Bijdragen tot de Dierkunde, 58 (2): 227-258 — 1988

Medusae of the Amsterdam Mid North Atlantic Plankton

Expeditions (1980-1983) with description of two new species

by

J. Bleeker & S. van der Spoel

Institute of Taxonomic Zoology (Zoologisch Museum), University of Amsterdam,

P.O. Box 4766, 1009 AT Amsterdam, The Netherlands

Abstract of the The present paper gives an account

Medusae collected these in The medusa fauna of the mid North Atlantic Ocean by expeditions

between 24° and 55° N along approximately 30° W is spring (1980), summer (1983) autumn (1981) studied. Two Oceania the Hydromedusae new to science, and winter (1982); data already published

and Annatiara are described. The dif- tydemani lempersi , mentioned. attention is are briefly Special given ferences in fauna south and north of 42° N, and faunal to vertical distribution and faunal borders. borders near 50°, 48°, 45°, 35°, 30°, and 34°-37° N are illustrated Some of the species are because discussed. The vertical distribution and for some species

earlier are the diurnal migration and subtropical submergence are published figures frequently

be recorded. diagrammatic. In some cases pictures could

prepared from colour photographs of living Résumé which show specimens the normal, not con-

dimensions of the La faune de Méduses de l’Océan Atlantique Nord central tracted, organism; e.g.

fine (entre 24° et 55° N; approximativement 30°O) est Chromatonema rubrum (figs. 20, 21) gives a étudiée. Deux nouvelles la science Hydromedusae pour of the effect of fixation and example preser- sont décrites: Oceania tydemani et Annatiara lempersi. On vation. discute les différences nord sud de faunistiques au et au

ainsi les limites trouvées 42° N, que faunistiques au

voisinage de 50°, 48°, 45°, 35°, 30°, et de 34° à 37° N. MATERIAL AND METHODS Est mentionnée la distribution verticale certaines et, pour

la diurne et la submersion sub- espèces, migration The material studied has been collected during four tropicale. expeditions between 55 °N and 24° N along approximately

30°W in the North Atlantic Ocean (fig. 1) during four

in the 1980 1981 seasons years (9/IV-6/V), (14/IX-14/X), INTRODUCTION 1982 (1/II-27/II) and 1983 (27/V-24/VI). During these

four cruises, stations were sampled as much as possible at

but the winter Winkler (1982) described the Hydromedusae comparable geographic localities, during

cruise in 1982 this was impossible due to bad weather con- collected in spring during the Amsterdam Mid be ditions preventing part of the transect to sampled. North Atlantic Plankton Expedition in 1980. Sampling was executed with the RMT 1+8, a com- Winkler Van Soest recorded & (1981) Deepstaria the bined rectangular midwater trawl developed at I.O.S. from the cruise and Van der enigmatica same (Baker et al., 1973; Roe et al, 1980) in depth layers of

listed Coronata of the 50 100 and 500 m thick between Spoel (1987a) some approximately m, m, 0 and 100 100 and 500 and 500 and respectively m Amsterdam Mid North Atlantic Plankton m, m,

deeper. The mesh sizes of the nets were 0.32 mm and 4.5 collected in the 1980-1983. Expeditions period the and mm so that only relatively large species specimens

were collected. For full data on stations and environmen-

tal conditions one is referred to Van der Spoel (1981,

* Amsterdam Mid North Atlantic Plankton and Van der Expeditions 1985) Spoel & Meerding (1983). Temper-

101A. and salinities in this all values for the (AMNAPE), Project Report no. 36, supported by tures given paper are

of the Netherlands of Education and of the a grant Ministry average depth samples.

Sciences. (Report no. 35 appeared in Bulletin Zoologisch Some species show remarkable differences in vertical

but did Museum, Universiteit van Amsterdam, 11 (18): 149-152 distribution at day- and nighttime, most not. As

(1988).) still some vertical shifts with the time are expected, where

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RESULTS

Of the total of 72823 specimens 232 could not

be identified due to damage. The number of

specimens ( = spm) collected are given between

parentheses.

Class SCYPHOMEDUSAE

(1) Deepstaria enigmatica Russell, 1967 (1 spm)

collected in from 510-1090 was spring a m

haul at 24°52'N 29°59'W (Winkler & Van

Soest, 1981).

Order CORONATA

Family NAUSITHOIDAE

Nausithoe 1913 (2) atlantica Broch, (4 spm) was

found in the spring, summer and winter

cruise between 55°-30°N at depths between

0 and 1010 m, temperature range 4.5-

17.4°C (fig. 2).

(3) Nausithoe spec. (1 spm) was found during

the summer cruise between 0-50 m, at

40°54'N.

1853 (4) Nausithoe punctata Kölliker, (fig. 3) (8

spm) was found in a sample at 39°59'N in

spring between 420 and 510 m depth and

two in winter at 30°N between 40 and 505

13.3-19.2°C. m. Temperature range

Family ATOLLIDAE

1880 (5) Atolla wyvillei Haeckel, (171 spm) is a

bathypelagic species found along the entire

cruise transect (Van der Spoel, 1987a). The

temperature and salinity ranges are 3-

11.5°C and 34.42-36.2l%o, respectively.

With Atolla likewise parva, a bathypelagic with cruise indica- Fig. 1. Investigated area transect and species, it shares the maximum abundance tion ofthe of for diamonds position stations; squares 1980, at between 8° and 11°C. for 1981, ovals for 1982 and circles for 1983. temperatures

(6) Atolla vanhoeffeni Russell, 1957 (304 spm) is

a deep mesopelagic species living less deep

than the other relatives but two showing no

shallow occurrence at like vertical as of total catch high latitudes, possible distribution percentages

for the and der per depth stratum, population at daytime at Periphylla periphylla (cf. Van Spoel, night, is calculated for each species for all stations and it 1987a). The temperature and salinity is recorded when an evident of the population percentage 4-14.5°C and ranges are 34.42-36.21%o, certain level between crosses a depth day and night. The shows respectively. temperature curve The material studied is preserved in the Institute of

two maxima for between Taxonomic Zoology (Zoologisch Museum), University of abundance, one

Amsterdam (ZMA). 8° and 11°C and one between 12° and

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54°20'N and 35°08'N at depths from 90 to

300 and 100 1750 m at daytime to m at

night. The temperature and salinity ranges

3.5-14.3°C and are 35.01-36.12% 0 , respectively.

Family PERIPHYLLIDAE

(9) Periphylla periphylla (Péron & Lesueur, 1809)

found in all (1004 spm) was seasons along

the entire transect of the cruises as a

mesopelagic species living also at shallow

depth north of 42°N (Van der Spoel,

The and 1987a). temperature salinity

and are 3.4-19.8°C 34.39-36.43% 0 ranges ,

This is not respectively. temperature range

reflecting real temperature preferences as

the majority of the specimens is collected at

between 4° and 11°C. It is temperatures

2. Naus ithoe cf. atlantica from station 65 trawl 13. that this cold- Fig. spec. notable, however, deep- or

is water species tolerating temperatures up

to 19.8°C.

Order SEMAEOSTOMEAE

Family PELAGIIDAE

(10) Pelagia noctiluca (Forskàl, 1775) (fig. 4)

(1739 spm) was not found in spring but

in in while occurs high numbers autumn,

regularly specimens were collected in sum-

Nausithoe from Fig. 3. punctata station 68 trawl 1.

14°C. This is characteristic as the two other

Atolla species do not show maxima in

temperature preference.

Atolla 1958 is (7) parva Russell, (214 spm) a bathypelagic species found along the entire

cruise transect (Van der Spoel, 1987a). The

and 3-13°C temperature salinity ranges are

and 34.42-36.21°/oo, respectively.

Family PARAPHYLLINIDAE

ransoni Russell, 1936 noctiluca from station 81 trawl (8) Paraphyllina (64 spm) Fig. 4. Pelagia 6, a young in between was only found summer specimen.

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Oceania mer and winter. It is an epipelagic species (15) tydemani n. sp. (fig. 7) (1 spm) was

with its highest abundance in autumn found in autumn at 34°11.4'N, between

and 300 Vertical 60-100 of 18.7°C. between 200 m. migra- m at a temperature

tion is not evident. This typically

in temperate species lives autumn between

51° N and 24°N, in summer between

45°N and 32°N and in winter between

40°N and The and 30°N. temperature

6.5-19.4°C salinity ranges are and 34.40-

36.43%o, respectively.

Class SIPHONOPHORA

Fig. 5. Cytaeis tetrastyla from station 66 trawl 9. (11) Porpita porpita (Linnaeus, 1758) (3 spm)

found in between was only autumn

34°55'N and in 27°10'N a night sample

in the 50 and in upper m a day sample

from 460 The and to 870 m. temperature

10.3-22.9°C and 35.59- salinity ranges are

36.97%o, respectively.

(12) Velella velella (Linnaeus, 1758) (5 spm) was

rarely found, and as young specimens

between 375 only, in spring and 500 m at

far north and in daytime as as 45°02'N

autumn in night samples between 0 and

350 m depth at 45°01'N at 30°08'N. The

is 11.9-15.4°C. temperature range

Class Fig. 6. Oceania armata (after colour photograph) from sta-

tion 83 trawl 9. Order ANTHOMEDUSAE

Family CYTAEIDAE

(13) Cytaeis tetrastyla Eschscholtz, 1829 (fig. 5) Family BOUGAINVILLIIDAE in °N and (9 spm) was found spring at 30 (16) Bougainvillia platygaster (Haeckel, 1879) in winter at 37°08'N-30°06'N at temper- (fig. 8) (78 spm) is a warm water species atures of 12.2-23.5°C and salinities of not found north of 30°N (fig. 9) and in The of two 35.61-36.51% 0 . depth day winter restricted to 30°N in the cruise 40-110 the samples was m, night samples transect, though it is known to occur from from 0 were depths between and 520 m. 45° S to 40°N in the Atlantic Ocean. In

This Family CLAVIDAE summer it was not collected. species

(14) Oceania armata Kölliker, 1853 (fig. 6) (14 occurred also in deeper hauls at night

while it spm) was found in autumn between (500-1000 m) at daytime was only

37°08'N and 26°08'N and in summer collected shallower than 200 m. Normal

between 37°00'N and 35°11'N. There diurnal vertical migration seems present

vertical the the lives also in the seems to be no migration as as at night species

25 while it is absent above 40 day level (40-200 m) was not significantly upper m, m of the different from the night level (30-305 m). at daytime, and 16% population

The is 12.5-21.1°C the 100 m level. The temperature range crosses daily

and the is is the salinity range 35.60-37.63%o- temperature range 10.5-25.1°C,

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Fig. 8. Bougainvillia platygaster from station 53 trawl 9.

31°30.9'N between 300 and 400 m at a

of 12.7°C. temperature 7. Oceania from station 48 trawl 13: Fig. tydemani n. sp. (19) Pandea rubra Bigelow, 1913 (fig. 14) (3 from lateral, mouth with stomach in detail, and

tentacles. spm) is an epipelagic species (fig. 15) from

the 300 in the and upper m spring autumn

cruise, liviner at temperatures of 13.6-

is 35.87-37.93°/ The 19.4°C. salinity range 0 o- sym-

biotic occurrence of the medusa Pegantha (20) Pandea (Quoy & Gaimard, 1827) (29

Winkler for distribution trilobata reported by (1982) the spm). For see fig. 16. It was

spring cruise is also found in the autumn only found in spring and autumn, at night

material. the 45- (only one sample) depth range was

95 m, at daytime it was 50-300 m; one Family PANDEIDAE in specimen was collected a haul of 300 to (17) Annatiara affinis (Hartlaub, 1913) (figs. 10, 400 The m (daytime). temperature ranee 11) (40 spm), a species mainly occurring is 13.9-16.7°C. in the East Atlantic collected (fig. 12), was (21) Neoturris pileata (Forskâl, 1775). Only two in all seasons in Sargasso Sea and North collected in specimens were spring near Atlantic Drift waters. Though the day and haul 35°N in a of 200-295 m and one of vertical 85-1000 do dif- night ranges m not 320-530 m at temperatures between 12.5° fer, 11 % of the population migrates and 15.4°C. 300 upwards through the m level from day

The is 7.8- CALYCOPSIDAE to night. temperature range Family

the is 35.28- 1957 17.0°C, salinity range (22) Calycopsis gara Petersen, (fig. 17) (1

was found in between 0 and 36.45% 0 . spm) spring

' Annatiara at (18) lempersi n. sp. (fig. 13): the single 200 m 41 °01 N and at a temperature of

collected in specimen was summer at 13.0-15.5°C.

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Fig. 9. Distribution of Bougainvillia platygaster.

Annatiara from Fig. 10. affinis from station 87 trawl 10, 30 mm Fig. 11. Annatiara affinis (after colour photograph) in diameter. station 88 trawl 9.

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Fig. 12. Distribution of Annatiara affinis.

13. Annatiara from station 84 trawl 36: animal from with and Fig. lempersi n. sp. latero-apical, part ofmargin tentacles, stomach from apical.

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(23) Bythotiara murrayi Günther, 1903 (1 spm)

found in was spring at 49°00'N between

375 and 500 m at a temperature of 9.3°C.

(24) Sibogita geometrica Maas, 1905 (figs. 18, 19)

in (6 spm) was found spring, summer and

autumn at 24°44'N, between 44°59' and

33°28'N and between 41°39'N and

35°07'N, respectively. Vertical migration

is evident all taken as night samples were

above and all day samples below 200 m.

The temperature range is 12.9-16.4°C

and the is 35.85-26.27% salinity range 0 .

Family TIARANNIDAE

(25) Chromatonema rubrum Fewkes, 1882 (figs.

is 20, 21) (49 spm) a deep living species

(fig. 22) occurring between 400 and 1750

is vertical m; probably there some migra-

tion but few Fig. 14. Pandea rubra from station 84 trawl 35. night samples were too to

Fig. 15. Distribution of Pandea rubra

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Fig. 16. Distribution of Pandea conica

17. from Station 16 trawl 1. 18. from station 85 trawl 12. Fig. Calycopsis gara Fig. Sibogita geometrica

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draw conclusions. The seasonal influence

this on species is clear as it retracts during

and summer to the north to greater

depths. It occurs in spring between 55°N

and 39°N, during summer between 55°N

and 48°N and during autumn between

55°N and 45°N; in winter it is absent.

The is 3.45-10.40°C temperature range

and the is 34.96- salinity range 35.41% 0 .

Comparison of a preserved (fig. 20) and

living specimen (fig. 21) learns that fixa-

tion causes 26% more shrinking of the Fig. 19. Sibogita geometrica (after colour photograph) from than of the manubrium. station 47 trawl 7. jelly

Order LEPTOMEDUSAE

Family DIPLEUROSOMIDAE

(26) Cuvieria huxleyi (Haeckel, 1879) (1 spm)

was found in summer between 45 and

100 m depth at 35°11'N, temperature

16.9°C, salinity 36.29%o-

Family MITROCOMIDAE

(27) Cosmetira pilosella Forbes, 1848 (12 spm)

was collected between 50 and 110m and

440 and 910 in m depth at daytime spring,

of 10.4-16.4°C. at temperatures

Family EIRENIDAE

(28) diegensis Torrey, 1909 (1 spm)

was collected in winter at 30°02'N be- Fig. 20. Chromalonema rubrum from station 76 trawl 26.

tween 40 and 115 m, temperature 19.2°C.

Family EUTIMIDAE

(29) flavilabris Eschscholtz, 1829 (252

spm) was only found in spring between

49°N and 24°N in the 500 with upper m

the highest concentrations between 0 and

300 m. Vertical migration is found as 80%

of the population daily crosses the 100 m

level. The is depth temperature range

7.8-19.5°C.

Family AEQUOREIDAE

1912 (30) Zygocanna vagans Bigelow, (fig. 23) (2

spm) is an epipelagic species collected in

the upper 300 m at temperatures of 14-

17°C. The Dana Expeditions collected the

species at 41°55'N 32°22'W (Kramp,

and in 1980 and 1983 the Chromatonema rubrum 1959) Fig. 21. (after colour photograph) present from station 39 trawl 14. material was collected from 41°35'N

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Fig. 22. Distribution of Chromatonema rubrum.

34°57'W and 39°47'N 35°32'W,

respectively, so that a very limited stable

the be population near Azores seems to

This small is the present. population only

one hitherto recorded from the Atlantic

Ocean, while numerous populations are

known from the Indo-Pacifxc Oceans. The

salinity is 36.12%o.

tenuis (31) Aequorea (Agassiz, 1862) was only

represented by one specimen from

40°58'N 35°27'W between of 500 23. from the around the Azores. depths Fig. Zygocanna vagans area

and 1000 m at a temperature of 8.5°C.

Order

Family HALICREIDAE (33) Botrynema brucei Browne, 1908 (fig. 25)

maasi 1909 (32) Halitrephes Bigelow, (fig. 24) (6 (355 spm) is a deep living species (fig. 26)

in spm) was only found in day samples from found the Atlantic between 60°N and

440-1090 in and 65°S. It in all m depth spring summer was found seasons below

between 41°47'N-24°48'N and 480 at of 3.5-9.4°C and at m, temperatures

The salinities of It is 40°58'N, respectively. temperature 34.75-35.15%o- a high

is 9.8-10.5°C. its border range latitude species with southern at

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Fig. 24. Halytrephes maasi from station 81 trawl 17. Fig. 25. Botrynema brucei from station 78 trawl 60.

Fig. 26. Distribution of Botrynema brucei

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49°N in 45°N in and spring, at summer,

at 40°N in autumn.

(34) Halicreas minimum Fewkes, 1882 (fig. 27)

all (547 spm). This species was found in

seasons along the entire cruise transect

from 55°N and below 24° to only a depth

of 500 m. The is temperature range 3.5-

abundances 11.0°C, though highest are

found below the at temperatures 8°C;

is salinity range 34.75-35.87°/o 0 -

(35) Haliscera bigelowi Kramp, 1947 (176 spm)

330 was found in night samples between

and 505 m and in daytime samples

between 205 and 1020 m. It occurs in

summer and autumn. The spring, Fig. 28. Rhopalonema velatum from station 84 trawl 36.

temperature range is 4.5-19.2°C, most

abundant between 8° and 11°C and only

above the between 0 and 1760 the northern sporadic at temperatures 12°C; m depth;

is 34.74-36.13% limit 49°N salinity range 0 . only changes slightly being at

in 45°N in 51 °N in spring, at summer, at

autumn and probably at 30°N in winter

(the winter cruise, however, sampled too

few stations be of this A to sure limit). very

slight tendency of vertical migration is

in this found eurybathic species as 5% of

the the population crossed 50 m level,

11% crossed the 100 m level and 2%

crossed the 200 m level daily. The

and 6.15- temperature salinity ranges are

25.7°C (most specimens are, however,

collected between 10° and 20°C) and

35.09-37.10%o, respectively. For general

distribution see fig. 29.

(38) Crossota spec. (fig. 30) (1 spm) was found

between 500 and 1000 m in summer, at Fig. 27. Halicreas minimum from station 81 trawl 6. 40°45'N and at 8.8°C and S. 35.45% 0

1913 (39) Crossota alba Bigelow, (5 spm) was

found in samples between 0 and 220 m

RHOPALONEMATIDAE and between but there Family 420 and 1752 m, is

(36) Rhopalonema funerarium Vanhöffen, 1902 no indication of diurnal migration.

found in winter (27 spm) was only at Though the shallow sample from 0 to 220

taken 30°00'N at temperatures of 18.5-19.0°C. m was by a malfunctioning discrete

it is excluded that the Though considered to be a bathypelagic depth net depth

it is found in 40- record is the species (Kramp, 1959) a incorrect as net was never

115 haul 395-995 m (24 specimens) and m lowered below 250 m, so it is concluded

hauls is It in (3 specimens). that the species eurybathic. occurs

(37) Rhopalonema velatum Gegenbaur, 1856 (fig. spring at 39°59'N, in summer at 45°N

in all and in between 28) (583 spm) occurred seasons winter 40°55'N and

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Fig. 29. Distribution of Rhopalonema velatum.

29°59'N. The is 4.4- temperature range

16.0°C and the salinity was 35.12%o-

(40) Crossota rufobrunnea (Kramp, 1913) (fig. 31)

found in between (404 spm) was spring

55° and 40°N, in summer between 55°

and 35°N and in autumn between 55° and

48°N. In the day samples the species

below and the occurs always 420 m depth

single night sample was from 520-1130 m

The and depth (1 specimen). temperature

4.2-9.9°C and 34.75- salinity ranges are

35.55°/oo, respectively.

(41) Sminthea eurygaster Gegenbaur, 1856 (flg.

32) (13 spm) was found in summer and

11 30. Crossata from station 81 trawl 6. winter at (probably 45°02 ')-35° 'N and Fig. spec.

29°59'-30°03'N, respectively. The

and temperatue salinity ranges are 8.2-

19.2°C and 35.41-35.75°/ 55° and 25°N and in the other 00 . seasons

Colobonema 1902 between and (42) sericeum Vanhöffen, (flg. 50° 25 °N as a deep living

in below 365 33) (246 spm) was found spring between species restricted to depths m.

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Fig. 33. Colobonema sericeum (after colour photograph) from

station 84 trawl 36.

(43) Pantachogon haeckeli Maas, 1893 (figs. 34,

35) (1650 spm) was most abundant at

greater depths. At daytime 1041 Fig. 31. Crossala rufobrunnea from station 81 trawl 6: animal of which specimens were collected no one from lateral and mouth and gonads from aboral. in hauls shallower than 870 At 21 m. night

specimens were collected of which 3

between 0 and 100 m and 4 between 360

and 520 Thus there exist m. may some

vertical migration. The species was found

the whole in all seasons along cruise

transect from 55° to 24°N. The

and 3.5- temperature salinity ranges are

19.2°C and 34.95-35.95% 0 , respectively.

This is distributed in all a widely species

between 70°N and 70°S oceans (fig. 36).

(44) Amphogona apsteini (Vanhöffen, 1902) (fig. Fig. 32. Sminthea eurygaster from station 84 trawl 6. in 37) (6 spm) occurred summer at

54°20'N and in autumn at 41°44'N,

it in The distribution in the Atlantic Ocean is though is literature mentioned as a

surface form between60°N and 60°S. The temperature (Kramp, 1959) between

and 4.5-15.2°C and of 460 and 1750 The salinity ranges are depths m.

The and 3.45- 35.09-36.70°/oo, respectively. tempe- temperature salinity ranges are

0 of 4.5-8.5°C are recorded for 10.25°C and 35.03-35.59/ ratures only 0o, respectively.

daytime samples; the maxima of abun- (45) Amphogona apicata Kramp, 1957 (fig. 38) (8

dance found 9- occurred in are at temperatures of spm) summer between 45°02'

12°C and at 14°C. and 35°09'N and in winter at 29°59'N

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Fig. 34. Pantachogon haeckeli from station 81 trawl 17. Fig. 35. Pantachogon haeckeli from station 78 trawl 60.

Fig. 36. Distribution of Pantachogon haeckeli.

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Fig. 37. Amphogona apsteini from station 78 trawl 39. Fig. 39. Tetrorchis erythrogaster from station 78 trawl 39.

between 1000 in 500 and m, summer at

The and 45°02'N. temperature salinity

8.15°C and 35 4 1 0/ were . 00.

(47) Aglaura hemistoma Péron & Lesueur, 1809

found in winter (21 spm) was only at

29°58'N at a depth of 0 to 150 m.

(48) Aglantha digitale (O. F. Müller, 1766) (figs.

40, 41) (61821 spm) occurred at depths

Fig. 38. Amphogona apicata from station 84 trawl 77.

below 490 The always m. temperature and

6.15-10.3°C and 35.41- salinity ranges are

33.55%o, respectively.

(46) Tetrorchis erythrogaster Bigelow, 1909 (fig.

39) was only represented by one specimen Fig. 40. Aglantha digitale from station 76 trawl 32.

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and 3.5- temperature salinity ranges are

18.0°C and 34.72-35.74%o, respectively.

Family GERYONIIDAE

(49) Geryonia proboscidalis (Forskâl, 1775) (8

spm) was found in spring and autumn at

night between 40 and 395 m and at day-

time between 200 and 1090 m depth at

temperatures of 9.8-22.2°C.

(50) Liriope tetraphylla (Chamisso & Eysenhardt,

1821) (2 spm) was only found in spring in

the 100 of 17.2°- upper m at temperatures

21,2°C at night.

Order NARCOMEDUSAE

Family AEGINIDAE

(51) Aegina citrea Eschscholtz, 1829 (figs. 43,

44) (67 spm) is a deep-sea species showing

diurnal vertical migration as 42% of the

the 300 level It population crosses m daily.

seems to live shallower south of 38°N. It is

found in spring between 53°00' and

24°44'N, in summer between 54°24' and

24°49'N, in autumn between 50°57' and Fig. 41. Aglantha digitale from station 75 trawl 6. 35°07'N, and in winter between 40°55'

and 39°36'N. The temperature and

4.5-16.5°C 35.09- salinity ranges are and

0 and 1130 with abun- found between m great 35.81%o, respectively. Always

dance between 0 and 100 and between below below m 100 m and at daytime mainly

500 and 1000 In it is found from 300 m. spring m.

55° to 39°N, in summer from 55° to (52) Aeginura grimaldii Maas, 1904 (fig. 45)

and 25°N, in autumn from 55° to 48°N. (2480 spm) was found at daytime always

It is thus northern 500 and a species that penetrates below m at night only 5 specimens

the whole in collected above this In 5 area investigated summer. were level.

This southwards is penetration a penetra- daytime samples below 1000 m 27

tion in The in 4 deeper layers only. species specimens were found and night sam-

occurred south of 40°N only in the ples below 1000 m 77 specimens were col-

It is thus with- twilight samples so that nothing on vertical lected. a deep-living species

be but north normal diurnal vertical migration can concluded, of out migration.

°N 40 no migration was found and south of The upper limit of vertical distribution

°N 40 it occurs only deeper than 500 m. seems to slope down from 40°N towards

The distribution is probably from 60° to the south when the single shallow sample

40°N (fig. 42) in shallow and deeper layers at station 85 trawl 15 is neglected. The

and from 40° to 20°N only in deeper species occurred along the entire transect

layers. Data on the southern oceans are 55°N-24°N in all seasons. The

make but the too scarce to conclusions, temperature and salinity ranges are 3.5-

exist there. The 19.2°C same patterns may and 34.75-3648%o, respectively.

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Fig. 42. Distribution of Aglantha digitale.

Fig. 43. Aegina citrea (after colour photograph) from station Fig. 44. Aegina citrea from station 84 trawl 37.

39 trawl 14.

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This species is widely distributed in all

oceans (fig. 46) between 60°N and 50°S.

Family SOLMARIDAE

(53) Solmaris flavescens (Kölliker, 1853) (fig. 47)

(17 spm) is probably a diurnal migrant as

from of 40 all night samples were depths to

the from 115 m and daytime samples

195 1000 It collected depths of to m. was

in spring at 37°48'N, in summer at

29°56'N and in winter between 40°57'-

30°N. The temperature and salinity

ranges are 9.9-19.2°C and 35.69-36.00%o,

respectively.

(54) Solmaris solmaris (Gegenbaur, 1856) (13

collected in at Fig. 45. Aeginura grimaldii from station 81 trawl 6. spm) was only night samples

depths between 0 and 528 m during sum-

south The mer and winter, only of 42°N.

and 13.0- temperature salinity ranges are

and 35.80-36.48°/ 20.3°C 00 , respectively.

Fig. 46. Distribution of Aeginura grimaldii.

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from m and those collected at night were

than depths shallower 200 m. The species

found in autumn was spring, summer,

and winter in low numbers at 38°00'N-

29°48'N, at 44°59'N-41°01'N, at

47°49'N-28°03'N and at 40°55'N-

30°02'N, respectively. The temperature

12.8-19.2°C and salinity ranges are and

35.35-36.29%o, respectively.

(59) Pegantha rubiginosa (Kölliker, 1853) (3 spm)

was found in summer and winter at

41°37' and 29°59'N, respectively and at Fig. 47. Solmaris flavescens from station 987 trawl 25. between 103 and 445 depths m. The

temperature is 14.9°C and the salinity is

Solmaris corona & (55) (Keferstein Ehlers, 1861) 36.13% 0.

triloba 1879 (1 spm) was collected near the Great (60) Pegantha Haeckel, (2 spm) was

Meteor Bank in haul found in winter between 30 and (30°N) a deep only once

and 1005 The 110 30°02'N with local between 752 m in summer. m at a temper-

the of At this also temperature was 9.7°C and salinity ature 19.4°C. locality

found. was 35.63%o- Bougainvillia platygaster was

(56) Pegantha laevis Bigelow, 1909 (80 spm) is Pegantha spec. (141 spm) are probably

P. laevis clearly a vertical migrant as 65% of the damaged specimens of or P. mar-

These abun- population passes daily the 200-300 m tagon. specimens were most 48°59'N depth stratum. It occurred at night dant in spring between and

and 500 28°20'N but also found in between 0 m but at daytime it was they were

found in between and only the 100-500 m layer as an autumn 45°03' 28°07'N

and in winter 40°56'N. A upper mesopelagic species. Most records at strong

' are from spring between 49°01 and migration seems present as 40% of the

the 32°07'N, while a few records in autumn population crosses 500 m level and

between 35°06'N. the 100 were made 50°49' and 46% crosses m level daily.

The and temperature salinity ranges are

10.9-17.5°C and 35.35-36.02°/ CUNINIDAE 00 res- , Family

1893 pectively. (61) Cunina duplicata Maas, (2 spm) was

1879 found in 41°39'N and (57) Pegantha martagon Haeckel, (68 spm) summer at

in it collected was always more abundant the night 24°52'N; was at night between

samples as compared to the day samples. 51 and 105 m and at twilight between 515

Moreover, 8-16% of the population and 1000 m. The temperatures at these

level localities crosses daily the 200-500 m depth so were 9.4°-15.4°C.

Cunina that vertical migration is tracable. The (62) frugifera Kramp, 1948 (2 spm) was

occurred in and found species spring autumn only in summer at 41°34'N at 198-

and found between and 340 The local and only was 41°31' m. temperature salinity

24°48'N and between 37°05' and are 14.2°C and 36.00% o .

The Cunina 25°10'N, respectively. temperature (63) peregrina Bigelow, 1909 (4 spm) was

and 9.9-19.3°C and collected in haul of 40 115m salinity ranges are only one to

winter at 35.53-27.23% 0 . depth during 30°02'N,

(58) Pegantha clara Bigelow, 1909 (23 spm) temperature 19.2°C.

shows all vertical migration as specimens (64) Solmissus marshalli Agassiz & Mayer, 1902

collected from 200 at daytime were below (fig. 48) (5 spm) is a shallow-living species,

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though considered by Kramp (1959) as

found between 0 and 200 deep-living, m,

in spring at 28°20'N, in summer at

29°59'N, and in winter at 29°58'N. The

and temperature salinity at depth are

19.2°C and 36.75% 0 .

(65) Solmissus incisa (Fewkes, 1886) (65 spm) is

a deep-living species (fig. 49). At night the

whole found below 500 population was m

but at daytime specimens are found as well

between 30 and 100 m (1 spm), 200 and

300 300 and 400 and m (2 spm), m (4 spm)

between 400 and 500 m (4 spm), but most Fig. 48. Solmissus marshalli from station 87 trawl 1. are from deeper strata. The

species is found between 53° and 33°N in

between 54° and 24°N in spring, summer,

between 55° and 27°N in autumn, and at

30°N winter. in The temperature range is

3.5°-19.4°C and the salinity range is

34.75-35.87% . 0

Fig. 49. Distribution of Solmissus incisa

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TAXONOMIC NOTES Type locality: 34°11.4'N 31°11.3'W, 60-

100 m, temperature 18.7°C, 23-IX-1981,

Sibogita geometrica Maas, 1905 daytime sample.

The is after the Etymology: name given The in this is for variability species very large; océanographie research vessel H.M.S. discussion occiden- a on the validity of the subsp. "Tydeman", the platform for the 101A project talis 1959 is referred Winkler Kramp, one to cruises. (1982) and Van der Spoel & Bleeker (1988). The most closely related species is O. armata,

with but it differs as the lining of the lips Crossota spec. (fig. 30) is and number of nematocysts continuous, the

The from station 81 trawl 6 tentacles is 100. The discontinuous specimen at only up to

40°56'N 500 and 1000 with is in between m was not lining nematocysts not agreement

attributed of the known of the to one species though with the diagnosis family (Kramp, 1959),

its It had all the charac- characters of the preservation was good. but the other specimen are

ters of the family Rhopalonematidae and of the evidently showing that it belongs to the

Crossota. genus There are 8 radial canals in the Oceania and family Clavidae.

the close the stomach specimen, gonads are to

the of the canals and there at apical point are Annatiara lempersi n. sp. (fig. 13) about 160 marginal tentacles. So the principle

8 characters of C. rufobrunnea are present. The Description: Umbrella bell-shaped, mm high

of the and 16 in the is thick and extreme length manubrium, reaching mm diameter, jelly

the umbrella and the there is exumbrella with halfway cavity very large no apical projection,

C. oral lips do not occur in rufobrunnea, how- nematocyst tracks at each tentacle. Velum

As different contractions fixation small. Stomach four-sided but ever. during short, not

and affect attached subumbrella described for preservation may strongly A.to as

manubrium length, no new species for the pres- affinis, the radial canals do reach only halfway

is the and in ent specimen proposed, more so as no the umbrella between the tops of the

other characters have been found. canals is formed the stomach walls discrimating a square by

so that the stomach is expanded interradially.

The musculature in the umbrella is intact and Oceania tydemani n. sp. (fig. 7) not distorted so that the configuration of the

8 in and 5 due Description: Umbrella mm diameter stomach can not be to damage. Mouth with

manubrium 3 in diameter. The radial mm high, mm strongly folded hps. The four canals run

medusa is The is thin. from the of the flatly topped. jelly perradial corners interradial

Gonads adradial of stomach the canal. on stomach wall; as they are square the to ring The

small not fully developed they are seen as warts gonads are probably not yet fully developed,

is short without line the stomach folded only. There a peduncle they as strongly bands.

vacuoles. The manubrium is broad and half as There are 24 hollow smooth marginal tentacles,

the umbrella in which curled in the long as cavity, quadrangular are typically preserved

cross section. The four lined abaxial small basal lips are only partly specimen; no spurs, only a with the interradial is lack- small nematocysts as area swelling present. One rudimentary ten-

There four tacle ing nematocysts. are simple narrow between each two normally developed ten-

radial Adaxial ocelli No tacles. Abaxial ocelli all canals. present. present on tentacles.

The velum is broad. There 180 ZMA Co. 101A statocysts. are Holotype: coll. no. 5932;

tentacles station 84 trawl 36. solitary marginal placed in a double, project zigzag row. Type locality: 35°1.0'N 31°30.9'W, 300-

ZMA coll. Coel. 101A 400 dusk Holotype: no. 5598; m, temperature 12.65°C, 6-VI-1983, project station 48 trawl 13. sample.

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is in honour of the its = the Etymology: The name given quality of sample by dominance; D

value adds the of the the commander of H.M.S. "Tydeman", a species to quality sample

KLTZ Ir. A. P. H. M. Lempers. by its contribution to the diversity.

The most closely related species is Annatiara The dominance value (C) of a species in a

in number of affinis from which it differs having only 24 specific sample is dependent on the tentacles (28-44 in A. affinis, 32 in the material specimens relative to the abundance of that of station attached in other and 87), a stomach along an species samples on the total

the relative that interradial square (along a perradial cross in A. numberof species in sample to affinis). number in other samples. The following for-

mula is the dominance proposed to express

value:

FAUNAL - BORDERS C = 100 X N x F/F (F ■ N-XN)/(F ■ max SN) max

F = number of species in the sample;

= of the in the Winkler (1982) found a faunal boundary zone N number of specimens species

for and at 38°- N = number of of the epi- mesopelagic Hydromedusae sample; max specimens

40°N. The latitudinal occurrence of all most abundant in the F = species species sample; max is given in fig. 50. number of species in the most diverse sample.

in Especially for the spring cruise (1980) (cf. The diversity value (D) of a species a

is Winkler, 1982) but also for the summer cruise specific sample likewise dependent on the

40°- numberof in the but relative (1983) a faunal border was found near specimens sample,

42°N. The autumn cruise did not show clear to the number of samples in which the species transitions to be based on first and last occur- is found and relative to the number of species

the winter cruise found in other The formula rence of taxa, and made too samples. following few stations this method. The is the value: to use summer proposed to express diversity

2 cruise showed numbers of first and last D = +A x x N high V(1 max-A) (1 +M-A)

and M = total number of in the occurrence at 45°, 42°, 35°, 30°N. samples study;

Mathematically the investigation of first and A = number of samples in which the species is last occurrence be refined. However, this found; A = maximum value for A for the can max and other methods detect faunal series of studied. many to samples

between The abundance and of borders or significant differences sam- total diversity a sam-

based methods. the is the of all the ples are mainly on statistical ple, sample loading, sum

The the For biology, however, it seems appropriate to specific loadings of one sample. greater

difference of 25 of the are develop a method based on biological prin- two samples, greater ciples. the differences in abundance, dominance and

One with the of the can start theoretical assumption diversity samples. that have for £5 for series of species no value a sample when The a hypothetical samples they do not contribute to the diversity of the and species is given in table I.

2 1 the £5 = sample and when they do not determine In the equation SV (Z) + C ) diversity

value influence the sample's quality by their dominance. The (D) has a much greater on

of the thus importance species for a sample is value of Sfi than the dominance value has, so

in the also 2 is used greater when its distance to the point where its comparisons SlyJC dominance value and its diversity value are separately.

is This in the zero greater. can be expressed The results of this method for the North formula: Atlantic Medusae shown in 51-54. In are figs.

2 2 B = V(£> + C ) spring (1980) (fig. 51) SB is on the average

B = the computed value of the species for the much larger north of 40 °N than to the south of

it is 38°N the sample in which present, or the specific that latitude. Between and 42°N

2 = the value adds the is much than other localities. So loading; C a species to £VC larger at

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Fig. 50. The latitudinal distribution of the species of Hydromedusae. Along the horizontal axis degrees north, along

the vertical axis the species. For each species a bar is used in which a dotted line connects the thick lines, indicating

situated: for in the for above the for winter under the and for presence, spring top, autumn centre, centre summer at

the bottom of each bar.

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TABLE I In but summer (1983) (fig. 54) at 45°N more

at of pronounced 50 °N the abundance increases ΣB for a hypothetical series stations (a-g) and species

(I-VI) compared to the lower latitudes; the diversity

maxima are found near 25°N, 35°N and 41°-

Stations a b c d e f A g 42°N. The maximum 35°N indicate the at may

transition of Sea and waters Species I 5 5 5 5 5 5 - 6 Sargasso temperate

II 5 4 3 2 - 100 6 6 (cf. Van der Spoel, 1985). The transition

III 1 2 3 4 2 - 5 6 Atlantic Drift between temperate and North

IV - 6 7 8 6 3 3 6 waters is found near 45°N, but the maximum

- V - 5 1 7 2 55 5 41°-42°N still be correlated with this at may VI - - - 100 - - 10 2 transition. The high abundance in subpolar

F 3 4 5 6 4 4 5 ~ 6 waters is reflected the £2? value north max by high SN 11 17 23 120 20 110 79 F = 6 max of 50°N.

N 5 6 7 100 7 100 55 M= 7 Jy max In autumn (1981) (fig. 52) a picture com-

to the situation is found with Sfi 200 190 224 259 204 135 199 parable spring

-I.B 10 34 35 1 55 68 1 64 abundances north of 48 °N and a £5] 2 high diversity

maximum near 48°N but also near 34°-37°N.

North of 48°N the fauna subpolar with some

less diverse with abun- abundant is it mixes a subpolar fauna some species found, near 48°N

with the North dant species lives north of 40°N and to the temperate, Atlantic Drift fauna.

The and south lower abundances are found in a warm- transition of subtropical temperate

fauna. The of the cold- and faunas is evident in than in water mixing more autumn

faunas the this transition is warm-water gives high diversity spring as near 34°-37°N

between 38°N and 42°N. marked by high diversity only in autumn.

Fig. 51. Diversity abundance analyses for the samples of the 1980 cruise, vertical axes for ΣB and Σ√C², horizontal

axis latitude north, columns indicate the Σb value, the crosses indicate the Σ√C² values.

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for Fig. 52. Diversity abundance analyses for the samples of the 1981 cruise, explanation see fig. 51.

Fig. 53. Diversity abundance analyses for the samples of the 1982 cruise, for explanation see fig. 51.

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Fig. 54. Diversity abundance analyses for the samples of the 1983 cruise, for explanation see fig. 51

The abundances in spring, autumn, and tic. Its seasonal migration consists of

in summer are comparable, though spring the withdrawal to colder waters either to the north

south of °N area 40 shows somewhat higher or to the depth. values. In values winter (fig. 53) the T,B near

41 °N lower than in and are summer autumn,

N the values BATHYMETRIC near 30° EZ? are evidently higher DISTRIBUTION

than in the other seasons.

it be stated that the sub- Most As a conclusion can bathypelagic and eurybathypelagic

fauna in in polar penetrates spring southwards to species occur all seasons along the entire about and in in 40°N retracts to 50°N summer, transect of the cruise. Exceptions are

southwards 48°N autumn it again spreads to Paraphyllina ransoni that is only found in sum-

winter it shows its lowest abundance. In maasi that found in and in mer, Halitrephes is only

the is and the do summer subtropical fauna most evidently spring bathypelagic species that not

northward of Haliscera present probably by penetration to occur south 42°N: bigelowi, about Chromatonema and 35°N. This pattern deduced from rubrum, more explicitly

of the 1000 of the brucei and both Hydromedusae upper m Botrynema Aglantha digitale,

of the latitudes water column is also shown by Radiolaria from species higher showing strong the upper 5 m of the water column (Van der subtropical submergence.

Spoel, 1987b). Aeginura grimaldii is also a species with sub-

rubrum is mentioned but it is Chromatonema as a species tropical submergence as frequently sensitive It is from to seasonal changes. not a recorded lower latitudes, which is not the

behaves temperate species (fig. 22) though it case in Aglantha digitale, it is probably sinking to

of element in the North Atlan- in like such a type a less deep submergence the tropical region.

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That P. shows shallow periphylla occurrence at (II) widely spread eurybathypelagic species, lower latitudes, viz. at stations 22 and 49 is like Rhopalonema velatum; probably due to upwelling near shallow banks, (III) species occurring in shallow layers at high

mentioned latitudes but as already by Van Utrecht (1982). showing subtropical submergence

Table II of the seasonal like and gives a survey occur- Aglantha digitale Periphylla periphylla.

of the in the north of 42 °N These three recorded for the entire rence species area types are with winter and south of 42°N with N.-S. mixing per- range of the area investigated.

stratification. The in the Atlantic Ocean manent bathymétrie occur- (IV) Species occurring

is the in the table. Some in the around like rence given at right only area the Azores, remarks should be made. In the Indo-Pacific Oceans Zygocanna vagans.

these have wider Annatiara affinis is according to Kramp (1959) species may a distribution;

and intermediate In the of the a deep species. present (V) species warmer waters occurring material it also showed in shallow and in the southern stations of the area up layers only diurnal migration is found. Probably it can be investigated, like Bougainvillia platygaster and better considered Oceania a eurybathic species. For armata;

Haliscera and also like Solmaris bigelowi Rhopalonema funerarium (VI) the temperate species

is found. The shallow that difficult to trace such an eurybathic occurrence flavescens are very as

of and deep subtropical submergence Aglantha in the present collections.

mentioned. Vertical diurnal is found in digitale was already Botrynema mur- migration

Sminthea Pandea rubra and of for 7 rayi, eurygaster, representatives most groups; species

found in be demonstrated and Rhopalonema funerarium are not very diurnal migration could

that their for 5 it is deep samples so bathypelagic nature species expected to occur. is dubious. Crossota alba is like others also con- Exclusively epipelagic species were not sidered bathypelagic by Kramp (1959) but a found, most shallow-living taxa are also

in the makes this doubtful. recorded from below 200 and record upper layers depths m, a large

From table II it is also clear that and most deep- number of species a high percentage of

in all the whole and living taxa occur seasons along specimens collected belong to meso- cruise This transect. bathypelagic species. may explain why

the of medusae of the faunal borders found for the Though mobility seems some

still for numberof diurnal vertical Medusae small, a taxa (spring 40°-42°N; summer 50°, 45°,

is found. The that migration Hydromedusae 42°, 35°, 30°N and autumn 48° and 34°- show diurnal 37 also reflected in the distribution of migration are: Bougainvillia °N) are platygaster, Annatiara affinis, Sibogita geometrica, Myctophidae and Mollusca (Van der Spoel,

P. laevis there Rhopalonema velatura, Pegantha martagon, unpublished data). That are also parallels and P. clara. Dubious indications for diurnal with borders found for Radiolaria is more sur-

recorded but these migration are for: Cytaeis tetrastyla, prising still understandable as pat-

Pandea Chromatonema the result of the conica, rubrum, Pantachogon terns are same hydrography haeckeli and Solmissus incisa. and climate.

Two new species are described.

CONCLUSIONS

The medusa fauna of the upper 1000 m of the ACKNOWLEDGEMENTS

North Atlantic Ocean between 25° and 55°N

The authors are indebted to Drs. J. Th. Winkler for the along approximately 30°W consists of 6 fanual permission to use his original notes and identifications of elements: the 1980 and part of the 1981 material. Commanders and distributed and (I) widely bathy- mesopelagic of H.M.S. for the crews "Tydeman" are thanked species like Halicreas minimum; enthousiastic help during collecting of the material.

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TABLE II

Latitudinal and seasonal differences in distribution, with the division into four ecological groups.

Species >42°N <42°N Ecology

Sp Su Au Sp Su Au Wi Ba Di Eu Ep *)

Periphylla periphylla XXX XXXX X...

Atolla vanhoeffeni XXX XXXX X...

Atolla parva XXX XXXX X...

Atolla wyvillei XXX XXXX X. ..

Annatiara affinis XXX XXXX .XX. **)

Halicreas minimum XXX XXXX X...

haeckeli Pantachogon XXX XXXX XX..

Colobonema sericeum XXX XXXX X...

velatum Rhopalonema XXX XXXX ..X.

Aggina citrea XXX XXXX XX..

Aeginura grimaldii XXX XXXX X...

Solmissus incisa XXX XXXX X...

Haliscera bigelowi XXX XXX. X **) Crossota rufobrunnea XXX X . X X

Aglantha digitale XXX XX. X ..XX **)

Chromatonema rubrum XXX X X

brucei Botrynema XXX X X ...

laevis Pegantha X . X X . X X

Pegantha martagon X . X X . X X

clara Pegantha XX XXXX X

noctiluca Pelagia XX X . X X ...

XX X Amphogona apsteini .... ***•)

Nausithoe atlantica X X X ?...

Pandea conica X . X . X X X

Zygocanna X XX.. X vagans ...

Tima flavilabris X X X . X

maasi Halitrephes X X X

Bythotiara murrayi X ...... ? . ••)

Calycopsis X X X gara ...

Paraphyllina ransoni X X X

Crossota alba X X .... *•)

Amphogona apicata X X . X X

X X X ? Sminthea eurygaster . **)

Sibogita geometrica X XXX. X

Solmaris flavescens X X X . X X

Bougainvillea platygaster X . X X X

Pandea rubra X .X X **)

. ? Geryonia proboscidalis X X

marshalli Solmissus X X X . . .X ***)

Pegantha rubiginosa X . X ?

Solmaris solmaris X . X X

Oceania armata XX. X ...

Cytaeis tetrastyla XX ? ...

Deepstaria enigmatica X X

Neoturris pileata X ?

Cosmetira pilosella X X

Liriope tetraphylla X X ...

Aequorea tenuis X ?...

Cunina duplicata X . ? ...

Cunina X ? frugifera ...

Solmaris corona X ?...

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Species >42°N <42°N Ecology

Sp Su Au Sp Su Au Wi Ba Di Eu Ep *)

Porpita porpita x x

x ? Cuvieria huxleyi ...

Rhopalonema funerarium X ..?.**)

hemistoma ? Aglaura X ...

Phialopsis X ? diegensis ...

triloba X ? Pegantha ...

Cunina X X peregrina ...

*) Au = autumn, Ba =bathy- and/or mesopelagic, Di = diurnal migrant, Ep = epipelagic, Eu = eurybathic, Sp - spring,

Su = summer, Wi = winter. **) According to Kramp these species are bathypelagic. ***) According to Kramp this

species is eurybathic. ***•) According to Kramp this species is a surface form.

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Zoopl. Coll., 5: 1-54.

Received: 26 February 1988

Revised: 17 May 1988

Downloaded from Brill.com10/10/2021 09:45:57PM via free access