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In this paper, we study material belonging to the hydroid genera Egmundella Stechow, 1921 and Cyclocanna Bigelow, 1918 collected off the coast of Northwest Africa, from Morocco to Guinea Bissau, between 2004 and 2012, during several international surveys. Currently, the genus Egmundella is included in the family Campanulinidae Hincks, 1869, but its taxonomic status is doubtful, since most of the life cycles of its species are unknown. A total of four species have been identified: E. grimaldii Leloup, 1940, E. modesta Millard & Bouillon, 1975, E. superba Stechow, 1921 and E. ansini n. sp. Egmundella grimaldii is found for the first time since its original description, and fertile material is described herein. Its gonotheca is morphologically similar to that of C. producta (G.O. Sars, 1874), suggesting that both species could be congeneric. A description of specimens of C. producta collected along the NW African coast is also provided.

Asteronyx loveni Müller & Troschel, 1842 Figs 2, 3A–B, 4A, D–E Asteronyx loveni Müller & Troschel, 1842: 119, pl. X figs 3–5. Ophiuropsis lymani Studer, 1884: 55, pl. V figs 12a–d. Asteronyx locardi Koehler, 1895: 470–471, fig. 10 Asteronyx loveni – Clark 1923: 314–315. — Mortensen 1927: 158–160, fig. 90 — Paterson, 1985: 13–15, fig. 15. Asteronyx locardi – Koehler 1896: 88–89, pl. 3 fig. 25. Material examined MAURITANIA • 1 spec., 25.22 mm dd; 19°34′14′′– 19°31′34′′ N, 17°31′44′′– 17°30′21′′ W; depth 1689– 1628 m; 23 Nov. 2007; Maurit-1107 exped.; stn MU22; Maurit-1107-04528; LZM-UV • 12 specs, 6.08–21.71 mm dd; 19°25′29″– 19°22′44″ N, 17°33′17″– 17°32′11″ W; depth 1778–1811 m; 26 Nov. 2007; Maurit-1107 exped.; stn MU31; Maurit-1107-05231; LZM-UV • 10 specs, 6.83–19.28 mm dd; 19°55′41″– 19°53′05″ N, 18°01′07″– 18°02′01″ W; depth 1808–1862 m; 21 Nov. 2008; Maurit-0811 exped.;stn MU92; Maurit-0811-03931; LZM-UV • 4 specs, 64.90– 22.98 mm dd; 19°51′02″– 19°49′33″ N, 17°55′33″– 17°53′00″ W; depth 1740–1769 m; 21 Nov. 2008; Maurit-0811 exped.; stn MU93; Maurit-0811-03725; LZM-UV • 2 specs, 9.60–12.56 mm dd; 19°35′15″– 19°32′43″ N, 17°35′13″– 17°33′37″ W; depth 1720–1734 m; 21 Nov. 2008; Maurit-0811 exped.; stn MU94; Maurit-0811-03928; LZM-UV • 1 spec., 11.07 mm dd; 19°59′28″– 19°59′01″ N, 17°57′28″– 17°59′07″ W; depth 1746–1749 m; 22 Nov. 2009; Maurit-0911 exped.; stn MU193; Maurit-0911-03154; LZM-UV • 1 spec., 25.74 mm dd; 16°08′44″– 16°11′14″ N, 17°10′08″– 17°08′40″ W; depth 1595 m; 6 Dec. 2010; Maurit-1011 exped.; stn MU274; Maurit-1011-02982; LZM-UV. WESTERN SAHARA • 1 spec., 11.01 mm dd; 21°33′13″– 21°36′08″ N, 18°07′26″– 18°07′09″ W; depth 1860– 1820 m; 17 Nov. 2006; Maroc-0611 exped.; stn MO198; Maroc-0611-16135; LZM-UV • 1 spec., 5.81 mm dd; 22°59′13″– 22°56′19″ N, 17°37′30″– 17°38′12″ W; depth 1562–1577 m; 26 Nov. 2006; Maroc-0611 exped.; stn MO230; Maroc-0611-16155; LZM-UV. GUINEA BISSAU • 2 specs, 13.24–18.81 mm dd; 10°01′18″– 10°00′24″ N, 17°24′56″– 17°25′05″ W; depth 902–908 m; 29 Oct. 2008; Bissau-0810 exp.; stn BS166; Bissau-0811-06529; LZM-UV. Distribution Asteronyx loveni Müller & Troschel, 1842 is a circumglobal species, widely distributed across the three major oceans (Indian, Pacific and Atlantic). In the Atlantic Ocean, it has been recorded on both sides: in the West Atlantic, from North USA to West Indies (Hernández-Herrejón et al. 2008), and in the East Atlantic, from Norway (Döderlein 1911) to South Africa (Mortensen 1933). It also has a wide bathymetric distribution, ranging from 100 to 4721 m (Smirnov et al. 2014). We collected the species at eleven stations from Western Sahara, Mauritania and Guinea-Bissau waters, between 902 and 1862 m. Remarks This is a deep-sea-water species generally associated with gorgonians and pennatularians (Mortensen 1927). Our specimens were always associated with pennatularians Distichoptilum gracile Verrill, 1882 and Anthoptilum murrayi Kölliker, 1880. Living colour of the species is cream or pinkish orange, more intense in the central part of the disc. The innermost arm spine much larger than the other spines and a hooked arm spine at the tip of the arm are the most distinctive characteristic for this species., Published as part of Calero, Belén & Ramil, Fran, 2023, Euryalida (Echinodermata, Ophiuroidea) from Northwest Africa, pp. 46-75 in European Journal of Taxonomy 870 on pages 51-53, DOI: 10.5852/ejt.2023.870.2117, http://zenodo.org/record/7938618, {"references":["Muller J. & Troschel F. H. 1842. System der Asteriden. F. Vieweg und Sohn, Braunschweig. https: // doi. org / 10.5962 / bhl. title. 11715","Studer T. 1884. Verzeichnis der wahrend der Reise S. M. S. \" Gazelle \" um die Erde, 1874 - 76 gesammelten Asteriden und Euryaliden. Abhandlungen der Preussischen Akademie der Wissenschaften: 1 - 64.","Koehler R. 1895. Draguage profonds executes a bord du ' Caudan' dans le Golfe de Gascogne. Rapport preliminaire sur les Echinodermes. Revue Biologique du Nord de la France VII: 439 - 506.","Clark H. L. 1923. The Echinoderm fauna of South Africa. Annals of The South African Museum XIII: 221 - 432.","Mortensen Th. 1927. Handbook of the Echinoderms of the British Isles. Oxford University Press, Rotterdam. https: // doi. org / 10.5962 / bhl. title. 6841","Paterson G. L. J. 1985. The deep-sea Ophiuroidea of the North Atlantic Ocean. Bulletin of the British Museum (Natural History) 49 (1): 1 - 162.","Koehler R. 1896. Resultats scientifiques de la campagne du Caudan dans le Golfe de Gascogne. Echinodermes. Annales de l'Universite de Lyon 26: 33 - 122. https: // doi. org / 10.5962 / bhl. title. 65730","Hernandez-Herrejon L. A., Solis-Marin F. A. & Laguarda-Figueras A. 2008. Ofiuroideos (Echinodermata: Ophiuroidea) de las aguas mexicanas del golfo de Mexico. Revista De Biologia Tropical 56 (3): 83 - 167.","Doderlein L. 1911. Uber japanische und andere Euryalae. KB Akademie der Wissenschaften, Munich. https: // doi. org / 10.5962 / bhl. title. 16334","Mortensen Th. 1933. Papers from Dr. Th. Mortensen's Pacific Expedition 1914 - 16. LXV. Echinoderms of South Africa (Asteroidea and Ophiuroidea). Videnskabelige Meddelelser fra Dansk naturhistorisk Forening i Kobenhavn: 93: 215 - 400.","Smirnov I. S., Piepenburg D., Ahearn C. & Juterzenka K. V. 2014. Deep-sea fauna of European seas: An annotated species check-list of benthic invertebrates living deeper than 2000 m in the seas bordering Europe. Ophiuroidea. Invertebrate Zoology 11 (1): 192 - 209."]}

Astrodendrum juancarlosi sp. nov. urn:lsid:zoobank.org:act: ECD0622E-6FAF-4C72-B102-F1B94D8ECBFB Figs 3E–F, 7–9 Diagnosis Species with small granule-like external ossicles, ending in a crystalline point, covering the dorsal and lateral interradial areas of the disc. Ventral disc areas and arms covered by domed granule-like external ossicles without any crystalline point. Two or three terminal projections on each arm spine; one secondary teeth on each valve. Etymology The specific epithet ‘ juancarlosi ’ was chosen as a tribute to Mr Juan Carlos Calero, father of the first author. Material examined Holotype GUINEA BISSAU • 2 specs, 40.43–56.81 mm dd; 10°18′55″ N, 16°25′07″ W; depth 79 m; 4 Nov. 2008; Bissau-0810 exped.; stn BS200; Bissau-0810-06403; MNCN 29.02/1534. Paratypes GUINEA BISSAU • 2 specs, 28.20–51.16 mm dd; 11°08′07″– 11°09′33″ N, 17°15′20″– 17°15′44″ W; depth 109 m; 29 Oct. 2011; CCLME-1110 exped.; CCLME-1110 exped.; stn BT53; MHN USC-10132 -1 and 2 • 1 spec., 40.43 mm dd; 10°18′55″ N, 16°25′07″ W; depth 79 m; 4 Nov. 2008; Bissau-0810 exped.; Bissau-0810 exped.; stn BS200; MNCN 29.02/1535. WESTERN SAHARA • 1 spec., 44.62 mm dd; 26°26′23″– 26°25′06″ N, 14°25′30″– 14°26′23″ W; depth 67– 58 m; 29 Nov. 2011; CCLME-1110 exped.; CCLME-1110 exped.; stn BT215; CFM-IEOMA-7776. • 1 spec., 46.70 mm dd; 14°57′00″– 14°58′09″ N, 17°39′08″– 17°38′13″ W; depth 797 m; 25 May 2012; CCLME-1205 exped.; CCLME-1205 exped.; stn BT368; CCLME-1205-03248; LZM-UV. Additional material GUINEA BISSAU • 1 spec., 10.07 mm dd; 11°05′09″– 17°03′15″ N, 11°04′15″– 17°03′10″ W; depth 46–47 m; 26 Oct. 2008; Bissau-0810 exped.; stn BS151; Bissau-0810-06146; LZM-UV. Description (holotype) DISC. Five-lobed in shape, slightly excavated inter-radially (Fig. 8A), with no peripheral calcareous plates on rim. Radial shields tumid, long (almost raising the centre of disc) and narrow, which is deeply sunken (Fig. 8C). Radial shields completely concealed by external ossicles, bar-shaped, as wide proximally as distally, but more separated distally, converging towards centre of disc. Distally, radial shields end on enlarged, slightly concave and oval-shaped plate covered by minute granules (Fig. 8C–D). Dorsal disc covered by small granule-like external ossicles (Fig. 8A, C–D), each one ending in terminal crystalline point. At edge of disc, ossicles more densely packed and without crystalline point (Fig. 8C), and bigger in size between radial shields (Fig. 8C–D). Ossicles concealing radial shields similar to those from dorsal disc but more densely packed.Ventral inter-radial areas densely covered by mosaic of small irregular flat plates with granule-like external ossicles without terminal point. Oral shield, adoral shield, oral plates, along edge of mouth frame and ventral arm plates more densely covered by similar external ossicles. Mouth frame sunken (Fig. 8E). Interradial surface of lateral disc covered by external ossicles similar but smaller than those covering dorsal disc. Two large genital slits on each interradius running almost vertically along first five or six brachial segments after first fork (Fig. 8F). Conical external ossicles with terminal crystalline point more developed on adradial edge of genital slits. One oval-shaped and well-developed madreporite located just outside mouth frame (Fig. 8E). Both, tooth and oral papillae spiniform, especially larger apical ones. Mouth and infradental papillae form continuous series along mouth frame (Fig. 8E). Teeth varying in position and size, being irregular in outline and more or less irregularly disposed. ARMS. Arms branching, with first fork before disc margin and second one located at margin. Nevertheless, in smaller specimens (juvenile), first fork located on margin of disc. Arms tapering gradually towards tips, completely covered, both, dorsally and ventrally, by domed granule-like external ossicles (Fig. 9A); these granules somewhat bigger than disc ones and without any crystalline point. Dorsal side of arms carry pedicellarial bands along whole arms. Valves with one secondary tooth downwardly curved (Fig. 9C). Some sunken transverse furrow between segments, giving arms an annulated appearance. Indication observed of median furrow along arm (Fig. 8G). Ventral side of arms with noticeable transverse naked furrows between segments until second fork; afterwards, furrows become smaller, disappearing after third fork. First two pores without arm spine. Arm spines beginning at third pair of pores with only one small spine at third and fourth pair of pores, two arm spines (sometimes one) afterwards and three arm spines (sometimes two) after second fork. Arm spines short and wide, ending in two or three hyaline points (Fig. 9F). Vertebrae streptospondylous (Fig. 9G–K). COLOUR. Living specimens showing varying colours, from creamish-pink to dark orange and brown to gray (Fig. 3E–F) with clear ventral part; preserved specimens are white. OSSICLE MORPHOLOGY. External ossicles on dorsal surface of disc, including radial shields, are granule-shaped and ending in a crystalline point (Fig. 9A). Baseplates oval-shaped with three to five tubercleshaped articulations for pedicellarial (Fig. 9D). External ossicles on baseplates granule-like shaped, approximately 200 µm in length and 100 µm in height (Fig. 9B). Valves with single inner tooth downwardly directed, and reticular structure (Fig. 9C). Lateral arm plates long, bar-like, with tuberculous stereom, spines placed in external lobe of plate (Fig. 9E). Arm spines ovoid-shaped with two or three small projections, not transforming into hook-shaped spines on distal portion (Fig. 9F). Vertebrae with hourglass-shaped streptospondylous articulations (Fig. 9G–K). Branching vertebra wider and with two surfaces for articulation. Distribution This species has been recorded in the Northwest African coast, from the Western Sahara to Guinea-Bissau waters. Its bathymetric distribution ranges between 47 and 797 m. Remarks The genus Astrodendrum was established by Döderlein (1911) for Gornocephalus sagaminus Döderlein, 1902. He realised that all species that belong to Gorgonocephalus Leach 1815 are characterised by the presence of a well-developed belt of calcareous plates at the margins of the disc. However, species of Astrodendrum have no ring of calcareous plates at the rim. Additionally, the arm spines appear before the first fork, as in Gorgonocephalus; however, in Astrodendrum Döderlein, 1911, these arm spines are much smaller, hardly reaching ⅓ of the segment length, and their number is reduced: with three (or rarely four) on each side. Taxonomic studies dealing with this genus are scarce, and we have only found a revision of the genus recently published by Okanishi & Fujita (2018). According to these authors, the genus is characterised by having five branching arms, with less than six segments before the first fork; lack of calcareous plates on the edge of the disc margin; variously shaped external ossicles or no ossicles on the disc; a madreporite placed on the innermost part of the interradial lateral disc; and valves from the dorsal arms with one secondary tooth. Currently, only six species have been assigned to this genus. Among them, only Astrodendrum capense (Mortensen, 1933), described from Durban, South Africa (Mortensen 1933; Clark & Courtman-Stock 1976), has been found in the Atlantic Ocean – Namibia (Alva & Vadon 1989). Astrodendrum elingamita Baker, 1974 has been reported in New Zealand and Philippines (Baker 1974; Okanishi & Fujita 2018); Astrodendrum galapagense A.H. Clark, 1916 from Galapagos Islands; Astrodendrum laevigatum (Koehler, 1897) from Colombo (Sri Lanka); and Astrodendrum sagaminum (Döderlein, 1902) from Japan, East China Sea and Sri Lanka (Döderlein 1902, 1911; Clark 1911; Bomford 1913; Matsumoto 1917; Irimura & Kubodera 1998); and the recently described Astrodendrum spinulosum Okanashi & Fujita, 2018 also from Japan. In addition to the shape, size and arrangement of external ossicles – widely used as an important specific taxonomic character (Baker 1974, 1980; McKnight 2000) – Okanishi and Fujita (2018) included the possibility of the lack of external ossicles (as in the case of A. laevigatum), and they also proposed three new taxonomic characters to distinguish species of Astrodendrum: • absence/ presence of bulges on lateral ridges of proximal portion of arm • number of terminal projections of arm spines on proximal portion of arm • number of secondary teeth of hook-shaped arm spines on distal portion of the arm The main morphological features of all known species of Astrodendrum, including A. juancarlosi sp. nov., are summarized in Table 2. Astrodendrum spinulosum differs from the rest of species by the presence of bulges on lateral ridges of proximal portion of the arm. The new species here described, also differs from A. spinulosum by the number of terminal projections of arm spines on the proximal portion of the arm (three in the case of the new species and one in A. spinulosum). In addition, A. spinulosun has cone-shaped external ossicles, while A. juancarlosi sp. nov. has granule like ossicles ending in a crystalline point at the dorsal surface of the disc. Astrodendrum juancarlosi sp. nov. is more similar to A. elingamita in the shape of the ventral coverage and the lack of a scale in the first tentacle pore. Nevertheless, A. elingamita has the first fork in the margin of the disc, while it is located before the margin in our species. The polygonal plates of the ventral covering are closer in the A. elingamita than in our specimen. Our specimens also differ from A. elingamita by having one type of dome-shaped granules with 1–2 hyaline terminal points rather than two smooth types. Astrodendrum sagaminum differs from Astrodendrum juancarlosi sp. nov. in also having two types of granules and naked arms and ventral disk. Astrodendrum capense has several medium-sized conical tubercles along the radial shields; it also has some smaller conical tubercles along the inter-radial disc margin, both ending in small thorns. Moreover, the disc is closely covered with minute and smooth plates. Astrodendrum galapagense has a dorsal coarse armament on the disc and arms. The external ossicles on the aboral disc are plate-shaped at periphery and conical at center, both slightly in contact, while on the oral surface has a few small widely scattered granules, except in the ventral interbrachial areas. Astrodendrum laevigatum is covered by a thin, transparent, soft and perfectly smooth tegument without any granules or spines. According to the description of this species in the literature, there are some doubts about the inclusion of this species in the genus Astrodendrum. We consider necessary to review the type material before we can reach a conclusion on this issue. Therefore, in this paper we follow Okanishi & Fujita (2018) and keep the species within the genus Astrodendrum. Finally, our specimen has marked rectangular furrows that are absent in the rest of the species of Astrodendrum. Even though Mortensen (1933) described the underside of the arms of A. capense as flat and without any grooves, he pointed out that this “may be an indication of a transverse furrow between the segments from the first forking onwards” (Mortensen 1933: 286). See Table 2 for comparison of main morphological characteristics among species., Published as part of Calero, Belén & Ramil, Fran, 2023, Euryalida (Echinodermata, Ophiuroidea) from Northwest Africa, pp. 46-75 in European Journal of Taxonomy 870 on pages 59-67, DOI: 10.5852/ejt.2023.870.2117, http://zenodo.org/record/7938618, {"references":["Doderlein L. 1911. Uber japanische und andere Euryalae. KB Akademie der Wissenschaften, Munich. https: // doi. org / 10.5962 / bhl. title. 16334","Doderlein L. 1902. Japanische Euryaliden. Zoologischer Anzeiger 25 (659 - 684): 320 - 326.","Okanishi M. & Fujita T. 2018. A taxonomic review of the genus Astrodendrum (Echinodermata, Ophiuroidea, Euryalida, Gorgonocephalidae) with description of a new species from Japan. Zootaxa 4392 (2): 289 - 310. https: // doi. org / 10.11646 / zootaxa. 4392.2.4","Mortensen Th. 1933. Papers from Dr. Th. Mortensen's Pacific Expedition 1914 - 16. LXV. Echinoderms of South Africa (Asteroidea and Ophiuroidea). Videnskabelige Meddelelser fra Dansk naturhistorisk Forening i Kobenhavn: 93: 215 - 400.","Clark A. M. & Courtman-Stock J. 1976. The Echinoderms of Southern Africa. Trustees of the British Museum (Natural History), London.","Alva V. & Vadon C. 1989. Ophiuroids from the western coast of Africa (Namibia and Guinea-Bissau). Scientia Marina 53 (4): 827 - 845.","Baker A. N. 1974. New species of brittle-stars from New Zealand (Echinodermata: Ophiiuroidea). Records of the Dominion Museum 8 (15): 247 - 266.","Clark H. L. 1916. Report on the Sea-Lilies, Starfishes, Brittle-Stars and Sea-Urchins obtained by the F. I. S. ' Endeavour' on the coast of Queensland, New South Wales, Tasmania, Victoria, South Australia, and Western Australia. Biological results of the fishing experiments carried on by the \" Endeavour \" 4 (1). Minister for Trade and Customs, Sydney. hhtps: // doi. org / 10.5962 / bhl. title. 13854","Clark H. L. 1911. North Pacific ophiurans in the collection of the United States National Museum. Bulletin of the United States National Museum (75): 1 - 302. https: // doi. org / 10.5479 / si. 03629236.75.1","Bomford T. L. 1913. A note on certain ophiiuroids in the Indian Museum. Records of the Indian Museum 9 (4): 219 - 225.","Matsumoto H. 1917. A monograph of Japanese Ophiuroidea, arranged according to a new classification. Journal of the College of Science, Imperial University, Tokyo, Japan XXXVIII (2): 1 - 407.","Irimura S. & Kubodera T. 1998. Ophiuroidea in the East China Sea. Memoirs of the National Science Museum, Tokyo 31: 135 - 143.","Baker A. N. 1980. Euryalinid Ophiuroidea (echinodermata) from Australia, New- Zealand, and the Southwest Pacific-Ocean. New Zealand Journal of Zoology 7 (1): 11 - 83. https: // doi. org / 10.1080 / 03014223.1980.10423763","McKnight D. G. 2000. The marine fauna of New Zealand: Basket-stars and Snake-stars (Echinodermata: Ophiuroidea: Euryalinida). National Institute of Water and Atmospheric Research, Wellington, New Zealand."]}

Gorgocephalus pustulatum (H.L. Clark, 1916) Figs 10–11 Astrodendrum pustulatum Clark, 1916: 84–85, pl. XXXIV figs 1–2. Gorgonocephalus pustulatum Baker, 1980: 54–56, figs 18B, 20, 30. Gorgonocephalus pectinatus Mortensen, 1933: 281–285, figs. 16–17, pl. XVIII figs. 1–2. Gorgonocephalus pustulatum – Rowe & Gates 1995: 368. — Calero et al. 2018: 3, 8. Gorgonocephalus pectinatus – Clark & Courtman-Stock 1976: 133. Material examined GUINEA BISSAU • 1 spec., 30.45 mm dd; 10°01′18″– 10°00′24″ N, 17°24′56″– 17°25′05″ W; depth 902–908 m; 24 Oct. 2008; Bissau-0810 exped.; stn BS166; Bissau-0810-18012; LZM-UV. Distribution This species has an Indo-Pacific distribution. It has been recorded in South Africa from Cape Province to East London (Mortensen 1933), the Indonesian region (Döderlein 1927) and Flinders Islands (Bass Strait, Australia) (Clark 1916); its bathymetric range extends from 182 (Clark 1916) to 860 m (Clark & Courtman-Stock 1976). Our material was recorded in one station in Guinea-Bissau waters, between 902 and 908 m. This material is the same as that reported by Calero et al. (2018). Description The dorsal side of disc covered by a skin with some scattered tubercles, ending in some small thorns. The same type of tubercles were found on the marginal belt of plates. Radial shields long and bar-shaped, nearly reaching the centre of the disc (Fig. 11A). They are almost completely covered by tubercles similar to those from the interradial areas but slightly bigger (Fig. 11C). The ventral interradial areas are almost fully covered by small granules. Plates of the oral frame swollen and obscured by a thick skin. Oral shields with some scattered small granules. There is a cluster of slender apical papillae flanked on each side by smaller oral papillae. Arms also covered by a skin concealing the plates. First pair of tentacle pores outside the mouth edge, without arm spines. Two arm spines from the second to fifth or sixth pores; afterwards, from the first fork on, three spines. Arm spines are small, less than one arm segment, and with some thorny ends. First fork within the edge of the disc. Dorsally, arms covered by flat granules, and with a longitudinal median furrow (Fig. 11F). Pedicellarial bands along the arms, appearing from the first segments. Remarks Even though the single specimen collected was badly damaged, the presence of the main distinctive features of Gorgonocephalus pustulatum (H.L. Clark, 1916), like the number of spines (max. 4), disc coverage (sparse and low tubercles) or the thin peripheral ring, legitimate our identification to species level. Our finding in Guinea-Bissau represents the first record of G. pustulatum in the Tropical East Atlantic Ocean, extending its geographical distribution to the north, from south Africa to Guinea-Bissau. This station also represents the deepest record for this species (908 m)., Published as part of Calero, Belén & Ramil, Fran, 2023, Euryalida (Echinodermata, Ophiuroidea) from Northwest Africa, pp. 46-75 in European Journal of Taxonomy 870 on pages 67-68, DOI: 10.5852/ejt.2023.870.2117, http://zenodo.org/record/7938618, {"references":["Clark H. L. 1916. Report on the Sea-Lilies, Starfishes, Brittle-Stars and Sea-Urchins obtained by the F. I. S. ' Endeavour' on the coast of Queensland, New South Wales, Tasmania, Victoria, South Australia, and Western Australia. Biological results of the fishing experiments carried on by the \" Endeavour \" 4 (1). Minister for Trade and Customs, Sydney. hhtps: // doi. org / 10.5962 / bhl. title. 13854","Baker A. N. 1980. Euryalinid Ophiuroidea (echinodermata) from Australia, New- Zealand, and the Southwest Pacific-Ocean. New Zealand Journal of Zoology 7 (1): 11 - 83. https: // doi. org / 10.1080 / 03014223.1980.10423763","Mortensen Th. 1933. Papers from Dr. Th. Mortensen's Pacific Expedition 1914 - 16. LXV. Echinoderms of South Africa (Asteroidea and Ophiuroidea). Videnskabelige Meddelelser fra Dansk naturhistorisk Forening i Kobenhavn: 93: 215 - 400.","Rowe F. W. E. & Gates J. 1995. Echinodermata. In: Wells A. (ed.) Zoological Catalogue of Australia Vol. 33. CSIRO Australia xii, Melbourne, Australia.","Calero B., Ramos A. & Ramil F. 2018. Distribution of suspension-feeder brittle stars in the Canary Current upwelling ecosystem (Northwest Africa). Deep Sea Research Part I: Oceanographic Research Papers 142: 1 - 15. https: // doi. org / 10.1016 / j. dsr. 2018.11.001","Clark A. M. & Courtman-Stock J. 1976. The Echinoderms of Southern Africa. Trustees of the British Museum (Natural History), London.","Doderlein L. 1927. Indopacifische Euryalae. Abhandlungen der Bayerischen Akademie der Wissenschaften XXXI (6): 1 - 105. https: // doi. org / 10.1515 / 9783486755459"]}

Egmundella modesta Millard & Bouillon, 1975 (Fig. 4a; Table 2) Lovenella (?)— Millard & Bouillon, 1973: 42–43, fig. 5E–F. Egmundella modesta Millard & Bouillon, 1975: 5–7, fig. 1E–H; Vervoort, 2006: 224–225, figs. 7 no. 3; 8 no. 3; 9d–h. Material examined. Western Sahara. MAROC-0611, stn MO235, 23º12′00″– 23º14′27″N, 17º11′16″– 17º12′27″W, 909–913 m, 27-XI-2006: a colony, 0.85 mm high, growing on Halecium sp., without gonothecae. Description. Colony stolonal, composed of hydrothecae and nematothecae arising from a filiform hydrorhiza. Hydrothecae borne on pedicels of varied length, though most are short, slender, generally smooth, occasionally with 2–5 basal annulations and sometimes a few irregularly-placed, additional annulations along its length, distally widening at junction with the corresponding theca, and there provided with a transverse, thin diaphragm. Hydrotheca deeply campanulate, tapering basally, walls almost parallel, aperture closed by a conical operculum, composed of 8–10 elongate, triangular flaps, independent from one another; flaps may be folded either inwards or outwards and, in this case, the rim is distinctly-marked. Nematothecae irregularly scattered, small, globular, borne on short pedicels, aperture apical, oval. No gonothecae observed. Biology. Egmundella modesta has been reported so far growing on an unidentifiable hydroid fragment (Vervoort 2006). In our material, it was found growing on a species of Halecium. Distribution. This species has previously been found in the Seychelles (Millard & Bouillon 1973, as Lovenella sp.; Millard & Bouillon 1975) and Mauritania (Vervoort 2006). Its bathymetric distribution ranges from the littoral zone (Millard & Bouillon 1975) to 1000 m (Vervoort 2006). Our material was found off Western Sahara at depths from 909 to 913 m. Remarks. The material agrees in morphology with the holotype described by Millard & Bouillon (1975) from the Seychelles and with the CANCAP material of E. modesta studied by Vervoort (2006). In our material most of hydrothecae have short pedicels. However, some hydrothecae are larger in size, and have longer pedicels (Fig 4a). This feature was also described by Vervoort (2006), but we now provide more extensive measurements (see table 2). Largest hydrothecae resemble those of E. grimaldii, but in that species the colonies form rhizocaulomic, stemlike structures, a character not observed in our material, where the hydrorhiza is composed of a single stolon growing on Halecium sp. Moreover, in E. grimaldii the hydrothecal pedicels are shorter and the nematothecae are larger. After comparing material of both species collected during the MAROC surveys, we concluded that the present material is clearly different from E. grimaldii, while fitting well the descriptions of E. modesta found in the literature., Published as part of Gil, Marta & Ramil, Fran, 2023, The genera Egmundella Stechow, 1921 and Cyclocanna Bigelow, 1918 (Cnidaria, Hydrozoa) in waters of Northwest Africa, pp. 490-504 in Zootaxa 5264 (4) on pages 495-496, DOI: 10.11646/zootaxa.5264.4.2, http://zenodo.org/record/7836965, {"references":["Millard, N. A. H. & Bouillon, J. (1975) Additional Hydroids from the Seychelles. Annals of the South African Museum, 69 (1), 1 - 15.","Millard, N. A. H. & Bouillon, J. (1973) Hydroids from the Seychelles (Coelenterata). Annales du Museum Royal de l´Afrique Centrale, Sciences Zoologiques, 206 (8), 1 - 106.","Vervoort, W. (2006) Leptolida (Cnidaria: Hydrozoa) collected during the CANCAP and Mauritania-II expeditions of the National History, Leiden, the Netherlands [Anthoathecata, various families of Leptothecata and addenda]. Zoologische Mededelingen, Leiden, 80, 181 - 318."]}

Egmundella ansini n. sp. (Fig. 5; Table 4) Material examined. Western Sahara. MAROC-0611, stn MO239, 23º28′05″– 23º24′32″N, 17º16′24″– 17º16′22″W, 963–969 m, 28-XI-2006: a colony, 2 mm high, with gonothecae, growing on the stem of an unidentified hydrozoan (Holotype, MNCN 2.03 /687). MAROC-0611, stn MO275, 25º27′17″– 25º29′34″N, 16º22′06″– 16º21′15″W, 1505–1510 m, 9-XII-2006: a colony, 4 mm high, growing on Streptocaulus chonae, one gonotheca present (Paratype, RMNH.COEL.43831). Etymology. The specific name ansini honours our colleague and friend Dr José Ansín-Agís, of the University of Vigo, Spain, in appreciation and recognition of his important contribution to the taxonomy of plumularioid hydroids. Description. Colonies stolonal, composed of hydrothecae, nematothecae and gonothecae arising from filiform hydroriza. Hydrothecae borne on pedicels of varied lengths, though mostly long (Fig. 5a, c–g), smooth, slender, with short basal annulations and occasionally a distally placed, additional annulation; distally widening at junction with the corresponding theca, and there provided with a transverse, thin diaphragm. Hydrotheca deeply campanulate, tapering basally, walls parallel, rim not apparent, aperture closed by a conical operculum composed of 15–18 elongate, triangular flaps, not connected between them, and folded either inwards or outwards. Nematothecae borne irregularly on the hydrorhiza between the hydrothecae; long, slender, without distinct pedicel, aperture distal, circular. Gonothecae arise perpendicularly to the hydrorhiza, tubular, elongate, tapering basally in small undulations, without distinct pedicel, rim imperceptible, aperture distal, closed by a conical operculum composed of 16 elongate triangular flaps, independent from one another (Fig. 5a, c). Biology. In our material, one colony was growing on the hydroid Streptocaulus chonae Ansín Agís, Ramil & Vervoort, 2001. Gonothecae have been observed in November and December. Distribution. Egmundella ansini n. sp. was collected from Western Sahara at depths between 696 and 1510 m. Remarks. This species is clearly different from both E. grimaldii and C. producta (see below) on the account of the shape of gonothecae and the appearance of its colonies. It is also different from E. modesta, which has colonies and pedicels much smaller than those of E. ansini n. sp. Our material resembles in morphology to E. superba, E. magellanica Galea et al., 2019 and the material from the “Galathea” Expedition described by Vervoort (1966) as Egmundella sp. Nevertheless, there are considerable differences in size allowing them to be confidently separated specifically. In E. ansini n. sp. the hydrothecae and pedicels are larger than those of the specimens of E. superba studied herein, and also larger than those described by Calder (1991). Conversely, E. ansini n. sp. has smaller and narrower gonothecae than those of E. magellanica. Also, its hydrothecae are larger and their pedicels slenderer and lacking the twists of E. magellanica (see table 4). Finally, Egmundella sp. from the “Galathea” Expedition (Vervoort 1966) has been only reported from Indonesia, and it seems unlikely that it could be conspecific, given its distribution. In addition, its hydrothecal pedicels have a “few distinct rings” basally (Vervoort 1966: fig. 9a), while in our material there are only some scarcely-defined annulations (Fig. 5a). Moreover, in our material the hydrothecal pedicels are shorter, while the hydrothecae and nematothecae are larger than those of the “Galathea” Expedition (Vervoort, 1966) (see table 4)., Published as part of Gil, Marta & Ramil, Fran, 2023, The genera Egmundella Stechow, 1921 and Cyclocanna Bigelow, 1918 (Cnidaria, Hydrozoa) in waters of Northwest Africa, pp. 490-504 in Zootaxa 5264 (4) on pages 498-500, DOI: 10.11646/zootaxa.5264.4.2, http://zenodo.org/record/7836965, {"references":["Ansin Agis, J., Ramil, F. & Vervoort, W. (2001) Atlantic Leptolida (Hydrozoa, Cnidaria) of the families Aglaopheniidae, Halopterididae, Kirchenpaueriidae and Plumulariidae collected during the CANCAP and Mauritania-II expeditions of the National Museum of Natural History, Leiden, the Netherlands. Zoologische Verhandelingen, Leiden, 333, 1 - 268.","Galea, H. R., Schories, D. & Holtheuer, J. (2019) Three new records of hydroids (Cnidaria: Hydrozoa) from southern Chile. Revue suisse de Zoologie, 126 (2), 235 - 247. https: // doi. org / 10.5281 / zenodo. 3463457","Vervoort, W. (1966) Bathyal and abyssal hydroids. Galathea Report. Scientific Results of The Danish Deep-Sea Expedition, 1950 - 1952, 8, 97 - 173.","Calder, D. R. (1991) Shallow-water hydroids of Bermuda. The Thecatae, exclusive of Plumularioidea. Royal Ontario Museum, Life Sciences Contributions, 154, 1 - 140."]}

Stegopoma giganteum Ramil & Vervoort, 1992 Fig. 3D–E; Table 3 Stegopoma giganteum Ramil & Vervoort, 1992: 36–38, fig. 5e–f. Material examined SOUTH ATLANTIC OCEAN • 5 colonies, up to 15 mm high (1 growing on Zygophylax sp., 1 on bivalve shell, 1 on ghost fishing net with a gonotheca); Valdivia Seamount, stn BT12; 24°49′01″–24°47′38″ S, 6°24′40″–6°25′26″ E; 887– 886 m depth; 7 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40222, SEAFO-2015-40612, SEAFO-2015-40811, SEAFO-2015-40827, SEAFO-2015-40852, LZM-UV slide R. 587. Description Colony composed of a thin and ramified stolon, growing attached on the hydrocaulus and branches of Zygophylax sp., from which arise pedicellate hydrothecae and gonothecae. Hydrothecae placed at the end of long, slender, smooth-walled and unbranched pedicels with some transversal scars due to regeneration after damage. Hydrothecae large, tubular, with smooth walls, almost bilaterally symmetrical, and slightly widening distally (Fig. 3D). Aperture closed by a triangular operculum adopting the shape of a gabled roof, formed by two opposite, semicircular sections on the distal part of the hydrothecal wall; opercular apparatus provided with longitudinal strips running downwards from top to basis. Hydranths are damaged or absent, and their description is not possible, but we can confirm that they are attached to the inner side of the hydrothecal base by means of a hyaline membranous ring, identical to the description given by Ramil & Vervoort (1992); this membranous ring indicates the boundary between the pedicel and the hydrotheca. The gonotheca shows similar morphology to that described for the hydrotheca, including the closing apparatus, but it is supported by a shorter pedicel (Fig. 3E). Remarks This is the first record of S. giganteum after its original description. The large size of the hydrothecae (2–3 mm long), with long and narrow pedicels, are distinctive features of this species. In addition, the opercular apparatus, the presence of a hyaline membranous ring at the attachment site of the hydranth to the hydrothecal base, and the gonothecal shape fit well with the original description of this species. Consequently, despite the wide geographical distance between the type locality and the present record, we include this material in S. giganteum. Distribution This species is only known from off Cape São Vicente (Portugal; type locality) where it was collected at a depth of 1523 m (Ramil & Vervoort 1992). This is the first record for the South Atlantic., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 60-61, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262."]}

Sertularella areyi Nutting, 1904 Fig. 4C; Table 8 Sertularella areyi Nutting, 1904: 83, pl. 17 fig. 6. Sertularella annulaventricosa Millard, 1975: 279 –281, fig 91F –H. Sertularella areyi – Vervoort 1993: 201–203, fig. 41c–g. — Vervoort & Watson 2003: 156–158, fig. 35f–i. — Calder 2013: 28–29, fig. 8h. Material examined SOUTH ATLANTIC OCEAN • 5 colonies, up to 5 mm high (2 growing on algae), all without gonothecae; Vema Seamount, stn BT5; 31°37′16″–31°36′58″ S, 8°22′37″–8°23′06″ E; 71–94 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40407, SEAFO-2015-40513, SEAFO-2015-40768, SEAFO-2015-40798, SEAFO-2015-40882, LZM-UV slide R. 585. Distribution Sertularella areyi is considered as a circumtropical species (Calder 2013). It was reported from the east coast of South Africa by Millard (1975, as Sertularella annulaventricosa Mulder & Trebilcock, 1915), but not from the west coast. Our record from Vema Seamount is the first one in the South Atlantic Ocean. The bathymetric distribution ranges from 47 (Millard 1975, as S. annulaventricosa) to a depth of 480 m (Vervoort 1993)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 68, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Nutting C. C. 1904. American hydroids, Part II. The Sertulariidae. Bulletin of the United States National Museum 4 (2): 1 - 325.","Vervoort W. 1993. Cnidaria, Hydrozoa, Hydroida: hydroids from the Western Pacific (Philippines, Indonesia and New Caldeonia). I: Sertulariidae. (Part I). In: Crosnier A. (ed.) Resultats des Campagnes MUSORSTOM. Memoires du Museum national d'histoire naturelle 11: 89 - 298.","Vervoort W. & Watson J. E. 2003. The marine fauna of New Zealand. Leptothecata (Cnidaria: Hydrozoa) (thecate hydroids). NIWA Biodiversity Memoir 119: 1 - 540.","Calder D. R. 2013. Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA. Zootaxa 3648 (1): 1 - 72. https: // doi. org / 10.11646 / zootaxa. 3648.1.1"]}

Monotheca bergstadi sp. nov. urn:lsid:zoobank.org:act: 3BFDE359-6A4B-4910-9AB5-226193B6584E Figs 7C–D, 8; Table 12 Plumularia pulchella – Millard 1957: 232; 1962: 300; 1966: 493; 1975: 398–399, fig. 125c–d [not Monotheca pulchella (Bale, 1882)]. Diagnosis Colonies monosiphonic, mostly unbranched. Hydrocaulus divided into internodes by straight nodes, each internode bearing one apophysis and three nematothecae. Hydrocladia composed of two internodes: one athecate proximal without nematothecae, with two internal perisarcal rings, and one thecate distal bearing a hydrotheca and three nematothecae. Hydrotheca deep campanulate and abcauline wall concave. Mesial inferior nematotheca long and lateral nematothecae short. Gonothecae arising frontally, large, barrel-shaped and smooth-walled. Etymology The specific name bergstadi honours Dr. Odd Aksel Bergstad, Institute of Marine Research (IMR), Bergen, Norway, leader of the SEAFO 2015 cruise, in recognition of his wide contribution to deep-sea research. Material examined Holotype SOUTH ATLANTIC OCEAN • colony, 10 mm high, with gonothecae; Vema Seamount, stn BT5; 31°37′16″–31°36′58″ S, 8°22′37″–8°23′06″ E; 71–94 m depth; 31 Jan. 2015; SEAFO-2015 leg.; LZM- UV slide R. 582; SAMC-A092083. Paratypes SOUTH ATLANTIC OCEAN • 7 colonies, 8–13 mm high (2 growing on algae), 3 colonies, with gonothecae; same collection data as for holotype; SEAFO-2015-40042, SEAFO-2015-40167, SEAFO-2015-40572, SEAFO-2015-40768. Additional material SOUTH ATLANTIC OCEAN • 1 colony, 10 mm high growing on algae, with gonothecae; Vema Seamount, stn PT4; 31°39′43″–31°38′10″ S, 8°22′37″–8°23′42″ E; 50–108 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40137 • 1 colony, growing on bryozoan, without gonothecae; Vema Seamount, stn GRAB9C; 31°36′09″ S, 8°22′29″ E; 84 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40080 • 1 colony, without gonothecae; Vema Seamount, stn GRAB12B; 31°37′56″ S, 8°23′12″ E; 89 m depth; 1 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40245. Description Colonies composed of a reticulate hydrorhiza growing on algae and a bryozoan, supporting erect, monosiphonic and mostly unbranched, occasionally branched once, hydrocauli (Fig. 7C). Stem regularly divided into internodes by straight nodes, each bearing a latero-distal apophysis and three nematothecae: two axillar, flanking the apophysis and one on the basal half on the opposite side. Apophyses alternately directed left and right and disposed almost in the same plane (Fig. 8A). Hydrocladia inserted on apophyses and composed of two internodes: one athecate basal and one thecate distal. Basal internode short, without nematothecae and with two internal perisarcal rings, one basal and the other distal. Thecate internode slightly longer than athecate, with one hydrotheca and three nematothecae: one mesial inferior and a pair of laterals (Figs 7D, 8A). Hydrotheca deep campanulate, adcauline wall fully adnate to internode, abcauline wall concave, margin straight, smooth and slightly flared. Mesial nematotheca long, reaching or even surpassing the middle of the abcauline wall of hydrotheca. Lateral nematothecae comparatively shorter and placed on small, yet distinct apophyses reaching the hydrothecal rim (Fig. 7D). All nematothecae two-chambered and movable; rim of upper chamber even throughout. Gonothecae arising frontally from apophyses of hydrocladia; large, barrel-shaped, smooth-walled, truncated apically; aperture wide and circular; operculum not observed (Figs 7C, 8B–C). Remarks The validity of the genus Monotheca or its synonymy with Plumularia Lamarck, 1816 has been widely discussed during the last few years in the literature. Watson (2011) and Calder (2019) indicated that, despite the traditional interpretation of the genus, Monotheca might involve a polyphyletic group. Indeed, some molecular analyses (Leclère et al. 2007, 2009; Moura et al. 2008; Maronna et al. 2016) revealed that the type species of both genera, Monotheca margaretta Nutting, 1900 and Plumularia setacea (Linnaeus, 1758), respectively, did not cluster together. In addition, the latest molecular study of the superfamily Plumularioidea (Moura et al. 2018) supports the validity of Monotheca. Taking into account that the new species is closely allied to M. margaretta, we have decided to assign it to this genus, under the name Monotheca bergstadi sp. nov. Our material is closely related to four nominal species of Monotheca, namely M. margaretta Nutting, 1900, M. pulchella (Bale, 1882), M. flexuosa (Bale, 1894) and M. femina (García, Aguirre & González, 1978). The latter is currently accepted as a junior synonym of M. margaretta (Calder 1977; Ansín Agís et al. 2001; Schuchert 2020; as Plumularia margaretta), and we agree. The remaining valid species are easily recognizable by the morphology of their gonothecae. In M. margaretta, they are barrel-shaped, with well-developed transverse ridges and a broad, apical aperture (Calder 1997; Ansín Agís et al. 2001); in M. pulchella the gonothecae are ovate, with an obliquely truncate aperture with a submarginal row of large, internal teeth surrounded by large, internal teeth (Bale 1882; Ralph 1961; Watson 1973, 2011); finally, in M. flexuosa, the gonothecae are fusiform, with slightly undulated walls and a rather small, apical aperture produced into a neck of variable height (Bale 1894; Watson 2011). In addition, M. margaretta is an amphi-Atlantic species, whereas M. pulchella and M. flexuosa are predominately Indo-Pacific. Nevertheless, M. pulchella was reported several times from the Atlantic Ocean and Mediterranean Sea (for a review, see Calder 1997 and Ansín Agís et al. 2001), and the actual status of these records have been subjected to different interpretations in the literature. The records from the Northeast Atlantic and the Mediterranean Sea, all with annulated and barrel-shaped gonothecae, were included in M. margaretta by Calder (1997) and Ansín Agís et al. (2001), and we agree with this conclusion, despite the fact that Watson (2011) considers that they are conspecific with M. flexuosa. The records of M. pulchella from the Mediterranean (Bouillon et al. 2004) are based on the material studied by García Corrales et al. (1978, as Plumularia femina) and Medel & Vervoort (1995), and belong to M. margaretta, despite some figures (Bouillon et al. 2004: fig. 92h, j) being based on Millard (1975: fig. 125c–d) and representing a different species (see below). The records of M. pulchella from the Argentinian coast (Blanco 1973, 1994; Genzano 1990, 1994; all as Plumularia pulchela), were provisionally placed under M. margaretta by Ansín Agís et al. (2001) because the involved colonies were sterile. The morphology of the colonies collected at the Vema Seamount studied in this report, with respect to their tropho- and gonosome, completely coincides with those described by Millard (1975) as M. pulchella from South Africa and the Vema Seamount. This material, characterized by its barrel-shaped, smooth-walled gonothecae, is clearly distinct from the current concept of M. pulchella, and also from other previously discussed species. In fact, Watson (2011) excluded the South African records from the synonymy of M. pulchella, but did not assign them to any known species of Monotheca. Consequently, we consider that this material represents a new species, for which we propose the name M. bergstadi sp. nov. Distribution Monotheca bergstadi sp. nov. has previously been reported from Vema Seamount (Millard 1966, as Plumularia pulchella) and South Africa, from the west coast of Cape Peninsula to Natal (Millard 1957, 1962, 1975; all as P. pulchella). Its bathymetric distribution extends from the littoral zone to a depth of 100 m (Millard 1975, as P. pulchella)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 78-82, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Millard N. A. H. 1957. The Hydrozoa of False Bay, South Africa. Annals of the South African Museum 43: 173 - 243.","Millard N. A. H. 1962. The Hydrozoa of the south and west coasts of South Africa. Part I. The Plumulariidae. Annals of the South African Museum 46 (11): 261 - 319.","Millard N. A. H. 1966. Hydroids of the Vema Seamount. Annals of the South African Museum 48: 489 - 496.","Bale W. M. 1882. On the Hydroida of south-eastern Australia, with descriptions of supposed new species, and notes on the genus Aglaophenia. Journal of the Microscopical Society of Victoria 2 (1): 15 - 48.","Watson J. E. 2011. Review of the genus Monotheca (Hydrozoa: Leptolida) from Australia with description of a new species and a note on Monothecella Stechow, 1923. Memoirs of Museum Victoria 68 (1): 71 - 91. https: // doi. org / 10.24199 / j. mmv. 2011.68.05","Calder D. R. 2019. On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA. Zootaxa 4689 (1): 1 - 141. https: // doi. org / 10.11646 / zootaxa. 4689.1.1","Leclere L., Schuchert P. & Manuel M. 2007. Phylogeny of the Plumularioidea (Hydrozoa, Leptothecata): evolution of colonial organization and life cycle. Zoologica Scripta 36: 371 - 394. https: // doi. org / 10.1111 / j. 1463 - 6409.2007.00283. x","Leclere L., Schuchert P., Cruaud C., Couloux A. & Manuel M. 2009. Molecular phylogenetics of Thecata (Hydrozoa, Cnidaria) reveals long-term maintenance of life history traits despite high frequency of recent character changes. Systematic Biology 58: 509 - 526. https: // doi. org / 10.1093 / sysbio / syp 044","Moura C. J., Harris D. J., Cunha M. R. & Rogers A. D. 2008. DNA barcoding reveals cryptic diversity in marine hydroids (Cnidaria, Hydrozoa) from coastal and deep-sea environments. Zoologica Scripta 37: 93 - 108. https: // doi. org / 10.1111 / j. 1463 - 6409.2007.00312. x","Maronna M. M., Miranda T. P., Pena Cantero A. L., Barbeitos M. S. & Marques A. C. 2016. Towards a phylogenetic classification of Leptothecata (Cnidaria, Hydrozoa). Scientific Reports 6: 1 - 23. https: // doi. org / 10.1038 / srep 18075","Linnaeus C. 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. L. Salvius, Stockholm. https: // doi. org / 10.5962 / bhl. title. 542","Moura C. J., Lessios H., Cortes J., Nizinski M. S., Reed J., Santos R. S. & Collins A. G. 2018. Hundreds of genetic barcodes of the species-rich hydroid superfamily Plumularioidea (Cnidaria, Medusozoa) provide a guide toward more reliable taxonomy. Scientific Reports 8 (1): 1 - 14. https: // doi. org / 10.1038 / s 41598 - 018 - 35528 - 8","Bale W. M. 1894. Further notes on Australian hydroids, with descriptions of some new species. Proceedings of the Royal Society of Victoria 6: 93 - 117.","Garcia Corrales P., Aguirre Inchaurbe A. & Gonzalez Mora D. 1978. Contribucion al conocimiento de los hidrozoos de las costas espanolas. Parte I: Halecidos, campanularidos y plumularidos. Boletin del Instituto Espanol de Oceanografia 5 (273): 5 - 73.","Ansin Agis J., Ramil F. & Vervoort W. 2001. Atlantic Leptolida (Hydrozoa, Cnidaria) of the families Aglaopheniidae, Halopterididae, Kirchenpaueriidae and Plumulariidae collected during the CANCAP and Mauritania-II expeditions of the National Museum of Natural History, Leiden, The Netherlands. Zoologische Verhandelingen, Leiden 333: 1 - 268.","Schuchert P. 2020. World Hydrozoa Database. Available from http: // www. marinespecies. org / hydrozoa / [accessed 14 Jan. 2021].","Calder D. R. 1997. Shallow-water hydroids of Bermuda: superfamily Plumularioidea. Life Sciences Contributions of the Royal Ontario Museum 161: 1 - 85.","Ralph P. M. 1961. New Zealand thecate hydroids, pt. III. Family Sertulariidae. Transactions and Proceedings of the New Zealand Institute 88 (4): 749 - 838.","Watson J. E. 1973. Pearson Island Expedition, 1969. - 9. Hydroids. Transactions of the Royal Society of South Australia 97 (3): 153 - 200. Available from https: // www. biodiversitylibrary. org / page / 41079927 [accessed 15 Jun. 2021].","Bouillon J., Medel M. D., Pages F., Gili J. M., Boero F. & Gravili C. 2004. Fauna of the Mediterranean Hydrozoa. Scientia Marina 68 (2): 5 - 438. https: // doi. org / 10.3989 / scimar. 2004.68 s 25","Medel M. D. & Vervoort W. 1995. Plumularian hydroids (Cnidaria: Hydrozoa) from the strait of Gibraltar and nearby areas. Zoologische Verhandelingen, Leiden 300: 1 - 72.","Blanco O. M. 1973. Nuevos plumularidos para aguas Argentinas. Neotropica 19: 73 - 78.","Blanco O. M. 1994. Enumeracion sistematica y distribucion geografica preliminar de los Hydroida de la Republica Argentina. Suborden Athecata (Gymnoblastea, Anthomedusae), Thecata (Calyptoblastea, Leptomedusae) y Limnomedusae. Revista del Museo de La Plata 14 (161): 181 - 216.","Genzano G. N. 1990. Hidropolipos (Cnidaria) de Mar del Plata, Argentina. Neritica 5 (1): 35 - 54.","Genzano G. N. 1994. La comunidad hidroide del intermareal rocoso de Mar del Plata (Argentina). I. Estacionalidad, abundancia y periodos reproductivos. Cahiers de Biologie marine 35 (3): 289 - 303."]}

Amphisbetia minima (Thompson, 1879) Fig. 4B; Table 7 Sertularia minima Thompson, 1879: 104���105, pl. 17 fig. 3. Amphisbetia minima ��� Millard 1975: 250, fig. 82h���k. ��� Galea & Schories 2012: 36, fig. 3n���o. Material examined SOUTH ATLANTIC OCEAN ��� 2 colonies, growing on algae (1 with gonothecae); Vema Seamount, stn BT5; 31��37���16������31��36���58��� S, 8��22���37������8��23���06��� E; 71���94 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40617, SEAFO-2015-40768, LZM-UV slide R. 584. Remarks The presence of ���pores��� or ���holes��� surrounded by a low perisarcal collar below various hydrothecae and usually located at the proximal internodes of the colonies was described by Ralph (1961), Millard (1975) and Vervoort & Watson (2003), but we have not observed any ���pores��� in our colonies. Nevertheless, these pores seem to be a variable feature in this species, as Vervoort & Watson (2003), after reviewing a large amount of material from New Zealand, stated that in some cases there is a pair of holes in the basalmost internode, but other colonies have a single pore or none at all. This structure has been interpreted as nematothecae (Ralph 1961), comparable to the mamelon of Plumularidae (Millard 1975), or glandular pores (Vervoort & Watson 2003), but their true significance remains unknown. Distribution Amphisbetia minima is considered as a circumglobal species, without records from Arctic and Antarctic waters (Millard 1975; Vervoort & Watson 2003). In the South Atlantic, it was reported from Vema Seamount (Millard 1966), the west coast of South Africa (Millard 1975) and the Tristan da Cunha group of islands (Galea 2010, 2015). Its bathymetric distribution extends from the littoral zone to 664 m depth (Vervoort & Watson 2003)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 67-68, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Thompson d'Arcy W. 1879. On some new and rare hydroid zoophytes (Sertulariidae and Thuiariidae) from Australia and New Zealand. The Annals and Magazine of Natural History, Series 5 3 (14): 97 - 114. https: // doi. org / 10.1080 / 00222937908682487","Galea H. R. & Schories D. 2012. Some hydrozoans (Cnidaria) from Central Chile and the Strait of Magellan. Zootaxa 3296 (1): 19 - 67. https: // doi. org / 10.11646 / zootaxa. 3296.1.2","Ralph P. M. 1961. New Zealand thecate hydroids, pt. III. Family Sertulariidae. Transactions and Proceedings of the New Zealand Institute 88 (4): 749 - 838.","Vervoort W. & Watson J. E. 2003. The marine fauna of New Zealand. Leptothecata (Cnidaria: Hydrozoa) (thecate hydroids). NIWA Biodiversity Memoir 119: 1 - 540.","Millard N. A. H. 1966. Hydroids of the Vema Seamount. Annals of the South African Museum 48: 489 - 496.","Galea H. R. 2010. Additional shallow-water thecate hydroids (Cnidaria: Hydrozoa) from Guadeloupe and Les Saintes, French Lesser Antilles. Zootaxa 2570 (1): 1 - 40. https: // doi. org / 10.11646 / zootaxa. 2570.1.1"]}

Eudendrium ramosum (Linnaeus, 1758) Tabularia ramosum Linnaeus, 1758: 804. Eudendrium ramosum – Marques et al. 2000: 104, figs 75–78. — Schuchert 2012: 322–323, fig. 281. Material examined SOUTH ATLANTIC OCEAN • 9 colonies, 7–44 mm high (2 growing on ghost fishing net), 8 of them with gonophores; Valdivia Seamount, stn BT12; 24°49′01″–24°47′38″ S, 6°24′40″–6°25′26″ E; 887– 886 m depth; 7 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40252, SEAFO-2015-40402, SEAFO-2015-40737, SEAFO-2015-40811, SEAFO-2015-40852. Distribution Eudendrium ramosum is considered as a cosmopolitan species by Bouillon et al. (2006), but many records are likely doubtful (Ramil & Vervoort 1992; Marques et al. 2000). Schuchert (2012) indicated that all records outside the East Atlantic (Arctic to South Africa, including the Mediterranean) need confirmation. The bathymetrical distribution of the species extends from intertidal areas (Ansín Agís 1992) to a depth of 1870 m (Ramil & Vervoort 1992)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 55, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Linnaeus C. 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. L. Salvius, Stockholm. https: // doi. org / 10.5962 / bhl. title. 542","Schuchert P. 2012. North-West European Athecate Hydroids and their Medusae. In: Crothers J. H. & Haywars P. J. (eds) Synopses of the British Fauna (New Series) 59. Field Studies Council, London.","Bouillon J., Gravili C., Pages F., Gili J. M. & Boero F. 2006. An Introduction to Hydrozoa. Memoires du Museum national d'Histoire naturelle, Paris 194: 1 - 591.","Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262.","Ansin Agis J. 1992. Hidrozoos de la Ria de Vigo. PhD thesis, Universidad de Vigo, Spain."]}

Sertularella polyzonias (Linnaeus, 1758) Fig. 4D Sertularia polyzonias Linnaeus, 1758: 813. Sertularella polyzonias – Ramil & Vervoort 1992: 225–227, fig. 63a–b. — Cornelius 1995: 74–76, fig. 17. Material examined SOUTH ATLANTIC OCEAN • 5 colonies, 6–13 mm high (2 growing on algae and 2 on bryozoan), 3 of them bear gonothecae; Vema Seamount, stn BT5; 31°37′16″–31°36′58″ S, 8°22′37″–8°23′06″ E; 71–94 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40197, SEAFO-2015-40347, SEAFO-2015-40387, SEAFO-2015-40602, SEAFO-2015-40768, LZM-UV slide R. 583. Distribution Sertularella polyzonias is a circumglobal species (Gil 2017). In the Southeast Atlantic, it was reported from Angola by Broch (1914). Its bathymetric distribution ranges from 2 (Peña Cantero & García Carrascosa 2002) to 2500 m (Fraser 1944)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 71, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Linnaeus C. 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. L. Salvius, Stockholm. https: // doi. org / 10.5962 / bhl. title. 542","Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262.","Cornelius P. F. S. 1995. North-West European Thecate Hydroids and their Medusae. Part 2. Sertulariidae to Campanulariidae. In: Barnes R. S. K. & Crothers J. H. (eds) Synopses of the British Fauna (New Series) 50. Field Studies Council, London.","Broch H. 1914. Hydrozoa benthonica. In: Michaelsen W. (ed.) Beitrage zur Kenntnis der Meeresfauna Westafrikas. Volume 1: 19 - 50. L. Friederichsen & Co., Hamburg.","Pena Cantero A. L. & Garcia Carrascosa A. M. 2002. The benthic hydroid fauna of the Chafarinas Islands (Alboran Sea, western Mediterranean). Zoologische Verhandelingen, Leiden 337: 1 - 180.","Fraser C. M. 1944. Hydroids of the Atlantic Coast of North America. University of Toronto Press, Toronto."]}

Amphisbetia distans (Lamouroux, 1816) Dynamena distans Lamouroux, 1816: 180, pl. 5 fig. 1. Sertularia distans – Broch 1914: 34. Sertularia distans – Millard 1975: 306–307, fig. 99e–h. — Ramil & Vervoort 1992: 227–228, fig. 63c. Tridentata distans – Calder 1991: 105–107, fig. 55. — Cornelius 1995: 108–111, fig. 27. Material examined SOUTH ATLANTIC OCEAN • 4 colonies, 4–5 mm high (3 growing on algae, 1 of them with gonothecae); Vema Seamount, stn BT5; 31°37′16″–31°36′58″ S, 8°22′37″–8°23′06″ E; 71– 94 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40377, SEAFO-2015-40437, SEAFO-2015-40768, SEAFO-2015-40912, LZM-UV slide R. 578 • 1 colony, without gonothecae; Vema Seamount, stn GRAB11A; 31°37′55″ S, 8°21′48″ E; 64 m depth; 1 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40853 • 1 colony, without gonothecae; Vema Seamount, stn Dive 4; 91–95 m depth; 1 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40661. Distribution Amphisbetia distans was considered as a circumtropical species by Ramil & Vervoort (1992, as Sertularia distans), and circumglobal by Calder (1991, as Tridentata distans). In the southeastern Atlantic, it is known from Angola (Broch 1914, as S. distans), Vema Seamount (Millard 1966, as S. distans gracilis) and South Africa (Millard 1975, as S. distans). Its bathymetric distribution ranges from 0 (Millard 1975; Cornelius 1995, as Tridentata distans) to 826 m (Ramil & Vervoort 1992)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 67, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Lamouroux J. V. F. 1816. Histoire des Polypiers coralligenes flexibles, vulgairement nommes Zoophytes. F. Poisson, Caen. https: // doi. org / 10.5962 / bhl. title. 11172","Broch H. 1914. Hydrozoa benthonica. In: Michaelsen W. (ed.) Beitrage zur Kenntnis der Meeresfauna Westafrikas. Volume 1: 19 - 50. L. Friederichsen & Co., Hamburg.","Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262.","Calder D. R. 1991. Shallow-water hydroids of Bermuda. The Thecatae, exclusive of Plumularioidea. Life Sciences Contributions of the Royal Ontario Museum 154: 1 - 140.","Cornelius P. F. S. 1995. North-West European Thecate Hydroids and their Medusae. Part 2. Sertulariidae to Campanulariidae. In: Barnes R. S. K. & Crothers J. H. (eds) Synopses of the British Fauna (New Series) 50. Field Studies Council, London.","Millard N. A. H. 1966. Hydroids of the Vema Seamount. Annals of the South African Museum 48: 489 - 496."]}

Genus Monostaechoides gen. nov. urn:lsid:zoobank.org:act: E7E0F40E-8573-4EDF-98F5-D3CD4EAA3ED2 Type species Plumularia providentiae Jarvis, 1922, designated herein. Additional species Monostaechoides bertoti (Galea & Ferry, 2015) gen. et comb. nov. (= Monostaechas bertoti Galea & Ferry, 2015). Diagnosis Halopteridids with monosiphonic hydrocladia arising directly from creeping stolons. Hydrocladia branched, with several cladia originating dorsally from the distal parts of its ahydrothecate internodes. All cladia directed towards the same side or arranged either alternately or irregularly left and right along the stem. Branches of second and third order frequent in, at least, one species. Hydrothecate internodes with one hydrotheca, two pairs of lateral nematothecae and one mesial inferior nematotheca. Ahydrothecate internodes with a variable number of nematothecae. Hydrotheca partly adnate to its corresponding internode, cup-shaped, with untoothed rim. All nematothecae conical, bithalamic and movable. Gonothecae provided with nematothecae on the basal part. Etymology The generic name Monostaechoides is derived from a combination of the generic name Monostaechas Allman, 1877, and the latinized form of the Greek word-forming element ‘- eidés ’, meaning ‘like, resembling’ and referring to the affinities of the new taxon with the genus Monostaechas. The gender of the name is masculine. Remarks The presence of hydrothecae on the hydrocaulus is the main defining character of the family Halopterididae Millard, 1962 (Millard 1962, 1975; Schuchert 1997), and the generic limits within the family are largely based on the shape of the colonies and their ramification patterns (Schuchert 1997). The new genus described herein is characterized by having monosiphonic stems or primary hydrocladia arising from hydrorhiza and supporting irregularly pinnate or unilaterally-arranged secondary hydrocladia that, in turn, can originate hydrocladia of second and third order, in at least the type species. Another distinctive feature is the origin of the subsidiary hydrocladia from the postero-distal parts of ahydrothecate internodes, on the backside of an oblique distal node. The general habit of the colonies, with single monosiphonic stems carrying laterally-placed hydrocladia, resembles those of Halopteris Allman, 1877, Monostaechas Allman, 1877 and the recently described Thamnopteros Galea, 2020. Resemblances with Halopteris are found in the ramified nature of the colonies belonging to both genera, but in Halopteris the hydrocladia are routinely arranged in either alternate or opposite pairs, and originate from the hydrothecate internodes of the stem, laterally to the hydrothecae. Thamnopteros builds polysiphonic colonies giving rise to monosiphonic branchlets bearing pinnate hydrocladia with the same origin as in Halopteris (Galea & Maggioni 2020). The new genus shows more affinities with Monostaechas Allman, 1877 in both the origin of subsidiary hydrocladia on the postero-distal part of ahydrothecate internodes, just behind the distal oblique node, and the tendency to a unilateral disposition of subsidiary hydrocladia. Nevertheless, in Monostaechas the ramification pattern is a helicoid or scorpioid sympodium, in which each subsidiary hydrocladium originates from the postero-distal part of the first ahydrothecate internode of the previous hydrocladium (Billard 1913; Millard 1975; Schuchert 1997), resulting in a false axis composed of the basal parts of successive hydrocladia (Billard 1913; Millard 1975). In Monostaechoides gen. nov., there is a ‘true axis’ represented by a stem or primary hydrocladium bearing several secondary hydrocladia irregularly disposed along the same axis. This branching pattern is clearly different from that displayed by Monostaechas, supporting the creation of a new genus. The colonies of Monostaechas fisheri Nutting, 1906, recently redescribed by Galea & Maggioni (2020), show another ramification pattern, different from that met with in Monostaechoides gen. nov. In this case, the stem is devoid of hydrothecae and the lateral ramification builds a true sympodium (see Billard 1913: fig. 7). The same type of ramification found in Monostaechoides gen. nov. was also described in specimens of Antennella secundaria (Gmelin, 1791) collected from Indonesia (Billard 1913: 8, pl. 1 figs 2–3), the Seychelles (Millard & Bouillon 1973: 78) and South Africa (Millard 1975: 334), suggesting the existence of other undescribed species within this genus. Both Billard (1913) and Millard (1975) pointed out that, in these colonies, the main axis is formed by the first hydrocladium, and does not originate from the basal part of successive hydrocladia, excluding these materials from Monostaechas. Ramified colonies assigned to A. secundaria were also described by Vervoort & Vasseur (1977: 66, fig. 28b), Ryland & Gibbons (1991: 526, fig. 1a) and Calder (1997: 30, fig. 7a), but, in all cases, the ramification fits well with a sympodial pattern and was clearly different from that in Monostaechoides gen. nov., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 71-72, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Jarvis F. E. 1922. The hydroids from the Chagos, Seychelles and other islands and from the coasts of British East Africa and Zanzibar. Transactions of the Royal Society of London, Zoology 18 (1): 331 - 360. https: // doi. org / 10.1111 / j. 1096 - 3642.1922. tb 00553. x","Galea H. R. & Ferry R. 2015. Notes on some hydroids (Cnidaria) from Martinique, with descriptions of five new species. Revue suisse de Zoologie 122 (2): 213 - 246. https: // doi. org / 10.5281 / zenodo. 29998","Millard N. A. H. 1962. The Hydrozoa of the south and west coasts of South Africa. Part I. The Plumulariidae. Annals of the South African Museum 46 (11): 261 - 319.","Schuchert P. 1997. Review of the family Halopterididae (Hydrozoa, Cnidaria). Zoologische Verhandelingen, Leiden 309: 1 - 161.","Galea H. R. & Maggioni D. 2020. Plumularioid hydroids (Cnidaria: Hydrozoa) from off New Caledonia collected during KANACONO and KANADEEP expeditions of the French Tropical Deep-Sea Benthos Program. European Journal of Taxonomy 708: 1 - 58. https: // doi. org / 10.5852 / ejt. 2020.708","Billard A. 1913. Les hydroides de l'expedition du Siboga, I. Plumulariidae. Siboga-Expeditie 7: 1 - 115.","Vervoort W. & Vasseur P. 1977. Hydroids from French Polynesia with notes on distribution and ecology. Zoologische Verhandelingen, Leiden 159: 3 - 98.","Ryland J. S. & Gibbons M. J. 1991. Intertidal and shallow water hydroids from Fiji, II. Plumulariidae and Aglaopheniidae. Memoirs of the Queensland Museum 30 (3): 525 - 560.","Calder D. R. 1997. Shallow-water hydroids of Bermuda: superfamily Plumularioidea. Life Sciences Contributions of the Royal Ontario Museum 161: 1 - 85."]}

Obelia geniculata (Linnaeus, 1758) Sertularia geniculata Linnaeus, 1758: 812. Laomedea geniculata – Broch 1914: 37. Obelia geniculata – Millard 1975: 229–230, fig. 75a–b. — Cornelius 1995: 301–303, fig. 70. — Calder 2012: 50–51, fig. 53. Material examined SOUTH ATLANTIC OCEAN •3 colonies, up to 5 mm high (all growing on brown algae, 2 colonies, with gonothecae); Vema Seamount, stn BT5; 31°37′16″– 31°36′58″ S, 8°22′37″– 8°23′06″ E; 71–94 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40317, SEAFO-2015-40327, SEAFO-2015-40768. Distribution Usually considered as a cosmopolitan species, with records from all oceans (Peña Cantero & García Carrascosa 2002), although absent from Antarctic waters (Peña Cantero 2004). In the Southeast Atlantic, it was recorded from Namibia (Broch 1914, as Laomedea geniculata (Linnaeus, 1758)), Vema Seamount (Millard 1966) and South Africa (Millard 1975). Its bathymetric distribution extends from the intertidal (Cornelius 1995) to 381 m (Gili et al. 1989)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 66, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Linnaeus C. 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. L. Salvius, Stockholm. https: // doi. org / 10.5962 / bhl. title. 542","Broch H. 1914. Hydrozoa benthonica. In: Michaelsen W. (ed.) Beitrage zur Kenntnis der Meeresfauna Westafrikas. Volume 1: 19 - 50. L. Friederichsen & Co., Hamburg.","Cornelius P. F. S. 1995. North-West European Thecate Hydroids and their Medusae. Part 2. Sertulariidae to Campanulariidae. In: Barnes R. S. K. & Crothers J. H. (eds) Synopses of the British Fauna (New Series) 50. Field Studies Council, London.","Calder D. R. 2012. On a collection of hydroids (Cnidaria, Hydrozoa, Hydroidolina) from the west coast of Sweden, with a checklist of species from the region. Zootaxa 3171 (1): 1 - 77. https: // doi. org / 10.11646 / zootaxa. 3171.1.1","Pena Cantero A. L. & Garcia Carrascosa A. M. 2002. The benthic hydroid fauna of the Chafarinas Islands (Alboran Sea, western Mediterranean). Zoologische Verhandelingen, Leiden 337: 1 - 180.","Millard N. A. H. 1966. Hydroids of the Vema Seamount. Annals of the South African Museum 48: 489 - 496.","Gili J. M., Vervoort W. & Pages F. 1989. Hydroids from the West African coast: Guinea Bissau, Namibia and South Africa. Scientia Marina 53 (1): 67 - 112."]}

Campanularia africana Stechow, 1923 Fig. 3G–H; Table 5 Campanularia africana Stechow, 1923: 104. Campanularia africana – Leloup 1938: 13–14, fig. 9. — Millard 1975: 204, fig. 67a. Material examined SOUTH ATLANTIC OCEAN • 2 colonies, growing on algae, without gonothecae; Vema Seamount, stn BT5; 31°37′16″–31°36′58″ S, 8°22′37″–8°23′06″ E; 71–94 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40437, SEAFO-2015-40768, LZM-UV slide R. 577. Distribution Campanularia africana has previously been reported from Australia (Watson 1990), Japan (Stechow 1923; Leloup 1938; Hirohito 1995) and Natal, South Africa (Millard 1975). Its bathymetric distribution extends from the littoral area to a depth of 102 m (Millard 1975; Stechow 1925). Our finding of C. africana at Vema Seamount represents the first record of this species for the Atlantic Ocean., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 62, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Stechow E. 1923. Uber Hydroiden der Deutschen Tiefsee-Expedition, nebst Bemerkungen uber einige andre Formen. Zoologischer Anzeiger 53 (9 - 10): 223 - 236.","Leloup E. 1938. Quelques hydropolypes de la baie de Sagami, Japon. Bulletin du Musee royal d'Histoire naturelle de Belgique 14 (28): 1 - 22.","Watson J. E. 1990. Studies on Australian Hydroids. The genus Eudendrium and the fauna of the seagrass Amphibolis. Unpublished D. Phil. Thesis, University of Deaking.","Hirohito Emperor of Japan. 1995. Hydroids of Sagami Bay II. Thecata. Publications of the Biological Laboratory, Imperial Household, Tokyo.","Stechow E. 1925. Hydroiden der Deutschen Tiefsee-Expedition. Wissenschaftliche Ergebnisse der Deutschen Tiefsee-Expedition auf dem Dampfer \" Valdivia \" 1898 - 1899 27: 383 - 546."]}

Campanulina denticulata Clarke, 1907 Fig. 3F; Table 4 Campanulina denticulata Clarke, 1907: 12–13, pl. 8. Campanulina denticulata – Stechow 1913: 122–123, fig. 92. Opercularella denticulata – Vervoort 1966: 104–106, figs 4–5. Material examined SOUTH ATLANTIC OCEAN • 2 colonies, up to 10 mm high (1 growing on ghost fishing net) and with gonothecae; Valdivia Seamount, stn BT12, 24°49′01″– 24°47′38″ S, 6°24′40″– 6°25′26″ E; 887– 886 m depth; 7 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40811, SEAFO-2015-40887. Remarks Campanulina denticulata was considered a synonym of Earleria panicula (G.O. Sars, 1874) by several authors (Leloup 1974; Schuchert 2003), but Calder (2012) suggested that the Atlantic E. panicula is a different species from the Indo-Pacific C. denticulata. The comparison of the material from the Valdivia Seamount with colonies of E. panicula collected in NW Africa showed some morphological differences, and agrees with descriptions of C. denticulata given by Clarke (1907) and Vervoort (1966). Distribution Campanulina denticulata has an Indo-Pacific distribution (Calder 2012). Its bathymetric distribution extends from more than 500 m (Clarke 1970, as Opercularella denticulata) to 4040 m deep (Vervoort 1966, as O. denticulata)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 61-62, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Clarke S. F. 1907. Reports on the scientific results of the expedition to the eastern tropical Pacific, in charge of Alexander Agassiz, by the U. S. Fish Commission steamer \" Albatros \", from October 1904 to March 1905, Lieut. - Commander L. M. Garrett, U. S. N., commanding. VIII. The hydroids. Memoirs of the Museum of Comparative Zoology at Harvard College 35: 1 - 18.","Stechow E. 1913. Hydroidpolypen der japanischen Ostkuste. II. Teil: Campanularidae, Halecidae, Lafoeidae, Campanulinidae und Sertularidae, nebst Erganzungen zu den Athecata und Plumularidae. Abhandlungen der Koniglich Bayerischen Akademie der Wissenschaften, Supplementband zu den Abhandlungen der Mathematisch-naturwissenschaftlichen Klasse 3 (2): 1 - 162. https: // doi. org / 10.5962 / bhl. title. 11621","Vervoort W. 1966. Bathyal and abyssal hydroids. Galathea Report. Scientific Results of the Danish Deep-Sea Expedition, 1950 - 1952 8: 97 - 173.","Leloup E. 1974. Hydropolypes calyptoblastiques du Chili. Report no. 48 of the Lund University Chile Expedition 1948 - 1949. Sarsia 55: 1 - 62. https: // doi. org / 10.1080 / 00364827.1974.10411252","Schuchert P. 2003. Hydroids (Cnidaria, Hydrozoa) of the Danish expedition to the Kei Islands. Steenstrupia 27 (2): 137 - 256.","Calder D. R. 2012. On a collection of hydroids (Cnidaria, Hydrozoa, Hydroidolina) from the west coast of Sweden, with a checklist of species from the region. Zootaxa 3171 (1): 1 - 77. https: // doi. org / 10.11646 / zootaxa. 3171.1.1"]}

Zygophylax sp. Fig. 3A–C; Table 2 Zygophylax ? biarmata – Millard 1958: 176–177, fig. 4a; 1975: 193, fig. 63c. Material examined SOUTH ATLANTIC OCEAN • 29 colonies, 16–61 mm high (1 growing on ghost fishing net), without coppiniae; Valdivia Seamount, stn BT12; 24°49′01″–24°47′38″ S, 6°24′40″–6°25′26″ E; 887– 886 m depth; 7 Feb. 2015;SEAFO-2015 leg.; SEAFO-2015-40192, SEAFO-2015-40282, SEAFO-2015-40432, SEAFO-2015-40492, SEAFO-2015-40767, SEAFO-2015-40811, SEAFO-2015-40827, LZM-UV slide R. 580. Description Colonies branched, stems erect, with a main primary tube surrounded by many secondary tubes, grading to monosiphonic distally. Lateral hydrocladia, originating from the primary tube, monosiphonic, forming an angle of 45° in all directions around the stem, always with an axillary hydrotheca. Some branches are occasionally branched once (secondary hydrocladia). The existence of internodes in both the stem and branches was not observed. Main stem and branches with the same structure and provided with alternately disposed hydrothecal apophyses, slightly directed to the ‘frontal’ side of the colony (Fig. 3B). Some isolated apophyses and hydrothecae were also observed arising from secondary tubes. Hydrothecae slightly shifted frontally, long, tubular, with the adcauline wall convex and the abcauline wall almost straight; basal part tapering below into a short pedicel, separated from hydrotheca by a slightly oblique, thin diaphragm; rim smooth, circular and slightly everted; renovations of the hydrothecal rim common and usually multiple; diaphragm occasionally renovated as well. Nematothecae inserting on small apophyses, usually one on each side of hydrotheca, but when lost, only a circular depression, corresponding to their origin, could be observed; tubular, with short, spherical pedicel; rim smooth, circular, slightly everted; renovations absent (Fig. 3C). Variabillity In one colony we found one hydrocladium that was polysiphonic at its basal part and distally monosiphonic. Remarks Our material clearly resembles Zygophylax biarmata Billard, 1905, but the hydrothecae are larger and, in addition, the arrangement of branches in all directions around the stem makes it easy to differentiate between species, as Z. biarmata presents branches that are arranged in the same plane as the main stem. Among all species of Zygophylax reported from West Africa, only one, Z. parabiarmata Vervoort, 2006, shows the lateral branches arranged in several planes, but in this case hydrothecae are arranged in different planes as well, whereas in Zygophylax sp. hydrothecae are almost in the same plane. Moreover, in Zygophylax sp. hydrothecae are longer and narrower than in Z. parabiarmata. Nevertheless, the material studied here agrees with that described by Millard (1958, 1975) as Zygophylax ? biarmata (not Z. biarmata Billard, 1905, see Ramil & Vervoort 1992: 60–65) in both measurements and the irregular disposition of the lateral branches around the stem, and the occasional presence of hydrothecae on secondary tubes. Consequently, we consider that all belong to the same species, but the absence of coppinia prevents us from assigning this material to a new species. Distribution This species has previously been recorded from off Natal, South Africa (Millard 1958, 1975, as Zygophylax ? biarmata), at depths of 164 to 333 m., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 57-59, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Millard N. A. H. 1958. Hydrozoa from the coasts of Natal and Portuguese East Africa. Part I. Calyptoblastea. Annals of the South African Museum 44 (5): 165 - 226.","Vervoort W. 2006. Leptolida (Cnidaria: Hydrozoa) collected during the CANCAP and Mauritania- II expeditions of the National Museum of Natural History, Leiden, The Netherlands [Anthoathecata, various families of Leptothecata and addenda]. Zoologische Mededelingen, Leiden 80 (1): 181 - 318.","Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262.","Clarke S. F. 1907. Reports on the scientific results of the expedition to the eastern tropical Pacific, in charge of Alexander Agassiz, by the U. S. Fish Commission steamer \" Albatros \", from October 1904 to March 1905, Lieut. - Commander L. M. Garrett, U. S. N., commanding. VIII. The hydroids. Memoirs of the Museum of Comparative Zoology at Harvard College 35: 1 - 18.","Stechow E. 1923. Uber Hydroiden der Deutschen Tiefsee-Expedition, nebst Bemerkungen uber einige andre Formen. Zoologischer Anzeiger 53 (9 - 10): 223 - 236."]}

Coryne pusilla Gaertner, 1774 Coryne pusilla Gaertner, 1774: 40–41, pl. 4 fig. 8. Coryne pusilla – Millard 1975: 51–52, fig. 19f–g. — Schuchert 2001b: 776–780, fig. 14a–b; 2012: 134–135, fig. 142. Material examined SOUTH ATLANTIC OCEAN • 1 colony, with sporosacs; Vema Seamount, stn BT5; 31°37′16″– 31°36′58″S,8°22′37″–8°23′06″E; 71–94m depth; 31Jan.2015;SEAFO-2015leg.; SEAFO-2015-40942 • 1 colony, with sporosacs, growing on sponge; Vema Seamount, stn Dive 5; 91 – 42 m depth; 1 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40191. Remarks Molecular studies carried out by Schuchert (2005) to explore species boundaries within the genus Coryne found that populations identified as Coryne pusilla from the Mediterranean, Japan and Korea are genetically different from the Northeast Atlantic ones. Based on these results, Schuchert (2005, 2010) indicated that C. pusilla appears to be a species complex, an opinion also shared by Calder (2017). The material examined here is scarce and prevents us from giving a detailed description of the species. Nevertheless, we want to highlight that we found two size-classes of stenoteles: small (8.2–10.3× 4.1– 5.5 µm) and large (15.1–17.6 × 10.3–11.8 µm) ones. These measurements concur with those obtained by Millard (1975) from South African material, but they are clearly inferior to those reported from East and West Atlantic populations (see Schuchert 2001b and Calder 2017, respectively). These data suggest that the Southeast Atlantic populations of C. pusilla could also represent a different species. Distribution Coryne pusilla is considered as a circumglobal species, although the records from Madagascar and Kerguelen Islands (Millard 1975) and those from the Pacific Ocean (Millard 1975; Schuchert 2005, 2012) are considered as uncertain. It was reported from South Africa by Millard (1975). Its bathymetric range extends from the intertidal level to 100 m depth (Hirohito 1988)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 52, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Gaertner J. 1774. Zoophyta. In: Pallas P. S. (ed.) Spicilega zoologica quibus novae imprimus et obscurae animalium species. August Lange, Berolini.","Schuchert P. 2001 b. Survey of the family Corynidae (Cnidaria, Hydrozoa). Revue suisse de Zoologie 108: 739 - 878. https: // doi. org / 10.5962 / bhl. part. 80165","Schuchert P. 2005. Taxonomic revision and systematic notes on some Halecium species (Cnidaria, Hydrozoa). Journal of Natural History 39 (8): 607 - 639. https: // doi. org / 10.1080 / 00222930400001319","Schuchert P. 2010. The European athecate hydroids and their medusae (Hydrozoa, Cnidaria): Capitata Part 2. Revue suisse de Zoologie 117 (3): 337 - 555. https: // doi. org / 10.5962 / bhl. part. 117793","Calder D. R. 2017. Additions to the hydroids (Cnidaria, Hydrozoa) of the Bay of Fundy, northeastern North America, with a checklist of species reported from the region. Zootaxa 4256 (1): 1 - 86. https: // doi. org / 10.11646 / zootaxa. 4256.1.1","Schuchert P. 2012. North-West European Athecate Hydroids and their Medusae. In: Crothers J. H. & Haywars P. J. (eds) Synopses of the British Fauna (New Series) 59. Field Studies Council, London.","Hirohito Emperor of Japan. 1988. The Hydroids of Sagami Bay Collected by His Majesty the Emperor of Japan. Publications of the Biological Laboratory Imperial Household, Tokyo."]}

Turritopsis sp. Turritopsis sp. – Gil 2017: 37–41, fig. 6a. — Gil et al. 2020: 7–8, fig. 2a. Material examined SOUTH ATLANTIC OCEAN • 3 colonies, up to 6 mm high, without gonophores; Vema Seamount, stn PT4; 31°39′43″–31°38′10″ S, 8°22′37″–8°23′42″ E; 50–108 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40072; SEAFO-2015-40093, SEAFO-2015-40273 • 2 colonies, without gonophores (1 growing on ascidian and 1 on a gorgonian); Vema Seamount, stn Dive 4; 91–95 m depth; 1 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40134, SEAFO-2015-40631. Distribution Turritopsis sp. was collected from depths of 18 to 1581 m at several localities stretching from Western Sahara to Gabon (Gil 2017)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 53, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Gil M., Ramil F. & Ansin Agis J. 2020. Hydroids (Cnidaria, Hydrozoa) from Mauritanian Coral Mounds. Zootaxa 4878 (3): 412 - 466. https: // doi. org / 10.11646 / zootaxa. 4878.3.2"]}

Obelia dichotoma (Linnaeus, 1758) Sertularia dichotoma Linnaeus, 1758: 812. Laomedea (Obelia) dichotoma – Vervoort 1959: 315– 316. Obelia dichotoma – Millard 1975: 229–230, fig. 75a–b. — Ramil & Vervoort 1992: 243–244, fig. 68c. — Cornelius 1995: 296–300, fig. 69. Material examined SOUTH ATLANTIC OCEAN • 2 colonies, up to 19 mm high, without gonothecae; Vema Seamount, stn Dive 4; 91–95 m depth; 1 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40020, SEAFO-2015-40131. Distribution Obelia dichotoma is a well-known species with a nearly cosmopolitan distribution (Cornelius 1995); it is absent from Arctic and Antarctic waters (Peña Cantero & García Carrascosa 2002). In the Southeast Atlantic, it was reported from Angola (Vervoort 1959, as Laomedea (Obelia) dichotoma) and South Africa (Millard 1975). Its bathymetric distribution ranges from the intertidal (Cornelius 1995) to 540 m (Vervoort 2006)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 65-66, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Linnaeus C. 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. L. Salvius, Stockholm. https: // doi. org / 10.5962 / bhl. title. 542","Vervoort W. 1959. The Hydroida of the tropical west coast of Africa. Atlantide-Report: Scientific Results of the Danish Expedition to the Coasts of Tropical West Africa 5: 211 - 325.","Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262.","Cornelius P. F. S. 1995. North-West European Thecate Hydroids and their Medusae. Part 2. Sertulariidae to Campanulariidae. In: Barnes R. S. K. & Crothers J. H. (eds) Synopses of the British Fauna (New Series) 50. Field Studies Council, London.","Pena Cantero A. L. & Garcia Carrascosa A. M. 2002. The benthic hydroid fauna of the Chafarinas Islands (Alboran Sea, western Mediterranean). Zoologische Verhandelingen, Leiden 337: 1 - 180.","Vervoort W. 2006. Leptolida (Cnidaria: Hydrozoa) collected during the CANCAP and Mauritania- II expeditions of the National Museum of Natural History, Leiden, The Netherlands [Anthoathecata, various families of Leptothecata and addenda]. Zoologische Mededelingen, Leiden 80 (1): 181 - 318."]}

Monostaechoides providentiae (Jarvis, 1922) gen. et comb. nov. Figs 5–6, 7A–B; Table 11 Plumularia providentiae Jarvis, 1922: 347–348, pl. 26 fig. 21. Antennella quadriaurita – Millard 1966: 492–493. — Calder 1997: 27–29, fig. 6 (not Antennella quadriaurita Ritchie, 1909). Material examined SOUTH ATLANTIC OCEAN • 3 colonies, 19–23 mm high, on sponge (1 with gonothecae); Vema Seamount, stn PT4; 31°39′43″–31°38′10″ S, 8°22′37″–8°23′42″ E; 50–108 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40063, LZM-UV slide R. 576 • 4 colonies, 5–7 mm high (1 colony, growing on algae, with gonothecae); Vema Seamount, stn BT5; 31°37′16″–31°36′58″ S, 8°22′37″– 8°23′06″ E; 71–94 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40227, SEAFO-2015-40497, SEAFO-2015-40768, LZM-UV slide R. 581. Description Hydrorhiza composed of a cluster of perisarcal tubes covered by a sponge growing on old gorgonian axis. In some cases, isolated hydrocladia are born directly on the hydrorhiza but, in most cases, several monosiphonic primary hydrocladia arise in tufts from a short, polysiphonic axis composed by several entangled stolons protruding from the sponge. The basal part of the primary hydrocladium is composed of one to five internodes separated by straight nodes, provided with a variable number of scattered nematothecae separated from the remainder of hydrocladium by an oblique node. This part is formed by a regular succession of hydrothecate and ahydrothecate internodes, delimited by alternating oblique and straight nodes; hydrothecate internodes with proximally oblique and distally straight nodes; ahydrothecate internodes with a reversed position of nodes (Figs 5E, 6C, 7B). Almost all primary hydrocladia carry lateral ramifications randomly disposed, always originating from their posterior side. In most cases, the subsidiary hydrocladia arise from the distal end of ahydrothecate internodes, just on the back side of the oblique nodes within the heteromerous part of the colony (Fig. 6A); occasionally, some ramifications are found on the basal part of primary hydrocladia (Figs 5F–G, 7A). All subsidiary hydrocladia (i.e., of the second, third and even fourth order) are born on small apophyses and are composed of a basal ahydrothecate internode of varied length carrying between one and four nematothecae (Figs 6A, D, 7A), followed by a regular succession of hydrothecate and ahydrothecate internodes with the same structure as the primary hydrocladia. Usually, all subsidiary hydrocladia originating from the same hydrocladium are directed to the same side in a linear succession, but irregularities also occur. Hydrothecate internodes with one hydrotheca and five nematothecae: one mesial inferior and two pairs of laterals. Hydrotheca cup-shaped, widening towards rim; adcauline wall adnate for about half its length; abcauline wall straight; hydrothecal rim circular, even and slightly everted. Mesial nematothecae not reaching hydrothecal base. Two pairs of lateral nematothecae; first pair borne on well-developed apophyses adpressed to the hydrothecal wall, and as long as the nematothecae proper, the latter reaching the hydrothecal rim; second pair small, inserted on bases of apophyses (Fig. 5D). Ahydrothecate internodes usually with two frontal nematothecae in a row, although the number may vary between one and three. All nematothecae bithalamic, movable and conical, with adcauline wall of distal chamber scooped. Colonies monoecious; gonothecae of both sexes found on same hydrocladia, arising from below the hydrothecal bases, just above the mesial nematothecae (Figs 6A–B, 7B). Male gonotheca small, sackshaped, with small and circular aperture located at the rounded top, basal part slightly curved and carrying one nematotheca, and narrowing into a short pedicel composed of one internode. Female gonotheca pear-shaped, rather curved, with a distal, slightly tilted, circular aperture, closed by lid; basally provided with two nematothecae and narrowing into a two-segmented pedicel. Variability In some hydrocladia, the regeneration processes when ahydrothecate internodes are damaged result in two ahydrothecate internodes, each one with one or two nematothecae, between two consecutive hydrothecate internodes. We have also observed a subsidiary hydrocladium originating from the back side of a hydrothecate internode (Fig. 6D), but this type of ramification is exceptional and probably related to regeneration processes. Remarks Our material agrees with the main features described by Jarvis (1922) as Plumularia providentiae. In both cases the colonies are ramified, with the subsidiary hydrocladia originating from the back side of a true axis (or hydrocladia) shifted on to one side, but that does not adopt the shape of a scorpioid sympodium. Moreover, the morphology of hydrothecae and the number and arrangement of the nematothecae are also similar. The main difference is found in the presence, in our colonies, of subsidiary hydrocladia originating from the basal part of some primary hydrocladia; however, this is an occasional feature and not the norm. Moreover, Jarvis (1922) described P. providentiae with homomerously segmented hydrocladia, but in our colonies the segmentation is heteromerous. Nevertheless, the existence of intermediate ahydrothecate internodes is clearly visible only in subsidiary and younger hydrocladia. In older parts of the colony, and mainly in primary hydrocladia, the perisarc of the wall is thick, masking the heteromerous segmentation. In our opinion, these differences do not justify the description of a new species and, therefore, we identify our material as Monostaechoides providentiae (Jarvis, 1922) gen. et comb. nov. In addition, the material described from the Vema Seamount by Millard (1966) as Antennella quadriaurita (Ritchie, 1909), with hydrocladia clustered together basally and ramified following the same pattern as our colonies, also belongs to this species. Colonies found in Bermuda with a similar morphology and with the same ramification pattern were described by Calder (1997) as A. quadriaurita (see Calder 1997: 28, fig. 6a). That material, excluded from A. quadriaurita by Galea & Ferry (2015), is also included here in M. providentiae gen. et comb. nov. Differences between M. providentiae gen. et comb. nov. and M. bertoti gen. et comb. nov. were discussed by Galea & Ferry (2015), and refer to the ramification pattern, with hydrocladia more or less alternately arranged in M. bertoti gen. et comb. nov., and a different number of nematothecae on both cauline and cladial internodes. Distribution This species has been reported from Providence Atoll, the Seychelles (Jarvis 1922, as Plumularia providentiae), Vema Seamount (Millard 1966; Berrisford 1969, both as A. quadriaurita) and Bermuda (Calder 1997, as A. quadriaurita) in depths from 42 to 85 m., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 73-78, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Jarvis F. E. 1922. The hydroids from the Chagos, Seychelles and other islands and from the coasts of British East Africa and Zanzibar. Transactions of the Royal Society of London, Zoology 18 (1): 331 - 360. https: // doi. org / 10.1111 / j. 1096 - 3642.1922. tb 00553. x","Millard N. A. H. 1966. Hydroids of the Vema Seamount. Annals of the South African Museum 48: 489 - 496.","Calder D. R. 1997. Shallow-water hydroids of Bermuda: superfamily Plumularioidea. Life Sciences Contributions of the Royal Ontario Museum 161: 1 - 85.","Ritchie J. 1909. New species and varieties of Hydroida Thecata from Andaman Island. The Annals and Magazine of Natural History, Series 8 3: 524 - 528.","Galea H. R. & Ferry R. 2015. Notes on some hydroids (Cnidaria) from Martinique, with descriptions of five new species. Revue suisse de Zoologie 122 (2): 213 - 246. https: // doi. org / 10.5281 / zenodo. 29998","Berrisford C. D. 1969. Biology and zoogeography of the Vema Seamount: a report on the first biological expedition made on the seamount. Transactions of the Royal Society of South Africa 38: 387 - 398. https: // doi. org / 10.1080 / 00359196909519099"]}

Halecium tenellum Hincks, 1861 Halecium tenellum Hincks, 1861: 252, pl. 6 figs 1–4. Halecium tenellum – Cornelius 1975: 409–411, fig. 12. — Ramil & Vervoort 1992: 90–91, fig. 21f–g. Material examined SOUTH ATLANTIC OCEAN • 7 colonies, without gonothecae (1 growing on Zygophylax sp., 1 on bivalve shell, and 5 on ghost fishing net); Valdivia Seamount, stn BT12; 24°49′01″–24°47′38″ S, 6°24′40″–6°25′26″ E; 887– 886 m depth; 7 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40282, SEAFO-2015-40402, SEAFO-2015-40762, SEAFO-2015-40797, SEAFO-2015-40811, SEAFO- 2015-40850, SEAFO-2015-40852. Distribution Halecium tenellum is a nearly cosmopolitan species (Cornelius 1975), with records from all oceans, including polar waters, although some identifications from high latitudes in the North Atlantic proved to be erroneous (Calder 1991; Schuchert 2005). Reported from South Africa by Millard (1975). Its bathymetric range extends from the intertidal zone to 1200 m (Peña Cantero & García Carrascosa 2002)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 66-67, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Hincks T. 1861. A catalogue of the Zoophytes of South Devon and South Cornwall. The Annals and Magazine of Natural History (3) 8: 152 - 161, 251 - 262, 290 - 297. https: // doi. org / 10.1080 / 00222936108697420","Cornelius P. F. S. 1975. A revision of the species of Lafoeidae and Haleciidae (Coelenterata: Hydroida) recorded from Britain and nearby seas. Bulletin of the British Museum Natural History. Zoology 28: 375 - 426. https: // doi. org / 10.5962 / p. 271711","Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262.","Calder D. R. 1991. Shallow-water hydroids of Bermuda. The Thecatae, exclusive of Plumularioidea. Life Sciences Contributions of the Royal Ontario Museum 154: 1 - 140.","Schuchert P. 2005. Taxonomic revision and systematic notes on some Halecium species (Cnidaria, Hydrozoa). Journal of Natural History 39 (8): 607 - 639. https: // doi. org / 10.1080 / 00222930400001319","Pena Cantero A. L. & Garcia Carrascosa A. M. 2002. The benthic hydroid fauna of the Chafarinas Islands (Alboran Sea, western Mediterranean). Zoologische Verhandelingen, Leiden 337: 1 - 180."]}

Stegolaria geniculata (Allman, 1888) Cryptolaria geniculata Allman, 1888: 41, pl. 20 figs 1, 1a–b. Stegolaria geniculata – Ramil & Vervoort 1992: 32–34, fig. 4c–e. — Watson & Vervoort 2001: 154, fig. 2a–d. Material examined SOUTH ATLANTIC OCEAN • 1 colony, 10 mm high, without gonothecae; Vema Seamount, stn Dive 3; 71–935 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40648 • 54 colonies, 15–62 mm high (2 colonies growing on bivalves, 2 on ghost fishing net and 2 on ropes), 21 colonies, with gonothecae; Valdivia Seamount, stn BT12; 24°49′01″–24°47′38″ S, 6°24′40″–6°25′26″ E; 887– 886 m depth; 7 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40220, SEAFO-2015-40342, SEAFO-2015-40462, SEAFO-2015-40582, SEAFO-2015-40707, SEAFO-2015-40792, SEAFO-2015-40811, SEAFO-2015- 40822, SEAFO-2015-40850, SEAFO-2015-40852. Distribution A circumglobal species (Ramil & Vervoort 1992), widely distributed in deep waters of the Atlantic Ocean (Vervoort 2006). Its bathymetric distribution extends between 300 and 1727 m (Stepanjants 2012; Gil 2017)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 60, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Allman G. J. 1888. Report on the Hydroida dredged by H. M. S. Challenger during the years 1873 - 76. Part II. The Tubularinae, Corymorphinae, Campanularinae, Sertularinae and Thalamorphora. Report on the Scientific Results of the Voyage of H. M. S. Challenger, Zoology 23 (70): 1 - 90.","Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262.","Watson J. E. & Vervoort W. 2001. The hydroid fauna of Tasmanian seamounts. Zoologische Verhandelingen, Leiden 334: 151 - 188.","Vervoort W. 2006. Leptolida (Cnidaria: Hydrozoa) collected during the CANCAP and Mauritania- II expeditions of the National Museum of Natural History, Leiden, The Netherlands [Anthoathecata, various families of Leptothecata and addenda]. Zoologische Mededelingen, Leiden 80 (1): 181 - 318.","Stepanjants S. D. 2012. Deep-water Hydrozoa (Cnidaria: Medusozoa) in the Sea of Japan, collected during the 51 st cruise of R / V Akademik M. A. Lavrentyev, with description Opercularella angelikae, sp. nov. Deep Sea Research Part II: Topical Studies in Oceanography 86 - 87: 231 - 237. https: // doi. org / 10.1016 / j. dsr 2.2012.08.014"]}

Leuckartiara octona (Fleming, 1823) Geryonia octona Fleming, 1823: 298. Leuckartiara octona – Millard 1975: 123–125, fig. 41a–d. — Schuchert 2012: 251–252, fig. 232. Material examined SOUTH ATLANTIC OCEAN • 1 colony, without gonophores; Valdivia Seamount, stn GRAB14B; 26°15′38″ S, 6°16′37″ E; 451 m depth; 5 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40452. Distribution Circumglobal in subtropical and temperate waters. In the eastern Atlantic, it has been reported from the Arctic Seas (Kramp 1938) to South Africa (Millard 1975). Its bathymetric range extends from the intertidal (Millard 1975) to depths of 418 m (Gil & Ramil 2017) and 451 m (this paper)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 55, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Fleming J. 1823. Gleanings of natural history, gathered on the coast of Scotland during a voyage in 1821. The Edinburgh Philosophical Journal 8: 294 - 303.","Schuchert P. 2012. North-West European Athecate Hydroids and their Medusae. In: Crothers J. H. & Haywars P. J. (eds) Synopses of the British Fauna (New Series) 59. Field Studies Council, London.","Kramp P. L. 1938. Marine Hydrozoa. Hydroida. The Zoology of Iceland 2: 1 - 82.","Gil M. & Ramil F. 2017. Hydrozoans from Mauritanian deep-waters. In: Ramos A., Ramil F. & Sanz J. L. (eds) Deep-Sea Ecosystems off Mauritania: 419 - 444. Springer Netherlands, Dordrecht. https: // doi. org / 10.1007 / 978 - 94 - 024 - 1023 - 5 _ 11"]}

Campanularia hincksii Alder, 1856 Campanularia hincksii Alder, 1856: 360–361, pl. 13 fig. 9. Campanularia hincksii – Ramil & Vervoort 1992: 233–235, fig. 66. — Cornelius 1995: 229–231, fig. 52. Material examined SOUTH ATLANTIC OCEAN • 9 colonies, 0.5–17 mm high (2 growing on antipatharians, 1 on sponge, 1 on Sertularella arbuscula, 1 on Sertularella striata, 1 on Turritopsis sp.), all without gonothecae; Vema Seamount, stn PT4; 31°39′43″–31°38′10″ S, 8°22′37″–8°23′42″ E; 50–108 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40003, SEAFO-2015-40093, SEAFO-2015-40123, SEAFO-2015-40153, SEAFO-2015-40213, SEAFO-2015-40243, SEAFO-2015-40273, SEAFO-2015- 40444, SEAFO-2015-40972 • 5 colonies, 8–12 mm high (2 with gonothecae); stn Dive 3; 71–935 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40132, SEAFO-2015-40257, SEAFO-2015-40678 • 2 colonies, without gonothecae (1 growing on Amphisbetia distans); Vema Seamount, stn Dive 4; 91– 95 m depth; 1 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40131, SEAFO-2015-40977 • 1 colony, growing on ghost fishing net, without gonothecae; Valdivia Seamount, stn BT12; 24°49′01″–24°47′38″ S, 6°24′40″–6°25′26″ E; 887– 886 m depth, 7 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40850. Distribution Campanularia hincksii is a circumglobal species, recorded in the eastern Atlantic from Iceland to South Africa (Peña Cantero & García Carrascosa 2002). Its bathymetric distribution extends from the tidal level to a depth of 1200 m (Peña Cantero & García Carrascosa 2002; Leloup 1940)., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on pages 62-63, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Alder J. 1856. A notice of some new genera and species of British hydroid zoophytes. The Annals and Magazine of Natural History series 2 18: 353 - 362. https: // doi. org / 10.1080 / 00222935608697652","Ramil F. & Vervoort W. 1992. Report on the Hydroida collected by the \" BALGIM \" expedition in and around the Strait of Gibraltar. Zoologische Verhandelingen, Leiden 277: 1 - 262.","Cornelius P. F. S. 1995. North-West European Thecate Hydroids and their Medusae. Part 2. Sertulariidae to Campanulariidae. In: Barnes R. S. K. & Crothers J. H. (eds) Synopses of the British Fauna (New Series) 50. Field Studies Council, London.","Stechow E. 1923. Uber Hydroiden der Deutschen Tiefsee-Expedition, nebst Bemerkungen uber einige andre Formen. Zoologischer Anzeiger 53 (9 - 10): 223 - 236.","Pena Cantero A. L. & Garcia Carrascosa A. M. 2002. The benthic hydroid fauna of the Chafarinas Islands (Alboran Sea, western Mediterranean). Zoologische Verhandelingen, Leiden 337: 1 - 180.","Leloup E. 1940. Hydropolypes provenant des croisieres du Prince Albert Ier de Monaco. Resultats des Campagnes scientifiques du Prince Albert I de Monaco 104: 1 - 38."]}

Filellum sp. Fig. 2F; Table 1 Material examined SOUTH ATLANTIC OCEAN • 2 colonies (1 growing on an antipatharian, 1 on Sertularella patagonica), no coppinia; Vema Seamount, stn PT4; 31°39′43″–31°38′10″ S, 8°22′37″–8°23′42″ E; 50–108 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40003, SEAFO-2015-40033 • 4 colonies (3 growing on Campanularia hincksii, 1 on a bryozoan), no coppinia; Vema Seamount, stn Dive 3; 71–935 m depth; 31 Jan. 2015; SEAFO-2015 leg.; SEAFO-2015-40132, SEAFO-2015-40257, SEAFO-2015-40921 • 1 colony, growing on Amphisbetia distans, no coppinia; Vema Seamount, stn Dive 4; 91–95 m depth; 1 Feb. 2015; SEAFO-2015 leg.; SEAFO-2015-40661. Description Stolonal colonies arising from a filiform hydrorhiza creeping on other hydroids and a bryozoan. Hydrorhizal stolons give rise to small, tubular hydrothecae adnate for ca half their length; adnate part parallel to hydrorhiza, upper, free part provided with numerous and very faint striations on abcaulinar side, and bent upwards from hydrorhiza at an angle between 45° and 90°, although only occasionally perpendicular to the adnate part; aperture circular, rim even, only slightly everted; renovations have not been observed. Cnidome: two size classes of nematocysts, with small (10–12.5× 5–7.5 µm) and large (15–17.5 × 7.5–10 µm). Coppinia absent. Remarks The shape of the hydrothecae in the colonies studied herein resembles those of Filellum serratum (Clarke, 1879), Filellum antarcticum (Hartlaub, 1904) and Filellum magnificum Peña Cantero, Svoboda & Vervoort, 2004, due to the presence of numerous transversal striations of the adnate part. Nevertheless, the measurements of both hydrothecae and nematocysts do not match with those of the species mentioned above. In our material, the hydrothecae are smaller and the nematocysts larger than those of F. serratum, F. antarticum and F. magnificum. Based on these differences, we considered this material to be a different species, but the absence of coppinia prevents us from establishing a more accurate identification., Published as part of Gil, Marta & Ramil, Fran, 2021, Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic), pp. 49-96 in European Journal of Taxonomy 758 on page 56, DOI: 10.5852/ejt.2021.758.1425, http://zenodo.org/record/5088125, {"references":["Pena Cantero A. L., Svoboda A. & Vervoort W. 2004. Antarctic hydroids (Cnidaria, Hydrozoa) of the families Campanulinidae, Lafoeidae and Campanulariidae from recent Antarctic expeditions with R. V. Polarstern, with the description of a new species. Journal of Natural History 28: 2269 - 2303. https: // doi. org / 10.1080 / 00222930310001647361"]}