This article was downloaded by:[Smithsonian Institution Libraries] On: 28 February 2008 Access Details: [subscription number 788752552] Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London WIT 3JH, UK % Marine Bialagy Research mrmp-iji ?jrsK ^t?jIp?elB Marine Biology Research Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t713735885 Glass sponges (Porifera, Hexactinellida) of the northern Mid-Atlantic Ridge Konstantin R. Tabachnick ^; Allen G. Collins ^ ^ P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia '^ National Systematics Laboratory of NOAA's Fisheries Service, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA Online Publication Date: 01 March 2008 To cite this Article: Tabachnick, Konstantin R. and Collins, Allen G. (2008) 'Glass sponges (Porifera, Hexactinellida) of the northern Mid-Atlantic Ridge ', Marine Biology Research, 4:1, 25 - 47 To link to this article: DOI: 10.1080/17451000701847848 URL: http://dx.doi.ora/10.1080/17451000701847848 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article maybe used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Marine Biology Research, 2OO85 4: 25^7 ORIGINAL ARTICLE Glass sponges (Porifera, Hexactinellida) of the northern Mid-Atlantic Ridge KONSTANTIN R. TABACHNICK^ & ALLEN G. COLLINS^ ^EP. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia, and ^National Systematics Laboratory of NOAA 's Fisheries Service, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA Abstract Glass sponges (Hexactinellida) collected under the framework of the MAR-ECO project on the G. O. Sars cruise to the northern Mid-Atlantic Ridge, between the Azores and the Reykjanes Ridge, and on the 49th cruise of Akademik Mstislav Keldysh to the Charlie-Gibbs Fracture Zone are described. Fourteen species were identified in the material. This relatively rich fauna includes several novel findings, indicating that the hexactinellid fauna of the northern Mid-Atlantic Ridge is poorly investigated. One genus, Dictyaulus, has never before been reported from the Atlantic Ocean. Two species belonging to the genera Heterotella and Amphidiscella are new to science. Two other species, Rossella nodastrella Topsent, 1915 and Doconestes sessilis Topsent, 1928, have been collected just one other time. Finally, a probable new genus of Euplectellidae, which unfortunately cannot be adequately described because of how small the specimens are, is represented among these collections. A large portion of dead, rigid skeletons of Euretidae and spicule mats of Rossellidae are also reported but not described in detail. Representation of some genera in the Charlie-Gibbs Fracture Zone, coupled with recent observations from elsewhere along the Mid-Atlantic mountain chain, suggests that this fauna is as similar to those of the Indian Ocean and Indo-West Pacific as it is to West or East Atlantic faunas. Key words: Hexactinellida, North Atlantic, Porifera Introduction Mid-ocean ridges are topologically and hydrographi- cally complex structures. Especially complex are transform faults, such as the Charlie-Gibbs Fracture Zone on the northern Mid-Atlantic ridge, where changes in depth are radical over small distances and two large adjacent transform faults serve as channels through which water is exchanged between the eastern and western Atlantic (Searle 1981; Calvert & Whitmarsh 1986; Saunders 1994; Belkin & Levitus 1996; Dobrolyubov et al. 2003). Given such a complicated nature of the region, it should be home to a diverse and interesting deep-sea fauna. This expectation has prompted recent biological investigations on the northern Mid-Atlantic Ridge, including the Charlie-Gibbs Fracture Zone area, within the framework of the international project MAR-ECO ('Patterns and Processes of the Ecosys- tems of the Northern Mid-Atlantic') (Bergstad 2002; Bartle 2003). Benthic animals were sampled on the ViMAkademik Mstislav Keldysh 49th cruise (2003) and the RV G. O. Sars MAR-ECO cruise (2004) (Bergstad & Gebruk 2008). Here we report on the hexactinellid sponges collected during these cruises. The hexactinellid fauna of the north Mid-Atlantic Ridge is thus far poorly investigated. Indeed, occur- rence data for hexactinellids is generally scant, limiting one's ability to make strong conclusions about biogeographic patterns. Nevertheless, our report contains several novel findings that are worth noting. Surprisingly, this fauna appears to have some connections with that of the Indo-West Pacific, sharing the presence of Saccocalyx pedunculata, though this species is broadly distributed. In addi- tion, two genera - represented on the north Mid- Atlantic Ridge by Dictyaulus sp. n. and Heterotella sp. n. [the latter genus was previously known in the Atlantic Ocean from a single record of H. pomponae (Reiswig 2000)] - are shared between this region and Correspondence: K. R. Tabachnick, P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Nakhimovsky Pr. 36, Moscow, 117997, Russia. E-mail: tabachnick@niail.ru Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark (Accepted 3 November 2007; Printed 18 February 2008) ISSN 1745-1000 print/ISSN 1745-1019 online ? 2008 Taylor & Francis DOI: 10.1080/17451000701847848 26 K. R. Tabachnick & A. G. Collins the Indo-West Pacific. On the other hand, a strong connection with the East Atlantic fauna (mainly described off the Azores) is obvious from records of such species as Farrea aff laniinaris, Rossella aff nodastrella and Doconestes aff sessilis. Typical ele- ments of the North Atlantic fauna were also present: Euplectella suberea, Hertwigia falcifera and Caulopha- cus (Caulophacus) arcticus. Finding complete specimens of Hertwigia falcifera, previously known only by fragments, clarifies its external shape and how it is constructed. We also document a very rare genus and species, Doco- nestes sessilis, previously known only from a single specimen. Material and methods On the G.O. Sars MAR-ECO cruise sponges were collected using a modified semi-commercial Otter trawl (the Campelen 1800 shrimp trawl) lined with a 5 mm mesh at the cod end. The trawl had an opening of 17 m x 12 m x4.5 m. In the MAR-ECO material sponges occurred at 11 stations (Table I). Specimens were preserved on board in 80? alcohol or dried. The collection of MAR-ECO sponges was examined during a 2-week visit to the Museum of Zoology, University of Bergen. In addition to the G.O. Sars material, sponges collected in the Charlie-Gibbs Fracture Zone on the 49th cruise of the By Akademik Mstislav Keldysh in 2003 using submersibles Mir-1 and Mir-2 were included in the present paper. Also included is one specimen from the Mid-Atlantic Ridge (the Azores area), stored in the Mus?um national d'Histoire naturelle, Paris. Abbreviations HM, Humboldt Museum (Berlin)^ lORAS, P.P. Shirshov Institute of Oceanology, Russian Academy Table I. MAR-ECO trawl stations on which sponges were sampled. of Sciences (Moscow); MNHN, Mus?um national d'Histoire naturelle (Paris); ZMBN, Museum of Zoology, University of Bergen. Species account Hexactinosida Schrammen, 1903 Euretidae Zittel, 1877 Chonelasma Schulze, 1886 Chonelasma choanoides Schulze & Kirkpatrick, 1910 (Table II) Material examined lORAS, Akademik Mstislav Keldysh, 49th cruise, St. 4535 (52?58'N, 35?1'W, depth 2156 m), cat. no. 5/2/ 3170, 5/2/3171, 5/2/3172. ZMBN, MAR-ECO St. 40/367, cat. no. 14948; St. 50/379, cat. no. 15433, 15444,15458; St. 62/380, cat. no. 15889.1,15889.2, 15889.3; St. 70/385, cat. no. 14794, 14850, 15248. Description Body: usually represented by fragments 1-7 mm in thickness. Three specimens (MAR-ECO cat. no. 14794, 14850 and 15444) tubular, everted cones 80-300 mm long, 35-180 mm in diameter in the upper part with walls 207 mm in diameter. Three other specimens (MAR-ECO cat. no. 15889) at- tached inside a dead part of large specimen of Hertwigia falcifera, tubular, stout and curved, 60-120 mm long, 12-18 mm in diameter with walls 2-2.5 mm in thickness. Spicules: rigid framework typical for the species. Loose spicules dermal and atrial pentactins, unci- nates, scopules of two types (small and mediate, statistically distinguishable from each other), spiny hexactins and various microscleres: oxyhexa- ctins predominate over the other rare types: hemioxyhexasters, oxyhexasters, onychohexactins. Super Trawl Sampling location Trawling depth (m) Areas sampled station station Date Latitude Longitude Mean Max. Min. North of the Azores 40 367 7 July 2004 42?55'N 30?20'W 2961 2968 2954 46 372 11 July 2004 42?46'N 29?16'W 3031 3050 3005 50 373 12 July 2004 43?01'N 28?33'W 2600 2607 2593 South-east of Charlie-Gibbs Fracture Zone 56 378 17 July 2004 5r45'N 29?33'W 1916 1950 1872 60 379 19 July 2004 5r33'N 30?18'W 1263 1296 1237 62 380 20 July 2004 51?55'N 30?25'W 1910 1959 1872 65 382 23 July 2004 52?16'N 31?00'W 753 979 607 North-west of Charlie-Gibbs Fracture Zone 66 383 24 July 2004 53?01'N 33?36'W 3030 3071 2995 68 384 25 July 2004 53?08'N 34?46'W 2350 2374 2306 70 385 26 July 2004 52?58'N 34?52'W 1650 1670 1630 72 386 27 July 2004 53?16'N 35?31'W 2548 2567 2522 Glass sponges of northern Mid-Atlantic Ridge 27 0 yi >i ra S 00 00 in ?-H O u w d ^ ? ? z CQ ;? c N 1 c 0 yi ? ? fTl a c-- .g fTl cl d o ?n un o ?g Co ^ os (U ? s ?? 1) N 3 .13 u IZl s c ?? S a a Q .^ (j ? ? O MH o ? S T3 - ?* ?* ^o _ a a M 2 fi ? -g T3 .S .9 3 ? c o. 3 o,. S 8 t? ^ a ? ? t? 3 A a ? 3 .2 3 S T3 t? o .t? rt? O .t? X! t? ^ B ? B 3 3 13 es cd -o ?? a ? o o .3 O O OJ cd O? t? a .3 iyytit J,JJ,JJJJ0 .t? XI o Q -a Q o t? hemionychohexactins, discohexactins and hemidis- cohexasters. Most significant measurements given in Table II. Remarks Unlike other specimens of C. choanoides the new ones have some peculiarities which are entirely within the dimensions of various specimens from the North Atlantic reported by Reiswig & Mehl (1994); the scopules are not distinguishable into two types. Further, unlike the specimen from the Wed- dell Sea Qanussen et al. 2004), the specimens from the North Atlantic have no large discoscopules. Farreidae Gray, 1872 Farrea Bowerbank, 1862 Farrea aff. latninaris Topsent, 1904 (Figure 1; Table III) Material examined ZMBN, MAR-ECO St. 70/385, cat. no. 14836. Description Body: sponge represented by several small and poor quality fragments of wall composed of one or two dictyonal farreoid layers. Loose spicules: dermalia and atrialia pentactins with spiny rays, uncinates of common size and shape, clavules of one type with pileate heads and rough shafts. Microscleres: discoidal and oxyoidal microscleres in the forms of hexasters, hemihexasters (with two, sometimes three secondary rays) and hexactins. Among discoidal microscleres, hemidiscohexasters and discohexactins more numerous than discohexa- sters. Among oxyoidal microscleres, oxyhexasters and hemioxyhexasters prevail; oxyhexactins very rare. Remarks The newly found sponge is similar to F. laminaris Topsent, 1904 (redescribed by Topsent in 1928) off the Azores but there are some differences. In the new specimen, there is an absence of two types of discohexasters, large and small (with four or five secondary rays). Thus, this sponge may represent a new subspecies. However, the poor condition of the specimen prevents it from being assigned holotype status. Furthermore, the insufficient original de- scription and our inability to examine bona fide specimens of F. laminaris prevent a proper compar- ison (for instance Topsent called discohexactins discohexasters, probably because he considered the former to be derivatives of the latter). 28 K. R. Tabachnick & A. G. Collins Farrea sp. (Figure 2) Material examined ZMBN, MAR-ECO St. 70/385, cat. no. 15542. Description Body: small ovoid specimen about 2 mm in dia- meter, dried after capturing. Framework: irregular skeleton with meshes 0.07- 0.17 mm, usually triangular or rectangular, com- posed of rough beams 0.008-0.015 mm in diameter. Some hexactins with smooth rays about 0.045/0.002 mm fused with this framework. Loose spicules: uncinates 0.6-0.7/0.011-0.015 mm. Clavules represented by several fragments with slightly cl?vate heads and no discs, head diameter exceeds 0.2 mm, whereas ray diameter about 0.002 mm. Dermalia rough pentactins with conically pointed outer ends, tangential rays 0.144-0.303 mm (n =25, mean =0.222 mm, standard deviation (SD) =0.043 mm), proximal ray 0.085-0.185 mm (n =5, mean = 0.144 mm, SD =0.036 mm); diameter of rays 0.011-0.014 mm. Microscleres: hemidiscohexasters prevail; 0.029- 0.052 mm in diameter (n=25, mean =0.043 mm, SD =0.007 mm) with primary ray 0.004-0.011 mm long; one or two rays not branching and two, rarely three, secondary rays). Discohexasters 0.036-0.061 mm in diameter (n=8, mean =0.048 mm, SD =0.008 mm) with primary rosette 0.017- 0.023 mm in diameter (n=8, mean =0.017 mm, SD = 0.004 mm). A-B C-K Figure 1. Spicules o? Farrea ?ff. laminaris Topsent, 1904 (cat. no. 14836). (A, B) Dermal/atrial pentactins; (C) uncinate; (D, E) clavules; (F) discohexactin; (G) hemidiscohexaster; (H) discohexaster; (I) oxyhemihexaster; Q) oxyhexaster; (K) oxyhexactin. Glass sponges of northern Mid-Atlantic Ridge 29 Table III. Spicule dimensions of Farrea laminaris Topsent, 1904 (in mm). From Topsent (1928) ZMBN MAR-ECO 14836 Mean Min. Max. Mean Min. Max. SD L dermal/atrial pentactin tangential ray L dermal/atrial pentactin unpaired ray L discoclavule D width of disc of discoclavule L of disc of discoclavule D large discohexaster D discohexaster d discohexaster D hemidiscohexaster D discohexactin D oxyhexaster d oxyhexaster D hemioxyhexaster D oxyhexactin 0.060 0.140 0.210 0.200 0.280 0.130 0.140 0.070 0.090 25 25 23 25 25 12 12 25 25 24 24 16 3 0.165 0.209 0.260 0.006 0.012 0.086 0.034 0.095 0.106 0.085 0.031 0.092 0.082 0.123 0.132 0.112 0.003 0.006 0.062 0.022 0.073 0.078 0.073 0.025 0.073 0.067 0.224 0.274 0.331 0.008 0.020 0.106 0.045 0.134 0.126 0.106 0.039 0.118 0.101 0.023 0.031 0.039 0.002 0.003 0.013 0.007 0.016 0.014 0.010 0.004 0.012 0.017 L, length; D, diameter; d, diameter of primary rosette. Remarks The specific identification of this specimen is impossible due to its small size and absence of a proximally collected adult. The presence of un- developed clavules similar to that described for newly settled Farrea sollasii off Japan (Okada 1928) leave little doubt that it is a representative of Farrea. 1887; Topsent 1892) or onychohexasters (onycha- sters in Topsent 1904). Floricomes and oxyhexa- sters as microscleres were also reported by Boury- Esnault et al. (1994). The atrial pentactins are very rare as mentioned by Schulze (1887) and they should perhaps be referred to choanosomal spi- cules. If so, specific atrial spicules are absent in this species. Lyssacinosida Zittel, 1877 Euplectellidae Gray, 1867 Euplectellinae Schulze, 1876 Euplectella Owen, 1841 Euplectella suberea Thomson, 1877 (Table IV) Material examined ZMBN, MAR-ECO St. 46/372, cat. no. 14878; St. 50/373, cat. no. 15150 (three specimens), 14976. Euplectella gibbsa sp. nov. (Figures 3, 4; Table V) Holotype: ZMBN, MAR-ECO St. 68/384, cat. no. 14401. Material examined Type 0? E. nobilis Schulze, 1904 (one of two speci- mens marked as type, another is HM 5449 and contains many fragments): HM 4392, Valdivia, St. 33. Description Body: sponges of tubular shape typical for the species, 90-210 mm high, 20-23 mm in diameter. Spicules: most important spicule measurements given in Table IV. Principal choanosomal spicules pentactins; most numerous choanosomal spicules tauactins; stauractins, paratetractins and pentactins (the latter not common). Remarks The microsclere content is very simple in the investigated specimens: no discohexasters (Schulze Description Body: sponge represented by the lower part of a considerably larger individual; diameter at the lower part at least 70 mm; entire length of the fragment 300 mm, of which basalia are about one-third. Walls thin, 1.5-2 mm in thickness, and composed of circular (inner) and longitudinal (outer) beams with no synapticular fusions. Lateral oscula irregu- larly situated between the square meshes of the beams; appear as numerous openings 1-1.5 mm in diameter. Spicules: principalia mostly stauractins (rarely, may be pentactins); rays 0.03-0.11 mm in diameter and 3-16 mm long when straight, longitudinally 30 K. R. Tabachnick & A. G. Collins 0.1 mm A-H Figure 2. Spicules o? Farrea sp. (cat. no. 15542). (A, B) Dermal pentactins; (C) uncinate; (D, E) young clavules; (F) hemidiscohexaster; (G) discohexaster; (H) oxyhexactin attached to a framework. directed^ curved rays, circularly directed 8-36 mm long with smooth, conically pointed outer ends. Most numerous choanosomal spicules tauactins, some paratetractins, stauractins and rare diactins. Un- paired ray of the tauactins shortest, about 0.5 mm long, long rays about 3 mm long with a diameter of 0.01-0.02 mm, their outer ends rounded or conically pointed, rough. Basalia long spicules with spiny shafts 0.014-0.023 mm in diameter and four-teeth anchorate heads, spicular centre situated some dis- tance from head about 0.06 mm long and 0.05 mm in diameter. Dermal hexactins with conically pointed, rough outer ends and distal ray carrying some spines. Distal ray of dermal hexactins 0.090-0.227 mm long, tangential rays 0.148-0.291 mm, proximal ray 0.336-0.924 mm^ diameter of rays 0.006-0.007 mm. Atrial pentactins with rays similar to dermal hexactins. Tangential rays of atrial pentctins 0.154- 0.447 mm long, distal ray 0.174-0.646 mm long, diameter of rays 0.007-0.009 mm. Microscleres: microscleres floricomes, oxyhexa- sters and graphiocomes. Floricomes with second- ary rays having three or four teeth, 0.123-0.151 mm in diameter^ primary rosette 0.014-0.028 mm in diameter. Graphiocomes reconstructed to be 0.403-0.504 mm in diameter with primary rosette 0.012-0.024 mm in diameter. Oxyhexasters with slightly curved secondary rays two or three (rarely four or five) in number, 0.095-0.174 mm in diameter, primary rosette 0.011-0.025 mm in diameter. Etymology The name of the species is given in connection with the location of this sponge in the Charlie-Gibbs Fracture Zone. Glass sponges of northern Mid-Atlantic Ridge 31 ?1 o U W O U W CQ O U W C? CQ 0 in o o o o o o o o o o o o en o o o o O o o o o o o o [2 o 00 O 00 00 (N O S o o en o o o o o o o o o o o o o o o TI en o IN CO CO CO 00 00 !N O 00 !N O O O ^ O o o o O o o c^ CO o O IN (N IN !N o O o 00 o o o o o O O O o o o o o o O) ?1 O 00 IN IN 00 00 m q in o q O O O O o r- iri i-H o o o o o o in iri iTi iri iTi iri oo-^oooooooo ooooooooooo ooooooooooo r-ovc^'-Hc^iniri?Niriiriiri CTv Ov o in CO i> O o -H o o o o o o d d d d d d d d d IN CO IN CO o CO 0^ CO in 00 00 o m 00 00 o o o ^ o o o o o o 00 IN CO CO IN o o CT. O o o CT O o O o o o o O o O o CO CO IN IN CO IN CO 00 CO CO CO !N CO IN in !N O IN m !N O o o o o o o >, B ? ? 5 a M >< c 2 2 a .S .9 o u P? cu X X CJ lU J3 .13 "rt Id S a ?s t? w 2 ^ ? ? 2 'B ^ S 8 ?% ?g.2 ^ O I4-. >i 0 0 W lU a V lU OJ lU ?3 ? "O T? X? cu cu J J J J J >, ? y lU " S a 2 ? c 5 ra 2 a 'c: -r ??, -S ?3 a? c = o J J Q T3 Q T3 g os e o a ?O o? a os ?3 O i Figure 3. Euplectella gibbsa sp. nov., holotype, lateral view. Scale bar: 50 mm. Remarks The numerous species of the genus Euplectella are separated into four main groups by the construc- tion of their principal skeleton: (1) mainly staur- actins; (2) mainly hexactins with a reduced proximal ray and some stauractins; (3) pentactins and some hexactins; (4) stauractins, hexactins, hexactins with a reduced proximal ray and hex- actins with two reduced rays (proximal and distal), tauactins and diactins (K.R. Tabachnick, D. Janus- sen & L. L. Menshenina, unpublished data). The new species should be referred to the first group without hesitation; most of these sponges have notable secondary silica deposition (as in E. asper- gillum), making the sponge rigid, at least in the lower part of the body. Only four species from this group have no fusion of the spicules: (1) E. marshalli Ijima, 1895; (2) E. oweni Herklots & Marshall, 1868; (3) E. curvistellata Ijima, 1901; and (4) E. nobilis Schulze, 1904. The first three are similar species known off Japan, whereas the fourth is found in the Atlantic, off the coast of Africa. The new species looks to be close to E. nobilis, but there are several differences. E. gibbsa has no sigmato- comes and its hexasters are larger (see Table V). Furthermore, the pinular rays of dermal hexactins are spindle-like in E. nobilis and stout with a smaller number of spines in E. gibbsa. Malacosaccus Schulze, 1886 Malacosaccus aff. heteropinularia Tabachnick, 1990 (Figure 5) Material examined ZMBN, MAR-ECO St. 72/386, cat. no. 15178. 32 K. R. Tabachnick & A. G. Collins 0.5 mm 0.2 mm 0.05 mm A-E G-K Figure 4. Spicules of Euplectella gibbsa sp. nov., holotype (cat. no. 14401). (A) Dermal hexactin; (B) atrial pentactin; (C) anchor; (D) choanosomal tauactin; (E) its outer end; (F) large choanosomal stauractin (principalia); (G) oxyhexaster; (H-J) floricome and its outer ends; (K) graphiocome. Description Body: specimen incomplete lower part of the bodyi peduncle about 260 mm long and 5 mm in diameter, including tuft of basalia about 30 mm in diameter and remnants of the funnel-like body about 40 mm long. Spicules: spicules of peduncle and basal tuft typical for all species of Malacosaccus, anchors and tauactins. Choanosomal spicules of the funnel-like body tauactins, stauractins, paratetractins and pen- tactins with conically pointed, rounded smooth, or rarely rough outer ends; rays about 2.5/0.008 mm. Dermalia and atrialia hexactins with ray directed outside the body rough or pinular, spindle-like or cl?vate in shape; other rays with conically pointed smooth outer ends; ray directed outside wall 0.101- 0.286 mm long (n = 17; mean =0.237 mm, SD = 0.051 mm); tangential rays 0.199-0.277 mm (n = 12; mean =0.239 mm, SD =0.022 mm); ray direc- ted into the wall about 0.672 mm long; diameter of rays 0.011 mm, with widened cl?vate rays directed outside the body up to 0.022 mm in diameter. Microscleres: mostly floricomes, rarely possible to find discohexasters similar to floricomes in shape, some oxyhexasters, oxyhemihexasters and oxyhexactins. Floricomes 0.067-0.112 mm in dia- meter (n =25, mean =0.077 mm, SD =0.010 mm) with primary rosette 0.011-0.022 mm in diameter (n=25, mean =0.018 mm, SD =0.002 mm); four to seven secondary rays with three or four very short teeth. Discohexasters 0.090-0.146 mm in diameter (n=4, mean =0.104 mm, SD =0.028 mm) with primary rosette 0.017-0.018 mm in diameter (n=4, mean =0.017 mm, SD =0.001 mm); outer ends have very fine teeth so it is also possible to call them onychoidal. Oxyoidal micro- scleres 0.073-0.123 mm in diameter (n = 14, mean =0.098 mm, SD =0.016 mm), having curved rays up to two in number; primary rosette in oxyhexaster 0.017-0.025 mm in diameter (n = ll, mean =0.020 mm, SD =0.004 mm). Glass sponges of northern Mid-Atlantic Ridge 33 Table V. Spicule dimensions of Euplectella gihbsa, sp. nov. and E. notais Schulze, 1904 (in mm). E. nobilis HM 4392, type E. gihbsa ZMBN MAR-ECO 14 401 n Mean Min. Max. SD n Mean Min. Max. SD L dermal hexactin distal ray 30 0.142 0.107 0.244 0.032 49 0.159 0.090 0.227 0.034 L dermal hexactin tangentia ray 28 0.231 0.174 0.307 0.037 45 0.212 0.148 0.291 0.035 L dermal hexactin proximal ray 21 0.639 0.392 0.862 0.123 35 0.512 0.336 0.924 0.085 L atrial pentactin tangential ray 25 0.192 0.148 0.233 0.027 16 0.226 0.154 0.447 0.085 L atrial pentactin distal ray 23 0.632 0.400 0.851 0.126 16 0.418 0.174 0.646 0.137 D floricome 24 0.097 0.059 0.118 0.020 25 0.134 0.123 0.151 0.008 d floricome 24 0.021 0.015 0.026 0.002 25 0.020 0.014 0.028 0.003 D sigmatocome 18 0.070 0.052 0.104 0.011 d sigmatocome 18 0.017 0.015 0.022 0.002 D oxyhexaster 26 0.098 0.074 0.118 0.010 25 0.153 0.095 0.174 0.017 d oxyhexaster 26 0.016 0.009 0.022 0.003 25 0.020 0.011 0.025 0.004 D graphiocome 5 0.374 0.326 0.414 0.035 9 0.453 0.403 0.504 0.029 d graphiocome 8 0.020 0.015 0.023 0.003 25 0.021 0.012 0.024 0.002 L, length; D, diameter; d, diameter of primary rosette. Remarks As in the type, the new specimen of M. heteropinu- laria has small floricomes with short teeth at their secondary rays. But unlike it, oxyoidal microscleres have very thin rays, and spiny hexactins with equal rays were not found. While subspecific status could ? fl ~]r- F GH 0.1 mm A-H 0.05 mm I-J 0.02 mm K-N 0.01 mm O Figure 5. Spicules o?Malacosaccus aff. heteropinularia Tabachnick, 1990 (cat. no. 15178). (A, B) Dermal/atrial hexactins; (C) choanosomal tauactin; (D) choanosomal stauractin; (E) choanosomal paratetractin; (F) choanosomal pentactin; (G, H) outer ends of choanosomal spicules; (I) oxyhexaster; Q) oxyhexactin; (K) discohexaster; (L-O) floricome and its outer ends. 34 K. R. Tabachnick & A. G. Collins be assigned to this specimen, its poor condition and small amount of dermal and atrial hexactins and oxyhexasters do not allow us to do so. Two other species of Malacosaccus common in the North Atlantic in adjacent areas, M. unguiculatus Schulze, 1886 and M. floricomatus Topsent, 1901, differ in their microscleres. M. unguiculatus has floricomes with large teeth, discohexasters and oxyhexasters with secondary rays more than two at each principal. M. floricomatus has floricomes with large teeth and large true discohexasters with easily recognizable discs. (n=25, mean =0.025 mm, SD =0.003 mm); length of the umbel 0.006-0.010 mm (n=25, mean =0.008 mm, SD =0.001 mm); diameter of the umbel 0.006-0.010 mm (n=25, mean =0.008 mm, SD =0.001 mm). Staurodiscs larger than amphidiscs, 0.036-0.043 mm in diameter (n=2, mean =0.040 mm, SD =0.005 mm), but umbels very similar; umbel length 0.005-0.007 mm (n=2, mean =0.006 mm, SD =0.001 mm); umbel dia- meter 0.008 mm (n =2, mean =0.008 mm, SD =0 mm). Bolosominae Tabachnick, 2002 Amphidiscella Tabachnick & L?vi, 1997 Amphidiscella atl?ntica sp. nov. (Figures 6, 7) Holotype: ZMBN, MAR-ECO St. 72/386, cat. no. 15192. Description Body: funnel-like, 40 mm high and 55 mm in diameter in the upper part of the body, walls 7-8 mm thick; peduncle long, at least 90 mm (broken, basal portion absent) and thin, 2.5 mm in diameter. Spicules: choanosomal spicules mostly diactins, sometimes tauactins, stauractins and pentactins. Diactins, 0.9-1.5/0.002-0.008 mm, with four rudi- mental tubercles in the middle or a widening; outer ends rough and rounded. Spicules of the peduncle diactins fused to each other by secondary silica deposition, diameter 0.011-0.025 mm. Der- malia and atrialia as hexactins with rays 0.014- 0.017 mm in diameter; outer ends of rays are rough, cl?vate, rounded or conically pointed. Distal ray of dermal hexactins 0.057-0.135 mm (n=9, mean =0.087 mm, SD =0.026 mm); tan- gential rays 0.220-0.369 mm (n = ll, mean = 0.282 mm, SD =0.045 mm); proximal ray 0.511 mm (n = l). Proximal ray of atrial hexactin 0.163- 0.383 mm (n=29, mean =0.244 mm, SD =0.053 mm); tangential rays 0.483-0.781 mm (n=20, mean =0.661 mm, SD =0.089 mm); distal ray 0.518-1.491 mm (n=7, mean =0.980 mm, SD =0.370 mm). Microscleres: only three types found: sigmato- comes, amphidiscs and staurodiscs. Sigmatocomes 0.319-0.426 mm in diameter (n=25, mean = 0.356 mm, SD =0.031 mm); primary rosette 0.020-0.028 mm in diameter (n=25, mean = 0.024 mm, SD =0.003 mm). Amphidisc shape typical for the genus with two rudimentary tuber- cles in the middle; total length 0.017-0.029 mm Remarks The new species differs from A. caledonica Tabach- nick & L?vi, 1997 and A. nionai Tabachnick, 1997 by absence of floricomes and branching rays in Figure 6. Amphidiscella atl?ntica sp. nov., holotype, lateral view. Scale bar: 40 mm. Glass sponges of northern Mid-Atlantic Ridge 35 F-G A-D M 0.05 mm H-M Figure 7. Spicules of Amphidiscella atl?ntica sp. nov., holotype (cat. no. 5192). (A-D) Dermal/atrial hexactin and their outer ends; (E, F) choanosomal diactin and its central part; (G) a fragment of the peduncle; (H) sigmatocome; Q, L) amphidiscs; (M) staurodisc. discoidal spicules. As in A. monai, the new species has sigmatocomes. A. atl?ntica is very similar in spicule combination to the specimen taken off the Falkland Islands mentioned by Tabachnick (2002), differing only in spicule measurements and the presence of rare large discoidal spicules. Description Body: sponge represented by a large portion of the wall. Spicules: choanosomal spicules as diactins, rare hexactins and stauractins. Dermal or atrial hexac- tins (in other specimens of 5. pedunculata they are not distinguishable from each other) with pinular ray slightly widening in the middle or towards the distal end (as in the type specimen, specimens in the North Atlantic, and some in the middle Pacific); length of pinular ray 0.140-0.412 mm (n = 14; mean =0.262; SD =0.081); tangential rays 0.120-0.308 mm long (n = 15; mean =0.209; SD = 0.054 mm); ray directed inside the body 0.148- 0.798 mm long (n = 14; mean =0.455; SD = 0.151 mm). Microscleres: specimen with complete set of microscleres typical for the species. Spirodiscohexa- sters 0.090-0.151 mm in diameter (n = 15; mean = 0.119; SD =0.019) with primary rosette 0.010- 0.017 mm in diameter (n = 15; mean =0.012; SD =0.002 mm). Anchorate discohexasters 0.050- 0.140 mm in diameter (n = 15; mean =0.071; SD =0.028 mm) with primary rosette 0.010- 0.014 mm in diameter (n = 15; mean =0.012; SD =0.001 mm). Drepanocomes 0.106-0.230 mm in diameter (n = 15; mean =0.193; SD = 0.035 mm) with primary rosette 0.011-0.017 mm in diameter (n = 15; mean =0.013; SD =0.002 mm). Plumicomes 0.045-0.084 mm in diameter (n = 14; mean =0.055; SD =0.012 mm) with pri- mary rosette 0.011-0.017 mm in diameter (n = 15; mean =0.020; SD =0.003 mm). One plumicome with only two primary rays. Remarks The spicules are typical for 5. pedunculata and they do not differ from other specimens in their measure- ments (see Tabachnick 2002). Bolosominae gen. sp. indet. (Figure 8; Table VI) Material examined ZMBN, MAR-ECO St. 70/385, cat. no. 15556, 15570, 15584, 15598, 15612, 15626. Saccocalyx Schulze, 1895 Saccocalyx pedunculata Schulze, 1895 Material examined ZMBN, MAR-ECO St. 65/382, cat. no. 14906. Description Body: specimens as small ovoid sponges 1.5-2 mm high and 1-1.5 mm in diameter. All dried and attached to a large dead skeleton of Herwigia falcifera. Atrial cavity is suspected because of the presence of specific marginalia oscularia. 36 K. R. Tabachnick & A. G. Collins Figure 8. Spicules of Euplectellidae/Bolosominae gen. sp. (A-K, M, N) Cat. no. 15584; (L) cat. no. 15570. (A) Dermal stauractin; (B) dermal pentactin; (C) dermal? stauractin of prostalia oscularia (marginalia); (E) basal diactin; (F, G) choanosomal diactins; (H- J) large discohexactins; (K) microdiscohexactin; (L) microhemi- discohexaster; (M) graphiocome; (N) spherical microdiscohexa- ster with numerous secondary rays. Spicules: choanosomal spicules are diactins 1/ 0.007 mm with a widening or four rudimental tubercles in the middle; outer ends rough, rounded or conically pointed. Basalia as diactins with rounded or cl?vate outer ends; distal ray short, 0.08-0.27 mm long; proximal ray 0.76-0.99 m long with diameter about 0.005 mm. Prostalia oscularia (=prostalia marginalia) as stauractins with one short ray directed upwards (probably above the osculum), 0.05-0.06 mm long rough and rounded; three other rays equal in size and shape to that of dermal pentactins and stauractins. Dermalia are pentactins and the rare stauractins with spiny conically pointed outer ends; tangential rays 0.091-0.327 mm long; proximal ray in pen- tactins 0.190-0.494 mm long, with diameter 0.011-0.013 mm. Microscleres: several discoidal types: large and small discohexactins, small hemidiscohexasters spherical discohexasters with numerous secondary rays and graphiocomes. Large discohexactins 0.079-0.227 mm in diameter. Small discohexactins 0.023-0.043 mm in diameter. Hemidiscohexasters similar to small discohexactins with one or two rays branching; observed in only one specimen (cat. no. 15570) in low numbers; diameter 0.029- 0.036 mm, with primary ray 0.005 mm long. Spherical discohexasters with numerous secondary rays 0.025-0.032 mm; diameter of the primary rosette 0.007-0.016 mm. Graphiocomes 0.083- 0.234 mm; diameter of the primary rosette 0.011-0.020 mm. Remarks These sponges are doubtless representatives of Lyssacinosida, and their possession of graphiocomes suggests that they belong to Euplectellidae. Further attribution to any valid genus of Euplectellidae is impossible because their microsclere composition is not similar to any of the previously known genera. These sponges appear to represent a new genus, but they are very small and thus it is premature to formally describe a new genus based on this material. Presence of diactins as basalia raise the possibility that these sponges are part of the subfamily Corbi- tellinae but it is more likely that they are developing a peduncle and the attribution of this sponge to Bolosominae, as it is suggested here, is more reliable. Besides the peculiarities in their microsclere compo- sition, these sponges represent the first known newly settled representatives of Euplectellidae, which war- ranted their careful description. Corbitellinae Gray, 1872 Dictyaulus Schulze, 1895 Dictyaulus marecoi sp. nov. (Figures 9 and 10; Table VII) Holotype: ZMBN, MAR-EGO St. 70/385, cat. no. 15220. Paratype: ZMBN, MAR-ECO St. 62/380, cat. no. 15889. Description Body: typical 'Venus-flower basket' form. Holotype represented by upper part of the body, 160 mm high, broken close to the basal part, with maximum diameter of 70 mm and osculum of 50 mm in diameter, covered with a colander-like sieve-plate. Paratype represented by lower part of the body, situated inside a dead fragment of Hertwigia falci- fera; 60 mm long and 25 mm in diameter, with a Glass sponges of northern Mid-Atlantic Ridge 37 Table VI. Spicule dimensions of Bolosominae gen. sp. (in mm). ZMBN MAR-ECO 15 584 ZMBN MAR-ECO 15 570 n Mean Min. Max. SD n Mean Min. Max. SD L dermal pentactin/stauractin 25 tangential ray L dermal pentactin proximal ray 2 D large discohexactin 22 D small discohexactin 4 D hemidiscohexaster D discohexaster with numerous 5 secondary rays d discohexaster with numerous 5 secondary rays D graphiocome 25 d graphiocome 25 0.248 0.091 0.296 0.046 0.247 0.129 0.418 0.204 0.185 0.112 0.227 0.032 0.036 0.034 0.038 0.002 0.030 0.025 0.032 0.003 0.014 0.011 0.016 0.003 0.162 0.108 0.234 0.024 0.016 0.014 0.020 0.002 25 0.233 0.137 0.327 0.051 9 0.338 0.190 0.494 0.121 25 0.148 0.079 0.198 0.029 25 0.034 0.023 0.043 0.006 3 0.033 0.029 0.036 0.004 5 0.027 0.025 0.029 0.002 0.008 0.007 0.011 0.002 13 13 0.127 0.083 0.013 0.011 0.173 0.021 0.016 0.002 L, length; D, diameter; d, diameter of primary rosette. bottom-plate similar in structure to the wall. Walls thin, about 2-A mm in thickness; constructed of oblique (exterior), longitudinal (mediate), and cir- cular (interior) beams. Lateral oscula numerous, rather regular in distribution, \?^ mm in diameter. Sieve-plate irregular, usually triangular and rectan- gular openings 2-A mm across. Choanosomal spicules mostly loose; some fusions only in the lower part of the body. Spicules: choanosomal spicules mainly staurac- tins and diactins, some tauactins, rare pentactins and paratetractins; rays 0.4-13/0.003-0.1 mm in length with conically pointed or sometimes rounded outer ends smooth in thick spicules and rough in thin ones. Diactins are thinner, 0.003- 0.040 mm in diameter, with a widening or four rudimental tubercles in the middle. Spicules of the sieve-plate as in other representatives of Euplectel- lidae, often with curved and unequal rays; propor- tion of small hexactins notably larger than among choanosomal spicules which construct lateral wall. Dermal spicules as hexactins with rays equal in shape being smooth, stout and conically pointed, rarely distal ray cl?vate and slightly rough; distal ray 0.107-0.391 mm; tangential rays 0.089-0.518 mm; proximal ray 0.107-0.781 mm; diameter of rays 0.004-0.011 mm. Atrialia likely to be entirely absent. Microscleres: floricomes, drepanocomes, spiny microhexactins and pileate discohexasters common in both specimens. Anchorate discohexasters ob- served in the holotype only but they look to have autochthonic origin because such spicules are known in other species of the genus and no sponges which may have such spicules were col- lected at the station from which the holotype was collected. Floricomes 0.095-0.118 mm in diameter with primary rosette 0.011-0.024 mm; secondary rays with three to five teeth. Drepanocomes 0.078- 0.126 mm in diameter with primary rosette 0.011- 0.022 mm. Microhexactins with relatively short spines, 0.174-0.314 mm in diameter. Pileate dis- cohexasters with many secondary rays terminating Figure 9. Dictyaulus marecoi sp. nov., holotype, lateral view. Scale bar: 50 mm. 38 K. R. Tabachnick & A. G. Collins A-L M-U Figure 10. Spicules of Dictyaulus marecoi sp. nov., holotype (cat. no. 15889). (A, B) Dermal hexactins; (C) choanosomal hexactin; (D) choanosomal pentactin; (E) choanosomal stauractin; (F) choanosomal tauactin; (G-L) choanosomal diactins (their central parts and outer ends); (M, N) spiny hexactins; (O-R) floricome and its outer ends; (S) drepanocome; (T) anchorate discohexaster; (U) spherical discohexaster with numerous secondary rays. in very small discsi diameter 0.034-0.078 mm^ diameter of the primary rosette 0.011-0.028 mm. Anchorate discohexasters with few, two to four, secondary raysi diameter 0.078-0.134; diameter of primary rosette 0.017-0.022 mm. Etymology The species is named after the MAR-ECO expedi- tion. neither large discohexasters, as in D. elegans, nor discasters corresponding to them, as in D. starmeri. Further distinguishing D. marecoi are the large anchorate discohexasters (found in the holotype only) and the pileate discohexasters with many secondary rays having very small discs. The spicule measurements of corresponding spicules are very similar in these three species. Remarks The two previously known species of Dictyaulus, D. elegans Schulze, 1895 (NW Indian ocean) and D. starmeri Tabachnick & L?vi, 2004 (SE Pacific ocean), have more types of microscleres than D. marecoi: three types of discoidal microscleres, one or two types of sigmatocomes. The new species has Hertiuigia Schmidt, 1880 Hertwigia falcifera Schmidt, 1880 (Figures 11, 12) Material examined ZMBN, MAR-ECO St. 60/379, cat. no. 14920, 15539; St. 62/380, cat. no. 15889; St. 70/385, cat. no. 14752, 15262. Glass sponges of northern Mid-Atlantic Ridge 39 Table VII. Spicule dimensions of Dictyaulus marecoi sp. nov. (in mm). ZMBN MAR-ECO 15220 (holotype) ZMBN MAR-ECO 15889 (paratype) n Mean Min. Max. SD n Mean Min. Max. SD L dermal hexactin distal ray 30 0.154 0.107 0.213 0.029 21 0.184 0.128 0.391 0.057 L dermal hexactin tangential ray 31 0.179 0.089 0.355 0.055 26 0.195 0.121 0.528 0.075 L dermal hexactin proximal ray 15 0.473 0.107 0.667 0.164 15 0.509 0.320 0.781 0.121 D floricome 25 0.112 0.101 0.118 0.005 24 0.110 0.095 0.118 0.007 d floricome 25 0.018 0.014 0.024 0.003 24 0.016 0.011 0.020 0.002 D pileate discohexaster 25 0.052 0.034 0.078 0.010 22 0.050 0.039 0.067 0.008 d pileate discohexaster 25 0.015 0.011 0.022 0.004 22 0.016 0.011 0.028 0.004 D anchorate discohexaster 8 0.096 0.078 0.134 0.018 d anchorate discohexaster 8 0.019 0.017 0.022 0.002 D drepanocome 5 0.106 0.078 0.126 0.118 25 0.110 0.095 0.118 0.007 d drepanocome 5 0.019 0.017 0.022 0.003 25 0.016 0.011 0.020 0.002 D microhexactin 25 0.217 0.174 0.280 0.028 25 0.235 0.174 0.314 0.035 L, length; D, diameter; d, diameter of primary rosette. Description Body: most specimens represent broken fragments composed from plexiform, thin-walled (about 1 mm in thickness) tubes 6-35 mm in diameter. Two specimens possess a funnel-like body form with walls constructed from the plexiform tubes: (1) (cat. no. 14752) 310 mm high, 300 x400 mm in maximal diameter in the upper part of the body and 150 mm in diameter in the lower (basal) part of the body; wall about 100 mm in thickness, constructed of tubes of different diameter, usually inner (close to the secondary atrial cavity) with larger diameter up to 30 X 40 mm and the outer ones thinner up to 6 mm in diameter; (2) more or less complete specimen (one of three specimens in cat. no. 15262), 85 mm high and 100 x 120 mm in diameter, with wall composed of plexiform tubes 6 mm in diameter outside and 15 mm in diameter outside. Impossible to follow the true atrial and dermal surfaces in these adult sponges; initially these surfaces should be situated inside and outside the neanic tube, but in the adult sponge the diverse common cavaedia and Figure 11. Hertwigia falcifera Schmidt, 1880 (cat. no. 14752), the largest known specimen. (Top) View from above; (bottom) lateral view. Scale bar; 100 mm. Figure 12. Hertwigia falcifera Schmidt, 1880 (cat. no. 15262), a specimen with a secondary atrial cavity clearly visible. Scale bar: 50 mm. 40 K. R. Tabachnick & A. G. Collins atrial surfaces often and many times come together one with the other. Spicules: no loose spicules found. Wall con- structed from choanosomal fused spicules typical for H. falcifera. Remarks The peculiarity of body construction in Hertwigia falcifera among other tubular Corbitellinae could be a feature used to distinguish a new subfamily in the future. Heterotella Gray, 1867 Heterotella midlatlantica sp. nov. (Figures 13, 14) Holotype: ZMBN, MAR-ECO St. 56/378, cat. no. 15455. Description Body: sponge with 'Venus flower basket' form, consisting of two parts: small base, 110 mm high and 40 mm in diameter, in the lower part and large upper part 350 mm high and about 110 mm in diameter; entire length of the body 460 mm. Upper part with a well-distinguished ring of the osculum about 60 mm in diameter with no sieve-plate; sieve- plate probably destroyed and lost when capturing because minute remnants show that this oscular edge carried some structures of the sieve-plate. Walls thin, about 2-3 mm in thickness, constructed of some oblique (exterior), longitudinal (mediate) and circular (interior) beams; in the upper part some longitudinal (exterior) and circular (interior) beams present. Wall penetrated by numerous not regularly situated lateral oscula 1-6 mm in diameter. Choa- nosomal spicules in lower part of the body possess notable synapticula fusions, rendering the wall rigid; fusions in the upper parts not numerous, leaving the wall flexible. Spicules: choanosomal spicules mostly diactins, rarely tauactins and pentactins. Thin diactins have a widening in the middle or four rudimental tubercles; thick ones have a widening or are stout, with outer ends smooth rounded or conically pointed. Diactins 1.2-30/0.004-0.16 mm in length. Dermalia and atrialia hexactins with smooth, thin (0.013-0.018 mm in diameter) rays and smooth conically pointed outer ends; distal ray 0.099-0.398 mm (n = 17, mean =0.223 mm, SD =0.088 mm), tangential rays 0.085-0.376 mm (n=21, mean =0.223 mm, SD =0.082 mm), proximal ray 0.426-1.299 mm (n = 19, mean =0.838 mm, SD =0.201 mm). Atria- Figure 13. Heterotella midlatlantica sp. nov., holotype, lateral view. Scale bar; 100 mm. lia as pentactins (it is possible that these spicules are also dermal as though for H. pomponiae Reiswig, 2000, but they are usually found in the preparations of the atrial skeleton). Atrial pentactins with rounded, smooth tangential outer ends and rounded, slightly rough distal outer ends; tangential rays 0.099-0.213 mm long (n=23, mean =0.167 mm, SD =0.032 mm), distal ray 0.533-1.143 mm (n = 17, mean =0.908 mm, SD =0.176 mm); ray diameter 0.006-0.012 mm. Microscleres: microscleres floricomes, sigmato- comes (probably not fully grown floricomes), gra- phiocomes, and spiny and smooth hexactins. Floricomes 0.090-0.118 mm in diameter (n=24, mean =0.107 mm, SD =0.008 mm), diameter of primary rosette 0.016-0.028 mm (n=25, mean = 0.020 mm, SD =0.004 mm), secondary rays with three or four teeth. Sigmatocomes rare, 0.100 mm in diameter with primary rosette 0.020 mm in diameter. Graphiocomes reconstructed as spicules 0.437-0.633 mm in diameter (n = 19, mean =0.568 mm, SD =0.043 mm), with primary rosette 0.028-0.042 mm in diameter (n=25, mean =0.034 mm, SD =0.004 mm). Hexactins with numerous relatively short spines or sometimes Glass sponges of northern Mid-Atlantic Ridge 41 Figure 14. Spicules of Heterotella midlatlantica sp. nov., holotype (cat. no. 15455). (A) Dermal hexactin; (B, C) atrial pentactins; (D) large choanosomal pentactin; (E) large choanosomal tauactin; (F-H) choanosomal diactins; (I) oxyhexactin; Q) spiny oxyhexactin; (K-M) floricome and its outer ends; (N) sigmatocome; (O) graphiocome. smooth rays, 0.174-0.381 mm in diameter (n=25, mean =0.258 mm, SD =0.055 mm)^ diameter of rays 0.002-0.004 mm. Etymology The species name is given due to its location in the middle Atlantic. Remarks Before now Heterotella contained three species: H. corbicula (Bowerbank, 1862) (West Indian Ocean); H. pomponae Reiswig, 2000 (West Atlantic); H. pacifica Tabachnick & L?vi, 2004 (South-West Pacific). The new species has three important features which allow it to be distinguished: (1) absence of large pinular hexactins as in H. pomponae (present in H. pacifica and H. corbicula); (2) diameter of floricomes (0.090-0.118 mm) is similar to that in H. corbicula (0.059-0.141 mm) (in the other two species they are smaller: 0.043-0.090 mm in H. pomponae and 0.047-0.079 mm in H. pacifica); and (3) absence, as in H. pacifica, of oxyoidal micro- scleres, hexactins which have rare very long spines, referred to as oxyhexasters in H. pomponae and in 42 K. R. Tabachnick & A. G. Collins H. corbicula. The sigmatocomes in H. pomponae are not less than fully grown floricomes as suggested for the new species. Current descriptions of the different species oi Heterotella show that they are distinguished by various combinations of features rather than by individual peculiarities. Thus, new investigations of sets of specimens collected from close locations is necessary to understand which features may or may not vary intraspecif?cally. RosseUidae Schulze, 1885 Rossellinae Schulze, 1885 Asconema Kent, 1870 Asconema fristedti nordazoriensis Tabachnick et Menshenina, 2007 Material examined ZMBN, MAR-ECO St. 60/379, cat. no. 15402; St. 70/385, cat. no. 15528; lORAS, Akademik Mstislav Keldysh, 49th cruise, St. 4535 (52?58'N, 35?1'W, depth 2156 m), cat. no. 5/2/3173. Remarks This is a new species that was described separately together with the revision of the genus. Asconema? sp. Material examined ZMBN, MAR-ECO St. 40/367, cat. no. 15010; St. 66/382, cat. no. 15034, 15080, 15094, 15108. Remarks These sponges are represented by small fragments or portions of spicule mats that contain very few informative spicules and thus their exact identifica- tion is impossible. Caulophacus Schulze, 1886 Caulophacus (Caulophacus) arcticus (Hansen, 1885) (Table VIII) Material examined lORAS, Akademik Mstislav Keldysh, 49th cruise, St. 4540 (52?47'N, 34?45'W, depth 4313 m), cat. no. 5/2/3174. Description Body: mushroom-like with peduncle 65 mm long and 5 mm in diameter and body 50 mm in diameter and 4 mm in thickness with folded margin. Remarks The investigated specimen is very likely a repre- sentative of C. (Caulophacus) arcticus, which would make it the most southern location. 60?N was reported once before (Koltun 1967). Some differ- ences in spicule measurements are noted but they do not preclude the identification to C. (Caulo- phacus) arcticus. In addition, rare discohexasters with two or three secondary rays were found in Table VIII. Spicule dimensions o? Caulophacus (Caulophacus) arcticus (Hansen, 1885) (in mm). L dermal hexactin/pentactin pinular ray L dermal hexactin/pentactin tangential ray L dermal hexactin proximal ray L atrial hexactin/pentactin pinular ray L atrial hexactin/pentactin tangential ray L atrial hexactin distal ray D dermal discohexactin D atrial discohexactin D discohexactin (both dermal and atrial) D dermal lophodiscohexaster d dermal lophodiscohexaster D atrial lophodiscohexaster d atrial lophodiscohexaster D lophodiscohexaster (both dermal and atrial) d lophodiscohexaster (both dermal and atrial) D discohexaster d discohexaster From Koltun (1967) [ORAS 5/2/3174 Min. Max. n Mean Min. Max. SD 0.055 0.120 25 0.057 0.042 0.106 0.013 0.090 0.140 25 0.076 0.042 0.095 0.011 0.040 0.100 21 0.052 0.036 0.081 0.011 0.110 0.500 11 0.376 0.210 0.568 0.126 0.130 0.198 18 0.119 0.087 0.174 0.024 0.110 3 0.119 0.078 0.162 0.043 25 0.154 0.130 0.176 0.016 25 0.150 0.115 0.184 0.020 0.145 0.210 50 0.152 0.115 0.184 0.018 13 0.086 0.043 0.137 0.028 13 0.054 0.025 0.094 0.020 14 0.091 0.056 0.112 0.020 14 0.057 0.029 0.070 0.014 0.050 0.220 27 0.089 0.043 0.137 0.024 27 0.055 0.025 0.094 0.017 2 0.120 0.101 0.140 0.028 2 0.028 0.028 0.028 0 L, length; D, diameter; d, diameter of primary rosette. Glass sponges of northern Mid-Atlantic Ridge 43 the new specimen. These are similar in shape and size to hemidiscohexasters, also with two or three secondary rays, which are known in the new specimen as well as in previously described specimens. There are some peculiarities which are common for Caulophacus but not described for C. arcticus (possibly not found by previous investiga- tors). For instance, among the large hexactins it is possible to find spicules with one ray directed outside the body, which are rough close to their proximal ends. Rossella Carter, 1872 Rossella nodastrella Topsent, 1915 (Table IX) Material examined MNHN (pi429), Biacores, Jean Charcot, St. ChG 180 (37?57.50'N, 25?33'W, depth 1235-1069 m). Description Body: conical sponge 30 mm high, 30 mm in diameter, with large osculum and vast atrial cavity. 0.1 mm A-E 0.05 mm F-H 0.03 mm I-L Figure 15. Spicules o? Rossella af?. nodastrella Topsent, 1915. (A-H, J, L) Cat. no. 15668; (I, K) cat. no. 15654. (A) Dermal diactin; (B-D) dermal stauractins; (E) hypodermal pentactin; (F) choanosomal diactin; (G) oxyhexaster; (H) oxyhexactin; (I) abnormal oxyoidal microsclere; Q) calycocome; (K) abnormal discohexaster; (L) spherical microdiscohexaster. 44 o. t? [2 ^ ^ U ?ti o ?tl o o U W ci < o u w Z K Z S f2 ? O IZI ? zw?'c k&A. G. Collins o O o o in o o o d d d d d m 00 o O m ?3< o d d d d d o o 00 q q 00 m o o o d d d d d ON o ON o NO o ON 00 o ON o o d d d d d t^ 00 iri O o CO o o 00 o o (M O o d d d d d o o in o m CO o ON 04 d d d d d d o o O o O en 00 o NO o o ON O d d d d d d o ON 00 o O o o ON o o ON o d d d d d d en CO in CO m ON CO o NO o ON o o o NO o o NO o NO o o o o o o o o o o 00 NO ON 00 o 00 CO CO o CO CO o o O o o o o o o o o o CO - CO o 00 o 00 o o o o o o o o o o o 00 NO 00 NO CO o ?* ?* CO q CO o q oooooooo in o o d in NO in q d o d iri CO o d ? o o o O o O o O o O a ?c o. o NO o o O 00 o o o o o o o ? ?5 U CO -^ - ? ^^- ?-I ?_; '^ j^ ^ J J Q -o ? ?o ? 6 ? I ? O ^ ?o ? ^ h-1 Most measurements are given in Table IX. This specimen corresponds closely to the description of Topsent (1915), but there are a few differences. It is probably not important that tauactins and diactins were rarely present among the dermal stauractins, hypodermal spicules have orthotropal rays, and oxyoidal microscleres are oxyhexasters and oxyhemihexasters. However, other differences between the two known specimens, such as in spicule measurements and the absence of micro- discohexasters in the specimen described herein, may indicate that the two specimens represent distinct species. However, microscleres could po- tentially be found after more exhaustive spicule preparation. Rossella aff. nodastrella Topsent, 1915 (Figure 15; Table IX) Material examined ZMBN, MAR-ECO St. 70/385, cat. no. 15668, 15654. Description Two small specimens about 2 mm in diameter attached to a skeleton of dead Hertwigia falcifera. Due to poor fixation (they were dried) it is im- possible to say anything about atrial cavity and osculum. Spicules: choanosomal spicules diactins 0.9-1.5/ 0.004-0.007 mm with a widening in the middle and rough conically pointed outer ends. Hypodermal spicules pentactins with rough conically pointed or rounded outer ends; tangential rays 0.2-0.3 mm long, proximal one 0.4-0.6 mm long; ray diameter 0.006-0.011 mm. Dermal spicules mostly staurac- tins with rough conically pointed rays 0.07-0.126/ 0.006 mm; occasional stauractins with one or two rudiments instead of distal and proximal rays; tauactins and diactins rare. Microscleres: calycocomes 0.068-0.108 mm in diameter with primary rosette 0.011-0.025 mm in diameter. An abnormal discohexaster was encountered once in cat no. 15654. Spherical microdiscohexasters found in very small numbers in cat. no. 15654, 0.029 mm in diameter with primary rosette 0.008-0.009 mm in diameter. Oxy- oidal microscleres as oxyhexasters, oxyhemihexa- sters and rare oxyhexactins, sometimes with spines; diameter 0.058-0.115 mm, diameter of primary rosette of oxyhexaster 0.006-0.014 mm. Glass sponges of northern Mid-Atlantic Ridge 45 Figure 16. Spicules oiDoconestes aff. sessilis Topsent, 1928 (cat. no. 14766). (A-C) Dermal diactins; (D, E) dermal tauactins; (F) dermal stauractin; (G) atrial? hexactin; (H) orthotropal hypodermal pentactin; (I) achorate hypodermal pentactin (prostalia pleuralia); (J, K) choanosomal diactin; (L) hemioxyhexaster; (M) oxyhexaster; (N) oxyhexactin; (O) strobiloplumicome. Remarks Two specimens from the Charlie-Gibbs Fracture Zone notably differ from the description of R. nodastrella in their spicule measurements (see Table IX), as well as their lack of discasters and spherical microdiscohexasters (in the holotype they are figured as stellate). Both of these specimens are juveniles and it is possible that the spicule differences are due to this fact. Thus, we consider them to be problematic representatives of R. nodastrella (all of them have dermal stauractins). Even within R. nodastrella, these sponges could represent a new subspecies. However, they are too small to be assigned a type status and it is possible that dermal stauractins represent a juvenile feature. Some calycocomes were found in other fragments of hexactinellid spicule mats composed of spicules of different Rossellidae (cat. no. 15388, 15024, 15038); these calycocomes are likely spicules of Rossella; their diameter is more than 0.22 mm, their primary rosette is 0.037-0.059 mm in diameter. Lanuguinellinae Gray, 1872 Doconestes Topsent, 1928 Doconestes aff. sessilis Topsent, 1928 (Figure 16; Table X) Material examined ZMBN, MAR-ECO St. 70/385, cat. no. 14766. Description Body: ovoid about 12x10 mm with some prostalia lateralia of pentactins with short tangential rays 46 K. R. Tabachnick & A. G. Collins Table X. Spicule dimensions o? Doconestes sessilis Topsent, 1928 (in mm). Holotype from Topsent (1928) ZMBN MAR-ECO 14766 Mean Min. Max. n Mean Min. Max. SD L dermal diactin tangential ray 0.160 0.195 25 0.107 0.078 0.140 0.017 L atrial hexactin ray 5 0.184 0.154 0.224 0.034 D oxyhexactin/oxyhemihexaster/oxyhexaster 0.100 0.110 25 0.113 0.090 0.146 0.013 d oxyhexaster 3 0.008 0.008 0.008 0.000 D strobiloplumicome 0.040 25 0.041 0.032 0.047 0.004 d strobiloplumicome 25 0.013 0.009 0.018 0.002 L, length; D, diameter; d, diameter of primary rosette. protruding more than 6 mm from the body. Sponge destroyed rendering it impossible to find the osculum. Sponge attached to a large specimen of Hertwigia falcifera by a basyphitouse mode of fixation. Spicules: choanosomal spicules diactins 0.9-16/ 0.008-0.062 mm, with a widening in the middle and conically pointed or rounded smooth or rough outer ends. Pentactins of two types: anchorate serving as prostalia lateralia and orthotropal situated beneath the dermal layer. Anchorate pentactin rays about 0.08 mm in diameter with conically pointed smooth outer ends; tangential rays about 0.6 mm long; proximal ray over 6 mm long. Hypodermal pentactin rays 0.018-0.043 mm in diameter with conically pointed rough outer ends 0.213-0.667 mm long; proximal ray usually 1.5-2 times longer than tan- gential rays. Dermalia mostly diactins (lying in tangential plane), also some tauactins, stauractins and paratropal diactins with rough rays and conically pointed or rounded outer ends. Diactines with two or four rudimental tubercles in the middle. Other dermalia also often with rudimentary tubercles instead of some rays. Ray of dermal diactin 0.078- 0.140/0.003-0.008 mm. Atrialia as hexactins with all rays nearly equal in length 0.154-0.224/0.004-0.008 mm, rough and conically pointed; ray directed proximally appears a little more spined. Microscleres: microscleres strobiloplumicomes and oxyoidal spicules. (Several discohexasters of two different sizes seem to be allochthonic.) Oxyoi- dal microscleres mostly oxyhemihexasters, some oxyhexactins and oxyhexasters with one to three secondary rays; 0.090-0.146 mm in diameter with primary rosette in oxyhexasters about 0.008 mm in diameter; rays slightly curved. Strobiloplumicomes 0.032-0.047 mm in diameter with primary rosette 0.009-0.018 mm in diameter. Remarks It is impossible to be sure of the specific identifica- tion of the newly found specimen because the description of D. sessilis by Topsent (1928) was made on a fragment of the basal part of the body which may not have had some spicules found in the new specimen. Differences in the spicule measure- ments do not look to be significant except that the dermal diactins are larger in the type specimen. Another difference is the presence of other rare spicules in addition to the dermal diactins in the new specimen. Hypodermal pentactins also vary: in the type specimen they have short proximal rays and no prostalia lateralia were observed. Redescription of new sponges from the type location is necessary to be certain of the specific identification. Lophocalyx Schulze, 1887 Lophocalyx atlantiensis Menshenina, Tabach- nick, Lopes et Hajdu, 2007 Material examined ZMBN, MAR-ECO St. 62/380, cat. no. 15318; St. 70/385, cat. no. 14822. Remarks This is a new species that was described by Menshenina, Tabachnick, Lopes & Hajdu sepa- rately. Acknowledgements We greatly appreciate our Norwegian colleagues from the Museum of Zoology, University of Bergen, Dr J. Kongsrud and Dr A. Willassen, for their kind help during our investigation of their collections, all the participants and organizers of the expeditions that resulted in the collection of these materials, as well as the careful reviewers of our manuscript. A.G.C. gratefully acknowledges support firom a grant from the A.P. 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