Towards a full inventory of planktonic Ostracoda (Crustacea) for the subtropical Northwestern Atlantic Ocean

Deep-Sea Research II 57 (2010) 2173–2188

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Towards a full inventory of planktonic Ostracoda (Crustacea) for the subtropical Northwestern Atlantic Ocean Martin V. Angel National Oceanography Centre, Southampton SO14 3ZH, UK

a r t i c l e in fo

abstract

Article history: Received 18 September 2010 Accepted 18 September 2010 Available online 21 September 2010

92 species of planktonic ostracods were identified from five total water column samples of macroplankton collected from the surface to depths of 5000 m in the northwest subtropical Atlantic. Thirteen of these species are either totally novel or previously undescribed. This brings the total inventory of planktonic ostracods known from this region to118 species, and for the whole Atlantic to 153. All but one of the undescribed species were collected from depths 41000 m. This region is already the most comprehensively studied in the global ocean for plankonic ostracods. Similar studies conducted in other less well studied regions particularly in the Pacific and Indian Oceans will reveal far higher numbers of novel species & 2010 Elsevier Ltd. All rights reserved.

Keywords: Zoogeography Species diversity Taxonomy Halocyprids Deep living Size

1. Introduction The objectives of the Census of Marine Zooplankton (CMarZ) include the creation a full inventory of holoplankton of the global ocean, and the barcoding of as many of these species as possible. Achieving these objectives will facilitate not only future ecological and taxonomic studies, but also the early detection of the impacts of climate change. This paper reports on the progress made on the first of these objectives for planktonic ostracods resulting from the Census of Marine Zooplankton (CMarZ) cruise conducted in April 2006 to the Sargasso Sea on board the RV Ronald H. Brown (Cruise 0603). Planktonic ostracods in oceanic waters are predominantly halocyprids with a few myodocopid species. They are a numerically abundant and diverse group of mesoplanktonic organisms that inhabit nearly all bathymetric zones of oceanic water columns from the surface to the benthopelagic. Despite their abundance, diversity, and the significant role they play in moderating organic fluxes within oceanic water columns, they are ignored in the majority of studies of zooplankton ecology. This lack of attention is partially a result of their small size and partially because of a general perception that they are difficult to identify. As they are seldom reported, effectively they have become ‘invisible’ in the majority of ecological and process studies of oceanic water columns. The one oceanic area in which they have been extensively studied and are reasonably well known, is the subtropical Northwest Atlantic (Sargasso Sea and some parts of the Caribbean, especially in the vicinity of Bermuda) (Angel, 1979; Baker et al., 1977; Deevey, 1968a, b, 1970, 1975,

E-mail address: [email protected] 0967-0645/$ - see front matter & 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.dsr2.2010.09.020

1977, 1978a, b, 1982; Deevey and Brooks, 1980; Kornicker, 1968, Kornicker et al., 1976; Moore and Sander, 1977; Skogsberg, 1920; BATS time series http://bats.bios.edu/index.html). Maps of the known zoogeographical ranges of planktonic Ostracoda in the Atlantic have recently been published on a website (Angel et al., 2008). This website also includes detailed bathymetric profiles of many of the species that occurred at 321N 651W near Bermuda in April 1973 together with taxonomic drawings of every species. Hence, this region is an ideal place, not only to begin the barcoding programme for the planktonic ostracods, but also to compile a full regional species inventory. This paper summarizes the preliminary results from the RB0603 cruise and discusses them in the context of previous studies. The barcoding results will be presented in another paper (Bucklin et al., 2010). A full description of the rationale, procedures, and cruise track of the cruise and the physical description of the water columns sampled are presented in Wiebe et al. (2010).

2. Material and methods Five stations were occupied during the cruise (Fig. 1) (see also Wiebe et al., 2010, Fig. 1). At each station a standard protocol was adopted using MOCNESS samplers (Wiebe et al., 1976, 1985) comprehensively to sample macrozooplankton from the total water column and measure physical parameters, from the surface to depths of 5000 m. A standard MOC1 sampler with 335 mm mesh was used to collect eight stratified oblique contiguous strata throughout the upper 1000 m of the water column, A MOC10 sampler specially fitted with 335 mm mesh nets for this programme was used to sample four contiguous strata between

2174

M.V. Angel / Deep-Sea Research II 57 (2010) 2173–2188

1 30°N

Bermuda

30°N

2 3

4 20°N

20°N

5 80°W

70°W

60°W

Fig. 1. Sketch map showing the station positions occupied during Cruise 0603 of the R.V. Ronald H. Brown.

1000 m and 5000 m. For the MOC1 tows, the standard strata sampled were:

A running list of the species identified at sea was maintained and subsequently has been checked and supplemented with reexamination of the sorted material back in the laboratory. After the first MOC10 tow an assessment of the composition of ‘live’ ostracod material compared with the published data on the bathymetric distributions of ostracods at 321N 641W (Angel, 1979) suggested that the MOC10 samples were quite heavily contaminated with shallow living species. A similar comparison for other taxonomic groups, notably the fish, confirmed this conclusion. Peter Wiebe quickly identified the source of this contamination as being water leaking in through the small gaps between the bars of the closed nets and the side folds of the closed nets. When sampling at shallow depths this is a trivial problem, but when sampling at great depth where populations are extremely sparse and towing times are extremely long, the slightest leakage results in a substantial contamination problem. Once identified, the problem was virtually eliminated by modifying the MOC10 sampler by attaching canvas flaps along the upper bars and down the sides of each net, effectively sealing these gaps during the deployment and retrieval of the sampler.

3. Results net #1 1000-800 m, #2 800-600 m, #3 600-400 m, #4 400-300 m, #5 300-200 m, #6 200-100 m. #7 100-50 m, and #8 50-0 m. For the MOC10 tows the standard horizons were: net #1 50004000 m, #2 4000-3000 m, #3 3000-2000 m, and #4 20001000 m. These sampling horizons were occasionally slightly modified, for example at Stations 3 and 5 where the soundings were less than 5000 m. In addition early in the cruise a vertical sample (0-100 m) collected with a Reeve Net (0.5 m2, 60 mm mesh) was examined. One small species was exclusively sampled in this net.

One of the many advantages of using the MOCNESS system rather than any of the other available net samplers (Wiebe and Benfield, 2003) is that detailed environmental data are collected during the tow together with detailed statistics of each net tow. The physical properties of the water column at each station are summarized in (Wiebe et al., 2010). The emphasis adopted in this analysis is on qualitative assessments of the community composition within each sampling horizon, rather than on quantitative analyses. As each codend was retrieved at the end of a tow, it was cooled with ice packs while being detached from the net, labelled, and taken temporarily to the ship’s cold room. Each codend bucket was taken to the wet laboratory for processing. The catch was poured from the bucket into a large tray, and digitally photographed in its entirety. A team of sorters quickly picked out the larger organisms and also as many of the gelatinous species as possible. The residual sample was then split into three aliquots. Half was preserved in 5% seawater formalin for later detailed taxonomic study and as a source of voucher specimens. One quarter was kept ‘live’ in cold sea water, from which the smaller zooplankton species were picked out for identification. The second quarter was immediately preserved in 100% ethyl alcohol, and was the source of the majority of the specimens selected for barcoding. At sea, the ostracods were picked out of most of the preserved deep MOC10 catches but only a few of the MOC1 catches under a stereo microscope at x10 magnification. The emphasis was on picking out exemplar specimens of every species from the bathypelagic and mesopelagic samples, rather than picking every ostracod specimen. This approach to the sorting, necessitated by the limited time available obviated a comprehensive quantitative analysis.

The station data for each of the MOC1 hauls and the one Reeve net examined are listed in Table 1. The station data for the MOC10 samples are listed in Table 2. The species identified in these samples are listed in Tables 3 and 4, for the MOC1 and MOC10 samples respectively. The 1900 specimens picked out of the MOC1 samples included 53 species, none of which are entirely novel. The small form of Archiconchoecissa cucullata has previously been recognised (Angel, 1979), but is yet still to be formally described. The 3268 specimens picked from the MOC10 samples included 87 species. Based on previously published data (Angel, 1979; Angel et al., 2008), 26 of these species are likely to have been shallow water contaminants. Hence 59 of the species sampled with the MOC10 are genuinely bathypelagic or abyssopelagic; 13 (22 %) are either undescribed or totally novel species.

4. Discussion In addition to the total of 93 species collected during RB0603 a further 26 species have been reported from the region (Table 5). Several of these species, notably most of the Bathyconchoecia species, are benthopelagic and inhabit a zone that was beyond the scope of the possible sampling. Several of the early descriptions of these species were based on gut contents from benthic fishes (Deevey, 1968b). If it had been possible to extend the sampling into the benthopelagic zone (i.e. to within 10-100 m of the seabed), the proportion of novel species would have been increased. For example, in 1979 a single sample collected within 10 m of the seabed at Discovery station 9541 (201180 W; 211410 W) at a depth of 4000 m collected 25 novel species, although all these species are yet to be described. The combined the MOC1 and MOC10 samples collection of 93 species, represents 66% of currently known ostracod fauna of 140 species in the Atlantic Ocean (Angel et al., 2008). However, the number of novel species caught on the RB0603 cruise increases the known ostracod richness of the Atlantic to 153. 60.7% were taken during RB0603 cruise. Hence the total planktonic ostracod fauna of the SW Atlantic region comprises at least 118 species, It is worth noting that this is more than double the number of species known from comparable latitudes in the Pacific, which highlights just how poorly the planktonic ostracod fauna of the Pacific is known.

M.V. Angel / Deep-Sea Research II 57 (2010) 2173–2188

2175

Table 1 Station and haul data for the MOC1 and ring net samples collected on the Ron Brown cruise 0603 in April 2006. Station

Tow

0

Date

Times

Latitude1N

Longitude1W

Depths (m)

Reeve

11/04

1432-1446

33102.723

75102.006

100-0

33131.467

69157.678

1000-800 800-600 600-400 400-200 200-100 100-50 50-25 25-0

1045.9 1154.8 1319.3 1155.1 655.1 414.0 384.5 504.9

993-797 797-600 600-400 400-200 200-100 100-50 50-25 25-0

802.4 924.9 820.4 1193.6 471.7 264.0 178.0 272.2

998-790 790-600 600-400 400-200 200-100 100-50 50-25 25-0

667.2 942.9 1218.2 961.3 667.4 547.5 312.1 288.8

100-800 800-594 594-400 400-195 195-100 100-50 50-25 25-0

782.8 754.8 821.9 896.0 412.1 203.7 150.9 305.8

1000-800 800-600 600-400 400-200 200-100 100-50 50-25 25-0

1065.1 1091.8 1058.6 1019.9 806.7 410.8 373.3 407.2

800-600 588-400 400-200 200-100 100-50 50-25 25-0 Did not fish

1484.1 1093.2 976.6 1159.6 872.2 634.1 200.8

1000-800 800-600 600-400 400-200 200-100 100-50 50-25 25-0

363.1 1005.2 908.2 946.3 1230.3 1019.2 409.1 259.1

1000-800 800-595 595-400 400-200 200-100 100-50 50-25 25-0

1189.9 927.7 852.1 989.3 892.9 479.7 269.6 326.7

1000-799 799-600 600-400 400-198 198-100

922.4 839.2 944.6 1043.7 475.3

1

#1

1 2 3 4 5 6 7 8

13/04

0618-0922

end

33135.900

69153.460

1

#2n

1 2 3 4 5 6 7 8

14/04

1805-2051

33137.589

69131.554

end

33133.904

69138.330

2

#3n

1 2 3 4 5 6 7 8

16/04

0042-0339

29159.711

70101.648

end

29153.241

70104.464

29152.090

70104.530

2

#4

1 2 3 4 5 6 7 8

16/04

0658-0930

end

29151.405

70108.427

3

#7

1 2 3 4 5 6 7 8

20/04

1244-1604

24152.133

60129.228

end

24157.692

60132.159

3

#8n

1 2 3 4 5 6 7 8

20/04

1909-2246

24159.966

60130.776

end

25103.294

60135.552

4

#9

1 2 3 4 5 6 7 8

23/04

1521-1839

19149.227

54143.585

end

19145.723

54137.532

1 2 3 4 5 6 7 8

23-24/04

2152-0119

19147.123

54135.625

end

19149.426

54128.627

1 2 3 4 5

25/04

0916-1238

14100.174

54159.976

n

4

#10

5

#11

Volume filtered (m3)

Net

2176

M.V. Angel / Deep-Sea Research II 57 (2010) 2173–2188

Table 1 (continued ) Station

Tow

Net

Date

6 7 8

Times

Latitude1N

Longitude1W

Depths (m)

Volume filtered (m3)

100-50 50-25 25-0

666.4 1125.2 216.3

1000-800 800-600 600-400 400-200 200-100 100-50 50-25 25-0

1017.0 703.5 1189.4 1385.7 650.1 341.9 364.1 361.1

547-527 527-516 516-496 496-488 489-477 477-473 473-464 464-461

366.5 261.6 379.1 389.4 222.3 288.9 294.3 252.1

end

14101.042

54155.089

5

#12n

1 2 3 4 5 6 7 8

25/04

1725-2041

14102.499

54153.482

end

14105.102

54148.879

5

#13

1 2 3 4 5 6 7 8

27/04

1051-1507

14124.772

53156.494

end

14125.119

53152.530

n

Indicates nighttime hauls.

Table 2 Station and haul data for the MOC10 samples collected on the Ron Brown cruise 0603 in April 2006. Station

Tow

Net

Date

Times

Latitude1N

Longitude1W

Depths (m)

Volume Filtered(m3)

1

#1

1 2n 3nn 4

13-14/04

2006-1146

33138.552

69147.717

147,297 71,943

end

33140.243

60113.418

5000-4000 4000-3000 broken tab 3000-1000

2

#2

1 2 3 4

16-17/04

1529-0416

29149.770

70114.292

end

29129.273

70129.875

4315-3500? 3500-2750? 2750-2000? 2000-1000?

345,456 49,127 37,129 16,363

25103.367

60137.536

5000-4000 4000-3000 Tab broke 3000-1000

28,665 35,051 44,849 38,980

5000-4000 4000-3000 3000-2000 2000-1000

38,177 64,341 49,301 53,128

4500-4000 4000-3000 3000-2000 2000-1000

33,551 55,233 52,965 55,329

5000-4000 4000-3000 3000-2000 2000-1000

70,880 40,928 44,481 40,589

5000-4000 4000-3000 3000-1000 1000-0

54.074 55,371 114,404 62,573

3

#3

1 2 3nn 4

19-20/04

2334-0925

end

25103.049

60158.849

3

#4

1 2 3 4

21/4

0011-1126

25109.583

601.37.632

end

251.03.054

60158,818

4

#5

1 2 3 4

23/04

0142-1256

20100.03

54159.805

end

19149.387

54144.379

5

#6

1 2 3 4

25-26/04

2156-1001

14105.830

54146.800

end

14112.948

54127.378

1 2 3 4

26-27/04

1410-0338

14146.800

54121.960

end

14127.378

53157.916

5

#7

n

154,756

Indicates a sample that was totally lost because the cod-end bucket became detached. Indicates a haul when the tab holding the closing bar in place broke so the sample from the sampling depth was retained in the next net.

nn

The species identified from the RB0603 samples include 29 genera of halocyprid ostracods and two genera of myodocopid ostracods. The composition of each of these genera is now reviewed: 1. Alacia. This genus includes eight described species (for the following genera the number of described species in each as listed

in Angel et al. (2008), will be shown in parentheses). A. valdiviae is the only species that occurred in the Ron Brown samples. Even so, it was unexpectedly quite uncommon - an adult female was taken in MOC10#6 net 4, and some juveniles in MOC10#7 nets 3 and 4. This, the largest halocyprid species, is immediately recognisable in fresh samples both by its size and its bright scarlet coloration.

M.V. Angel / Deep-Sea Research II 57 (2010) 2173–2188

2177

Table 3 Species of halocyprid ostracod identified in the MOC1 samples and the ring net sample at station #0 from the upper 1000 m; p indicates presence.

Station Haul number Net number Archiconchoecheta bispicula (Deevey, 1978a) Archiconchoecissa cucullata Small form n.sp Archiconchoecissa cucullata (Brady, 1902) Conchoecia hyalophyllum Claus, 1890 Conchoecia magna Claus 1874 ¨ Conchoecia lophura Muller 1906 ¨ Conchoecia macrocheira Muller 1906 Conchoecilla daphnoides Claus 1890 ¨ Conchoecissa ametra (Muller (1906) Conchoecissa imbricata (Brady 1890) ¨ Conchoecissa plinthina (Muller (1906)) Discoconchoecia aff. elegans (Sars, 1866) ¨ Euconchoecia chierchiae Muller (1906) ¨ Gaussicia incisa (Muller (1906)) Halocypria globosa Claus, 1874 Halocypris inflata Dana, 1849 Halocypris pelagica Claus, 1890 ¨ Loricoecia loricata (Muller (1906)) Macroconchoecia macroreticulata (Ellis, 1984) Macroconchoecia spinireticulata (Ellis, 1984) Macrocypridina castanea (Brady, 1897) Metaconchoecia acuta (Gooday,1981) ¨ Metaconchoecia macromma (Muller (1906)) Metaconchoecia discoveryi (Gooday, 1981) Metaconchoecia fowleri (Gooday, 1981) ¨ Metaconchoecia glandulosa (Muller (1906)) ¨ Metaconchoecia kyrtophora (Muller (1906)) Metaconchoecia obtusa (Gooday, 1981) ¨ Metaconchoecia rotundata (Muller (1906)) Mikroconchoecia curta (Lubbock, 1860) Mikroconchoecia echinulata Claus, 1891 ¨ Mikroconchoecia stigmatica (Muller (1906)) Orthoconchoecia atlantica (Lubbock, 1856) Orthoconchoecia bispinosa (Claus, 1890) Orthoconchoecia haddoni (Brady and Norman, 1896) Orthoconchoecia secernenda (Vavra, 1906) ¨ Paraconchoecia aequiseta (Muller (1906)) ¨ Paraconchoecia cophopyga (Muller (1906)) ¨ Paraconchoecia dorsotuberculata (Muller (1906)) ¨ Paraconchoecia hirsuta (Muller (1906)) Paraconchoecia inermis Claus, 1890 ¨ Paraconchoecia mamillata (Muller (1906)) Paraconchoecia nanomamillata (Deevey & Brooks, 1980) Paraconchoecia oblonga Claus, 1890 form A Paraconchoecia oblonga Claus, 1890 form B Paraconchoecia spinifera Claus, 1891 ¨ Porroecia parthenoda (Muller (1906)) Porroecia porrecta (Claus, 1890) Porroecia spinirostris (Claus, 1874) ¨ Proceroecia brachyaskos (Muller (1906)) Proceroecia convexa (Deevey, 1977) Proceroecia microprocera (Angel, 1971) ¨ Proceroecia procera (Muller (1906)) n

1

0

2n

1

0n 0

2

1

2

p

3

4

1

2

p

3

4 4

5

6

2

p

p

p

p

p p p

p

3

3

5

7

4

0

1

p

p p p p

p

p

p p p

p p

p

p

p

p

p

p

p

p

p

4 8n

1

2

p

p p p

10n 4

p

p

p

p p

5

3

11 1

2

12n 5

8

p p p

p p p p

5

p p

p

p

p p

p p

p

p p

p

p

p p

p p

p p

p

p

p p

p p

p p

p

p p

p

p

p

p p

p

p

p p

p

p p

p

p

p

p p

p

p

p

p

p p p p p p

p p

p

p

p

p

p p

p

p

p p

p

p

p

p p

p

p p

p

p

p

p

p

p p p p

p

p

p

p

p

p

p

p

p p p p

p

p

p p p p p p

p p p

p

p p

p

p

p p p p

p

p p

p p p p

p p p p

p p p p

p

p

p

p

p p p p

p p p p

p p

p p p

p p p

p

p

p p

p p

p p p p P p

p

p p p

p

p

p p

p p

p p

p

p

p

Indicates nighttime hauls.

¨ A beautiful painted illustration is published in Muller (1906), and a photograph of it is featured on the title page of Blachowiak-Samolyk and Angel’s (2003) website ‘an Atlas of Southern Ocean Planktonic Ostracods’. However, like other highly characteristic species that are instantly recognisable, they are seldom been examined critically. Poulsen (1973) reported two adult size categories; in the Western Pacific the mean sizes of females and males are 6.4 mm and 5.9 mm respectively; whereas in the tropical Atlantic their mean sizes are 5.5 mm and 5.1 mm respectively. Sizes of specimens in Discovery Collections from the Eastern Tropical Atlantic are somewhat larger than those Poulsen reported. The length range of females is

5.58-6.00 mm (mean 5.8070.119 mm (n¼20), and of males is 5.25-5.58 mm (Mean 5.4770.082 mm n¼16). Whereas those from the Southern Ocean are smaller; female range 5.08-5.58 mm (mean 5.3970.13 mm, n¼ 109), male range 4.92-5.33 mm (mean 5.037 0.11 mm, n¼60). The one adult female in the RB0603 samples was intermediate in length at 5.50 mm. As will be discussed below carapace length tends to be a very conservative character in halocyprids and differences in carapace length are often a good indication of the occurrence of cryptic species. Four of the other species in the genus are characterised by having winged edges to their shoulder vaults, and include the

2178

Table 4 Species of halocyprid ostracod identified in the MOC10 samples from 1000-5000 m; p indicates presence, K indicates species that are probably contaminants. Station Haul number Net

1

2 #2 4

1

3 #3 2

p

1

2

3 #4 4

1

2

4 #5 3

4

2

3

5 #6 4

1

5 #7 1

2

p p p

p p

p p

4

p p p

p

p p

p

3

p

p

p

p

p

p

p p

p p

p p

p p p

p

p p p

p p p

p

p p p p

p p p p p p p p

p p p p p p p p p p

p p

p

p

p p p

p

p p p p

p p p

p

p p p

p p

p

p p p p p p p

p

p

p

p

p

p p

p

p

p

p

p

p p

p

p

p p

p p

p p

p p

p

p p

p

p

p p

p

p p p

p p

p

p p p

p

p p

p p

p p

p

p p p p p

p p p p

p p

p

p

p

p

p

p

p p

p

p p

p

p

p

p

p p p

p

p p

p p

p

p p p p p p

p

p

p

p

p p p p

p p

p p

p p

p p p p p p

p

p p p

p

p

p

p p p

p p

p

p

p p

p

p p

p

p p

p

p p

p p

p

p p

p p

M.V. Angel / Deep-Sea Research II 57 (2010) 2173–2188

¨ Alacia valdiviae Muller, G.W., 1906) Archiconchoecemma simula (Deevey, 1982) Archiconchoecetta bispicula (Deevey, 1978a) Archiconchoecilla versicula (Deevey, 1978a) ¨ Archiconchoecinna cuneata (Muller , 1908) Archiconchoecetta n.sp. Archiconchoecissa cucullata (Brady 1902) Archiconchoecissa pljusnini Chavtur and Stovbun, 2003 Bathyconchoecia RB#1 nov.sp. Bathyconchoecia RB#2 nov.sp. Bathyconchoecia RB#3 nov.sp. Bathyconchoecia RB#4 nov.sp. Bathyconchoecia RB#5 nov.sp. Boroecia borealis (Brady 1902) KConchoecetta acuminata Claus, 1890 KConchoecia hyalophyllum Claus, 1890 ¨ Conchoecia lophura Muller, G.W., 1906 ¨ Conchoecia macrocheira Muller, G.W., 1906 KConchoecia subarcuata Claus, 1890 Conchoecilla daphnoides Claus, 1890 ¨ Conchoecissa ametra (Muller, G.W., 1906) KConchoecissa imbricata (Brady, 1880) ¨ Conchoecissa plinthina (Muller, G.W., 1906) KDiscoconchoecia aff. elegans (Sars 1866) aff. Fellia n.sp. ¨ Fellia bicornis (Muller, G.W., 1906) ¨ Gaussicia gaussi (Muller, G.W., 1906) ¨ Gaussicia incisa (Muller, G.W., 1906) Gigantocypris dracontovalis Cannon, 1940 Gigantocypris muelleri Skogsberg, 1920 Halocypria globosa Claus, 1874 KHalocypris inflata Dana, 1849 Loricoecia acutimarginata Chavtur, 1977 Loricoecia loricata (Claus, 1894) Macroconchoecia macroreticulata (Ellis, 1984) ¨ Macroconchoecia reticulata (Muller, G.W., 1906) Macroconchoecia spinireticulata (Ellis, 1984) Macrocypridina castanea (Brady, 1897) KMetaconchoecia acuta (Gooday, 1981) Metaconchoecia arcuata (Deevey (1978a, b)) Metaconchoecia discoveryi (Gooday, 1981) Metaconchoecia fowleri (Gooday, 1981) ¨ Metaconchoecia glandulosa (Muller, 1906) KMetaconchoecia inflata (Gooday, 1981) Metaconchoecia lunata (Deevey,1978c) ¨ Metaconchoecia macromma (Muller, G.W., 1906) KMetaconchoecia obtusa (Gooday, 1981) ¨ Metaconchoecia pusilla (Muller, G.W., 1906) Metaconchoecia pusilla small form Metaconchoecia skogsbergi (Iles, 1953) Metaconchoecia sp.A KMikroconchoecia curta (Lubbock, 1860)

1 #1

p

p

p

p

p

p

p

p

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M.V. Angel / Deep-Sea Research II 57 (2010) 2173–2188

KMikroconchoecia echinulata Claus 1891 ¨ Mikroconchoecia stigmatica (Muller, G.W., 1906) ¨ Mollicia kampta (Muller, G.W., 1906) ¨ Mollicia mollis (Muller, G.W., 1906) ¨ Mollicia tyloda (Muller, G.W., 1906) Orthoconchoecia atlantica (Lubbock, 1856) KOrthoconchoecia bispinosa (Claus, 1890) Orthoconchoecia secernenda (Vavra, 1906) ¨ Paraconchoecia aequiseta (Muller, G.W., 1906) ¨ Paraconchoecia dasyophthalma (Muller, G.W., 1906) ¨ Paraconchoecia dentata (Muller, G.W., 1906) ¨ Paraconchoecia dorsotuberculata (Muller, G.W., 1906) ¨ KParaconchoecia echinata (Muller, G.W., 1906) ¨ Paraconchoecia hirsuta (Muller, G.W., 1906) KParaconchoecia inermis Claus, 1890 ¨ Paraconchoecia mamillata (Muller, G.W., 1906) KParaconchoecia nanomamillata (Deevey and Brooks, 1980) KParaconchoecia oblonga Claus, 1890 form A KParaconchoecia oblonga Claus, 1890 form B ¨ Paraconchoecia plactolycos (Muller, G.W., 1906) KParaconchoecia spinifera Claus, 1891 ¨ Paraconchoecia cophopyga (Muller, G.W., 1906) ¨ Paramollicia dichotoma (Muller, G.W., 1906) ¨ KPorroecia parthenoda (Muller, G.W., 1906) KPorroecia porrecta (Claus, 1890) KPorroecia pseudoparthenoda (Angel, 1972) KPorroecia spinirostris (Claus, 1874) ¨ Proceroecia brachyaskos (Muller, G.W., 1906) Proceroecia convexa (Deevey, 1977) KProceroecia microprocera (Angel, 1971) ¨ KProceroecia procera (Muller, G.W., 1894) Conchoecinid Sp. D Conchoecinid Sp. E Conchoecinid Sp. F Conchoecinid Sp. G

2179

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Table 5 Ostracod species previously recorded from the Bermudan and Caribbean region that were not taken during RB0603, see Angel (1979), Deevey’s various papers are listed in the references, 1. Poulsen (1973), 2. Moore and Sander (1977) and 3. Gonzales and Breman, (1982). Species 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

¨ Alacia alata (Muller, 1906) Archiconchoecerra longiseta (Deevey, 1978a, b) Archiconchoecetta bifurcata (Deevey, 1978a) Archiconchoecetta bimucronata (Deevey, 1978a) Archiconchoecetta fabiformis (Deevey, 1978a) Archiconchoecetta falcata (Deevey, 1978a) Archiconchoecetta gastrodes (Deevey, 1978a, b) Archiconchoecetta pilosa (Deevey, 1978a, b) ¨ Archiconchoecetta ventricosa (Muller, 1906) ¨ Archiconchoecia striata (Muller, 1894) Bathyconchoecia diacantha (Deevey, 1975) Bathyconchoecia foveolata (Deevey, 1978a, b) Bathyconchoecia galitera (Deevey, 1978a, b) Bathyconchoecia hardingi (Deevey, 1975) Bathyconchoecia kornickeri (Deevey, 1978a, b) Bathyconchoecia laqueata (Deevey, 1978a, b) Bathyconchoecia paulula (Deevey, 1978a, b) Bathyconchoecia sagittarius (Deevey, 1978a, b) ¨ Discoconchoecia discophora (Muller, 1906) Gaussicia subedentata (Gooday, 1976) Metaconchoecia subinflata (Gooday, 1981) ¨ Metaconchoecia nasotuberculata (Muller, 1906) Obtusoecia obtusata (Sars, 1866) ¨ Paramollicia plactolycos (Muller, 1906) ¨ Paramollicia rhynchena (Muller, 1906) ¨ Pseudoconchoecia concentrica (Muller, 1906)

type species A. alata, which has been occasionally reported from the region (Table 5), and is abundant in the upwelling region off Mauritania, NW Africa. Two of other species currently classified in the genus are Southern Ocean endemics (Blachowiak-Samolyk and Angel, 2003) and lack the sharp edges to the shoulder vaults of the type species. These should probably be classified in a separate genus. Similarly, the final species currently classified in the genus, A. leptothrix, which has also been reported a few occasionally from the Eastern Atlantic, but only once over the Mid-Atlantic Ridge at 241N bordering on the Sargasso Sea (Angel et al., 2008), is also probably sufficiently different to merit being assigned to a separate genus. The genus Alacia is a highly heterogeneous and requires revision. 2. Archiconchoecia (4). This is a genus that has recently been revised substantially by Chavtur and Stovbun (2003). They show that the composition of the original genus is highly polyphyletic, and so they have subdivided it into seven genera. They retain the genus Archiconchoecia for the original type species, A. striata, and add a further three novel species from Pacific and Arctic waters. Rather surprisingly A. striata was absent from the RB0603 samples although it is known to be quite common at shallow mesopelagic depths near Bermuda (Deevey, 1968a; Angel, 1979). It is a very small, slim species (~ 0.54-0.62 mm; # 0.62 mm), so its absence from the Ron Brown samples was probably because they were extruded through the 335 mm mesh of the nets and the cod-ends. 3. Archiconchoecetta (11). Deevey (1978a, b) described ten new Archiconchoecia species, most of which she recorded from the Sargasso (the exception was A. poulseni, which she named based on Poulsen’s (1969) description of the large form of A. ventricosa ¨ (Muller, 1906) from the Western Pacific to the north of New Zealand. Chavtur and Stovbun (2003) re-classified the majority of Deevey’s Archiconchoecia species into this genus. The only one of Deevey’s species identified in the RB0603 samples was A. bispicula. Most of the others are small enough for extrusion through the 335 mm meshes of the nets to be a reasonable explanation for their absence. Most of them are rather uncommon

Angel (1979)

Deevey various

Others 1

+ + +

+ + + +

+ + + + + + + + + + + + + + + + + +

2,3

+ + + +

+ +

1,2,3

mesopelagic species, and may not have been abundant enough to have been caught by the limited sampling effort at these depths. 4. Archiconchoecissa (2). Chavtur and Stovbun (2003) established this genus to accommodate A. cucullata (Brady, 1902) and their newly described species A. pljusnini, which they designated as the type species for their new genus. Both these species occurred in the RB0603 samples. A. pljusnini is a deep bathypelagic species that is rare in collections, but is a regular component of samples collected from depths 42000 m. The specimens of A. cucullata in the MOC 10 samples (i.e. from depths 41000 m) are of a size consistent with Brady’s original description. The samples taken at shallower in the MOC 1 samples were significantly smaller (see Table 6). Angel (1979) reported the presence of this small form off Bermuda and considered it to be a separate species, but it still awaits formal description. Both size forms of A. cucullata occur throughout much of the N.E. Atlantic (Angel et al., 2008). The larger sensu strictu form inhabits deep mesopelagic depths at temperate latitudes, but submerges to become bathypelagic at subtropical latitudes, where it is replaced at mesopelagic depths by the small form. 5. Archiconchoecilla (2). This is another genus established by Chavtur and Stovbun (2003) with A. maculata (Chavtur, 1977) from the N. Pacific designated as the type species. This genus includes A. versicula (Deevey, 1978a, b), which occurs at deep bathypelagic depths throughout much of the N. Atlantic (Angel et al., 2008). Seven females were taken in net 1 of MOC 10#6. 6. Archiconchoecemma (2). Another of genus established by Chavtur and Stovbun (2003), with A. orientalis (Chavtur, 1987) from the N. Pacific designated as the type species. The type species is very similar in appearance to A. simula (Deevey, 1978a, b), which is widespread at deep bathypelagic depths throughout much of the N. Atlantic (Angel et al., 2008). However, A. simula was absent from the first three station but was quite abundant in the deep nets at last two MOC 10 stations. 7. Archichoecinna (3). Another genus established by Chavtur and Stovbun (2003), which includes two species they describe one

M.V. Angel / Deep-Sea Research II 57 (2010) 2173–2188

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Table 6 Mean carpace lengths in mm (7 standard deviations) and size ranges of all the planktonic ostracod species taken in numbers 45 during RB0603. These data have been supplemented with data for Loricoecia ctenophora from the Eastern Atlantic, and Proceroecia barchyaskos from the Southern Ocean and from off Bermuda at Discovery station 8281 (Angel 1979) (see text). Species

Alacia valdiviae Archiconchoecemma simula Archiconchoecetta bispicula Archiconchoecilla versicula Archiconchoecinna cuneata Archiconchoecissa cucullata small form Archiconchoecissa cucullata ss Archiconchoecissa pljusnini Bathyconchoecia RB#4 Conchoecetta acuminata Conchoecia hyalophyllum Conchoecia lophura Conchoecia macrocheira Conchoecia magna Conchoecia subarcuata Conchoecilla daphnoides Conchoecissa ametra Conchoecissa imbricata Conchoecissa plinthina Discoconchoecia aff. elegans Euconchoecia chierchiae aff. Fellia n.sp. Fellia bicornis Gaussicia gaussi Gaussicia incisa Halocypria globosa Halocypris inflata Halocypris pelagica Loricoecia loricata Loricoecia ctenophoran Macroconchoecia macroreticulata Macroconchoecia reticulata Macroconchoecia spinireticulata Metaconchoecia acuta Metaconchoecia arcuata Metaconchoecia arcuata s Metaconchoecia discoveryi Metaconchoecia fowleri Metaconchoecia glandulosa Metaconchoecia inflata Metaconchoecia kyrtophora Metaconchoecia lunata Metaconchoecia macromma Metaconchoecia obtusa Metaconchoecia pusilla Metaconchoecia rotundata Mikroconchoecia curta Mikroconchoecia echinulata Mikroconchoecia stigmatica Mollicia kampta Mollicia tyloda Orthoconchoecia atlantica Orthoconchoecia bispinosa Orthoconchoecia secernenda Paraconchoecia aequiseta Paraconchoecia cophopyga Paraconchoecia dasyophthalma Paraconchoecia dentata Paraconchoecia dorsotuberculata Paraconchoecia echinata Paraconchoecia hirsuta Paraconchoecia inermis Paraconchoecia mamillata Paraconchoecia nanomamillata Paraconchoecia oblonga A Paraconchoecia oblonga B Paraconchoecia spinifera Paramollicia dichotoma Paramollicia plactolycos Porroecia parthenoda Porroecia porrecta

Female

Male

Mean carapace length

Range

Number

Mean carapace length

Range

Number

5.80 70.119 1.27 70.022 0.95 70.052 0.82 70.037 0.82 70.029 1.68 70.037 2.22 70.126 2.13 70.059 3.64 70.086 3.39 70.087 1.66 70.076 2.45 70.073 3.48 70.124 1.84 70.050 2.12 70.090 4.79 70.278 4.01 70.288 2.96 70.123 5.45 70.243 1.23 70.036 1.19 70.053 3.44 70.172 1.93 70.047 3.61 70.143 2.52 70.051 2.19 70.112 1.66 70.056 1.23 70.073 1.95 70.071 2.52 70.093 4.11 70.124 3.41 70.261 3.69 70.173 0.93 70.026 1.00 70.037 0.90 70.030 1.06 70.028 1.18 70.041 1.46 70.101 1.03 70.029 0.81 70.021

5.58-6.00 1.22-1.34 0.86-1.03 0.74-0.92 0.76-0.86 1.58-1.90 2.05-2.57 2.04-2.22 3.52-3.84 2.88-3.60 1.50-1.86 2.28-2.68 3.24-3.84 1.70-1.96 1.94-2.36 4.17-5.25 3.48-4.40 2.60-3.20 4.92-5.83 1,12-1.36 1.08-1.30 3.12-3.72 1.80-2.24 3.32-3.84 2.30-2.60 1.92-2.44 1.52-1.80 1.04-1.38 1.78-2.14 2.32-2.76 3.76-4.26 3.08-3.80 3.28-3.92 0.86-1.02 0.94-1.16 0.86-0.96 1.00-1.12 1.10-1.28 1.30-1.74 0.94-1.12 0.76-0.86 1.36-1.46 0.98-1.12 0.90-1.00 0.78-0.93 0.74-0.84 0.78-0.90 0.68-0.84 0.94-1.14 2.84-3.20 3.16-3.52 3.36-3.92 1.68-2.00 2.40-3.04 2.96-3.12 2.92-3.28 2.88-3.47 1.88-2.10 2.48-2.72 1.80-2.04 3.08-3.52 2.00-2.18 1.50-1.90 1.24-1.50 1.56-1.84 1.56-1.80 1.88-2.14 1.94-2.38 2.56-2.88 1.46-1.66 1.48-1.76

20 49 28 128 63 119 772 16 7 56 91 83 102 216 92 172 48 116 54 267 43 38 29 16 5 50 439 133 95 79 26 5 49 467 197 39 242 227 29 116 118 2 160 200 155 207 68 145 41 19 24 38 40 204 20 50 59 183 19 204 76 21 136 141 160 219 216 15 8 48 24

5.47 70.082 1.26 0.79 70.050 0.84 70.033 0.70 70.15 1.71 70.042 2.35 70.141 2.25 3.32 2.41 70.078 1.58 70.045 2.35 70.092 3.02 70.072 1.70 70.044 1.90 70.032 2.86 70.117 3.43 70.075 2.48 70.079 5.17 70.247 1.23 70.034 1.21 70.034 3.30 70.104 1.78 70.041 3.13 70.169 No data 2.01 70.071 1.45 70.043 1.14 70.047 1.79 70.063 2.37 70.056 3.80 70.156 3.16 70.108 3.27 70.096 0.91 70.025 1.03 70.037 0.87 70.024 1.03 70.022 1.15 70.047 1.52 70,130 1.04 70.043 0.77 70.020

5.25-5.58 1.24-1.28 0.70-0.86 0.76-0.92 0.70-0.76 1.62-1.82 2.12-2.64 2.22-2.30 2.24- 2.53 1.44-1.66 2.16-2.72 2.84-3.20 1.56-1.80 1.84-1.96 2.40-3.12 3.30-3.60 2.28-2.64 4.67-5.50 1.16-1.32 1.16-1.26 3.16-3.48 1.70-1.94 2.80-3.44

16 3 30 44 10 61 407 3 1 40 126 50 75 216 12 152 24 90 24 98 15 19 17 13

1.80-2.20 1.32-1.60 1.02-1.24 1.60-1.92 2.28-2.52 3.60-4.12 3.00-3.28 3.00-3.40 0.86-0.98 0.90-1.12 0.84-0.92 0.98-1.08 1.10-1.30 1.36-1.80 0.90-1.10 0.72-0.82 1.52-1.58 0.92-1.00 0.88-0.96 0.73-0.76 0.72-0.86 0.76-0.90 0.66-0.82 1.06-1.28 2.52-2.84 2.88-3.16 3.44-3.88 1.54-1.70 2.20-2.56 2.48-2.80 2.96-3.20 2.51-2.91 1.72-1.88 2.40-2.56 1.58-1.78 2.72-3.00 1.88-2.02 1.50-1.79 1.20-1.40 1.36-1.56 1.40-1.60 1.60-1.84 1.92-2.16 2.36-2.52 1.34-1.52 1.28-1.42

44 389 88 59 29 21 10 49 330 90 31 142 199 11 52 67 2 50 210 59 216 110 90 35 19 18 18 27 207 13 26 19 124 10 196 52 12 67 40 161 216 212 4 6 24 35

1.06 70.027 0.95 70.021 0.85 70.032 0.79 70.024 0.83 70.031 0.76 70.035 1.07 70.048 2.97 70.095 3.36 70.087 3.66 70.143 1.85 70.070 2.71 70.103 3.02 70.043 3.15 70.074 3.19 70.113 2.00 70.050 2.61 70.061 1.92 70.043 3.36 70.089 2.10 70.042 1.72 70.096 1.39 70.059 1.72 70.051 1.70 70.043 2.01 70.047 2.20 70.148 2.74 70.089 1.58 70.048 1.61 70.059

0.95 70.021 0.93 70.017 0.81 70.028 0.79 70.026 0.83 70.032 0.74 70.039 1.19 70.054 2.67 70.110 3.00 70.090 3.62 70.107 1.65 70.037 2.40 70.071 2.61 70.086 3.11 70.069 2.74 70.110 1.91 70.036 2.46 70.045 1.68 70.029 2.89 70.057 1.95 70.018 1.67 70.064 1.34 70.037 1.47 70.036 1.46 70.043 1.72 70.038 2.07 70.091 2.47 70.055 1.45 70.038 1.35 70.034

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Table 6 (continued ) Species

Porroecia pseudoparthenoda Porroecia spinirostris Proceroecia brachyaskos (Bermuda) Proceroecia brachyaskos (Southern Ocean) Proceroecia convexa Proceroecia microprocera Proceroecia procera

Female

Male

Mean carapace length

Range

Number

Mean carapace length

Range

Number

1.82 70.038 1.19 70.037 1.42 70.043 1.60 70.027 1.53 70.054 0.95 70.035 1.17 70.028

1.72-1.90 1.08-1.30 1.28-1.52 1.54-1.64 1.40-1.60 0.86-1.04 1.10-1.24

222 676 209 17 36 218 216

1.64 70.036 1.05 70.045 1.26 70.056 1.48 70.027 1.40 70.025 0.84 70.020 1.00 70.025

1.22-1.34 0.98-1.18 1.06-1.36 1.42-1.54 1.34-1.46 0.76-0.90 0.94-1.08

120 405 168 18 37 213 216

from the Arctic and another from the N. Pacific, together with the ¨ long established species A. cuneata (Muller, 1908). It normally occurs, albeit rather sparsely, at mesopelagic depths in the Bermuda region (Deevey, 1968a; Deevey and Brooks, 1980; Angel, 1979). Its absence from the MOC 1 samples is hard to explain other than the sampling effort at mesopelagic depths was too small or this small, insignificant species was overlooked during the sorting at sea. A. cuneata did occur, probably as a contaminant in one of the deeper MOC 10 samples (#2 net 2). 8. Archiconchoecerra (1). This monospecific genus was established by Chavtur and Stovbun (2003) to accommodate A. longiseta (Deevey, 1978a, b). It was not encountered in the RB 0603 MOC 10 samples, although this rare deep bathypelagic species is known to occur in the region, and has been taken in the N.E.Atlantic (e.g. during Polarstern XXIV/1). 9. Bathyconchoecia (26). Deevey (1968b) first described six species in this genus from specimens retrieved from the gut contents of benthopelagic fishes caught in the Gulf of Mexico, designating B. paulula as the type species. As might be expected from the source of the material, the original descriptions are somewhat incomplete, and given the distortion suffered by many of the specimens possibly misleading in some respects. Since Deevey’s original description of the genus a further 20 species have been described including two more by Deevey (1975) from the Gulf of Mexico. Discovery collections from abyssopelagic and benthopelagic depths in the N.E. Atlantic contain about 25 species of which 15 are undescribed. Additionally material collected during several Polarstern cruises to the Southern Ocean have includes a further ten novel species. When all this material is described the present genus will include in excess of 50 species. The principle character used to recognise the genus is the presence of a thick curtain of fine setae inserted in multiple rows (up to 12 rows with up to 20 setae per row) on a pad on the ventral surface of the second segment of the first antenna. The setae are arranged as curtains across the opening beneath the rostra through which the inhalant respiratory flow enters the carapace. In the majority of species the frontal organ has been lost (however, one of the new species taken during this campaign was the second to be found still retaining a frontal organ). However, preliminary investigations of these many species show there are at least five sets of carapace characteristics and at least five types of mandibles (in the Conchoecini mandibular structures are very similar in all species). So the present concept of Bathyconchoecia is undoubtedly highly polyphyletic and the genus needs to be subdivided into several genera and may be even subfamilies. Five species attributable to the current concept of Bathyconchoecia were found in the Ron Brown samples, all in the deep MOC10 samples. Only one specimen was adult, but the carapace characteristics of four of these species show them to be completely novel. The fifth species is an undescribed species previously collected from the NE Atlantic. An SEM of this strikingly sculptured species collected in the NE Atlantic is shown in Fig. 2. Another specimen was collected on the recent CMarZ on

Fig. 2. Scanning electron microscope image of one of the undescribed species of Bathyconchoecia captured during Cruise 0603 of the R.V. Ronald H. Brown. The length of this female specimen was 3.68 mm, (Discovery station 9541#18 depth 3790-4020 m, 18 April 1977).

the Polarstern cruise XXIV/1. Bathyconchoecia is in need of a major revision, and until bethopelagic sampling to within 5–10 m of the seabed at abyssal depths becomes more routine, the full diversity and zoogeographical distribution of this ‘supergenus’ will remain poorly known. 10. Boroecia (3). Just two specimens of B. borealis were taken in the MOC10 samples at station 1. There are currently two known Boroecia species in the North Atlantic, both appear to be endemic to high latitudes in the Northern Hemisphere. B. borealis, is almost entirely restricted to the North Atlantic (Angel et al., 2007, Bashmanov and Chavtur, 2008). However, its presence at high latitudes in the Arctic has recently been confirmed in samples collected in the Canada Deep to the Northeast of the Bering Strait (Hopcroft, personal communication). The other species, B. maxima, is the dominant halocyprid species throughout the Arctic (Chavtur and Bashmanov, 2007). A third species, B. antipoda is a Southern Ocean endemic, however, Poulsen (1973) reported it from tropical waters off Indonesia and in the Gulf of Panama, but I have re-examined his material and found that only one of his specimens (collected at 461S in the Indian Ocean) is B, antipoda. Otherwise all his tropical specimens belong to a different, undescribed species. A fifth, undescribed species, which resembles B. maxima, has been found recently in the Gulf of Alaska. Deevey (1968a) and Deevey and Brooks (1980) report B. borealis to be a rare bathypelagic species off Bermuda. Thus its presence in temperate waters in the N. Atlantic as a deep mesopelagic/ bathypelagic species, off Bermuda is an example of submergence, and its presence is probably indicative of the southward advection of cold water masses that had down-welled at high latitudes. 11. Conchoecetta (2). Both species occur in the North Atlantic, but only C. acuminata occurred in the RB603 samples and then only at the last two stations. The distributional maps for these two species (Angel et al., 2008) show that they are generally restricted to latitudes o401, but there are gaps in their ranges in the southern Sargasso Sea. C. acuminata has been reported off Bermuda (Deevey, 1968a; Deevey and Brooks, 1980; Angel, 1979). C. giesbrechti was absent from the RB0603 samples, but it was

M.V. Angel / Deep-Sea Research II 57 (2010) 2173–2188

abundant in the samples collected in November 2007 from the Polarstern at tropical and subtropical latitudes in the Eastern Atlantic. The factors responsible for these distributional gaps in ranges of these two species are not obvious, unless it is associated with an aversion for the 181C Water. 12. Conchoecia (7). This genus was represented by five species in the RB0603 samples, four in the MOC1 samples and one, ¨ C. macrocheira Muller, 1906, in the MOC10 samples, and predominantly in net 4 (i.e. at 1000-2000 m). There is an element of uncertainty about the identities of C. magna and C. hyalophyllum. Skogsberg (1930), usually a thorough and reliable author, described C. tetragona from the central Atlantic. This species has been synonymized with C. magna but the possibility remains that this lumping is incorrect, and needs to be investigated. C. lophura ¨ Muller (1906) has been reported regularly from the region (Deevey, 1968a; Deevey and Brooks, 1980; Angel, 1979) where it is a common, deep mesopelagic species. C. subarcuata Claus 1890 is a shallow mesopelagic species that is reasonably common at latitudes of o401 but less frequent at higher latitudes. It was not abundant in the RB0603 samples. Adults of the bathypelagic species C. macrocheira predominantly occur at bathypelagic depths, but its juveniles are regularly encountered at shallower depths. The outline shape of the juvenile rostrum is humped, particularly in the early instars, which differentiates them markedly from the adults. So much so that they were described as a separate species, C. zetesios (Fowler, 1909) when they were sampled in the Western Approaches. 13. Conchoecilla (2). This genus was represented at all RB 0603 stations by C. daphnoides. It is a species that not only has a highly characteristic carapace shape, but also has the right asymmetrical gland on the ventral margin of the carapace opening anteriorly just under the rostral incisure. The highly characteristic carapace of this species means that it can be easily identified seldom and so seldom gets examined critically. In common with several other ¨ halocyprid species there are two adult size categories. Muller (1906) described the shorter form as a subspecies, C. daphnoides minor. Whenever similar distinct size classes have been examined

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critically in other genera, they have been split into separate species. The sizes of all the specimens taken on RB0603 were consistent with the larger typical form. 14. Conchoecissa (5). The three of species that are well known in the region (Deevey 1968a,b; Angel, 1979) and are generally widespread in the North Atlantic generally occurred in the RB603 ¨ samples. C. ametra Muller (1906) is a deep mesopelagic species, which can be abundant in temperate waters, but it was never abundant in the RB0603 samples and was not taken at the two southernmost stations. This agrees with the distributional map derived from published records (Angel et al., 2008), which shows that it has seldom been taken in the Sargasso Sea. Likewise for C. imbricata (Brady, 1880) published records in the Sargasso Sea are sparse, which is in stark contrast to its high abundance at mesopelagic depths in the Eastern Atlantic, where it is a strong diel vertical migrant (Roe, 1974; Angel, 1969, 1979). The third species that occurred in the RB0603 samples is C. plinthina ¨ (Muller, 1906). This large, strikingly red-coloured bathypelagic species was almost entirely restricted to the MOC10 samples. A single specimen occurred in the MOC1#5 net 0 (the only net 0 sorted), and was probably taken at the very bottom of the sampling range. It was notable that this sample contained several other bathypelagic species that otherwise did not appear in any other MOC 1 samples. Its recorded zoogeographical distribution (Angel et al., 2008) is discontinuous, but this is probably more a reflection of the discontinuity of the sampling at the deep bathypelagic depths than being representative of the species’s distribution. 15. Discoconchoecia (4). Only one Discoconchoecia species, D. elegans, occurred abundantly in the RB0603 samples. This species is something of an enigma. It was first described by Sars (1866) from near the Lofoten Islands, off northwest coast of Norway. Its geographical range is reported as stretching continuously from 801N near Svalblad to the Southern Ocean at 651S. Throughout this range it is a shallow mesopelagic species, which very occasionally occurs in nighttime neuston samples (Moguilevsky and Angel, 1975). Table 7 shows that its adult sizes

Table 7 Carapace lengths of Discoconchoecia elegans from a range of localities. Svalblad samples from Norwegian/Polish programme, Labrador Sea samples from Canadian Monitoring programme, Benguela Current from Discovery Investigations Iles (1953), Southern Ocean Discovery Investigations (Unpublished), Celebes Sea Japanese Celebes CMarZ cruise, British Columbia samples (McHardy and Bary, 1965), CMarZ cruises (RB0603 and Polarstern XXIV), all others are Discovery Stations (see Angel et al., 2007). Location

~ mean size (mm)

# mean size

A-1 mean size

A-2 mean size

Svalblad 791N 601N 201W

2.07 70.082 n ¼20 1.70 70.059 n ¼217 1.90 70.066 n ¼72 1.70 70.058 n ¼212 1.25 70.036 n ¼275 1.23 70.036 n ¼267 1.27 70.038 n ¼226 1.36 70.055 n ¼150 1.64 70.060 n ¼187 1.64 70.60 n ¼65 1.26 70.039 n ¼86 1.25 70.037 n ¼265

2.19 7 0.087 n ¼ 11 1.86 7 0.057 n ¼ 215 2.03 7 0.088 n ¼ 13 1.81 7 0.059 n ¼ 213 1.23 7 0.053 n ¼ 175 1.23 7 0.034 n ¼ 98 1.19 7 0.032 n ¼ 215 1.27 7 0.034 n ¼ 86 1.76 7 0.070 n ¼ 92 1.78 7 0.041 n ¼ 39 1.24 7 0.031 n ¼ 13 1.20 7 0.053 n ¼ 141

1.77 7 0.034 n ¼ 13 1.507 0.055 n ¼ 189 1.62 7 0.042 n ¼ 40 1.47 7 0.045 n ¼ 239 1.067 0.032 n ¼ 219 1.057 0.025 n ¼ 84 1.037 0.024 n ¼ 121 1.047 0.057 n ¼ 185 1.45 7 0.039 n ¼ 174 n.d

1.51 7 0.073 n¼8 1.25 7 0.050 n ¼ 219 1.36 7 0.048 n ¼ 31 1.19 7 0.047 n ¼ 203 0.947 0.018 n ¼ 151 0.927 0.027 n ¼ 81 0.957 0.020 n ¼ 93 0.747 0.038 n ¼ 59 1.207 0.045 n ¼ 113

1.077 0.042 n ¼ 74 1.047 0.27 n ¼ 74

0.917 0.038 n ¼ 21 0.947 0.048 n ¼ 82

Labrador Sea 531 N 201N 301N 231W 321N 651W 101N 201W Benguela Current Southern Ocean British Columbia Celebes Sea CMarZ

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range from 42 mm at high latitudes to ca.1 mm at tropical and subtropical latitudes. It seems certain that the present species concept is a complex of several cryptic species, which are yet to be resolved. 16. Euconchoecia. (7) There are currently seven species described in the literature, but there are several others awaiting description. Poulsen (1969) classified the members of this genus together with Bathyconchoecia in the subfamily Euconchoecinae. However, there are some stark differences between these two genera, which suggest that this classification does not reflect their phylogeny. For example, Euconchoecia species are small, predominantly shallow-living species (many are neritic), and have plain, unadorned delicate carapaces. They often occur in swarms. In contrast Bathyconchoecia species are predominantly solitary deepliving benthopelagic or abyssopelagic species with highly sculptured carapaces. The only character the two genera share is the possession of numerous setae on the first antennae (Poulsen, 1969). In Euconchoecia there are only about 10-12 setae, which are carried splayed out ahead of the carapace when the animal is swimming. In contrast Bathyconchoecia species have curtains of up to 200 of fine setae arranged in up to ten rows. These ‘curtains’ of setae appear to function to act a screen across the inhalant respiratory current which prevents the inner parts of the carapace becoming clogged by detritus. Both genera have in common the carapace glands placed symmetrically near the posterior dorsal corner of the carapace, but the mandible structure in Euconchoecia is quite distinct from the all five of the different structures in Bathyconchoecia. In addition the mode of reproduction is different. The Euconchoecia species brood their embryos within the carapace, which sets them aside from all other halocyprids, but is the general mode in the majority of Myodocopida. Thus Euconchoecia appears to be a link between the Myodocopida and the Halocyprida, whereas the Bathyconchoecia species may be more derived, possibly adapted to the benthopelagic environment. Euconchoecia chierchiae was only taken in the first ring sample. This is the only Euconchoecia species reported from the open Atlantic Ocean, but it can be very abundant in neritic waters (Baker et al., 1977). It was ¨ first described by Muller (1890) from inshore waters off Brazil. A second species, E. aculeata (Scott, 1894) was first described from the Gulf of Guinea, from shallow waters. Neither of the original descriptions of these species meets with modern standards and redescpritions are needed. Skogsberg (1920) gave a very detailed description of E. chierchiae, based on material collected from oceanic waters off Brazil. But, detailed comparisons of the original drawings, with drawings published by Skogsberg (1920), Deevey (1968a) and published on the web by Blachowiak-Samolyk and Angel (2003) show differences that suggest that they may not all be of the same species (Graves, personal communication). 17. Fellia (3). Poulsen (1969) established this genus when he ¨ re-evaluated the subfamily Halocyprinae. Muller (1906) had combined Claus’s two genera Halocypris and Halocypria and described two new species Halocypris cornuta and H. bicornis. Poulsen (1969) re-established Claus’s two genera and placed ¨ Muller’s two species in a new species Fellia. Muller (1906) had also described a subspecies H. cornuta dispar from the Southern Ocean, which Deevey (1982) later raised to full species status, as F. dispar. The RB0603 samples contain a few specimens of F. bicornis, which has lateral spines on the shoulder vaults and lateral tubercles on each carapace valve. In the very deep samples was an undescribed species, which is tentatively attributed here to Fellia, but will be placed in a new genus. Specimens of this new species had been collected previously from abyssal depths off the NW African margin and were collected again during the recent CMarZ cruise on Polarstern. 18. Gaussicia (4). Two of the four species occurred in the RB0603 MOC10 samples - G. gaussi and G. incisa. This genus

established by Poulsen (1973) and was thoroughly redescribed by Gooday (1976), although at the time, Gooday did not accept Poulsen’s new genus. Species in this genus are characterised by having a group of large medial glands opening on the ventral margin of each carapace valve. Both species are quite rare in samples and are poorly known. 19. Halocypria (1). H. globosa Claus (1874) is the sole species. ¨ Muller (1906) synonymised it with Halocypris, but the genus was re-instated by Poulsen (1969). The sole species is enigmatic. Juveniles and adult females can dominate the ostracod assemblages in the upper 100 m around Bermuda (Deevey, 1968a, Angel, 1979). The males have a very restricted bathymetric range at 700-900 m (Angel et al., 2008), so adult females must migrate down to encounter them. They then appear to continue to migrate deeper, so that they occur at low densities at depths of 2000 m or deeper. The species has spasmodically been reported from the N.E. Atlantic, but never in the high abundances reported off Bermuda. However, adults were caught in quite large numbers in benthopelagic samples collected 5-10 m above the seabed at depths of around 1000 m over the continental slope in the Southwest Approaches (Ellis, 1985a, b). Assuming these specimens are indeed the same, this species undertakes remarkable ontogenetic migrations. H. globosa was very abundant at the two northernmost RB0603 stations in both MOC1 and MOC10 samples, but was absent from the two southernmost stations. The map of this species’s reported zoogeographical range (Angel et al., 2008) shows that it is apparently absent from the Southern Sargasso Sea and central tropical Atlantic (despite being so abundant off Bermuda), while being present in the tropical eastern Atlantic. 20. Halocypris (3). Both the two Halocypris species that occur in the Atlantic occurred in the RB603 samples. They are extremely similar in external appearance, having globular carapaces with almost no rostrum. H. inflata and H. pelagica are clearly distinguished on size. They are often very abundant in the upper 100-200 m, and so not surprisingly they have been regularly reported, synonymised, re-split, misnamed and confused, and so have a very complex synonymy. Angel (1982) eventually sorted out the two species, but it remains impossible to establish which of the two species are being referred to in much of the early literature, especially, when the invalid name H. brevirostris was applied. The two species can co-occur in the same water column, albeit with a degree of depth segregation (Angel, 1982). In the northern RB0603 samples the majority of specimens belonged to the larger species H. inflata, but it was largely replaced by the smaller species H. pelagica at the two southern stations. 21. Loricoecia (3) All three known species of Loricoecia occurred in the RB0603 samples. L. loricata and L. ctenophora are very similar, but are readily separated on the basis of size. L. ctenophora is not only the larger (Table 6) but also lacks the oblique striae on the anterior region of the carapace below the incisure that are a clear feature in L. loricata. L. ctenophora occurred in only one sample, whereas L. loricata occurred in nine of the MOC1 and MOC10 samples. The third species, L. acutimarginata, was represented by a single A-2 instar in the deepest net at MOC10 # 6. This species was originally described from deep water in the N.E. Pacific. It has been taken frequently in deep water on the Eastern side of the Atlantic, so its presence in the Atlantic implies there is some global continuity in the composition of abyssopelagic communities. 22. Macroconchoecia (4) Three of these species occurred in the ¨ RB603 samples. Ellis (1984) revised the species in Muller’s ‘reticulata’ group, which Poulsen (1973) had placed in the genus Macroconchoecia established by Granata and Caporriaco (1949); it was then monotypic at the time making M. reticulata the type species. Ellis observed that specimens that conformed to the

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¨ description of C. reticulata Muller 1906 caught in the N. Atlantic formed a complex of three species. All three inhabit bathypelagic depths of 41500 m and have rarely been sampled since first described. They are all large (#4 2.8 mm; ~43.0 mm) and covered with a conspicuous reticulate sculpturing. M. spinireticulata also carries spines along the bars especially around the margins of the shoulder vaults, spines which are also present in the most spectacular species in the genus, M. caudata. M. caudata has long spine-like extensions of the rostra and a very long spine at the posterior dorsal corner of the left carapace valve. These spines effectively double the animal’s carapace length. This spectacular species has been reported from the South Atlantic, but not from the western tropical Atlantic. 23. Metaconchoecia (27). This is a large and complex genus that is currently being revised (Chavtur and Angel, in preparation). This revision will establish a new subfamily and subdivide the present large and disparate genus into nine genera. Members of the current genus (and hence the new subfamily) are immediately recognisable by the locations of the asymmetrical carapace glands. The gland on the left valve opens on the anterior half of the dorsal surface in Metaconchoecia and in many of the species very close to the rostrum (c.f. in other genera of Conchoecini is located close to the posterior dorsal corner). The gland on the right carapace valve opens on the posterior margin close to the rounded posterior dorsal ‘corner’ and the posterior end of the hinge between the valves (c.f. near the posterior ventral corner in the majority of Conchoecini). The carapace outline ranges from being cylindrical to globular, and generally there is a lack of surface ornamentation. The various Metaconchoecia species differ in size, the precise positions of the gland openings, and relative height and breadth of the carapace. Identifying the species live without dissection is difficult, but can be achieved, bearing in mind the differences in the bathymetric distributions of the various species. Until Chavtur and Angel’s revision is finally published, reliance has to be placed on a series of earlier papers including Gooday (1981), Deevey (1968a), Iles (1953) and Skogsberg (1920), and the recently published website an Atlas of Atlantic Planktonic Ostracoda (Angel et al., 2008). The identifications of the thirteen species in the RB0603 samples are generally reliable, especially those taken in the MOC 1. The bathypelagic species in the MOC 10 samples are more of a problem. For example, Chavtur (personal communication) has ¨ pointed out inconsistencies between Muller’s (1906) original description of C. macromma, and subsequent illustrations by Deevey (1974, p. 364, fig. 5, c-f; 1980, p. 91, fig. 24 a-m) and ¨ Angel, (1981, p. 557, fig. 194-37). Muller (1906) described the species from both the eastern equatorial Atlantic Ocean and the equatorial Indian Ocean, yet, as was his custom, failed to nominate a type locality and to identified from whence came the material he illustrated. Despite Chavtur’s reservations I am confident that the specimens taken in these samples are identical to those described by Deevey (1974) and Angel (1981) from the Atlantic, but Deevey’s (1980) specimens from the Southern Ocean and probably not identical. Specimens collected from the Indian Ocean needs to be re-evaluated. Another example of problematic identification is presented by the RB0603 specimens of M. aff. lunata. These resemble Deevey’s somewhat incomplete description of this species from the Southern Ocean, and if this can be confirmed by comparison of the Atlantic specimens with others from the Southern Ocean, this species may prove to be an indicator of deep Antarctic Water ¨ flowing northwards. M. glandulosa Muller is another problematic species. It is a large rather fragile bathy/abyssopelagic species that ¨ has seldom been reported since Muller’s (1906) first description, but has been regularly taken when sampling extends deeper than 3000 m. The RB603 specimens are smaller than the sizes given by

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¨ Muller. The RB 0603 specimens of M. pusilla, which is a small characteristically, shaped species that is abundant at deep mesopelagic to bathypelagic depths at temperate latitudes in the N.E. Atlantic (Angel et al. 2004), included a small form as well ¨ as typically sized specimens. When Muller (1906) first described this species, he noted two sizes, but the small RB forms were even ¨ smaller than Muller’s subspecies M. pusilla minor. M. skogsbergi Iles 1953 continues to be problematic. Iles used Skogsberg’s (1920) excellent description of C. rotundata from the Southern Ocean as the type description, but when Gooday (1981) examined Discovery material he found at least two sizes of this species in both in the Southern Ocean and in deep water samples from the N.E.Atlantic. The MOC10 samples collected on RB0603 similarly contained two size categories with the larger forms tending to occur deep than the smaller. The question of whether or not these are separate species need to be targeted both by a classical morphological approach and DNA barcoding. Finally a few specimens of a species that closely resembles a new species being described by Chavtur and Angel (in press) from the Pacific occurred in the deepest MOC 10 tows. This species is unusual in Metaconchoecia in having a clear sculpturing of longitudinal striae over the flanks of the carapace. If this species is found to be conspecific with the new Pacific species, then it will again indicate that there is a degree of global conformity in species composition of deep abyssal holoplanktonic faunas, and will raise questions about how gene flow is maintaining this uniformity. 24. Mikroconchoecia. This genus includes four described species, three of which occurred in the RB0603 samples. However, the smallest two species M. curta and M. echinulata are both globular and with highly sculptured carapaces, and are easily confused, apart from their relative lengths. Specimens caught at the northern Bermudan end of the RB0603 transect where predominantly the smaller M. echinulata, but there was a shift to the populations being predominantly M. curta at the southern end. There was confusion in separating these two species at sea, which has become evident from the preliminary barcoding results (Angel et al, in preparation). The third species, M. stigmatica, is larger and has a characteristic anterior taper to the carapace. It bathymetric distribution is much deeper than the other two. 25. Mollicia (7) Two species of this genus were caught during this study. M. kampta, which occurred in just one haul (MOC10#2 net 2) is a common bathypelagic species in the Northeast Atlantic, and had been reported previously from near Bermuda (Deevey, 1968a, Angel, 1979; Deevey and Brooks, 1980). Apart from Deevey’s (1978b) record from the Cariaco Trench region it has not been reported from the Caribbean and is almost entirely restricted to the Northeast Atlantic (Angel et al., 2008). In the eastern Atlantic M. kampta is replaced by M. mollis to the south of 101N (Angel et al., 2008), but this latter species appears to be absent from the Caribbean. The other species collected in three MOC10 samples was M. tyloda, which had not previously been collected from the Western Atlantic, probably because it inhabits depths greater than 2000 m, which had not been sampled before in the region. 26. Orthoconchoecia (7) Four species occurred in the Ron Brown samples. The most abundant was O. secernenda, which predomi¨ nantly occurred in the MOC1 samples. Muller (1906) considered it to be synonymous with O. bispinosa and subsequently all authors ¨ followed Muller’s lead. Consequently the species was overlooked until Angel (1970a) demonstrated the two species are morphologically distinct. Their separation is more straight forward when dealing with fresh material, because O. secernenda is not only the larger, but is also more opaque and more intensely pigmented. Angel (1979) reported that at the eastern end of a transect along 301N extending from the Northwest African coast to Bermuda, O. bispinosa was the more abundant in the east, and

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was progressively replaced by O. secernenda to the west. Near Bermuda Angel found O. secernenda was over an order of magnitude more abundant. O. bispinosa was absent from the three northerly Ron Brown stations, but did occur at the two southernmost stations. The other common Orthoconchoecia species was O. atlantica, which is larger than the previous two species and has a very characteristically shaped carapace; the posterior and dorsal margins of the carapace form an acute angle and there are no spines at the posterior dorsal corner. It occurred at most of the stations, with juveniles most abundant in the MOC1 samples and adults in the MOC 10 samples. The fourth species, O. haddoni occurred only once. It is a species that most occurs at latitudes 4401. It also is one of the commoner species associated with upwelling areas. In the Mauritanian upwelling region off Northwest Africa, the population is smaller than those found at the type locality off the west coast of Ireland (Brady and Norman ¨ 1896). Confusingly, Muller (1906), whose typically sized specimens all came from the Southern Hemisphere, referred to these smaller specimens as the ‘northern race’. Populations of these two-size forms need to the critically assessed to see if they are indeed conspecific. If they are found to be separate species then it is also feasible that the Southern Hemisphere populations are also different species. 27. Paraconchoecia (19) Nine species occurred in the MOC 1 samples and 12 in the MOC 10 samples, but six of the latter were probably contaminants. The genus is highly heterogeneous and is almost certainly polyphyletic in its present state. P. mamillata and P. nanomamillata is a pair of sibling species originally described by ¨ Muller (1906) as a single species with two size forms. These two size forms were later divided by Deevey and Brooks (1980) into separate species. Both species often co-occur in the same water column, but are segregated bathymetrically; the smaller species P. nanomamillata is mesopelagic (and so occurred predominantly in the MOC 1 samples), and P. mamillata is bathypelagic, and so was taken almost exclusively in the MOC10. P. dentata and P. cophopyga are another pair of sibling species that are morphologically similar, but with distinct size ranges. P. dentata is much the commoner of the two species with a deep mesopelagic to bathypelagic distribution. P. cophopyga is slightly deeper living. P. hirsuta and P. aequiseta are species that are extremely similar in size, appearance, and most morphological characteristics. At present only the male can be separated reliably, and then only on the basis of a single rather trivial male character (i.e. the first of the two setae on the first segment of the endopodite of the second antenna carries a patch of long hairs in P. hirsuta, but is bare in P. aequiseta). Males of both species were identified in both MOC1 and MOC 10 samples and so females of both species were probably ¨ present. P. oblonga presents a another scenario. Muller (1906) pointed out there are two forms of this species; form A with the opening of the right asymmetrical gland located at the posterior ventral corner, and form B in which the gland opens slightly anterior to the corner. The difference is clear and the juvenile instars can be attributed unequivocally to one or other of the forms. Angel (1979) showed that the bathymetric distributions of the two forms are almost identical. Form B was more abundant in the Ron Brown samples from the western Atlantic, whereas Angel (1979) reported that Form A is the commoner form in the eastern Atlantic. The barcoding results suggest that these two forms are different species (Bucklin et al. 2010). There were two bathypelagic species in the RB0603 samples. P. dorsotuberculata is a unique in having the left asymmetrical gland opening just posterior to midlength on the dorsal surface. The posterior region of the carapace is also broadly extended and lined with densely staining cells. It bathymetric range is 900-1500 m (Angel et al. 2008). The other bathypelagic species is P. dasyophthalma, which inhabits depths of 42000 m, and so

has rarely been sampled. Its carapace is quite fragile and the right asymmetrical gland opens just posterior to midlength. It is also one of just eight species that have sharp edged shoulder vaults. It has a sibling species P. mesadenia (Ellis, 1985a, b), which inhabits even deep depths and the right asymmetrical gland opens anterior to midlength, which was described from the Eastern Atlantic, but surprisingly did not occur in theses samples. Paraconchoecia inermis occurred in MOC 10 samples at three stations, but surprisingly only in a single MOC 1 sample. This is somewhat unexpected as the bathymetric range this non-migrant is reported as being 400-600 m (Angel et al., 2008). Finally the type species of the genus P. spinifera is the most abundant mesopelagic Paraconchoecia species in the temperate north-east Atlantic that has sharp-edged shoulder vaults. It is abundant in the Bermuda region (Deevey, 1968a, Angel, 1979, Deevey and Brooks, 1980) where its bathymetric distribution is centred at 500 m and it undertakes diel vertical migrations. It occurred at most RB0603 stations, most abundantly in MOC1 samples, and is a likely contaminant in the MOC10 samples. 28. Paramollicia (7) Only one species of Paramollicia was ¨ identified in the RB0603 samples. P. dichotoma (Muller, 1906) was originally described from near the Equator in the Atlantic and Indian Oceans, and has since been reported from much of the North Atlantic (Angel et al., 2008) where it is a deep bathypelagic species occurring at depths of 900-2000 m, and in the RB0603 samples it mainly occurred in the MOC10 samples collected from depths of 1000-2000 m. It has also recently been reported from the deep basins of the Arctic Ocean close to the North Pole (Chavtur, personal communication). If all these records are of the same species, this species will have a remarkable zoogeographical distribution. 29. Porroecia (7) Four species occurred in the RB0603 samples. They are all shallow mesopelagic species. P. spinirostris, P. porrecta and P. parthenoda were redescribed by Angel (1969a, b), and all three are very common in the Bermuda region (Deevey, 1968a; Angel, 1979; Deevey and Brooks, 1980). Male P. spinirostris often swarm in the neuston at night (Angel, 1970b; Moguilevsky and Angel, 1975). P. pseudoparthenoda was described from the tropical Atlantic and was only sampled in the last of the MOC10 hauls, probably at the fringes of its distributional range. 30. Proceroecia (7) Four Proceroecia species were identified in the RB0603 samples. P. procera and P. microprocera are both shallow mesopelagic species with widespread distributions in the North Atlantic. P. brachyaskos is a deep mesopelagic/bathypelagic species that occurs in two sizes. The larger, deeper living, form is similar in size to P. brachyaskos from the Southern Ocean, and may be indicative of the deep northward flow of Antarctic water (see ¨ Table 6). Muller (1906) in his original description of the species notes that Southern Ocean specimens are larger, suggesting that the smaller forms should be regarded as the typical forms should the two sizes be found to be distinct species. The fourth species P. convexa was described relatively recently from the Gulf of Mexico (Deevey, 1977), and has been reported from the 01-301N in the North Atlantic. It is a mesopelagic species in the Eastern Tropical Atlantic (Angel et al., 2007), but in the RB0603 samples it occurred are three MOC10 stations and only in the final MOC1 sample. It is an uncommon species, so its absence from most of the MOC1 samples was probably the results of the sampling effort within its bathymetric range being rather low.

4.1. Unidentified There were a few single adult female specimens that could not be attributed to known species. Some of these specimens are probably novel, but are some too distorted to use for species descriptions.

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Myodocopids Three species of myodocopids were caught in the RB 0603 samples. Macrocypridina (2). M. castanea was the only species caught. It is relatively large compared to the majority of halocyprids, and usually has a characteristic chocolate brown coloration. Newly moulted specimens and juveniles can lack the full pigmentation. Laterally, there is a transparent window in the pigmentation of the carapace overlying the compound eye (Davenport, 1990). The presence of this compound eye immediately shows this species is a myodocopid and nor a halocyprid, which without exception lack both compound and naulpiar eyes. It also differs from the halocyprids in being a carnivore. It occurs regularly in mesopelagic samples, but is seldom abundant ( 41 per 1000 m3). The other species in the genus (M. poulseni) has been reported from the tropical North Atlantic, but it appears to be a Southern Hemisphere species, so it is questionable if these reports are correct. Gigantocypris (7) In the temperate and subpolar Northeast Atlantic Gigantocypris muelleri is abundant at deep mesopelagic/ bathypelagic depths. It seems to be quite rare at subtropical latitudes in the Western Atlantic as only a single specimen was taken in one of the MOC10 samples, and none were taken in the MOC1. Skogsberg (1920) described this species from the Southern Ocean, and it has been assumed ever since that the North Atlantic specimens are conspecific, but without critically assessing their status. The size ranges of Southern Ocean specimens collected by Discovery Investigations are for females 15.5-18.7 mm and for males 13.5-15.8 mm, whereas in the North Atlantic the size ranges are smaller, for females 12.8-15.1 mm, and for males 10.3-13.1 mm. Such size differences in halocyprids would be enough to suspect they are not conspecific, but at present this must remain and open question. In the MOC 10 samples the commonest specimens have been assigned tentatively to G. dracontovalis Cannon 1940, which was originally described from the Northwest Indian Ocean. They occurred regularly at depths of around 3000 m. Once again there is an element of doubt as to whether these specimens are correctly attributed. Canon’s original description is incomplete, but recently the holotype, dissected and mounted on three slides, has been discovered and is now deposited at the Natural History Museum, London (registration number NHM 2009.261). Only this material has been reexamined the identity of these specimens from the deep Atlantic be verified.

4.2. Significance of size in halocyprids Carapace size is a stable character in halocyprid species, so whenever populations taken either in different localities or at different depths are found to diverge in size it is a strong indication that they are different species (Angel, 1977). As a general rule the large species either occurs at higher latitudes or at deeper depths, as shown by the two forms of Archiconchoecissa cucullata, Paraconchoecia mamillata and P. nanomamillata and the two size forms of Proceroecia brachyaskos. Poulsen (1973) lists sizes of a number of species whose populations in different ocean areas differ quite substantially. The sizes of Discoconchoecia elegans populations from a wide variety of localities have already been listed in Table 7. To help with future identification of potential cryptic species, the adult sizes of all species sampled during RB0603 for which a large number of specimens have been available for measurement are listed in Table 6. Additional data has been included for Proceroecia brachyaskos from the Southern Ocean to illustrate the divergent and no-overlapping size ranges of specimens from the two regions, and for Loricoecia ctenophore.

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5. Summary 1. 93 species of planktonic ostracods have been identified in samples collected throughout the total water column to depths of 5000 m at five stations in the Western North Atlantic, during RV Ronald H. Brown Cruise 0603. 2. 52 species were collected from the upper 1000 m, and 87 from 1000-5000 m, of which 40 were restricted to depths 41000 m 3. Thirteen of the species collected below 1000 m were either novel or undescribed. 4. A literature survey shows that a further 26 species have been reported from the Western Atlantic region that were not collected during this cruise. Most of these species are either benthopelagic or small enough to be extruded through the nets. 5. This total planktonic ostracod fauna for the region inventory now stands at 118, and for the whole Atlantic Ocean at 153.

Acknowledgments This was the first major CMarZ cruise in the Northwestern Atlantic. The success of the cruise was due to the collective efforts of Captain, Officers, Crew, and all members of the Scientific Party. Peter Wiebe, as principle scientist, not only orchestrated the team effort fulfilling the objectives of the sampling programme, but also operated the gears with the help of Larry Madin, enabling the individual experts to focus fully on the analysing the samples. Nancy Copley and Dicky Allison were principally responsible for arranging logistical elements for the cruise. Support for this cruise was provided by the NOAA Ocean Exploration Program Grant #NA06OAR4600091, the Sloan Foundation, and the Census of Marine Life (CMarZ) project. The latter covered my personal travel expenses. I also thank Professor David Billett for continuing to provide me with laboratory facilities at the National Oceanographic Centre, Southampton, and Kasia Blachowiak-Samolyk (Sopot), Moira Galbraith (Vancouver), Erica Head (Halifax) and Professor Shuhei Nishida (Tokyo) for providing the additional material reported on in Table 7. References Angel, M.V., 1969a. The ostracod Conchoecia porrecta Claus redescribed and compared with C. spinirostris Claus. Crustaceana 17, 35–44. Angel, M.V., 1969b. The redescription of three halocyprid ostracods, Conchoecia ¨ hyalophyllum Claus, C. magna Claus and C. parthenoda Muller from the North Atlantic. Crustaceana 17, 45–63. Angel, M.V., 1970a. The redescription of Conchoecia bispinosa Claus, C. haddoni Brady and Norman and C. secernenda Vavra from the North Atlantic. Crustaceana 18, 147–166. Angel, M.V., 1970b. Observations on the behaviour of Conchoecia spinirostris. Journal of the Marine Biological Association of the United Kingdom 50, 731–736. Angel, M.V., 1971. Conchoecia from the North Atlantic. The ‘procera’ group. Bulletin of the British Museum of Natural History (Zoology) 21, 259–283. Angel, M.V., 1972. Conchoecia pseudoparthenoda (nov. sp.) a new halocyprid ostracod for the tropical North Atlantic. Bulletin of the British Museum of Natural History (Zoology) 21, 289–296. Angel, M.V., 1977. Some speculations on the significance of carapace length in ¨ planktonic ostracods. In: Loffler, H., Danielopol, D. (Eds.), Aspects of Ecology and Zoogeography of Recent and Fossil Ostracods. Junk, pp. 45–54. Angel, M.V., 1979. Studies on Atlantic halocyprid ostracods: their vertical distributions and community structure in the central gyre region along latitude 301N from off Africa to Bermuda. Progress in Oceanography 8, 1–122. Angel, M.V., 1982. The Atlantic halocyprid ostracods Halocypris inflata (Dana 1848) and H. pelagica Claus 1880, sibling species which possibly show character displacement. In: Bate, R., Robinson, E., Sheppard, L. (Eds.), Fossil and Recent Ostracods. Ellis Horwood/British Micropalaeontological Society, pp. 327–343. Angel, M.V., Blachowiak-Samolyk, K., Drapun, I., Castillo, R., 2007. Changes in the composition of planktonic ostracod populations across a range of latitudes in the North-east Atlantic. Progress in Oceangraphy 71, 60–78. Angel, M.V., Blachowiak-Samolyk, K., Chavtur, V.G., 2008. An atlas of Atlantic planktonic Ostracoda. /http://www.nhm.ac.ukS.

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