Zootaxa 3737 (5): 501–537 ISSN 1175-5326 (print edition) Article ZOOTAXA www.mapress.com/zootaxa/ Copyright © 2013 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3737.5.1 http://zoobank.org/urn:lsid:zoobank.org:pub:B5FE322D-4D0A-45E6-84BF-F00FA6308DE1 Aglaopheniid hydroids (Cnidaria: Hydrozoa: Aglaopheniidae) from bathyal waters of the Flemish Cap, Flemish Pass, and Grand Banks of Newfoundland (NW Atlantic) ÁLVARO ALTUNA1, FRANCISCO J. MURILLO2 & DALE R. CALDER3 1INSUB, Museo de Okendo, Zemoria, 12, Apartado 3223, 20013 Donostia-San Sebastián, Spain. E-mail: [email protected] 2Instituto Español de Oceanografía, Centro Oceanográfico de Vigo, Programa de Pesquerías Lejanas, Apartado 1552, 36280 Vigo, Spain. E-mail: [email protected] 3Department of Natural History, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario, Canada M5S 2C6. E-mail: [email protected] 1Corresponding author Abstract Five species of aglaopheniid hydroids (Aglaophenopsis cornuta, Cladocarpus diana, C. formosus, C. integer, and Nema- tocarpus ramuliferus) were collected from the Flemish Cap, Flemish Pass, and Grand Banks of Newfoundland during sur- veys with bottom trawls, rock dredges, and scallop gear. All are infrequently reported species, with C. diana being discovered for the first time since its original description from Iceland. We document here the southernmost collections of C. diana and N. ramuliferus, both previously unknown in the western Atlantic. Each of the five species is described and illustrated based on fertile material, a key is provided for their identification, and bathymetric distributions are noted. Known depth ranges are extended for A. cornuta, C. diana, and C. integer. Aglaophenopsis and Nematocarpus are recog- nized as genera distinct from the polyphyletic Cladocarpus, based on the unique structure of the phylactocarp in the for- mer, and the existence of appendages with nematothecae (ramuli) on almost all thecate internodes of hydrocladia in the latter. These appendages occur even in the absence of gonothecae, and are here considered defensive structures that protect the hydranths. In differing from typical phylactocarps, we accept the contention that they are characters of generic value. Key words: Aglaophenopsis, Cladocarpus, Nematocarpus, deep-sea, northwestern Atlantic Introduction The hydrozoan family Aglaopheniidae Marktanner-Turneretscher, 1890 is a speciose taxon comprising around 248 valid species worldwide (see Bouillon et al. 2006). Division of genera within the group is based mainly on the gonosome, because reliable differential characters are lacking in the trophosome (Leloup 1932). Aglaopheniids have been reported infrequently in the western Atlantic northwards of the 40ºN parallel, and especially so in waters off the east coast of Canada. While the hydroid fauna of shallow waters off the Atlantic coast of Canada is relatively well known (Fraser 1944), that of deeper neritic and bathyal waters has received little attention and is consequently poorly known. At such depths off Newfoundland, only two species of aglaopheniids have been recorded previously. Aglaophenopsis cornuta (Verrill, 1879) was reported from two locations north of the island (53°34’N–52°01’W, ca. 1792 m; 52°25’N–52°12’W, ca. 296 m) by Jäderholm (1919: 11), while A. cornuta and Cladocarpus integer (G.O. Sars, 1874) were found in collections from a station to the northeast of Newfoundland (51°22’30”N–50°31’30”W, 457 m) by Calder (1970: 1540). Two other aglaopheniid species penetrating into bathyal waters, Lytocarpia myriophyllum (Linnaeus, 1758) and Cladocarpus formosus Allman, 1874, range both north and south of Newfoundland along the North American Atlantic coast (Fraser 1944, 1946) but have yet to be reported from that locale. Accepted by A. Collins: 29 Oct.. 2013; published: 22 Nov. 2013 501 Licensed under a Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0 FIGURE 1. Distribution of the five aglaopheniid species in the study area. A) Aglaophenopsis cornuta (Verrill, 1879). B) Cladocarpus diana Broch, 1918. C) Cladocarpus formosus Allman, 1874. D) Cladocarpus integer (G.O. Sars, 1874). E) Nematocarpus ramuliferus (Allman, 1874). FC, Flemish Cap; FP, Flemish Pass; GB, Grand Banks. In a literature review, we found records of only eight species of aglaopheniids, referable to the genera Aglaophenopsis Fewkes, 1881, Cladocarpus Allman, 1874, and Lytocarpia Kirchenpauer, 1872, in the region between 40ºN (New York Bight east of New Jersey) and Baffin Bay (including the west coast of Greenland) (Table 1). Some have been recorded only a few times and appear to be quite rare, while another is probably not valid. Scarcity of aglaopheniids in the northwestern North Atlantic may be attributed in part to the fact that they are predominantly a warm-water group (Calder 1997a: 40). 502 · Zootaxa 3737 (5) © 2013 Magnolia Press ALTUNA ET AL. AGLAOPHENIID HYDROIDS FROM THE NW ATLANTIC Zootaxa 3737 (5) © 2013 Magnolia Press · 503 According to the generic diagnoses of aglaopheniids in Bouillon (1985) and Bouillon et al. (2006), all species of the family known to occur between Baffin Bay and the Maritime Provinces of Canada are referable to Cladocarpus, with the exception of Lytocarpia myriophyllum. Cladocarpus was originally established by Allman (1874) to accommodate C. formosus, a species first described from the Faroe-Shetland Channel in the northeastern North Atlantic. Its primary distinguishing characters, according to Allman, were differences in morphology of the reproductive structures: gonothecae were solitary and protected by phylactocarps (‘gonangia not included in corbulae’) arising as appendages of an unmodified hydrocladium. Bouillon et al. (2006) listed 66 species of Cladocarpus worldwide, most of them from deep-water. However, the genus has essentially become a collective group, and a revision is needed. Some genera merged with it appear distinctive in characters of their phylactocarps and, in our opinion, are valid (see also Ramil & Vervoort 1992). One of these is Aglaophenopsis, with several representatives in the western North Atlantic. Fraser (1944) included four species in that genus from the Atlantic coast of North America, with three of them being seldom recorded and poorly known. During 2006–2010, the Spanish Institute of Oceanography, in collaboration with several other institutions, carried out a number of research surveys on the Flemish Cap, the Flemish Pass, and the “tail” and “nose” of the Grand Banks of Newfoundland (Figure 1). Abundant material of sessile benthic fauna was collected over a wide range of depths, mainly in the bathyal zone (see Murillo et al. 2011). Hydroids comprise a significant part of those catches, and numerous colonies of aglaopheniids referable to five species were collected. All five are described and illustrated in this paper. Two of them are rare and previously unknown in the western Atlantic, one of which is reported for the first time since its original description. The generic value of certain gonosomal characters is discussed, with special emphasis on the genera Aglaophenopsis and Nematocarpus Broch, 1918. Material and methods Material examined during this study came from two research programs. Part was obtained during groundfish bottom trawl surveys carried out by the Spanish Institute of Oceanography (Instituto Español de Oceanografía, IEO) and the European Union (EU) on board the Spanish R/V “Vizconde de Eza”. The remainder came from rock dredge and scallop gear samples taken by the Spanish R/V “Miguel Oliver,” operated by the Spanish General Secretariat of the Sea (Secretaría General del Mar) under the NEREIDA project. Groundfish bottom trawl surveys covered the “tail” of the Grand Banks of Newfoundland between 40 and 1500 m, the Flemish Cap between 130 and 1450 m, and the Flemish Pass between 110 and 1450 m. These surveys were carried out annually between spring and summer using a random stratified sampling design with standardized 30-min tows and vessel speed of three knots. Campelen 1800 bottom trawl gear was used in the Flemish Pass and the Grand Banks of Newfoundland, whereas Lofoten bottom trawl gear was used at Flemish Cap. NEREIDA surveys were undertaken in the Flemish Pass, Flemish Cap, and slope of the Grand Banks of Newfoundland at depths between 700 and 2000 m. These surveys were carried out during spring and summer using a rock dredge and scallop gear. Tows of 15-min were made at a vessel speed of about 1.5 knots. NEREIDA is a multidisciplinary research project involving scientists from Instituto Español de Oceanografía (IEO), Fisheries and Oceans Canada (DFO), Natural Resources Canada (NRCAN), Centre for the Environment, Fisheries and Aquaculture Science (Cefas), Instituto de Investigaciones Marinas (CSIC), Secretaría General del Mar (SGM), Polar Research Institute of Marine Fisheries and Oceanography (PINRO), and the P.P. Shirshov Institute of Oceanology (RAS). Our study is based on material from groundfish bottom trawl surveys undertaken on the “tail” of the Grand Banks and Flemish Cap during 2007 and on the “nose” of the Grand Banks and Flemish Pass from 2006–2010, as well as from NEREIDA surveys during 2009 and 2010. Samples were fixed on board in 70 % ethanol. Voucher material of each species has been deposited in collections of the Invertebrate Zoology Section, Department of Natural History, Royal Ontario Museum (Canada), the Oceanographic Center of Vigo (IEO, Spain), and the Okendo Museum, Donostia-San Sebastián (Spain). Depths in Levinsen (1893) and Broch (1918) were given in Danish fathoms (favne), equivalent to 1.883 m. Fathoms in other papers have been taken to equal 1.828 m. 504 · Zootaxa 3737 (5) © 2013 Magnolia Press ALTUNA ET AL. TABLE 2. Species of aglaopheniid hydroids reported from the western North Atlantic between 40°N (New York Bight) and Baffin Bay (including western and southwestern Greenland) but not recorded during the present study. Literature records are not intended to be exhaustive. Aglaophenopsis bonnevieae (Jäderholm, 1909): 60º16’5N–47º48’W and 60º22’N–47º27’W (southwest Greenland, 135 m and 120 m) [Kramp 1932a, as Aglaophenopsis compressa (Bonnevie, 1899)]. No further records in the western Atlantic. Aglaophenopsis verrilli Nutting, 1900: 40º34’N–66º04’W (off Georges Bank, 3184 m) [Nutting (1900) and Fraser (1944)] = Cladocarpus verrilli in Bouillon et al. (2006) and Schuchert (2012b). Cladocarpus campanulatus Ritchie, 1912: 60º22’N–47º27’W (southwest Greenland, 120 m) (Kramp 1932a). No further records in the western Atlantic. Cladocarpus crenatus (Fewkes, 1881): 41º25’N–65º35’W (2270 m) [Fewkes (1881), as Aglaophenia crenata)], Nutting (1900) as Aglaophenia ? crenata referring to Fewkes (1881), east of Nantucket (Fraser 1944), referring to Fewkes (1881), as Cladocarpus ? crenatus with unknown gonosome. Likely coterminous with Cladocarpus formosus. Cladocarpus flexilis Verrill, 1885: southern coast of New England (Verrill 1885), seven stations in the Georges Bank area at different depths (Fish Hawk and Albatross stations) (Nutting 1900), Martha’s Vineyard and several stations in the Georges Bank area (Fraser 1944, some stations referring to Nutting 1900). Lytocarpia myriophyllum (L., 1758): Massachusetts Bay, Mingan Islands (Quebec), Eastport, Maine (A. Agassiz 1865 as Sertularia myriophyllum; Whiteaves 1901 and Fraser 1918 as Thecocarpus myriophyllum), 41°44’N–64°36’W (Le Have Bank, Nova Scotia, ca. 110 m) (Smith & Harger 1874 as Aglaophenia myriophyllum; Whiteaves 1901 and Fraser 1918 as T. myriophyllum), off Cape Gaspé (Gulf of St. Lawrence, Quebec, ca. 55 m) (Whiteaves 1901 and Fraser 1918 as T. myriophyllum), eastern Canada [(Kindle & Whittaker 1917, ca. 55–110 m, as T. myriophyllum, based on literature records)]. Results Class Hydrozoa Owen, 1843 Subclass Leptolina Haeckel, 1879 Order Leptothecata Cornelius, 1992 Suborder Conica Broch, 1910 Family Aglaopheniidae Marktanner-Turneretscher, 1890 Aglaophenopsis cornuta (Verrill, 1879) (Figs. 1A, 2A–G, tables 1, 3, 9–12) Cladocarpus cornutus Verrill, 1879: 310.—Levinsen 1893: 208, pl. 8, fig. 19–22.—Vanhöffen 1897: 246.—Jäderholm 1909: 110.—Kramp 1913: 28.—Kramp 1914: 1059.—Fraser 1946: 417.—Calder 1970: 1540, pl. 8, fig. 7.—Peña Cantero & García Carrascosa 1999: 214.—Schuchert 2001: 137, fig. 117A–E.—Bouillon et al. 2006: 283. Aglaophenia cornutus: Bonnevie 1899: 94. Aglaophenopsis cornuta: Nutting 1900: 120, pl. 30, fig. 6–9.—Whiteaves 1901: 28.—Broch 1910: 234.—Kindle & Whittaker 1917: 232.—Broch 1918: 77, fig. 39a–b, fig. 40a–d, fig. 41.—Jäderholm 1919: 11.—Fraser 1921: 177, fig. 102.—Kramp 1932a: 56.—Kramp 1932b: 20.—Kramp 1943: 44.—Fraser 1944: 395, pl. 85, fig. 382.—Vervoort 1972: 204.—Calder 1997b: 88.—Henry 2001: 163. Material examined. FN3L06 L51, 2 fertile colonies, largest one 9.5 cm high; FN3L06 L85, one fertile colony 7.0 cm high; FN3L06 L88, one fertile colony 10.5 cm high; FN3L06 L92, one fertile colony 15.0 cm high; PLA07 L61, one sterile colony 8.4 cm high; PLA07 L99, one sterile colony 10.0 cm high; PLA07 L107, one fertile colony 6 cm high; FC07 L74, one sterile colony 7.2 cm high; FC07 L133, one sterile colony 4.3 cm high; FC07 L153, one sterile colony 13.0 cm high; FC07 L171, one sterile fragment 1.6 cm high; FC07 L177, one sterile colony 5.5 cm AGLAOPHENIID HYDROIDS FROM THE NW ATLANTIC Zootaxa 3737 (5) © 2013 Magnolia Press · 505 high; FC07 L178, one fertile fragment 6.2 cm high; FN3L08 L88, 3 fertile colonies, largest one 21.0 cm high; FN3L08 L89, 3 fertile colonies, largest one 15.0 cm high; FN3L09 L80, one fertile colony 10.0 cm high; FN3L09 L89, one fertile colony 16.0 cm high; FN3L10 L35, one fertile colony 14.0 cm high; FN3L10 L57, one fertile colony 9.0 cm high; FN3L10 L87, one fertile colony 15.5 cm high; NEREIDA0509 RD4, one fertile colony 12.2 cm high; NEREIDA0509 RD6, 5 colonies, largest one 15.3 cm high, 2 of them fertile; NEREIDA0509 RD7, 6 colonies, up to 15.6 cm high, some fertile; NEREIDA0609 RD26, 2 sterile colonies, largest one 4.2 cm high; NEREIDA0609 RD27, 3 colonies, largest one 5.5 cm high, one fertile; NEREIDA0609 RD28, 2 fertile colonies, both 6.0 cm high; NEREIDA0609 RD41, 34 colonies, up to 11.3 cm high, some fertile; NEREIDA0709 RD49, 5 colonies, largest one 6 cm high, 2 fertile; NEREIDA0709 RD59, 2 fertile colonies, largest one 9.5 cm high; NEREIDA0709 RD60, one sterile colony 5.2 cm high; NEREIDA0610 RD62, one sterile colony 2.0 cm high; NEREIDA0610 RD67, one fertile colony 3.0 cm high; NEREIDA0610 RD71, one sterile fragment 2.2 cm high; NEREIDA0610 RD74, 23 colonies, up to 10.3 cm high, some fertile; NEREIDA0710 RD75, one sterile colony 6.0 cm high; NEREIDA0710 RD76, one fertile colony 8.7 cm high; NEREIDA0710 RD77, 2 sterile colonies, largest one 5.7 cm high; NEREIDA0710 RD78, one sterile colony 3.0 cm high; NEREIDA0710 RD79, one fertile colony 10.2 cm high; NEREIDA0710 RD80, 8 colonies, up to 8.4 cm high, some fertile; NEREIDA0710 RD87, one fertile colony 12.0 cm high; NEREIDA0710 RD88, 3 colonies, largest one 6.6 cm high, 2 fertile; NEREIDA0710 RD92, 2 sterile colonies, largest one 8.4 cm high; NEREIDA0810 RD97, 5 colonies, largest one 8.0 cm high, 3 fertile; NEREIDA0810 RD98, 4 colonies, largest one 8.4 cm high, one fertile; NEREIDA0810 RD99, 13 colonies, up to 8.5 cm high, some fertile; NEREIDA0810 RD100, 3 sterile colonies, largest one 9.0 cm high; NEREIDA0810 RD101, one sterile colony 9.1 cm high; NEREIDA0810 RD102, 2 colonies, largest one 7.8 cm high, one fertile; NEREIDA0810 RD103, 9 colonies, up to 18 cm high, some fertile; NEREIDA0810 RD104, 15 colonies, up to 28.7 cm high, some fertile. Description. Colonies up to 28.7 cm high, formed by a broad hydrorhizal mass supporting a polysiphonic stem, up to 3.0 mm wide proximally, thinning out to monosiphonic distally. Stem rigid, thick, erect. Ramification in one plane, profuse, up to the fourth order. Branches almost opposite, arising at slightly acute angles, long, polysiphonic for most of their length, slightly tapering distally. Stem deep brown basally and light brown distally; branches also light brown. Main axial tube on front of stem and branches, divided into short internodes, 550–600 µm long. Successive internodes each with one apophysis alternately right and left, giving rise to branches and hydrocladia. Three nematothecae surrounding the apophyses: one basal and two distal. Accessory tubes numerous, with neither hydrothecae nor nematothecae. Hydrocladia alternate, up to 1.2 cm long, divided into up to 15 thecate internodes by more or less well-marked transverse nodes. Internodes with 2–9 internal septa, one hydrotheca, and three one-chambered nematothecae. Hydrotheca as long as the internode, large, conical in lateral view and somewhat oval to round in cross-section, with depth/width at rim= 1.08–1.48 (n= 25). Intrathecal septum inconspicuous, very small, arising from the adaxial wall of hydrotheca and projecting forwards in its lumen. A characteristic abcauline median keel with a sharp, hollow tip, arising above mesial nematotheca; strong, large, laterally compressed, slightly curved, extending 332– 528 µm beyond level of hydrothecal margin, reaching end of mesial nematotheca of the following distal internode, or nearly so. Hydrothecal rim with 9–11 low cusps, including a small mesial tooth aligned with the keel. Mesial nematothecae extending for 1/3–1/2 the length of abaxial hydrothecal wall, slightly tapering distally, with wide aperture and crenulated rim, as well as a thickening of perisarc at its basis in the axil between the wall of the hydrotheca and the nematotheca; on first internode it is slightly displaced to one side. Lateral nematothecae arising from hydrocladium, partially attached to distal hydrothecal wall, with end slightly surpassing hydrothecal rim and crenulated margin. Phylactocarps forked (Y–shaped), segmented, up to 2.3 mm long, arising laterally from hydrothecal bases of proximal thecate internodes beside mesial nematotheca; not replacing nematotheca. Internal septa numerous. Segments short, carrying unpaired nematothecae with margin of aperture finely crenulated. Both branches with one terminal hydrotheca. Gonothecae borne on short pedicels, obovate, curved, arising singly from apophyses of stem and branches; aperture broadly oval to almost circular, latero-distal. Sex could not be ascertained. Remarks. This species is readily distinguished from others in the study area by the characteristic shape of its hydrothecae (Figure 2A–C). Especially noteworthy is the presence of a pronounced median hydrothecal keel with thickened perisarc. Its tip normally reaches the base of the mesial nematotheca of the following internode, and sometimes also approaches its end. The variability of this keel was discussed by Broch (1918). Aglaophenopsis 506 · Zootaxa 3737 (5) © 2013 Magnolia Press ALTUNA ET AL. bonnevieae (Jäderholm, 1909), sometimes sympatric with A. cornuta in Greenland and subarctic waters of the northwestern Atlantic (see Kramp 1932a; Schuchert 2001), likewise has a prominent, although somewhat less developed, hydrothecal keel. Moreover, its hydrotheca differs from that of A. cornuta in having a conspicuous intrathecal septum, and the hydrothecal rim is slightly crenulated rather than cusped. Paired nematothecae on the internodes of the main axial tube also occur in the upper axil of the apophyses rather than at its sides. Phylactocarps of A. bonnevieae also differ in being much more ramified and in having more hydrothecae. FIGURE 2. Aglaophenopsis cornuta (Verrill, 1879). A) Detail of a hydrocladium, including distalmost thecate internode. B) Hydrotheca. C) Phylactocarp; note the two distal hydrothecae, one on each branch. D) Detail of a phylactocarp showing mesial nematothecae adjacent to hydrothecae (arrows); one of them is double. E–G) Gonothecae, one of them (F) in lateral view showing curvature. Scale bar: A, C, E–G= 500 µm; B, D= 200 µm. A, E–G= NEREIDA0810 RD104; B= PLA07 L99; C, D= NEREIDA0710 RD79. AGLAOPHENIID HYDROIDS FROM THE NW ATLANTIC Zootaxa 3737 (5) © 2013 Magnolia Press · 507 TABLE 3. Aglaophenopsis cornuta (Verrill, 1879). Measurements (in μm) of colonies from different locations and sources. PLA07 L99 NEREIDA0810 RD104 Schuchert (2001) Colony Height (mm) 100 150 70 Hydrocladia Length of internode 752–900 810–923 --- Diameter at node 181–239 250–257 --- Hydrothecae Depth 703–794 834–860 500 Diameter at rim 380–416 380–426 300–400 Diameter at rim including the mesial tooth 550–616 588–600 --- Nematothecae Length of laterals 283–297 301–316 --- Diameter at level of terminal aperture 92–164 86–92 --- Length of mesial 328–378 294–340 --- Diameter of terminal aperture 62–70 65–70 --- Gonothecae Length --- 1200–1328 --- Maximal diameter in frontal view --- 512–606 --- Hydrothecae of A. cornuta somewhat resemble certain species of Gymnangium Hincks, 1874, including the European G. montagui (Billard, 1912) and others from South Africa (see Millard 1975). However, the ‘horn’ in such species of Gymnangium is a hypertrophied mesial nematotheca, while that of A. cornuta is a large median hydrothecal keel arising distal to the mesial nematotheca. The keel does not represent a highly modified median abcaulinar cusp of the hydrothecal margin because that cusp is both present and small. The margin of the median inferior nematotheca of the thecate internodes (and also of the terminal hydrothecae of the phylactocarp), is at times deeply indented in the middle, giving the impression of a twin theca (NEREIDA0710 RD79, Figure 2D). Colonies with gonothecae on stem apophyses, unprotected by any phylactocarps, were found in samples from some stations (NEREIDA0709 RD49). Although originally assigned to Cladocarpus, this species has also been referred to Aglaophenopsis by several authors. According to Fraser (1944), phylactocarps of this species represent a modified mesial nematophore. In our material, however, the phylactocarp arises laterally from the base of a hydrotheca borne on a proximal thecate internode. It is situated beside a clearly distinct mesial nematotheca and does not replace it. Moreover, contrary to Fraser, both branches of the phylactocarp bear a terminal hydrotheca. The species was assigned to Cladocarpus (as C. cornutus) by both Bouillon et al. (2006) and Schuchert (2012a). Observed depth range: 240–1885 m. The known maximum depth for the species is extended from 1200 m (Kramp 1932a) to 1885 m. A neritic-bathyal species (Calder 1997b). Fertile material. Collected in August 2006 (240–1233 m depth), June and July 2007 (460–878 m depth), August 2008 (392–1198 m depth), from May to August 2009 (425–1885 m depth), and from June to August 2010 (345–1353 m depth). Distribution. A North Atlantic species known from Denmark Strait (Broch 1918, ca. 253–603 m; Schuchert 2001, 200–700 m), eastern Greenland (Broch 1918, ca. 260–621), southwest Greenland at 63º36’N–55º15’W (1200 m) and 60º16’N–47º48’W (135 m) (Kramp 1932a), two stations in Bredefjord, south Greenland (Kramp 1932b, 310–330 m and 700 m), Davis Strait (Levinsen 1893, ca. 188–544 m; Kramp 1913, 700–1055 m; Broch 1918, ca. 544 m), western Greenland (Broch 1918, ca. 1095 m), Baffin Bay (Jäderholm 1909, ca. 731 m), 72°32’N–58°05’W (ca. 212 m), 60º27’N–48º31’W (Vervoort 1972, 326–366 m), 53°34’N–52°01’W (ca. 1792 m) and 52°25’N–52°12’W (ca. 296 m) (Jäderholm 1919), eastern Canada (Kindle & Whittaker 1917, ca. 365 m, based 508 · Zootaxa 3737 (5) © 2013 Magnolia Press ALTUNA ET AL. on literature records), off northeast Newfoundland, 51°22’30”N–50°31’30”W (Calder 1970, 457 m, as Cladocarpus cornutus), Flemish Cap, Flemish Pass, and Grand Banks (present study), Northeast Channel, south of Nova Scotia, at 42°02’N–65°36’W (Henry 2001; personal communication, 24.11.2012), off Sable Island on Banquereau (Verrill 1879, ca. 365 m, first description; Nutting 1900; Whiteaves 1901; Fraser 1918, 1944), east of Gloucester (Massachusetts) (Fraser 1944, ca. 310 m). Not recorded further south by Henry et al. (2008), but there is a recent southern record from 53º56’S–63º51’W (250 m) by El Beshbeeshy (2011). Cladocarpus diana Broch, 1918 (Figs. 1B, 3A–G, tables 1, 4, 9, 11–12) Cladocarpus Diana Broch, 1918: 87, fig. 47a–c. Cladocarpus diana: Vervoort 1966: 149.—Schuchert 2001: 138, fig. 118A–D.—Bouillon et al. 2006: 283. Material examined. FC07 L165, one fertile colony 7.0 cm high; FC07 L169, 3 fertile colonies, largest one 6.0 cm high; FC07 L171, one fertile colony 3.0 cm high; NEREIDA0509 RD15, 4 colonies, largest one 4.3 cm high, 3 fertile; NEREIDA0509 RD18, one fertile colony 4.7 cm high; NEREIDA0509 RD20, 5 colonies, largest one 5.8 cm high, 4 fertile; NEREIDA0609 RD36, one sterile fragment 1.5 cm high; NEREIDA0609 RD38, one sterile fragment 1.0 cm high; NEREIDA0610 RD62, 2 fertile colonies, largest one 2.7 cm high; NEREIDA0610 RD63, 2 fertile colonies, largest one 4.0 cm high, and a sterile fragment 1.4 cm high; NEREIDA0610 RD64, 3 colonies, largest 4.6 cm high, 2 fertile; NEREIDA0610 RD67, one fertile colony 5.0 cm high; NEREIDA0610 RD71, one sterile fragment 2.0 cm high. Description. Colonies up to 7.0 cm high and 2.5 cm wide, formed by a root-like hydrorhiza consisting of a tuft of tubules supporting a polysiphonic stem, thinning out to monosiphonic distally. Stem light brown, flaccid when out of liquid, 0.9 mm wide proximally and tapering distally; distal part sometimes slightly geniculated. No ramification. Main axial tube in front of stem and branches divided into 970–1200 µm long and 470–500 µm wide internodes by indistinct transverse nodes. Internodes with one apophysis more or less in middle, alternately right and left in successive internodes, giving rise to hydrocladia. Three nematothecae surrounding apophyses, one basal and two distal, one on each side. Accessory tubes scarce, parallel, with neither hydrothecae nor nematothecae. Hydrocladia up to 1.65 cm long, alternate, spaced, given off at slightly acute angles with stem and branches, divided into up to 12 thecate internodes by more or less well-marked transverse nodes. Internodes with 6–7 internal septa (occasionally absent), one hydrotheca, and three one-chambered nematothecae. Hydrothecae large, deep, shorter than corresponding cormidia, with almost parallel walls in side view, but widening distally in frontal view; long axis parallel to that of internode, with depth/width at rim= 2.07–2.28 (n= 25). Perisarc thin, with a longitudinal mesial thickening on abcauline side. Intrathecal septum arising from behind hydrotheca, projecting forwards into its lumen, very reduced, thin, frequently oblique. Hydrothecal rim at right angle with the segment, with 9–11 cusps separated by deep embayments. Cusps rounded, sometimes uneven, with first abcauline pair clearly less pointed than others and almost blunt distally (Figure 3C). Mesial nematothecae adnate to hydrotheca except on first internode, where there is a distinct gap between distal end of nematotheca and hydrothecal base. Aperture as wide as hydrotheca when seen frontally, rim smooth to sinuous, sometimes with an embayment in middle; distal end extending for 1/10–1/11 of adaxial hydrothecal wall. Lateral supra-calycine nematothecae arising oblique from hydrocladium, partially adpressed to distal hydrothecal wall, with aperture at level of hydrothecal rim; margin finely crenulated. Phylactocarps up to 4.4 mm long, arising singly on hydrocladia, laterally from base of hydrotheca of first cormidium. They are formed by a first small internode devoid of nematothecae, followed by a jointed antler-shaped branched structure arching over the gonothecae. Branches normally three (occasionally up to four), each with a single row of nematothecae and some internal septa. Nematothecae with wide apertures and finely crenulated margins. Gonothecae 1–2 on each phylactocarp, attached by a small pedicel to points of ramification; obovate and curved distally, with lateral aperture tilted towards phylactocarp. Sex could not be ascertained. Remarks. In material of the species described earlier, every phylactocarp divided dichotomously to form a structure of three branches (Broch 1918; Schuchert 2001). In some colonies examined here (NEREIDA0610 RD67), however, one of the branches may divide twice, resulting in a four-branch phylactocarp. AGLAOPHENIID HYDROIDS FROM THE NW ATLANTIC Zootaxa 3737 (5) © 2013 Magnolia Press · 509 TABLE 4. Cladocarpus diana Broch, 1918. Measurements (in µm) of colonies from different locations and sources. *) Inferred from drawings. FC07 L165 NEREIDA0610 NEREIDA0610 Broch Schuchert RD63 RD67 (1918)* (2001) Colony Height (mm) 70 14–40 50 --- 50 Hydrocladia Length of internode 1373–1600 1354–1430 1295–1460 1416 1314* Diameter at node 165–217 125–163 167–190 125 200* Hydrothecae Depth 1080–1194 1063–1106 1100–1134 983 1000 Diameter at rim 430–536 452–512 480–525 366 350 Nematothecae Length of laterals 226–242 201–217 190–206 150 200* Diameter at level of terminal aperture 81–96 87–100 75–95 66 114* Length of mesial 280–285 240–280 248–282 250 228* Diameter of terminal aperture ---- ---- ---- 250 257* Gonothecae Length 1118–1165 ---- 1035–1043 833 1071* Maximal diameter in frontal view 550–600 ---- 590–651 383 570* The margin of the median inferior nematotheca is highly varied, although its position in relation to the hydrotheca is decidedly regular. Sometimes it is almost even, as depicted by Broch (1918), but at times it is deeply indented in the middle, roughly leaving two symmetric lobes and giving the impression of a bifid theca. Transitions between the two extremes occur. In most aglaopheniid species from the study area, the mesial nematotheca tapers distally when seen frontally, with its end rather thinner than its base. However, in C. diana the distal end is much wider than its base, being equal to the contiguous part of the hydrotheca. The position of the centrally placed nematotheca on the internodes of the main tube varies. Normally, it is close to the apophysis, but sometimes the internodes are longer and the nematotheca is distant from it and is close to the proximal node instead (NEREIDA0610 RD63). One colony from this station is particularly delicate, having a thin stem and only a few accessory tubules, the hydrocladia are quite distant, and there are only a few phylactocarps. In addition, a colony from the Flemish Cap (FC07 L165), the largest known to date (7.0 cm high), has the longest internodes and deepest hydrothecae (Table 4). Broch (1918) observed hydrothecae on an outer branch of a phylactocarp, and regarded it as an abnormality. A similar observation was noted in one phylactocarp from NEREIDA0610 RD67. Nomenclaturally, the specific name diana applied to this hydroid is taken to be a personal name formed as a noun in apposition. As such, the original spelling, Cladocarpus diana (first published as Cladocarpus Diana), is correct. While the Fourth Edition of the International Code of Zoological Nomenclature (ICZN) recommends avoidance of personal names as nouns in apposition (Recommendation 31A) to avoid possible confusion over authorship of the accompanying generic name, changing the species-group name diana to dianae in this case would result in an incorrect subsequent spelling (ICZN Art. 33.3). Observed depth range: 600–1575 m. These are the shallowest and the deepest records, respectively, of the species, previously known only from European waters (south of Iceland) at depths of 1358–1504 m (Broch 1918). Fertile material. Collected in July 2007 (838–1216 m depth), June and July 2009 (1071–1575 m depth), and June 2010 (600–1486 m depth). Distribution. Previously known only from two stations south of Iceland (Broch 1918, ca. 1355–1504 m; Schuchert 2001). This is the first record of Cladocarpus diana in the western Atlantic, with collections from the Flemish Cap and the Beothuk Knoll. Present records also constitute the southernmost reports of the species. 510 · Zootaxa 3737 (5) © 2013 Magnolia Press ALTUNA ET AL.