, noticeable variations in size could be observed. Thus, the colony #3 from sample BIOCAL, Stn. DW46 has the slenderest hydrothecae, while those from NORFOLK 1, Stn. DW1699 are the widest ones. In the sample from BIOCAL, Stn. DW66, incipient antero-dorsal diverticuli are seen in most hydrothecae (Fig. 5F). Gonothecae of both sexes are present in the available material. Although they conform to the original description, the male gonothecae in the colony #3 from BIOCAL, Stn. DW46 are arranged on both anterior and posterior sides of the stem, and some exhibit bifid (Fig. 6M) or trifid apices. The female gonothecae from BIOCAL, Stn. DW66 are likely abortive, as they originate from within the hydrothecae (Fig. 6N-0); in addition, they are not fully formed, as their distal ends are missing; their sex is indeterminate. The female gonothecae from NORFOLK 1, Stn. DW1699 (Fig. 6Q-R) are the longest with respect to those present in the other samples. Geographical distribution New Caledonia and Norfolk Ridge (Vervoort 1993; present study). Gonaxia aff. similis Vervoort, 1993 Figs 5H, 6S-X Gonaxia similis Vervoort, 1993: 174, figs 33e-f, 34, 36a, 39a. Material examined MUSORSTOM 6: Stn. DW423, a 2.7 cm high, sterile colony (MNHN-IK-2012-16545). Remarks The present specimen is likely part of the material in RMNH-Coel. 25839 (also from MUSORSTOM 6, Stn. DW423) studied by Vervoort (1993). According to Vervoort, his material had gonothecae adnate to the stem (p. 174, fig. 34c), not arranged perpendicularly to it, as in the majority of samples assigned by him to G. similis. Consequently, the material in hand may belong to a separate species. One hydrocladium in the present specimen is branched, and the secondary cladium is borne on a short, quadrangular apophysis originating from below the hydrothecal base of the first internode of a cladium. Not mentioned by Vervoort in his sample RMNH-Coel. 25839 is the constant presence of well-developed antero-posterior diverticuli within the hydrothecae (Figs 5H, 6S-V). Such variably developed diverticuli also occur in other congeners discussed herein, viz. G. amphorifera (Fig. 3 A), G. ampullacea (Fig. 3C), and G. scalariformis (Fig. 5F). In the present material, their development is considerable, and extends well on each lateral side of the hydrotheca. A frontal view of the free adaxial wall of the hydrotheca (Fig. 6W), and a frontal view of the aperture (Fig. 6X) show two empty lateral “pockets” which narrow considerably the hydrothecal lumen; the foramen for the passage of the hydranth within the hydrotheca is minute and horseshoe-shaped. Geographical distribution New Caledonia (Vervoort 1993; present study). 20 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Genus Idiellcma Cotton & Godfrey, 1942 Idiellana pristis (Lamouroux, 1816) Fig. 7A Idiapristis Lamouroux, 1816: 199, pi. 5, fig. 5. Idiellana pristis - Schuchert 2003: 175, fig. 32. Material examined MUSORSTOM 3: Stn. CP 121, sterile colony composed of two stems, 1.7 and 3.7 cm high (MNHN- IK-2012-16546); Stn. CP134, sterile colony composed of two stems, 1.5 and 2.7 cm high (MNHN- IK-2012-16547). MUSORSTOM 8: Stn. DW1021, two sterile stems, 3.5 and 5 cm high (MNHN-IK-2012-16548); Stn. CP1131, several sterile stems, 1.5-8.5 cm high (MNHN-IK-2012-16549). TAIWAN 1: Stn. DW1, four sterile stems, 0.7-1.4 cm high, on gravel (MNHN-IK-2012-16550). Remarks For the latest redescription and a list of synonyms, refer to Schuchert (2003). Geographical distribution Circumglobal in tropical and subtropical seas (Precker & Lawn 2010). Genus Salacia Lamouroux, 1816 Salacia macer Vervoort & Watson, 2003 Fig. 7B-G Salacia macer Vervoort & Watson, 2003: 154, figs 34g, 35a. Material examined BATHUS 3: Stn. DW809, single sterile stem, 2.4 cm high, partly damaged (several cladia missing) (MNHN-IK-2012-16551). NORFOLK 1: Stn. DW1659, four stems 3—4.5 cm high, two of which bear female gonothecae (MNHN- IK-2012-16552). Remarks The slender habit of these colonies, their regularly-pinnate branching pattern and their division into intemodes, each of which bears a single pair of strictly opposite hydrothecae, are diagnostic (Vervoort & Watson 2003). The gonothecae, not previously described, are present in this material, and are female. They are borne on either the stem or cladia, and are arranged perpendicularly from below one hydrotheca of a pair. Urn-shaped, smooth-walled, 3280-3565 pm long and 1110-1170 pm wide, tapering basally into a short pedicel; distally truncate, aperture circular, 590-615 pm wide, borne on a short, 565-575 pm wide neck region. Possibly up to 100 oocytes per gonotheca, though their number is difficult to ascertain. Geographical distribution Norfolk Ridge (Vervoort & Watson 2003; present study). 21 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Fig. 7. (continued on next page) —A. Idiellanapristis (Lamouroux, 1816) (TAIWAN 1, Stn. DW1), stem internode and basal part of cladium. — B-G. Salacia macer Vervoort & Watson, 2003 (NORFOLK 1, Stn. DW1659). B. Stem internode and basal part of cladium. C. Hydrothecae, frontal view. D. Same, dorsal view. E. Hydrothecal aperture, frontal view. F. Hydrothecal aperture, oblique view, showing 22 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Salacia sibogae Billard, 1924 Fig. 7H Salacia sibogae Billard, 1924: 64, fig. lb-c. Salacia sibogae - Schuchert 2003: 177, fig. 34. Material examined MUSORSTOM 3: Stn. DR126, four small (0.4-1.1 cm high), sterile stems on axis of dead gorgonian (MNHN-IK-2012-16553). Remarks A recent redescription of this species and a list of synonyms are available in Schuchert (2003). Geographical distribution Previosuly known from Indonesia and Japan (Schuchert 2003). The present material originates from the Philippines. Genus Sertularella Gray, 1848 Sertularella acutidentata Billard, 1919 Fig. 71 Sertularella acutidentata Billard, 1919: 20, figs le, 2. Sertularella acutidentata acutidentata - Vervoort & Watson 2003: 154, fig. 35b-e. Material examined TAIWAN 2: Stn. DW118, two infertile colonies, 7 and 8 cm high (MNHN-IK-2012-16554). Remarks For a redescription of this species, refer to Hirohito (1995). Its synonymy is given by Vervoort & Watson (2003). Geographical distribution Indonesia, Japan, Philippines, New Caledonia, and north of New Zealand (Vervoort & Watson 2003). operculum. G. Female gonotheca. — H. Salacia sibogae Billard, 1924 (MUSORSTOM 3, Stn. DR126), portion of stem and basal part of cladium. — I. Sertularella acutidentata Billard, 1919 (TAIWAN 2, Stn. DW118), portion of stem with basal part of side branch. — J. Sertularella areyi Nutting, 1904 (BATHUS 3, Stn. CP813), portion of fertile stem. — K-L. Sertularella diaphana (Allman, 1885) (MUSORSTOM 8, Stn. CPI 104). K. Two hydrothecae. L. Gonotheca. — M. Sertularella mirabilis Jaderholm, 1896 (TAIWAN 2, Stn. DW118), portion of colony. — N-Q. Sertularella novaecaledoniae Vervoort, 1993 (MUSORSTOM 4, Stn. DW221). N. Portion of stem and proximal part of a branch. O-P. Hydrothecae. Q. Portion of stem with gonothecae. — R. Sertularella quadridens (Bale, 1884) (MUSORSTOM 3, Stn. CP121), portion of stem and proximal part of a side branch. Scale bars: A-B = 500 pm; C-F = 400 pm; G-N, Q-R = 1 mm; O-P = 300 pm. 23 European Journal of Taxonomy 218: 1-52 (2016) Sertularella areyi Nutting, 1904 Fig. 7J Sertularella areyi Nutting, 1904: 83, pi. 17, fig. 6. Sertularella areyi - Vervoort & Watson 2003: 156, fig. 35f-l. Material examined MUSORSTOM 4: Stn. CC174, several stems, up to 1.4 cm high, all but one sterile (MNHN- IK-2012-16555). BATHUS 3: Stn. CP813, fertile colonies with stems up to 1.4 cm high on two fragments of gorgonian (MNF1N-IK-2012-16556); Stn. CP814, two infertile colonies with stems up to 1.5 cm high, one on dead gorgonian, the other on sponge (MNHN-IK-2012-16557). LITHIST: Stn. DW13, small colony composed of a few sterile stems, up to 1.2 cm high, growing on Acryptolaria sp. (MNF1N-IK-2012-16558). BORDAU 2: Stn. DW1513, small colony composed of several sterile, up to 5 mm high, stems growing on G. ceramensis (MNHN-IK-2012-16559). NORFOLK 1: Stn. DW1704, small colony composed of a restricted number of stems, some fertile and up to 1 cm high, epizoic on Zygophylax sp., Sertularella helenae Vervoort, 1993, and tube of coronate medusa (MNHN-IK-2012-16560). Remarks This very distinctive species needs no additional comments on morphology. Its synonymy, as well as a redescription, are provided by Vervoort & Watson (2003). Geographical distribution Tropical and subtropical parts of the Atlantic and Indo-Pacific (Vervoort & Watson 2003). Sertularella diaphana (Allman, 1885) Fig. 7K-L Thuiaria diaphana Allman, 1885: 145, pi. 18, figs 1-3. Sertularella diaphana - Vervoort & Watson 2003: 159, fig. 36g-h. Material examined MUSORSTOM 8: Stn. CPI 104, colony composed of several fertile (male gonothecae) stems, up to 6 cm high, epizoic on stem of aglaopheniid hydroid (MNHN-IK-2012-16561). Remarks For lists of synonyms and descriptions, see Calder (1991), Vervoort (1933) and Galea (2010). Geographical distribution Circumglobal in tropical and subtropical seas (Vervoort & Watson 2003). 24 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Sertulcirella mirabilis Jaderholm, 1896 Fig. 7M Sertularella mirabilis Jaderholm, 1896: 9, pi. 2, fig. 1. Sertularella mirabilis - Schuchert 2015: 339, fig. 13. Material examined TAIWAN 2: Stn. DW118, a 3.2 cm high, sterile colony (MNHN-IK-2012-16562). Remarks Hirohito (1995) provided a thorough description of this peculiar species. Its synonymy is given by Schuchert (2015). Geographical distribution From the South China Sea to Korea and Japan (Schuchert 2015). Sertularella novaecaledoniae Vervoort, 1993 Fig. 7N-Q Sertularella novaecaledoniae Vervoort, 1993: 225, figs 50, 51aA, 52a. Material examined MUSORSTOM 4: Stn. DW221, a 4 cm high, fertile colony (MNHN-IK-2012-16563). Remarks The present material, represented by a colony with flabellate appearance, with fascicled stem and side branches divided into very short intemodes, each carrying a tubular hydrotheca adnate for about half its length, conforms to the description of the type given by Vervoort (1993). The gonothecae have undulated walls, and their apical part is flattened (Fig. 7Q). Geographical distribution New Caledonia (present study), Norfolk Ridge (Vervoort 1993). Sertularella quadridens (Bale, 1884) Fig. 7R Thuiaria quadridens Bale, 1884: 119, pi. 7, figs 5-6. Sertularella quadridens - Schuchert 2003: 185, fig. 41. Material examined MUSORSTOM 3: Stn. DR117, a 18 mm high, sterile colony (MNHN-IK-2012-16564); Stn. CP121, a complete colony, 3 cm high, as well as four fragments, 1.4-3.2 cm high, all sterile (MNHN- IK-2012-16565). Remarks For a list of synonyms and a recent redescription, see Schuchert (2003). 25 European Journal of Taxonomy 218: 1-52 (2016) Geographical distribution Widely distributed throughout the tropical Indo-Pacific (Precker & Lawn 2010). Sertularella folliformis sp. nov. um:lsid:zoobank.org:act:7A654AE7-6B4E-465C-9F5A-lD48528466E5 Fig. 8A-G; Table 3 Diagnosis Sertularella species with flabellate colonies; branching irregular; stem and branches strongly polysiphonic basally, grading to monosiphonic distally; internodes short, slightly geniculate to collinear; hydrothecae exceedingly long, tubular, curved downwards, with 8-10 broad, complete annuli and four internal, submarginal cusps. Gonothecae large, elongated-ovoid, distally truncate. Etymology From the Latin words follis, meaning bellows, and forma , meaning shape, with reference to the plicate condition of the hydrothecal wall, recalling the bellows of an accordion. Material examined Holotype BATHUS 3: Stn. DW809, a 4.5 x 4.5 cm sterile colony and four smaller fragments, three of which bear one gonotheca, and the fourth two gonothecae (MNHN-IK-2012-16566). Paratype BATHUS 3: Stn. DW809, a few colonies and fragments, largest one 7.5 x 3.5 cm, all sterile (MNHN- IK-2012-16567). Description Colonies flabellate, attaining 7.5 cm high, arising from rhizoid stolons firmly attached to substrate. Branching irregular, with up to 3 rd order branches arranged roughly in one plane. Stems and side branches polysiphonic, main stem reaching as much as 2 mm wide basally. Both stem and branches divided into internodes by slightly-marked nodes slanting in alternate directions. Internodes short, slightly geniculate to collinear, each carrying a hydrotheca in its distal half. Side branches originate laterally below the bases of stem hydrothecae; first intemode comparatively longer than subsequent ones. Hydrothecae exceedingly long, tubular, slightly curved downward, adnate for % th or less their length, tapering imperceptibly towards aperture, walls provided with 8-10 broad, complete annuli; margin occasionally renovated; rim provided with four short cusps separated by shallow embayments; four submarginal, intrathecal projections of perisarc, two latero-adaxial and two latero-abaxial. Gonotheca originating from axil of hydrotheca, in front and/or backside of colony; elongated-ovoid, tapering abruptly below, distally truncate, wall smooth to slightly undulate. Remarks The hydrothecal shape is diagnostic in this species. There are few congeners which approach this condition, viz. S. catena (Allman, 1888) and S. pseudocatena sp. nov. (Fig. 9J), but both have much shorter hydrothecae, and their transverse ribs do not extend over the abaxial wall. Three other species, namely S. helenae Vervoort, 1993 (Fig. 8H), S. paucicostata Vervoort, 1993 (Fig. 81), and S. pseudocostata Vervoort, 1993, exhibit comparatively more prominent hydrothecal ridges. The eastern Pacific S. exilis Fraser, 1938 has isodiametric hydrothecae “regularly curved upward and then outward” (Fraser 1938), but their surface is reportedly smooth. In addition, it is “an especially diminutive species” 26 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Table 3. Measurements (in pm) of Sertularella folliformis sp. nov. and S. plicata sp. nov. S. folliformis sp. nov. S. plicata sp. nov. Internodes - length (in general) 680-865 660-890 - length (1 st cladial internode) 1360-2405 1365-1450 - diameter at node 325M00 125-145 Hydrotheca - free adaxial side 1025-1235 365-440 - adnate adaxial side 375—415 190-225 - abcauline side 1170-1295 450M95 - maximum width 320-345 255-275 - diameter at rim 290-305 170-180 Gonotheca - length 2245-2345 — - maximum width 780-850 — - apical width 445M55 — (Calder et al. 2009). Sertularella whitei Rees & Vervoort, 1987 also has exceedingly long, outwardly- curved hydrothecae, but their surface is entirely smooth (Rees & Vervoort 1987). Geographical distribution New Caledonia. Sertularella helenae Vervoort, 1993 Fig. 8H Sertularella helenae Vervoort, 1993: 218, fig. 47b-e. Material examined BIOCAL: Stn. DW37, several sterile stems, up to 2.6 cm high, and smaller fragments (MNHN- IK-2012-16568); Stn. DW38, single, sterile colony 3 cm high and 4.7 cm wide (MNHN-IK-2012-16569). BATHUS 3: Stn. CP804, a 2.5 cm high and 3.8 cm wide, sterile colony (MNHN-IK-2012-16570); Stn. CP821, a 3.4 cm high, sterile colony (MNHN-IK-2012-16571); Stn. DW830, four sterile colony fragments, 0.7-1.5 cm high (MNHN-IK-2012-16572). NORFOLK 1: Stn. CP1719, a 4.2 cm high, sterile colony (MNHN-IK-2012-16573). SALOMON 1: Stn. DW1741, two sterile colonies, 2.2 and 2.6 cm high (MNHN-IK-2012-16574). Remarks This very distinctive species needs no additional comments on morphology. For a thorough description, see Vervoort (1993). The gonothecae still remain to be discovered. Geographical distribution New Caledonia (Vervoort 1993; present study), Norfolk Ridge and Solomon Islands (present study). 27 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Sertularella paucicostata Vervoort, 1993 Fig. 81 Sertularella paucicostata Vervoort, 1993: 227, figs 51b-f, j. Material examined MUSORSTOM 3: Stn. DW809, several infertile stems, some branched, up to 1.3 cm high, epizoic on Sertularella folliformis sp. nov. (MNHN-IK-2012-16575). 28 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Remarks Surprisingly, Vervoort (1993) compared his new species with Sertularella costata Leloup, 1940, which is a much smaller and delicate hy droid (compare Fig. 81 and 8J), as illustrated by specimens of this species from the Andaman Sea, Thailand belonging to my private collection. Sertularella costata is a rather poorly known species, with a few records around the world. Hirohito (1995) provided succinct measurements of the hydrothecae, while Calder et al. (2003) gave the first description and measurements of the gonotheca. The dimensions of the hydrothecae in the Thailand material are as follows: abcauline side 315-360 pm, free adcauline side 265-280 pm, adnate adcauline side 100-110 pm, maximum width 155-170 pm, diameter at aperture 130-140 pm. The external wall is provided with 10-13 transverse ridges, and three internal, submarginal cusps are present within the hydrothecae (Fig. 8K). Through the size of its hydrothecae, the material from Thailand comes close to the Japanese specimens examined by Hirohito and, through the number of external ridges, it approaches that of the Galapagos specimens, which is apparently 10-11 (Calder et al. 2003: fig. 14). In contrast, about 20 ridges ornament the hydrothecal walls in material from Japan (Leloup 1940; Hirohito 1995). In my opinion, S. paucicostata most closely resembles both S. helenae and S. pseudocostata Vervoort, 1993. However, unlike S. paucicostata , S. helenae forms fascicled colonies with shorter internodes, and its hydrothecae are smaller (compare Fig. 81 and 8H) and provided with numerous perpendicular creases between the transverse ridges. According to Vervoort (1993), the hydrothecae of S. pseudocostata are comparatively larger and their outer wall has frilled ribs. Geographical distribution New Caledonia, Norfolk Ridge (Vervoort 1993), and the Philippines (present study). Sertularellaplicata sp. nov. urn:lsid:zoobank.org:act:5CBEB7F6-12F7-403C-AC8D-58AE01BllAC7 Fig. 8F-0; Table 3 Diagnosis Small Sertularella with monosiphonic stems; side branches given off irregularly in one plane. Internodes moderately long and geniculate. Hydrothecae piriform, with 8-10 conspicuous, transverse ribs; aperture on short, narrow neck facing outwards; 3 or 5 internal, submarginal, lamellar cusps. Gonothecae unknown. Fig. 8. (previous page) —A-G. Sertularellafolliformis sp. nov. (BATHUS 3, Stn. DW809). A. Holotype. B. Paratype. C. Portion of stem with proximal part of a side branch. D. Successive internodes with their hydrothecae. E. Hydrothecal aperture, frontal view, showing internal cusps. F. Portion of stem with gonotheca, showing insertion site. G. Gonotheca. — H. Sertularella helenae Vervoort, 1993 (SAFOMON A, Stn. DW1714), two successive internodes with their hydrothecae. — I. Sertularella paucicostata Vervoort, 1993 (BATHUS 3, Stn. DW809), two consecutive intemodes with their hydrothecae, and comparison with Sertularella costata Leloup, 1940 (J-K). — L-O. Sertularella plicata sp. nov. (MUSORSTOM 3, Stn. CP 121). L. Portion of stem and proximal part of a side branch. M. Two consecutive internodes with their hydrothecae. N. More detailed view of the hydrotheca, to show its wrinkled surface. O. Hydrothecal aperture in frontal view, showing internal cusps. — P-S. Sertularella aff. sinensis Jaderholm, 1896. P. Portion of stem (BATHUS 3, Stn. DW829). Q. Hydrotheca (BORDAU 2, Stn. DW1595). R. Frontal view of three hydrothecal apertures, to show variation in the number of internal cusps. S. Gonotheca (BORDAU 2, Stn. DW1595). Scale bars: A-B = 1 cm; C, F-G, F, P = 1 mm; D, H-J, M, Q, S = 500 pm; E, K, O, R = 100 pm; N = 200 pm. 29 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Etymology From the Latin plico , - atum , -are (and the Greek izlt/yo), meaning “pleat, pleated, to pleat”, to characterize the appearance of the external surface of the hydrothecal wall. Material examined Holotype MUSORSTOM 3: Stn. CP121, colony composed of several sterile stems up to 1 cm high, epizoic on dead gorgonian (MNHN-IK-2012-16576). Description Colony composed of up to 1 cm high, monosiphonic stems arising from creeping, branching hydrorhiza. Basal parts of stems of varied length and ahydrothecate, perisarc smooth; above, stems divided into regular, moderately long, geniculate intemodes, by means of slightly oblique nodes slanting in alternate directions; each intemode with one, distal hydrotheca. Side branches arising irregularly from below the bases of stem hydrothecae and in the same plane as the stem; from one to several hydrothecae between two successive side branches; up to second order branching observed; structure identical to that of stem, except for the first internode, which is comparatively longer than following ones; distal-most, tendril-like internodes occasionally anastomose with each other or with neighboring stems. Hydrothecae swollen basally, then narrowing gradually distally to a short neck region projecting the aperture slightly outwards; adaxial side less than l A adnate; walls with 8-10 conspicuous transverse ridges encircling the theca; numerous creases, perpendicular to the ridges, give the hydrotheca a wrinkled appearance; aperture rhomboidal, rim with four blunt cusps separated by shallow embayments; opercular apparatus composed of four triangular valves forming a low roof; 3 or 5 internal, submarginal, lamellar cusps (two latero-adaxial and one adaxial and, in some hydrothecae, two additional, latero-adaxial ones). Gonothecae not observed. Remarks Hydrothecae with such deep, transverse ridges are present in a number of congeners, but several distinctive features allow their separation from the new species: 1) S. areyi Nutting, 1904, but its hydrothecae are provided with only 2-3 transverse ridges (Fig. 7J); 2) S. costata Leloup, 1940 is a much smaller hydroid (compare Fig. 8J and 8M); 3) S. crenulata Nutting, 1905 possesses a considerable number of closely-set, transverse ridges, and its hydrothecae are tronconical (Vervoort 1993); 4-6) S. helenae Vervoort, 1993 (Fig. 8H), S. paucicostata Vervoort, 1993 (Fig. 81) and S. pseudocostata Vervoort, 1993, but their hydrothecae are larger and more tubular; 7) S. fraseri Galea, 2010 is a more delicate hydroid and its hydrothecae are provided with fewer ridges; 8) S. quadrata Nutting, 1895 has densely-striated, exceedingly long and tubular hydrothecae, with characteristically squared cross-section (Nutting 1904); 9) the hydrothecae of S. sinensis Jaderholm, 1896 are only half adnate, and the number of ridges they carry reaches as many as 15 in the northern hemisphere (Naumov 1969); 10) S. striata Stechow, 1923, but in this species the internodes are comparatively shorter, almost collinear, and the hydrothecae are less fusiform and only about half adnate (Millard 1964). Geographical distribution Philippines. Sertularella aff. sinensis Jaderholm, 1896 Fig. 8P-S; Table 4 Sertularella sinensis Jaderholm, 1896: 11, pi. 2, figs 2-3. Sertularella sinensis - Vervoort & Watson 2003: 111 , fig. 41d-h. 30 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Table 4. Measurements (in pm) of Sertularella sinensis Jaderholm, 1896 from various sources. Present study Naumov (1969) Vervoort(1993) Vervoort & Watson (2003) (CHALCAL 2, Stn. DW80) (NZOl Stn. K825, slide 2270) (NMNZ BS437, slide 2977) Internode - length 655-865 — — — — - diameter at node 180-215 — — — — Hydro theca - free adaxial side 480-540 230-270 250-310 345-390 395M25 - adnate adaxial side 315-335 250-270 265-310 345-375 280-360 - abcauline side 555-590 350-370 295-355 425-460 420M30 - maximum width 335-360 — 250-275 310-330 280-295 - diameter at aperture 205-220 150-170 170-185 145-165 195-215 - number of ridges 19-21 11-15 10-12 16-20 ca 18 Material examined BATHUS 3: Stn. DW829, a sterile, polysiphonic, flabellate colony 3 cm high and 3.8 cm wide, broken off from its 2.3 cm long basal part (MNHN-IK-2012-16577). BORDAU 2: Stn. DW1595, a single fertile stem, 6.7 cm high, polysiphonic basally, with only two side branches left, one of which is incomplete (MNHN-IK-2012-16578). Remarks The specimen from BORDAU 2 comprises a tall, erect, straight stem with only two side branches left, while numerous lateral apophyses indicate the presence of pre-existent branches. The upper part of the specimen from BATHUS 3 is flabellate, and this structure most probably arose upon the breakage of the apical part of the initial stem and the subsequent profuse development of several distal side branches, which divided up to four times. Though of different appearance, both specimens bear hydrothecae of the same shape and size, and are believed to be conspecific. The identification of the present material is provisional, owing to multiple discrepancies exhibited by the specimens from a wide geographical area assigned to S. sinensis by various authors. Among the points of difference, the following ones are noteworthy: 1) the habit of the colonies is apparently strictly monosiphonic in the material from the northern hemisphere (Hirohito 1995), and polysiphonic in that from the southern one (Vervoort 1993; Vervoort & Watson 2003; present study); 2) the shape of the hydrothecae illustrated in the literature varies from decidedly compressed longitudinally in their free part (Jaderholm 1896; Rho & Chang 1974; Hirohito 1995) to “normally” shaped (Vervoort & Watson 2003); 3) the number of transverse ridges accounts from 6-8 (Hirohito 1983) to 11-15 (Naumov 1969), and to as many as 19-21 (present material); 4) the dimensions of the hydrothecae exhibit a wide range of variation, as exemplified in Table 4; 5) the number of transverse ridges at the surface of the gonothecal wall varies from 5-6 (Vervoort & Watson 2003), to ca 8 (Hirohito 1995), and to ca 14 (Jaderholm 1896: pi. 2, fig. 3); 6) the number of apical projections of the gonotheca reported, for instance, is either 4 (Jaderholm 1896; Hirohito 1995) or 8 (Vervoort & Watson 2003); 7) small gonothecae (750-800 x 550- 700 pm) were reported by Hirohito (1995), while comparatively larger ones (1720-1935 x 1230-1280 pm) occurred in the material studied by Vervoort & Watson (2003). The available data suggest that we are possibly dealing with at least two sibling species: the northern hemisphere form is apparently monosiphonic in habit, the free parts of their hydrothecae are 31 European Journal of Taxonomy 218 : 1-52 ( 2016 ) characteristically compressed longitudinally, the number of annulations they carry is low (not exceeding 15), and their gonothecae are small and provided with 4 apical projections; conversely, the specimens from the southern hemisphere are represented by colonies with fascicled stems and branches, the hydrothecae are “normally” shaped, the number of annulations they carry may reach as many as 21, their gonothecae are comparatively larger, and their apices are provided with 8 projections. In addition, the present material comes closer to that from New Zealand (Vervoort & Watson 2003), judging by the size and number of ribs of the hydrothecae, than to the New Caledonian one (Vervoort 1993), which have smaller hydrothecae, with a lesser number of transverse ridges (see Table 4). The gonotheca depicted in Fig. 8S is likely immature, owing to its apparently incomplete rings and flattened apical part, and originates from an auxiliary tube running up the main stem of the colony from BORDAU 2, similarly to some gonothecae examined by Vervoort &Watson (2003). Geographical distribution Sertularella sinensis sensu stricto occurs from China (Jaderholm 1896) to the Sea of Okhotsk (Naumov 1969). Additional material, possibly not conspecific, was recorded from New Caledonia (Vervoort 1993; present study), Tonga (present study), and New Zealand (Vervoort & Watson 2003). Sertularella cf. anguina Vervoort, 1993 Fig. 9A; Table 5 Sertularella anguina Vervoort, 1993: 198, figs 40b-d, 41a-b. Material examined NORFOTK 1: Stn. DW1722, a sterile, unbranched stem, 3 cm high (MNHN-IK-2012-16579). Remarks This lightly fascicled stem (only basally), divided into moderately long, slender, geniculate internodes, each carrying distally an exceedingly long, slender hydrotheca with tapering walls and five internal, submarginal cusps (two latero-adaxial, one abaxial, and two latero-abaxial), fits the diagnosis of S. anguina given by Vervoort (1993). This author gave no precise information on the exact number of internal projections of the perisarc, but assumed that four may have been present in his material, possibly two latero-adaxial and two latero-abaxial. The fifth, strictly abaxial cusp observed in the present material is only visible when the hydrothecal apertures are seen frontally, but not laterally. Although the measurements between the material in hand and the holotype appear similar (Table 5), certain differences (as the width of the hydrotheca) may be attributed to the fact that the former was measured in water, while the latter is a microslide preparation that suffered a certain degree of shrinkage. Geographical distribution New Caledonia (Vervoort 1993) and Norfolk ridge (present study). Sertularella cf. bipectinata Vervoort, 1993 Fig. 9B-C; Table 5 Sertularella bipectinata Vervoort, 1993: 207, figs 43c-e, 44. Material examined BATHUS 3: Stn. DW809: a 2.2 cm high, sterile, lightly fascicled (a couple of accessory tubes) stem, provided with two short side branches (MNHN-IK-2012-16580). 32 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Table 5. Measurements (in pm) of Sertularella cf. anguina Vervoort, 1993, S. cf. bipectinata Vervoort, 1993, and S. leiocarpoides Vervoort, 1993, and comparisons with their respective holotypes (second column for each species). S. cf. anguina Vervoort, 1993 S. cf. bipectinata Vervoort, 1993 S. leiocarpoides Vervoort, 1993 Present study: NORFOLK 1, Stn. DW1722 Vervoort (1993): MUSORSTOM 6, Stn. CP464 Present study: BATHUS 3, Stn. DW809 Vervoort (1993): BIOCAL, Stn. DW36 Present study: BATHUS 3, Stn. DW829 Vervoort (1993): MUSORSTOM 4, Stn. DW212 Internode - length 830-1200 755-850 1050-1110 1150-1260 755-1025 870-1040 - diam. at node 255-310 175-205 325-355 435M55 300-340 280-305 Hydrotheca - free adax. side 840-900 760-845 1110-1170 1000-1065 680-765 695-735 - adn. adax. wall 305-340 235-245 380-390 450-520 395^430 410-435 - abaxial wall 925-1010 890-935 1245-1285 1195-1300 900-950 870-910 - max. width 300-315 235-245 375-390 410M35 395M20 390M10 - diameter at rim 210-245 150-170 260-270 260-265 300-310 280-305 Gonotheca - length ca 2955 3100-3255 - max. width — — — — ca 1055 1000-1020 - apical width — — — — ca 425 — Remarks The present material, although similar to that assigned above to S. aff. anguina Vervoort, 1993, differs from it through its comparatively thicker intemodes, a more reduced ratio of internode length/hydrothecal depth, and the comparatively larger size of its hydrothecae (Table 5). These features, in combination with the presence of three internal, submarginal cusps (two latero-adaxial and one abaxial), also reported by Vervoort (1993), suggest that it may belong to S. bipectinata , and this identification should be regarded as provisional in the absence of fertile material. Geographical distribution New Caledonia (present study), Norfolk Ridge (Vervoort 1993). Sertularella leiocarpoides Vervoort, 1993 Figs 9D-G, 10A; Table 5 Sertularella leiocarpoides Vervoort, 1993: 223, fig. 49. Material examined BATHUS 2: Stn. CP737, a 5 cm high, sterile colony devoid of hydrorhiza (MNHN-IK-2012-16581). BATHUS 3: Stn. DW829, a 3.5 cm high colony fragment bearing one gonotheca (MNHN-IK-2012-16582); Stn. DW830, a 5 cm high and 7.5 cm wide sterile colony (MNHN-IK-2012-16583). SALOMON 1: Stn. DW1741, a 2 cm high, sterile colony (MNHN-IK-2012-16584). Remarks The four available specimens were compared to a colony of Sertularella leiocarpa (Allman, 1888) from Inaccessible Island (see Galea 2015b). Portions of three of them are illustrated altogether with S. 33 European Journal of Taxonomy 218 : 1-52 ( 2016 ) 34 GALEA H.R., Sertulariid hydroids from the tropical western Pacific leiocarpa, so as to show their specific differences (compare Fig. 5D-F and 5G). As already noted by Vervoort (1993), the internodes are thick, short and geniculate in S. leiocarpoides , and comparatively more slender, longer, and less geniculate in S. leiocarpa. In addition, the hydrothecae of Vervoorfs species have the adaxial cusps characteristically upturned, and there are generally also two inconspicuous latero-adaxial, internal, submarginal projections of the perisarc and, occasionally, a third one, on the abaxial side. Geographical distribution New Caledonia (Vervoort 1993; present study), Solomon Islands (present study). Sertularellapseudocatena sp. nov. urn:lsid:zoobank.org:act:3395EF3F-3DFF-489B-AB25-B4E2A58F8F7C Figs 9H-M, 10B-C; Table 6 Sertularella catena - Vervoort 1993: 210, fig. 45a-c [not Sertularella catena (Allman, 1888)]. Diagnosis Flabellate colonies with highly polysiphonic stems and branches; branching irregular, given off roughly in one plane; internodes rather short; hydrothecae long, tubular, almost straight; free adaxial wall with 5-7 transverse ridges extending almost to abaxial wall; gonotheca sac-shaped, with 1-3 broad, transverse ridges and 2-5 inconspicuous apical projections. Etymology The specific epithet results from the word-forming element pseudo- (derived from the Ancient Greek y/EvdfiQ, pseudes), meaning false, in appearance only, or resembling, and catena , the name of a species created by Allman (1888), suggesting that the new species superficially resembles S. catena. Material examined Holotype BATHUS 3: Stn. DW809, single flabellate colony ca 6.5 x 6.5 cm, as well as three fragments from it, two of which bearing one gonotheca, w hil e the third one carries two gonothecae (MNHN-IK-2012-16585). Paratype BATHUS 3: Stn. DW809, several colonies up to 8.5 cm high, as well as numerous smaller fragments (MNHN-IK-2012-16586). Fig. 9. (previous page) —A. Sertularella cf. anguina Vervoort, 1993 (NORFOLK 1, Stn. DW1722), hydrotheca. — B-C. Sertularella cf. bipectinata Vervoort, 1993 (BATHUS 3, DW809), two hydrothecae. — D-F. Sertularella leiocarpoides Vervoort, 1993, three hydrothecae (D = BATHUS 2, Stn. CP737; E = BATHUS 3, Stn. DW829; F = Stn. DW829), and comparison with Sertularella leiocarpa (Allman, 1888) (G) from Inaccessible Island. — H-M. Sertularella pseudocatena sp. nov. (BATHUS 3, Stn. DW809). H. Holotype. I. Paratype. J. Portion of stem with side branch. K-M. Three hydrothecae. — N-P. i Sertularella splendida sp. nov. (BATHUS 3, Stn. DW809). N. Portion of stem and proximal part of a side branch. O-P. Two hydrothecae. — Q-T. Sertularella tronconica sp. nov. Q. Portion of side branch (NORFOLK 1, Stn. DW1704). R. Portion of stem and proximal part of a side branch (BATHUS 3, Stn. DW809). S-T. Two hydrothecae (NORFOLK 1, Stn. DW1704). — U-X. Sertularella tubulosa sp. nov. (BATHUS 3, Stn. DW810). U. Distal portion of stem. V. Portion of stem and proximal part of side branch. W-X. Two hydrothecae. Scale bars: A-G, K-M, O-P, S-T, W-X = 500 pm; J, N, Q-R, U-V = 1 mm; H-I = 1 cm. 35 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Table 6. Measurements (in jam) of four new species of Sertularella discussed herein. S. pseudocatena sp. nov. (BATHUS 3, Stn. DW809) S. splendida sp. nov. (BATHUS 3, Stn. DW809) S. tronconica sp. nov. (NORFOLK 1, (BATHUS 3, Stn. DW1704) Stn. DW809) S. tubulosa sp. nov. (BATHUS 3, Stn. DW810) Internodes - length (in general) 495-680 965-1260 660-825 620-890 825-990 - length (1 st cladial internode) 1135-1395 ca 1730 — 1260-1630 ca 2240 - diameter at node 225-290 335-365 220-240 195-245 275-315 Hydrotheca - free adaxial side 560-635 1050-1170 565-605 445-480 900-1050 - adnate adaxial side 295-330 325—410 300-315 290-355 350-420 - abcauline side 705-740 1170-1320 660-690 585-660 1125-1170 - maximum width 270-290 400^110 295-310 265-300 315-350 - diameter at rim 240-255 280-300 170-185 150-160 275-290 Gonotheca - length 1235-1445 ca 2135 - maximum width 615-765 — ca 925 — — - apical width 345-395 — — — — Description Colonies flabellate, up to 8.5 cm high, of rigid appearance, though rather brittle upon manipulation, as demonstrated by the highly fragmented condition of the present material. Stolon rhizoid, firmly attached to substrate. Stems strongly fascicled, attaining up to 3 mm wide basally; irregularly ramified (up to 5 th order branches, but possibly more in living specimens), branches roughly coplanar. Perisarc moderately thick, straw colored. Basal parts of side branches also polysiphonic, thinning out to monosiphonic distally. Main tube of both stems and side branches divided into rather short intemodes by means of oblique nodes slanting in alternate directions; internodes distinctly geniculate, each carrying a hydrotheca distally. Side branches arising laterally from below the bases of hydrothecae; first internode longer than subsequent ones. Hydrothecae alternate, long, tubular, given off at about 25° with axis of internode; free adaxial side with 5-7 conspicuous wrinkles reaching abaxial wall, which appears undulated; wrinkles backward-oriented at site of origin on adaxial wall (Fig. 9L-M), becoming transverse towards abaxial wall (Fig. 9K); base of hydrotheca with an incomplete septum, leaving a large foramen for the passage of hydranth; margin generally renovated several times, provided with four short cusps separated by shallow embayments; aperture quadrangular in frontal view; no internal, submarginal projections of perisarc. Coenosarc poorly preserved, tentacle number could not be ascertained. Gonothecae (only 4 seen) arising from an internode on side opposite hydrotheca, midway between base of theca and proximal node; thick-walled, with 2-3 transverse “ribs”, aperture on well-formed neck, enclosed by filmy perisarc; 2-5 blunt, inconspicuous projections around aperture; body tapering below into indistinct pedicel; sex could not be ascertained. Remarks Vervoort(1993) assigned his infertile material from New Caledonia to S. catena\ Allman, 1888), a species known only from the Caribbean region, on the account of morphological similarities in the “structure and shape of the hydrothecae”. Unfortunately, Vervoort did not provide any updated illustrations of Allman’s holotype to facilitate a comparison with the New Caledonian specimens. However, though of nearly similar size, the appearance of the holotype of S. catena , illustrated by Allman (1888: pi. 27, fig. 2), differs radically from the silhouettes of the colonies from New Caledonia (Fig. 9H-I), in having a definite main stem and a comparatively more sparing branching pattern. In 36 GALEA H.R., Sertulariid hydroids from the tropical western Pacific addition, unlike the strictly tubular hydrothecae observed in the material in hand (Fig. 9J-M), those of S. catena appear “subcylindrical” (especially on the adaxial side) and “narrowed slightly at each end” (Nutting 1904: pi. 15, fig. 3); this is also evident from Allman’s illustration (1888: pi. 27, fig. 2a). The present material bears several gonothecae and, consequently, allows a much more reliable distinction from Allman’s species to be made. Unlike the transversely ribbed gonothecae observed here, those of S. catena are reportedly “elongate ovate, destitute of annulation, with a small terminal, bicuspate orifice” (Allman 1888). Upon a reexamination of the type. Nutting (1904) added the following: “Gonangia [... ] large, terete in form, orifice terminal, small, armed with two shallow processes or teeth” (Nutting 1904). Although their surface was originally illustrated as totally smooth (Allman 1888: pi. 28, fig. 2a), Nutting (1904) added that “There is apparently a series of very shallow rugosities or annulations on the distal portion of the gonangia” (illustrated in his pi. 15, fig. 3). This is corroborated by Vervoort’s observation, which confirms the existence “at the apical third” of the gonotheca of “two indistinct furrows”, though he states that “there is no funnel and no distinct opening”. In addition, the length of the gonothecae in the present material encompasses that of a whole internode with its associated hydrotheca, measured from the proximal node to the hydrothecal aperture. In contrast, the gonothecae of S. catena are comparatively bigger: in Allman’s figure (1888: pi. 28, fig. 2a), the gonotheca is illustrated being as long as three successive internodes, while in Nutting’s figure (1904: pi. 15, fig. 3) is encompasses the length of 2.5 intemodes. Taken together, the appearance of the colonies, with their profuse branching pattern, the perfectly tubular and slightly curved hydrothecae marked with conspicuous furrows at their surface, as well as the comparatively smaller and transversely ribbed gonotheca, suggest that we are dealing with a species distinct from S. catena. Additional, geographical considerations support this view. Geographical distribution New Caledonia (Vervoort 1993; present study). Sertularella splendida sp. nov. urn:lsid:zoobank.org:act:900C4DlA-64A7-402E-B695-3BF396F 18579 Fig. 9N-P; Table 6 Diagnosis Sertularella with lightly fascicled, irregularly and sparsely branched stems; internodes moderately long, geniculate; hydrothecae exceedingly long, gradually narrowing slightly from base to aperture, adnate for % or less, free adaxial side with 7-9 transverse ridges, an intrathecal cusp abaxially. Gonothecae unknown. Etymology From the Fatin adjective splendido, -a, -um (splendeo), originally meaning brilliant, dazzling, or glowing, but subsequently retained as “splendid” or “magnificent” in modern usage, to denote the beautiful appearance displayed by this species. Material examined Holotype BATHUS 3: Stn. DW809, a 23 mm high, sterile stem fragment devoid of its basal part, but carrying a short, distally broken side branch; an accessory tube on the stem (MNHN-IK-2012-16587). 37 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Paratypes BATHUS 3: Stn. DW809, four sterile stems or fragments, 7-14 mm high; side branches occur in two specimens; accessory tubes also present in two specimens (MNHN-IK-2012-16588). Description Colonies up to 23 mm high, arising from rhizoid stolon firmly attached to substrate; stems either lightly fascicled basally (with 1-2 auxiliary tubes) or monosiphonic; basal part of varied length, ahydrothecate, with smooth, thick perisarc; above, stem divided into regular internodes by means of slightly oblique nodes sloping in alternate directions; internodes geniculate, moderately long, widening gradually towards distal end, where they bear a hydrotheca. Side branches, when present, originating from below a stem hydrotheca, either laterally, or slightly in front of colony; first internode longer than subsequent ones, constricted basally at insertion on stem; remainder of side branch with same structure as stem. Hydrothecae alternate on stem and branches, originating at an angle of 50-60° with the intemode; exceedingly long, slightly curving downward proximally and upward distally, tapering gradually, though rather imperceptibly, towards aperture; adaxial wall % to A adnate to internode; free part with 7-9 prominent grooves; abaxial wall slightly sigmoid; basal foramen wide; distal end of hydrotheca slightly upturned; margin with four short, triangular cusps separated by shallow embayments; aperture quadrate in frontal view; an intrathecal cusp abaxially. Gonothecae absent. Remarks A careful search of the relevant literature reveals no other Sertularella species which approaches the present hydroid in the morphology of its hydrothecae. Geographical distribution New Caledonia. Sertularella tronconica sp. nov. urn:lsid:zoobank.org:act:CC79A536-B897-4CA4-9C85-DB835908E5BE Figs 9Q-T, 10D; Table 6 Diagnosis Sertularella with lightly fascicled, irregularly and sparsely branched stems; colonies coplanar; intemodes moderately long, geniculate; hydrothecae tronconical, adnate for A their length; adaxial wall with 4-5 transverse ridges; 5 prominent intrathecal, submarginal cusps; gonotheca large, transversely ridged adaxially. Eymology From the Latin words, truncare , meaning to truncate, and conus (also xojvoc in Greek), meaning cone, to characterize the shape of the hydrotheca. Material examined Holotype NORFOLK 1: Stn. DW1704, single, unbranched colony, 2 cm high, devoid of its hydrorhiza, but bearing a basal accessory tube running up the stem; a female gonotheca present (several large oocytes still noticeable inside) (MNHN-IK-2012-16589). Paratypes BATHUS 3: Stn. DW809, several sterile stems and fragments, up to 1.4 cm high, some branched and some with lightly fascicled stems (MNHN-IK-2012-16590). 38 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Description Colonies up to 2 cm high, arising from creeping (young colonies) to rhizoid (adult colonies) hydrorhiza, firmly attached to substrate. Basal part of stem of varied length, ahydrothecate, bearing a reduced number of accessory tubes; perisarc thick and smooth. Remainder of stem divided into regular internodes by means of oblique constrictions of the perisarc slanting in alternate directions. Internodes moderately long, width increasing imperceptibly towards distal ends, so as to accommodate the basal part of a hydrotheca. Branching scarce and irregular, in one plane, with up to 2 nd order branches observed; side branches originating laterally from below the base of a stem hydrotheca; first internode comparatively longer than subsequent ones, constricted basally at insertion on stem; remainder of side branches with similar structure as the stem. Hydrothecae arranged alternately at an angle of 35M0° with the internode; moderately long, tronconical, widening slightly below aperture; adaxial wall adnate for about A its length; free part with 4-5 transverse, though incomplete, ridges, not reaching abaxial side, running parallel to adnate side of adaxial wall; abaxial wall nearly straight; margin occasionally renovated; aperture quadrate in frontal view, bearing 4 short cusps separated by shallow embayments; five prominent, submarginal, intrathecal cusps: two latero-adaxial, two latero-abaxial, and one abaxial. Gonothecae originating from the internode, on side opposite hydrotheca, midway between its base and proximal node; large, transversely ribbed; a short, distal neck; aperture large, surrounded by 3-4 almost imperceptible, blunt cusps; a few large oocytes noticeable by transparency. Remarks Several species possess hydrothecae that resemble, more or less, the shape of those of S. tronconica sp. nov., but the latter may be reliably distinguished from its congeners as follows: 1-2) in both S. anguina and S. bipectinata the length/width ratio of the hydrotheca is comparatively higher (Vervoort 1993); 3) the hydrothecae of S. inconstans Billard, 1919 are adnate for a greater extent of their adaxial wall (Rees & Vervoort 1987), and the transverse ridges, which encircle the bodies of proximal hydrothecae, gradually fade off towards the distal end of the colony, and are eventually represented by indistinct undulations of the perisarc on the adaxial side (Billard 1925b); in addition, the internodes are only slightly geniculate and do not reach the degree of geniculation encountered in S. tronconica sp. nov.; 4) S. keiensis Billard, 1925b, but in this species the hydrothecae are slightly smaller and adnate for a longer extent, their surface varies from wrinkled (Billard 1925b) to smooth (Leloup 1937), and there are four lamellar, internal, submarginal cusps (two latero-adaxial and two latero-abaxial); 5) S. leiocarpoides , but this species has comparatively larger, smooth-walled hydrothecae (compare Fig. 9S-T with 9D-F); 6) although very similar morphologically, the hydrothecae of S. natalensis Millard, 1968 have a length/ width ratio of ca 2.1-2.3 (calculated from Millard 1968, 1975), while those of S. tronconica sp. nov.are comparatively more slender, with a ratio of ca 2.4-2.9; in addition, the ridges are common in younger hydrothecae and may totally disappear in the older ones (Millard 1968); moreover, its gonothecae appear more fusiform, only their distal end is wrinkled, and the aperture is surrounded by 3-4 projections of perisarc (Millard 1975); 7) unlike in the present species, the length/width ratio of the hydrotheca in S. undulitheca Vervoort, 1959 is lower, between 2.1 and 2.3 (calculated from Vervoort 1959), its internodes are comparatively shorter and slightly geniculate, and both the hydro- and gonothecae are wrinkled throughout. Geographical distribution New Caledonia and Norfolk Ridge. 39 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Sertularella tubulosa sp. nov. um:lsid:zoobank.org:act:8D56454C-7B2C-451C-BFB2-9C42603F3005 Fig. 9U-X; Table 6 Diagnosis Sertularella with lightly polysiphonic, irregularly and sparsely ramified stems; internodes moderately long, geniculate; hydrothecae exceedingly long, tubular, isodiametric throughout, walls entirely smooth; four small marginal cusps, and four submarginal, intrathecal projections of perisarc. Gonothecae unknown. Etymology The specific name is derived from the Latin tubulus , meaning tube, and describes the shape of the hydrotheca. Material examined Holotype BATHUS 3: Stn. DW810, single, sterile, branched stem, 2.6 cm high, lightly fascicled basally, but devoid of hydrorhiza (MNHN-IK-2012-16591). Description The colony, devoid of hydrorhiza, is composed of a single stem, 2.6 cm high, giving rise to a side branch towards its middle. Perisarc thick basally, thinning out gradually towards tip of colony. Basal part of stem ahydrothecate, overgrown by a few accessory tubes; upper and longest part divided into regular internodes by oblique constrictions of the perisarc slanting in alternate directions. Internodes moderately long, geniculate, widening distally so as to accommodate a hydrotheca. The single side branch originates laterally from below a stem hydrotheca; first internode comparatively longer than subsequent ones; the latter with same structure as the stem. Hydrothecae angled at 40-45° with the stem; long, tubular, isodiametric throughout, adnate for about % their length; free adaxial wall nearly straight and smooth; abaxial wall basally convex, becoming rapidly straight for most of its length; basal foramen wide; aperture squared in frontal view, with four inconspicuous marginal cusps separated by shallow embayments; four intrathecal, submarginal cusps: two latero-adaxial and two latero-abaxial; margin often renovated in damaged hydrothecae. Gonothecae unknown. Remarks The characteristic tubular shape of the hydrothecae of this species is diagnostic. Tubular, smooth-walled hydrothecae are only encountered in a few congeners that can be distinguished from the new species on the following accounts: 1) the hydrothecae of S. billardi Vervoort, 1993 have a comparatively lower length/width ratio of the hydrothecae (Vervoort 1993); 2) S. exilis Fraser, 1938 has typically curved hydrothecae (Fraser 1938), and the species is minute (Calder et al. 2009); 3) S. vervoorti El Beshbeeshy, 2011 possesses huge hydrothecae, whose length/width ratio is lower than in S. tubulosa sp. nov. (El Beshbeeshy 2011); 4) in S. whitei the hydrothecae originate at a more acute angle with the axis of internode, are smaller, curve slightly outwards, and the stem internodes are longer and more slender than in the present species (Rees & Vervoort 1987). Geographical distribution New Caledonia. 40 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Genus Sertularia Linnaeus, 1758 Sertularia tongensis (Stechow, 1919) Fig. 10E Sertularella tongensis Stechow, 1919: 89, fig. f-g 1 . Sertularia tongensis - Galea 2010: 18, fig. 5h-m (synonymy); 2015b: 10, fig. 3s. Material examined MUSORSTOM 9: Stn. CP 1265, small colony composed of a few sterile, unbranched stems, up to 1 cm high (MNHN-IK-2012-16592). Remarks As stated by Galea (2010, 2015b), this species is immediately recognizable, even in sterile condition, through its alternate hydrothecae whose apertures are closed by two opercular flaps pleated along a median line. Geographical distribution Likely circumglobal in temperate to tropical seas (Galea 2015b). The present record is from the Marquesas. Genus Symplectoscyphus Marktanner-Turneretscher, 1890 Symplectoscyphus effusus Vervoort, 1993 Fig. 10F-H; Table 7 Symplectoscyphus effusus Vervoort, 1993: 253, figs 59, 60a-e. Material examined NORFOLK 1: Stn. DW1712, small colony composed of several stems up to 11 mm high, mostly fertile (female), on worm tube covered by sand grains (MNHN-IK-2012-16593). Remarks The long, tubular, upwardly-curved hydrothecae, and the transversely ribbed gonothecae with frilled margin, characteristically curving downwards, are diagnostic (Vervoort 1993). In addition, the comparative measurements of this material and of the holotype (see Table 7) leave no doubt about their conspecificity. The gonothecae in the specimen examined have 4-5 prominent ribs, and these are definitely transversely and not spirally arranged, as stated by Vervoort. Two large oocytes or planulae occur in each gonotheca. Geographical distribution New Caledonia (Vervoort 1993), Norfolk Ridge (present material). Symplectoscyphus fasciculatus nom. nov. Fig. 10I-L Symplectoscyphus johnstoni tropicus Vervoort, 1993: 259, figs 61, 62a-d [not S. johnstoni (Gray, 1843)]. non Symplectoscyphus johnstoni tropicus - Vervoort & Watson 2003: 217, fig. 5 If—1. 41 European Journal of Taxonomy 218 : 1-52 ( 2016 ) 42 GALEA H.R., Sertulariid hydroids from the tropical western Pacific Table 7. Measurements (in pm) of S ymplectoscyphus effusus Vervoort, 1993 and S. paucicatillus sp. nov. _ S- effusus Vervoort, 1993 _ & paucicatillus sp. nov. Present study: NORFOLK 1, Vervoort (1993): (present study: BATHUS 4, Stn. DW1712 CHALCAL 2, Stn. DW08 Stn. DW923) Internodes - length (in general) 415-745 405-690 455-875 - diameter at node 95-105 65-90 155-230 Hydrotheca - free adaxial side 305-340 215-235 405-470 - adnate adaxial side 150-160 115-170 215-245 - abcauline side 325-340 295-320 465-530 - maximum width 135-150 105-120 230-250 - diameter at rim 130-135 135-140 185-195 Gonotheca - length ca 1175 ca 1110 1240-1480 - maximum width ca 835 ca 645 865-890 - tube length — ca 120 165-180 - tube diameter — — ca 155 - diameter at aperture ca 175 ca 110 260-270 non Symplectoscyphus tropicus (Hartlaub, 1901). Diagnosis Symplectoscyphus species of flaccid appearance; stems and side branches fascicled basally, geniculate at origin of branches; branching pseudodichotomous; internodes composed of two alternate hydrothecae and a lateral apophysis with its associated hydrotheca; all hydrothecae tubular, curved outwards; gonothecae sac-shaped, nearly fully adnate, perisarc undulated, aperture round, on top of short funnel. Etymology From the Latin fascis , meaning fascicled, to characterize the polysiphonic habit of the colonies. Fig. 10. (previous page) — A. Sertularella leiocarpoides Vervoort, 1993 (BATHUS 3, Stn. DW829), gonotheca. — B-C. Sertularella pseudocatena sp. nov. (BATHUS 3, Stn. DW809), two gonothecae. — D. Sertularella tronconica sp. nov. (NORFOLK 1, Stn. DW1704), gonotheca. — E. Sertularia tongensis (Stechow, 1919) (MUSORSTOM9, Stn. CP1265), internode with hydrotheca. — F-H. Symplectoscyphus effusus Vervoort, 1993 (NORFOLK 1, Stn. DW1712). F. Portion of colony. G. Hydrotheca. H. Gonotheca. — I-L. Symplectoscyphus fasciculatus nom. nov. (MUSORSTOM 4, Stn. CC174). I. Portion of colony. J-K. Two hydrothecae. L. Male gonotheca. — M-V. Symplectoscyphus ralphae Vervoort, 1993 (NORFOLK 1, Stn. DW1712). M-N. Samples #1 and #2, repectively. O-P. Portions from samples #1 and #2, respectively. Q-T. Hydrothecae from samples #1 (Q-R) and #2 (S-T). U-V. Gonothecae from samples #1 and #2, respectively. — W-Z. Symplectoscyphus paucicatillus sp. nov. (BATHUS 4, Stn. DW923). W. Paratype, colony silhouette. X. Portion of colony. Y. Two hydrothecae. Z. Two gonothecae. Scale bars: A-D, F, I, O-P, X = 1 mm; E = 300 pm; G, J-K, Q-T, Y = 200 pm; H, L, U-V, Z = 500 pm; M-N, W = 1 cm. 43 European Journal of Taxonomy 218 : 1-52 ( 2016 ) Material examined Holotype MUSORSTOM 4: Stn. CP153, “several well developed, flabellate colonies 30^50 mm, stems basally polysiphonic; many appressed gonothecae [...]. One large colony 30x40 mm is holotype (MNHN-Hy. 1117)” (Vervoort 1993). Additional material MUSORTSOM 4: Stn. CC174, a 4.5 cm high, fertile (male) colony. Description Flaccid, flabellate, up to 4 cm high and 5 cm wide colonies arising from branched, rhizoid stolon. Stems strongly fascicled basally, thinning out gradually to monosiphonic distally; flexuous, usually regularly and alternately branched; occasionally with “irregular” branches resulting from considerable development of secondary stems from branches growing as long as the main stem itself, and resulting in multiple tangled stems, whose distalmost branches form multiple anastomoses between them and with neighboring stems. Division into internodes indistinct, even in monosiphonic parts, but equivalents of internodes long, geniculate, comprising a basal apophysis and its associated axillar hydrotheca, as well as two alternate hydrothecae above. Apophyses alternate. Side branches straight (until they rebranch again in pseudodichotomous manner), nodes indistinct, but each equivalent of internode bearing hydrothecae arranged alternately. Hydrothecae tubular, curving away from internode, adnate for nearly half their length. Free adaxial wall straight to slightly convex; abaxial wall straight basally, curving suddenly in its distal third. Hydrothecal aperture nearly parallel to longitudinal axis of internode; margin with three pointed cusps separated by rather deep embayments; adaxial cusp recurved; renovations common and numerous. No conspicuous submarginal, intrathecal cusps, except for an occasional abaxial thickening. Gonothecae given off from below hydrothecal bases, fitting tightly and neatly against internodes. Male and female similar in shape; sac-shaped, wall undulated and never ribbed; undulations more pronounced distally, fading off basally; aperture distal, borne on outwardly-projecting, trumpet-shaped terminal tube. Remarks The description provided above combines Vervoorfs (1993) account with personal observations of the material in hand. The latter apparently belongs to a “large tangled tuft of c. 30 mm high colonies on wormtubes” previously examined by Vervoort. Owing to the fasciculate habit of its stems and the gonothecae with undulated walls, the large material studied by Vervoort was assigned to a new subspecies, tropicus , of Symplectoscyphus johnstoni (Gray, 1843). In doing so, Vervoort distinguished it from its congeners with monosiphonic stems and transversely-ribbed gonothecae, viz. S. johnstoni johnstoni (Gray, 1843) and S. johnstoni sub tropicus Ralph, 1961, the latter being additionally characterized by the presence of three submarginal, intrathecal cusps. As stated by Ralph (1961), S. johnstoni is a species with strictly monosiphonic stems, and its gonothecae are provided with “8 to 14 evenly spaced transverse ridges”. Consequently, the subspecies tropicus could be confidently raised to species. However, when doing so, it becomes an invalid junior homonym of S. tropicus (Hartlaub, 1901). To avoid this situation, the junior homonym is replaced here with the binomen S. fasciculatus nom. nov., whose holotype remains the same for both the original and the new name of the single biological species (ICZN Art. 72.7). The measurements of S. fasciculatus nom. nov. are given by Vervoort (1993: 260, table 51). A restricted number of species belonging to this highly speciose genus are polysiphonic in habit: six congeners from the Antarctic [S. bellinghauseni Pena Cantero, 2012 (Pena Cantero 2012); 44 GALEA H.R., Sertulariid hydroids from the tropical western Pacific S. cumberlandicus (Jaderholm, 1905) (Pena Cantero et al. 2002); S. frondosus Pena Cantero, 2010 (Pena Cantero 2010); S. hesperides Pena Cantero, 2012 (Pena Cantero 2012); S. liouvillei (Billard, 1914) (Pena Cantero et al. 2002); S. sofiae Pena Cantero et al., 2002 (Pena Cantero et al. 2002)], ten from the subantarctic [S. adpressus (Ritchie, 1911) (Ritchie 1911); S. amoenus Vervoort & Watson, 2003 (Vervoort & Watson 2003); S. arboriformis (Marktanner-Turneretscher, 1890) (Millard 1975); S. columnarius (Briggs, 1914) (Ralph 1961); S. divaricatus (Busk, 1852) (Ralph 1961); S. magellanicus (Marktanner-Turneretscher, 1890) (Galea & Schories 2012); S. patagonicus Galea & Schories, 2012 (Galea & Schories 2012); S. paulensis Stechow, 1923 (Watson 2003); S. procerus (Trebilcock, 1928) (Ralph 1961); S. subarticulatus (Coughtrey, 1875) (Millard 1977)], and two from the tropics, both assigned to S. tropicus Hartlaub, 1901 [sensu Clarke 1894 (as Sertularella variabilis ) and sensu Billard 1925b], Ecologically, S. fasciculatus nom. nov. occurs in a biogeographical area radically different from that of the majority of species listed above. Its gonothecae are different from those of the following species, which exhibit transverse ridges: S. aggreggatus (Jaderholm, 1917) (Pena Cantero et al. 2002), S. arboriformis (Millard 1975), S. columnarius (Ralph 1961), S. cumberlandicus (Jaderholm 1905), S. magellanicus (Galea & Schories 2012), S. patagonicus (Galea et al. 2014), S. procerus (Ralph 1961), S. sofiae (Pena Cantero et al. 2002), and S. subarticulatus (Ralph 1961). The gonothecae of S. frondosus (Pena Cantero 2010) and S. liouvillei (Pena Cantero et al. 2002) are exceedingly long and tubular, while those of S. amoenus (Vervoort & Watson 2003) and S. paulensis (Pena Cantero 2012) are ovoid and have smooth to slightly undulated walls, yet they are not adherent to their corresponding internodes, and their distal tubes are not eccentrically placed. The habit and shape of the gonothecae of S. fasciculatus nom. nov. come closest to those of S. adpressus. However, the latter is a more robust species, with pinnate appearance, and its hydrothecae are subopposite and highly immersed into their intemodes (Ritchie 1911). Although not completely formed in the specimens of S. bellinghauseni studied by Pena Cantero (2012), the gonothecae seem “to be characterized by the presence of rings”. Similarly, the gonothecae of S. hesperides were incipient and apparently smooth (Pena Cantero 2012), but this species is distinguished through its hydrothecae that are adnate for one-third or less their adaxial length. Finally, the gonothecae of S. divaricatus are unknown yet, but this species possesses rather highly immersed hydrothecae (Ralph 1961). Geographical distribution New Caledonia (Vervoort 1993). Symplectoscyphus ralphae Vervoort, 1993 Fig. 10M-V Symplectoscyphus ralphae Vervoort, 1993: 270, figs 65e-f, 66a-c. Material examined NORFOLK 1: Stn. DW1712, two fertile colonies, ca 18 mm high, both detached from substrate (sample A) (MNHN-IK-2012-16594); two colonies, 10 and 20 mm high, the largest bearing two gonothecae (sample B), on bryozoan (MNHN-IK-2012-16595). Remarks The trophosomes of both samples are indistinguishable morphologically (compare Figs 10M and 10N; 10O and 10P; 10Q-R and 10S-T), but the gonothecae they bear are different. Those in sample A are smaller, provided with 12-14 transverse ridges and a narrow, trumpet-shaped distal tube (Fig. 10U), while those in sample B are comparatively larger, exhibit about 15 ridges, and their distal tube is much wider and has an everted rim (Fig. 10V). Although the gonothecal content in sample A could not be 45 European Journal of Taxonomy 218 : 1-52 ( 2016 ) confidently ascertained, it may prove to be male; that in sample B contains two large ovoid bodies (either oocytes or developing planulas), and is consequently assigned to the female sex. Vervoort (1993) did not compare his new species with its congeners, and the present identifications are mainly based on the shape of the gonotheca. However, other symplectoscyphid hy droids belonging to the present collection, but not included in this study, exhibit indistinguishable trophosomes, but their gonothecae are of different sizes and bear a varied number of transverse ridges. Consequently, it is felt that the discrimination of species belonging to certain morphologically related groups of Symplectoscyphus is not possible in the absence of molecular studies, owing to the absence of reliable morphological characters. Geographical distribution New Caledonia (Vervoort 1993), Norfolk Ridge (present study). Symplectoscyphus paucicatillus sp. nov. urn:lsid:zoobank.org:act:B00A7B9A-265C-48D9-BDDB-71DB49EA7DE7 Fig. 10W-Z; Table 7 Diagnosis Symplectoscyphus with monosiphonic stems; branching pseudodichotomous, occurring at irregular intervals; intemodes moderately long, slender, geniculate; hydrothecae long, tubular, sigmoid in shape; gonothecae transversely ribbed distally, undulated basally, with trumpet-shaped apical tube. Etymology From the Latin words pauci, -drum , meaning a few, and catillus , meaning small dish(es), making reference to the shape of the gonotheca, which resembles several stacked dishes. Material examined Holotype BATHUS 4: Stn. DW923, ca 2.8 cm high colony, bearing 3 fully formed and one incipient gonotheca (MNHN-IK-2012-16596). Paratypes BATHUS 4: Stn. DW923, two sterile colonies 2 and 3 cm high (MNHN-IK-2012-16597). Description Colonies up to 3 cm high arising from creeping, branching hydrorhiza. Stems monosiphonic throughout, composed of a long (up to 1.4 cm), lower, ahydrothecate part, and an upper and longest part bearing hydrothecae. Perisarc rather thick and straw colored, thinning out gradually towards tips of colonies; basally a little tortuous, rapidly becoming straight and smooth. Hydrothecate part divided into rather poorly indicated internodes by means of oblique constrictions of the perisarc slanting in alternate directions; each intemode moderately long, slender, distinctly geniculate, bearing a hydrotheca distally. Branching pattern pseudodichotomous; side branches arising at irregular intervals from slightly below a hydrotheca, the latter becoming axillar (Fig. 10X); structure identical to that of stem; first internode not significantly longer compared to subsequent ones; up to 2 nd order side branches, and all in roughly one plane, giving the colony a flabellate appearance. Hydrothecae originating at very acute angles with the axis of corresponding internode; long, tubular, slightly sigmoid (facing outward basally and upwards distally); adaxial wall adnate for about A its length; aperture with three pointed, triangular cusps separated by moderately deep embayments; adaxial cusp produced adaxially; opercular apparatus 46 GALEA H.R., Sertulariid hydroids from the tropical western Pacific usually lost; renovation of margin common. Gonothecae borne on both the main stem and side branches, arising usually from below the hydrothecal bases, occasionally from the axil formed by free adaxial wall with next internode; body elongated ovoid, provided distally with 2-3 broad, conspicuous, transverse ribs, and undulated basally, where it tapers to an indistinct pedicel; apical part a flattened plateau from the center of which arises a short trumpet-shaped tube; sex of gonothecae apparently female, judging from the remains of soft tissues (presence of a spherical body, likely an oocyte). Remarks The hydrothecae of this species resemble those of other congeners, but there are points of difference which allow their specific separation, as follows: 1 ) S. amoenus Vervoort &Watson, 2003 is a species with fascicled stems, its hydrothecae are deeper (755-920 pm, compared to 590-625 in the present material), and its gonothecae have undulated walls (Vervoort & Watson 2003); 2) S. amphoriferus (Allman, 1877) has comparatively slender hydrothecae (judging from the size of their apertures), and its gonothecae are pear-shaped, with “eleven raised transverse ridges and a slender terminal neck” (Millard 1977); 3) S. effusus Vervoort, 1993, but this is a comparatively smaller species (compare Fig. 10G and 10Y); 4) S. macrocarpus (Billard, 1918), has more slender [according to the size of their apertures (see Billard 1925b; Schuchert 2003)] and shorter hydrothecae (420-470 pm); in addition, its gonothecae (of both sexes) are characteristically amphora-shaped (Billard 1925b); 5) S. pedunculatus (Billard, 1919) has longer, more slender, and less adnate hydrothecae (Billard 1925b; Vervoort 1993). Geographical distribution New Caledonia. Discussion Large collections of hy droids originating from the tropical western Pacific were obtained during various expeditions of the French Tropical Deep-Sea Benthos program. Their study, entrusted to various experts, yielded a number of reports dealing with several families of thecate hy droids (see Introduction). The present work, focusing on hy droids of the family Sertulariidae Lamouroux, 1812, is a continuation of the large account published by Vervoort (1993) and the recent study by Galea (2015), who introduced three new genera, viz. Gonaxia , and Caledoniana and Solenoscyphus, respectively. In addition to the genera Abietinaria Kirchenpauer, 1884, Caminothujaria von Campenhausen, 1896, Dictyocladium Allman, 1888, Dynamena Lamouroux, 1812, Geminella Billard, 1925b, Hydrallmania Hincks, 1968, Idiellana Cotton & Godfrey, 1942, Sertularella Gray, 1848, and Symplectoscyphus Marktanner-Turneretscher, 1890 dealt with by Vervoort, members of three other genera, viz. Diphasia L. Agassiz, 1862, Salacia Lamouroux, 1816, and Sertularia Linnaeus, 1758, are discussed herein. Of the forty-three species, belonging to ten genera, dealt with in the present report, 9 are new to Science, and a subspecies is raised to full species level, accompanied by a name change. Of these, two new species of Gonaxia , added to the 21 congeners described earlier by Vervoort, raise their number to 23 within the study area. Six and two species are added to the widely distributed and speciose genera Sertularella and Symplectoscyphus , respectively. Additional hydroids, partly discussed earlier by Vervoort, also occur in the present collection, and additional notes on their morphology are provided. Finally, other hydroids, such as the poorly known Diphasia cristata Billard, 1920 and Salacia macer Vervoort & Watson, 2003, occurred as fertile colonies, allowing descriptions of their hitherto unknown gonothecae. As already underlined by Vervoort for the family Sertulariidae, but also by Pena Cantero & Vervoort (2010) for the species of Acryptolaria Norman, 1875 (family Lafoeidae Hincks, 1868), the deep-water 47 European Journal of Taxonomy 218 : 1-52 ( 2016 ) species composition in the study area reveals a high degree of endemism. Regarding the sertulariid hydroids, this is especially true with respect to the genera Caledoniana , Gonaxia , Sertularella and Solenoscyphus. Among the main factors involved, the lack of a free-swimming dispersive stage (Pena Cantero & Vervoort 2010) limits the capabilities of an efficient dispersal, causing a marked reproductive isolation and, consequently, a high degree of speciation. Although the hy droid fauna of the study area can be considered as relatively well investigated, it is likely that, with future sampling, new genera and species will be discovered. Acknowledgements Thanks are due to Philippe Bouchet and Pierre Lozouet, both of MNHN, for giving me access to the material described in this paper, and to Aude Andouche for curatorial assistance. The acknowledgements to cruises senior scientists, collectors, captains and crew in Bouchet et al. (2008) also apply here. I am grateful to Dr. Dale Calder (Royal Ontario Museum, Toronto, Canada) for his helpful advice on ICZN matters. Sincere thanks are due to Drs Peter Schuchert (MHNG, Switzerland) and Henry H.C. 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Manuscript received: 22 January 2016 Manuscript accepted: 21 March 2016 Published on: 2 August 2016 Topic editor: Rudy Jocque Desk editor: Kristiaan Hoedemakers Printed versions of all papers are also deposited in the libraries of the institutes that are members of the EJT consortium: Museum national d’Histoire naturelle, Paris, France; Botanic Garden Meise, Belgium; Royal Museum for Central Africa, Tervuren, Belgium; Natural History Museum, London, United Kingdom; Royal Belgian Institute of Natural Sciences, Brussels, Belgium; Natural History Museum of Denmark, Copenhagen, Denmark; Naturalis Biodiversity Center, Leiden, the Netherlands. 52