ZoologicalJournal ofthe Linnean Society, 68: 99-109. With 4 figures
Feb~
uary 1980
BathytyphZops seweZZi (Pisces: Chlorophthalmidae)
a senior synonym of B . axorensis, from the
eastern North Atlantic with notes on its
biology
N . R. MERRETT
Institute ofoceanographic Sciences, Brook Road, Wormley,
Godalming, Surrey GU8 5 U B
AlcgPtedfor publication October I978
Evidence provided by six specimens of abyssal 5 a ~ h y ~ y ~ coltected
h f o ~ ~ in the eastern North Atlantic
indicates the conspecificity of the Atlantic E . azorensu with the Indian Ocean B . sewelli. The data also
clarily the distinction between 5. sewelli and its congener, E. marionae. The benthic habit of E . sewelli
is contirnied. Its reproductive biology is examined and the hermaphroditic pattern substantiated.
The species is evidently a multiple spawner with a fecundity of around 6000 eggs. Observations in
support of the probable epipelagic larval development of 5 . sewelli are dicussed. Stomach and
intestinal contents analysis suggests that this species Feeds largely on benthopelagic crustaceans.
Digenetic trematode parasites were found in the digestive tracts of three specimens.
KEY WORDS: - Bathytyphlops sewelli
- abyssal
fish - taxonomy
- reproduction
- hermaphrodite -
lecundity - feeding - parasites.
CONTENTS
Introduction
. . . . .
Materials and methods
. .
Keaults and discussion . . .
Systematic considerations
Environmental observations
Biological observations
.
Reproduction
. . .
Feeding . . . . .
Acknowledgements
. . .
Keferences
. . . . . .
. .
. .
. .
. .
.
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. . .
. .
. . .
. .
. .
. .
. . .
. . .
. . .
. . .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
. .
.
. .
. .
. .
.
.
.
.
99
100
101
10 1
107
107
107
108
108
109
INTRODUCTION
The chlorophthalmid genus Bathytyphlops (sensu Sulak, 1977 ) is represented
in the literature by two specimens of B . sewelli (Norman, 1939) from the
tropical western Indian Ocean, 18 specimens of B . marionae Mead, 1958 from
the tropical Atlantic and western Indian Oceans and two specimens of B . azorensis
Geistdoerfer, Hureau 8c Rannou, 1970 from the tropical and temperate Atlantic
Ocean. Sulak (1974) summarized the distribution and depths of capture of all
99
0024-4082/80/0200991
1 1/$02.00/0
0 1980 The Linnean Societv of London
N. R.MERRE'IT
100
recorded specimens prior to those ( 7 reported by Golovan ( 197 6) from the slope
1 7 O 36'W, 1740-1920m). While previous
waters off West Africa (09O 25",
workers have indicated the close relationship of the three nominal species, the
chart given by Sulak emphasises the salient difference in depth distribution
between B. marionae, an essentially slope-dwelling species (living in soundings
shallower than 2000 m or waters warmer than 4°C-Sulak, pers. commn), and
the abyssal B . sewelli and B . atorensis. Anatomically the degree of development of
the rakers on the first gill arch has been considered the principal character in
separating B . marionae from its congeners, B . azorensis (Geistdoerfer, Hureau &
Rannou, 1970; Sulak, 1974) and B . sewelli (Nielsen, 1966). The distinction
between 5. sewelli and B . azorensis given by Geistodoerfer, Hureau & Rannou
(1970) is less trenchant and it is therefore appropriate to reappraise the
relationship of these species in the light of a further six specimens of abyssal
Bathytyphlops collected from the tropical and subtropical eastern North Atlantic.
The results clarify the taxonomy of the genus and add to the knowledge of its
biology.
MATERIALS AND METHODS
The specimens of Bathytyphlops were collected in the course of benthic surveys
off northwest Africa carried out by RRS 'Discovery' during 1969-77. The relevant
sampling data are given in Table 1, while the localities of capture are shown in
Fig. 1 within the context of the overall collections. Epibenthic sledges (BN2.4;
2.4 m wide x 0.8 m high and BN1.5; 2.3 m x 0.6 m) took one specimen each,
while the remainder were caught in a 14 m headline length Marinovich semiballoon otter trawl (OTSB14).The BN 1.5 incorporates a mouth closing system,
in which a blind occludes the entrance of the net at all times other than when the
sledge is on the bottom (Aldred, Thurston, Rice & Morley, 1976), but the other
two are open nets.
Table 1. Collection data for six specimens of Bathytyphlops from the eastern North
Atlantic. See Materials and methods for gear notation. ( 0 )denotes non-closing
gear
std tlon
Date
Position
7092
8933#3
913l#lO
954 1#6
251x1169
11x1175
191x1176
16lIVl77
2.i007'N, 19"lO'W
24°56.6'N, 1B0O1.2'W
20°15.1'N, 21'35.5'W
20°09.6'N, 21'43.3'W
Gear
Sounding range (m)
BN2.4
OTSB14
BN1.5
OTSB14
331 1-35] 140)
2980-2990-(0)
3950-3952
3929-3929-(0)
Number
1
2
1
2
Measurements were made directly from a sliding caliper to the nearest half
millimetre. Standard length is used throughout and morphometric characters
are expressed in percentages of it. Meristic counts were made from the left hand
side of specimens only. Vertebral counts were taken from X-radiographs and
exclude the urostyle.
In addition to the 'Discovery' specimens, the following material was examined
for comparative purposes :B. sewelli, holotype, 300 mm. British Museum (Natural History), BMNH
1939.5.24.458.
BATHYTYPHLOPS FROM THE EASTERN NORTH ATLANTIC
101
v
'Canary Isiands
0
9131
c
0
-
15'
0
Cape & * -
Q
Verde
o
Islands
-
0'
.a
-
D
-
-
0
10" -
.
I
l
l
l
l
l
l
l
l
l
l
l
l
l
r
l
l
Figure I Chai t of the eastern North Atlantic off northwest Africa showing the localities of capture of
t h e 'Discovery' 5 ~ ~ ~ ~ among
t ~ p other
~ ~ stations
o p ~ sampled during 1969-1977 0, 0-500 m, 0,
500-1000 111, A, 1000-1500 m , H, 1500-2000 m, A, 2000-2500m, 7 2500-3000 m , v,
3000-3500 m , 0,3500-4000 m , 0,4000-4500 m , 5500 m
*,
B . azorensis, holotype, 2 10 mm. Museum National d'Histoire Naturelle, Paris,
M N H N 1970-30.
B . marionae, Virginia Institute of Marine Science, VIMS 03298, 111 mm,
37O05.4'N, 74O23.6'W, 1520 m sounding; VIMS 05232, 325 mm, 2S049'N,
88'27'W, 1289 m sounding.
Supplementary data on B. marionae were kindly provided by K. J. Sulak who
made selected measurements on the following VIMS specimens: VIMS 0492 1 ,
180 mm, off British Guiana, 914 m sounding; VIMS 05233, 265 mm, 07O41'N,
53O35'W, 882 m sounding; VIMS 05234, 277 mm, 07O20'N, 53OO4'W, 692 m
sounding; VIMS 05235,203 and 320 mm, 09'58'N, 76O29'W, 127 1 m sounding;
VIMS 04964, 356 mm, 2 8 O 17'N, 7 7 O 10.5'W, 1106 m sounding.
RESULTS AND DISCUSSION
Systematic considerations
The overall size range of the 'Discovery' specimens was 146-282 mm. Their
vital statistics are given in Table 2. The ranges of characters for 'Discovery'
specimens are compared with those published for B . marionae, B . sewelli and B .
azorensis, together with data from hitherto unreported specimens of B. marionae
(Table 3). Inspection of Table 3 reveals that the new eastern North Atlantic
material overlaps several of the distinguishing proportions and counts previously
N. R. MERREIT
102
Table 2. Morphometric measurements, in percentages of standard length, and
meristic counts for six specimens of B a ~ ~ ~collected
~ ~ ~ from
~ l ‘Discovery’
o ~ s
in
the eastern North Atlantic
Station number
Standard length (mm)
9541#6
146
147
Head length
Snout length
Premaxillary length
Eye diameter
Interorbital width
Snout to dorsal origin
Snout to anal origin
Snout to pelvic origin
Snout to pectoral base
Snout tO dnUS
Pelvic to anal origin
Anus to anal origin
Depth of body at origin of dorsal
Length base dorsal
Length base anal
Length pelvic
Length pectoral
Length raker in angle of 1st gill arch
22.6
7.5
17.5
0.7
8.6
38.1
65.4
35.3
21.2
43.2
32.5
22.6
12.3
11.6
17.8
16.1
20.9
2.3
22.8
6.8
17.7
0.7
8.5
38.1
67.7
35.0
21.1
42.9
34.4
24.8
11.6
12.2
16.3
17.0
21.8
2.6
12
12
15
8
12
14
6+1+12
64
24 + 40
68
Number dorsal fin rays
Number anal fin rays
Number pelvic fin rays
Number pectoral fin rays
Number branchiostegal rays
Number gill rakers (1st arch)
Number vertebrae - total
Number vertebrae - precaudal
Number lateral line scales
I7
+ caudal
8
13
15
6+1+12
65
25 + 42
70
913l#lO
193
21.5
6.7
16.6
0.8
8.8
38.9
68.4
35.0
20.7
43.5
34.2
25.4
11.9
11.4
16.1
14.5
20.7
1.7
11
14
8
12
15
7+1+12
65
24 + 41
70
8933#3
7092
282
25 7
265
21.8
7.4
17.5
0.6
8.6
40.9
69.5
35.8
21.6
44.7
32.9
23.0
13.2
12.8
16.7
16.3
20.2
1.6
22.6
7.2
16.9
0.6
8.7
40.0
66.4
36.0
21.7
44.5
30.2
21.1
12.8
11.3
17.0
16.2
21.1
I .5
21.6
6.7
16.3
0.5
8.5
39.9
67.4
35.6
20.7
44.1
33.2
24.8
13
15
8
13
15
6+1+13
63
23 + 40
68
11
16
8
13
14
6+1+12
63
23+40
69
12
13.1
11.7
18.1
16.8
18.6
1.5
17
8
14
15
6+1+12
64
23 t 4 1
70
used to separate the three species (viz. number of pectoral, dorsal and anal rays,
lateral lines scales and gill rakers; relative proportions of body depth and length
of dorsal fin base, see Mead, 1958, 1966; Nielsen, 1966; Geistdoerfer, Hureau &
Rannou, 1970).As a result it is necessary to re-examine the status of each species
in the light of the new data.
The only diagnostic feature immediately apparent from Table 3 is the relative
length of the anal fin base. This, when judged by the ratio-on-size approach of Pam
(19561,is found to be an isometric character (Fig. 2), which is confirmed by a sizeon-size logarithmic regression giving a log linear relationship for each species
(slopes; B . sewelli 1.015, Q = & 0.047; B . marionae 1.007, o=f-0.061). In addition,
the values of the log of the anal base length when the log of the standard length
= 2.000 (= 100 mm SL) are significantly different at the 95% level ( B . sewelli 1.22 1,
Q=
0.015; B . marionae 1.123, Q= k 0.025)which isolates B . marionae (anal base
length 12.1-14.4% SL) from B . azorensis and B . sewelli, whose proportions
(15.5-17.6% SL) are matched by the range found in the ‘Discovery’ specimens
(16.1-18.1% SL). Correspondingly, the number of rays in the anal fin of B .
marionae is generally lower ( 13-14) than in the sewelli-azorensis-‘Discovery’
specimens ( 14-1 7 ), although the range found among the ‘Discovery’ material
makes this no longer invariably diagnostic. The development of‘the rakers on the
Table 3. Comparison of the ranges of morphometric measurements, in percentages of standard length, and meristic
counts of the ‘Discovery’ Bathytyphlops with similar data for B . sewelli, B . arorensis and B . marionae. (a, Nielsen, 1966;
b, Sulak, 1974; c, Geistdoerfer, Hureau 8c Rannou, 1970; d, Mead, 1958; e, unpublished data from VIMS material.
’”, Counts and measurements taken from type material during the course of this study)
‘Discovery’
specimens
Standard length (mm)
Head length
Snout length
Prerriaxillary length
Eye diameter
Interorbital width
Snout to dorsal origin
Snout to anal origin
Snout to pelvic origin
Snout to pectoral base
Snout to anus
Pelvic to anal origin
Anus to anal origin
Depth ofbody at originofdorsal
Length base dorsal
Length base anal
Length pelvic
Length pectoral
Length raker in angle of 1st gill arch
146-282
21.5-22.8
6.7-7.5
16.3-17.7
0.5-0.8
8.5-8.8
38.1-40.9
65.4-69.5
35.0-36.0
20.7-21.7
42.9-44.7
30.2-34.4
21.1-25.4
11.6-13.2
11.3-12.8
16.1-18.1
14.5-17.0
18.6-2 1.8
1.5-2.6
Number dorsal fin rays
Number anal tin rays
Number pelvic fin rays
Number pectoral tin rays
Number branchiostegal rays
Number gill rakers ( G t arch)
Number vertebrae- total
Numbervertebrae-precaudal
Number lateral line scales
11-13
14-17
8
12-14
14-15
6-7+1+12-13
63-65
(23-24) + (40-42)
68-70
+ caudal
B. azorensts
B sewellt
93a
23.0
7.7
18.5
0.9
9.3
40.0
67
36.5
148b
22
21oE
B . mananae
300a
21.5
7.0
17.0
0.5
7
-
8.8
8
38
65
-
-
-
41.5
67
38.0
-
45.0
43.5
-
30.9
21.9
12.3
10.9
17.6
16.6
21.4
1.7’
-
12
17
8
I3
12
I2
17
8
13
13
8
14
16
..
0.6
-
-
32
-
-
9.1
9.7
16.0
17.5
10.0
15.5
13
-
-
3.8
11
16
8
12
14
7+1+11
62
24 + 38
c.70
1.8*
11
16
8
12
14
6+1+11
63
25 + 38
c.65
10
I7
1.9
22.1
7.1
-
0.7
8.0
40.4
67.1
7+1+12 7+1+12
65
64*
24 + 40*
67
263d
22.4
6.6
16.6
0.11
8.5
40.3
69.0
37.9
21.7
I
12.2
12.4
15.4
17.1
4.2
12
279d
23.1
7.5
17.0
0.7
8.6
39.1
69.6
37.5
21.3
-
22.0
16.0
12.7
14.0
16.7
20.1
-
13
14
8
13
17
15
b + lc(12-14)
62
63
L5+37
65
64
llOe
22.7
7.3
17.2
09
8.2
39.0
67.2
36.4
21.8
45.5
33.6
22.7
11.4
11.8
13.6
16.4
17.2
3.2
315e
22.8
7.3
16.2
0.5
8.2
37.4
69.5
38.0
21.2
46.4
35.2
24.4
13.6
13.3
13.3
13
13
13
14
12
8
8
SO@
-
-
-
-
-
-
14.5
-
-
3.3
15
15
15
7+1+13 7+1+13
65
62
25+40
24+38
64
66
13
16.8
20.6
3.5
I3
8
14
15
7+1+13 62
24+38
64
104
N. R.M E R R E I T
Standard length (mm)
Figure 2 Length of the anal fin base, as a percentage of the standard length, plotted against standard
length in B. manonut (A,published data; A, VIMS data), B sewelli (0).E azorensu (m) and ‘Discovery’
Bathytyphlops (0).Data for closed symbols taken from Table 3, with the addition off, Norman, 1939.
first gill arch, hitherto considered sufficient to distinguish marionae from both
sewelli and azorensis, must now be qualified as a diagnostic feature. The degree of
development of rakers on the epi-, cerato- and hypo-branchial bones varies and, as
the photographs in Fig. 3 show, this is particularly marked in small specimens.
The rudimentary nature of the gill rakers in larger specimens of B. murionue,
however, serves as a useful confirmatory character (see Mead, 1958 for
description). The relative length of the enlarged raker in the angle of the
epibranchial and ceratobranchial bones can be used to distinguish marionae from
both sewelli and azorensis, at least among specimens larger than 130mm. In
contrast to the isometric growth of the anal fin base, however, this gill raker is
strongly negatively allometric among the sewellz-atorensis-‘Discovery’ material
group (Fig. 4),so it is of value only in relation to the size of specimen concerned.
This allometry is confirmed by logarithmic regression as above, while the data
for B. mmianae indicate again a log linear relationship (slope; 1.133, Q= 0.110),
which is thus isometric. Individual data are not given by Golovan (1976)for his
seven specimens (302-353 mm) of B . marionae, but the ranges shown for the
length of the base of the anal fin (11.9-15.1% SL), the number of rays in this fin
(12-14) and the length of the enlarged raker in the angle of the first gill arch
(3.6-4.2% SL) are consistent with, and so serve to confirm, the features found
here to be diagnostic for this species. The status of B. marionae is further
strengthened by its predominantly slope-dwelling habit (p. 1001, which contrasts
with the abyssal occurrence of the sewelli-azorensis-‘Discovery’ group of
specimens.
The comparison of the features above serves, not only to confirm the
distinction of B. marionae, but also to unite the nominal species sewelli and
atorensis. Two of these features (uiz. the number of anal fin rays and the relative
Figure 3. Comparison o f t h e first gill arches o f t h e 'Discovery' Bathytyphlops (A, 146 mm: B, 147 mm;
C, 193 inin; E, 257 m n ; F, 265 inin; G, 282 mrn) with the holotypes of E . azorensis (D, 210 mm) and
B . rewvlli iH, 300 nun) and two specimens o f E . rnarzonac (I, 110 mm, J , 315 mm). j All removed from
LHSexceptforD.)Scalelines= 10 mm.
N. R.MERRETT
106
A
.a*
4-
-
*a
d
h
f
m
.a
3
‘
Q
3-
2
-
z
A
A
0
c
0
f
In
2-
.b
tl
x
z
*f
.C
0
0
-
0
0
’c
f
m
a
nI
I-
0-
1
100
1
1
1
1
I50
1
1
1
l
1
1
200
1
1
1
1
1
250
1
1
1
1
1
300
1
1
1
1
351
Figure 4. Length of the raker in the angle of the first gill arch, as a percentage of standard length,
plotted against standard length in B. manonae (A, published data; A. VIMS data), B . sewelli (01,B.
azorewts (U)and ‘Discovery’Bdhytyphlops (0).
Data for closed symbols is the same as given for Table 3
and Fig. 2, with the addition ofa”, Nielsen, 1966.
length of the raker in the angle of the first gill arch) were among the four adopted
by Geistdoerfer, Hureau & Rannou (1970) to distinguish B. azoremis from B.
sewelli. The number of rakers on the first gill arch, their third diagnostic
character, has already been invalidated by the range evident from the ‘Discovery’
data (Table 3). Finally they stressed the differences in the obscurity of the eye
between azorensis and sewelli. Examination of the ‘Discovery’specimens suggests a
regression in the conspicuousness of the eye with size. The degree of obscurity of
the eyes of the holotypes of B . azorensis and B . sewelli matches this trend in relation
to their length. At all sizes the skin over the eyes bears scale pockets, but in small
specimens little opaque tissue separates this from the minute eye. With body
growth the eye appears to become deeper set, but barely any larger. Overlying
tissue renders it less conspicuous to the point where the holotype of B . sewelli led
Norman ( 1939) to comment on “the complete absence of eyes” in describing the
species. Hence the new data overrule the distinctions apparent to Geistdoerfer,
Hureau & Rannou ( 19 701,while further comparison of the ‘Discovery’specimens
with the type material of both species reveals no other differences worthy of
specific rank. The discrepancy in number of caudal vertebrae between the two
s ecimens of sewelli (38-Table 3) and the uzormis-‘Discovery’ fishes (40-42) is
t e largest variation, but it is comparable with that observed in marionae (37-40).
I t is considered to be within the range of individual variation for a species of
Bathytyphlops, especially as the range in the total number of vertebrae from the
‘Discovery’ material conforms with the ranges in both B. azorensis and B. sewelli.
Hence, all the available evidence indicates that B . azorensis is a synonym of B.
sewellz.
K
BATHYTYPHLOPS FROM THE EASTERN NORTH ATLANTIC
107
Environmental observations
With this new information, the known range of B . sewelli is extended into the
Atlantic Ocean to give a geographic distribution broadly similar to that of B .
murionae, except for the absence of B . sewelli in the western Atlantic (cf. Sulak, 1974:
fig. 2). The lack of a swimbladder in B . sewelli and its robust skeleton are indicative
of a bottom-living habit, which is confirmed by the capture of one ‘Discovery’B .
sewelli in the mouth-closing epibenthic sledge (BN1.&see Materials and
methods). A conductivity-temperature-depth profile taken at Stn. 9541#4, in the
same area as one of the captures (Stn. 9541#6) and a few hours prior to it, gave a
temperature of 2.3OC at 3944 m depth in a sounding of 3950 m. This confirms my
initial conclusion (based on the maps in Fuglister, 1960) that all the ‘Discovery’
specimens were collected from temperatures lower than 3OC. The substrates at two
of the collection sites, sampled by box corer, were calcareous clay (Stn. 8933#3)
and pink calcareous ooze (Stn. 9 131#10)(S.E.Calvert,pers. commn).
Biological observations
Reproduction
Nielsen ( 1966) studied the reproductive biology of several of the ipnopine
species in detail, but B . sewelli was not among them. Examination of the
‘Discovery’ material largely confirms the reproductive pattern he revealed. Thus
B. sewelli is hermaphrodite. The testicular portion of the ovotestes in adults is a
relatively inconspicuous line of light-coloured tissue running mid-ventrally
along the length of the gonad. First maturity had not been attained in the three
smaller specimens ( 146-196 mm). Oocyte development was in the early stages
prior to chorion formation (oocyte diameter < 0.1 mm) and the testicular string
was barely distinguishable in the unstained gonad. Maturation of the ovotestes
was more advanced among the three larger ‘Discovery’specimens (257-282 mm)
and the holotype. While none of the testicular portions were swollen with milt,
the ovarian sections were in the growth phase of maturation with yolk formation
in the developing ova well advanced (c. 0.6-0.8 mm diameter). The left hand side
of the ovotestis of the 282mm fish was removed and the most advanced
generation of eggs counted. There were 2940 present and, with the right hand
side of similar size, a total fecundity in this generation of about 6000 eggs would
be expected. This contrasts with the considerably lower count of 300 or less in
Zpnops and Bathymtcrops (Nielsen, 1966). Apparently two other generations,
represented by resting oocytes of < 0.1 mm diameter and ova in the chorion
formation stage of oogenesis of 0.1-0.2 mm diameter, were present in this and
the other maturing ovaries examined.
Also, free in the lumen of the left hand ovary of the 282 mm specimen were ten
residual ovulated eggs, presumably of a previous spawning. Although collapsed,
they were noticeably larger than any developing ova, probably > 1 mm diameter.
A certain amount of degeneration had occurred internally, but a conspicuous
oily globule was present in each. Whether or not such a globule would provide
buoyancy in healthy eggs is uncertain, yet the observation lends added credence
to the identification of B u t ~ ~ p h i o plarvae
s
from near surface waters (Okiyama,
1972). In the related genus Zpnops, Sulak (1977 ) found that ovarian eggs were not
buoyant and he used this observation, together with the low fecundity, to
conclude that the eggs developed close to the bottom. In contrast, the 20-fold
108
N.R. MERRETT’
greater fecundity of B . sewelli argues for epipelagic development. Oval tailless
spermatozoa, about twice the size of blood cells, were found in the testis of this
282mm fish, which accords with their morphology in B. marionae and other
Ipnopinae (Nielsen, 1966). It would appear from these specimens that B. sewelli is
a multiple spawner, which attains first maturity around 200-250 mm. The interpretations given by Nielsen ( 1966) on synchronous hermaphroditism in this
group remain substantially unaltered in the light of the present data. While the
collection is too small for observations on seasonality, for future reference it is
noted that the specimens with ripening gonads were caught in November (cf.
Sulak (1977) regarding Zpnops).
Feeding
Stomach and intestinal contents were removed and examined separately. No
stomachs were more than half full or contained undigested organisms. The only
identifiable remains of prey were crustacean. Fragments were found amongst the
amorphous digested contents of the stomachs and/or intestines of all but one
fish. The intestine of the 193 mm specimen contained mysid remains, while
decapod material was identified from three fishes ( 2 5 7 mm-stomach,
265 mm-stomach,
282 mm-intestine;
the contents of the two largest
specimens have already been reported by Marshall & Merrett (197 71, under the
preliminary diagnosis of B . uzorensis). Decapod remains could be recognised as
natant forms in the 257 and 282 mm specimens. Together with these fragments in
the largest fish were a few foraminiferan shells of the Globigerina type. This was the
only bottom substrate present in any of the specimens and it might have
originated from the decapod prey. Such general absence of sediment and the
active nature of the identifiable prey suggests that, while B sewelli without
buoyant means must be a benthic species, it has a marked preference for pelagic
food. It presumably feeds on benthopelagic organisms swimming close to the
sea-land interface and must compete with the more active buoyant fishes which
can “hover and explore” for food (see Marshall & Merrett, 1977).
Trematode parasites were present in the digestive tracts of the three specimens
in stomach; 265 mm-6
in stomach, 2 in
mentioned above (257 mm-1
intestine; 282 mm- 10 in intestine). They were identified as undescribed
opecoelid digeneans of the genus Neolebouria Gibson, 1976 (D. I. Gibson, pers.
commn). It is noteworthy that this genus, which was described from antarctic
material (Gibson, 19761, should have an abyssal semi-tropical representative.
ACKN 0WLED GEMENTS
The loan of specimens was kindly arranged from the British Museum (Natural
Histo ) by Mr A. C. Wheeler, from the Museum National d’Histoire Naturelle,
Paris,?y D r J.-C. Hureau and from the Virginia Institute of Marine Science by
Dr K. J. Sulak. Dr Sulak also generously provided data from additional material.
I am grateful to Dr D. I . Gibson (British Museum (Natural History)) for
identifying the gut parasites and to Dr A. L. Rice (1.0.S.) for identifying the food
organisms. Finally, I wish to thank Mr J. R. Badcock and Mr P. M. David
(I.O.S.),Dr J . G. Nielsen (Zoologisk Museum, Copenhagen), Dr J.-C. Hureau
and Dr K. J. Sulak for their helpful criticism of the manuscript.
BATHYTYPNLOPS FROM T H E EASTERN N O R T H ATLANTIC
109
REFERENCES
ALDRED, R. G., THURSTON, M. H., RICE, A. L. & MORLEY, D. R., 1976. An acoustically monitored
opening and closing epibenthic sledge. Deep-sea Research, 2 7 : 167-1 74.
FUGLISTER, F. C . , 1960. Atlantic Ocean atlas of temperature and salinity profiles and data from the
International Geophysical Year of 1957-1958. The Woods Hole Oceanographic Institution, Wood.i Hole Atlas
Series, 1 : 209 pp.
G I B S O N , D. I . , 1976. Monogenea and Digenea from fishes. Discovery Reports,36: 179-266.
GEISTDOERFER, P., HUREAU, J.-C. c! RANNOII, M., 1970. Deux poissons abyssaux nouveaux raptures
darts I’Atlantique Nard et Est: Eathjtyphlops azorensi,! n. sp. (Ipnopidae) et Lycenchelys labradorensis n. sp.
(Zoarcidae). Bulletin du Musium National d’tltstoire Naturelle, ( 2 )42: 452-459.
GOLOVAN, G. A,, 1976. Redkie i vpenye obnaruzhennye na materikovom sklone Zapadnoi Afriki
khryashchenvye i kosmye ryby. (Rare and firstly recorded chondrostean and teleostean fishes of the continental
slope ofWest Africa.) Trudy Instituta Okeanologii tm P. P . Shirshou, 104. 277-3 1 7 . (In Russian).
MARSHALL, N. B. & MERRETT, N. R., 1977. The existence o f a benthopelagic fauna in the deep sea. In: M.
V. Angel, (Ed.), A Voyage ofDiicovety. George Deacon 70th Anniuersav Volume: 483-497, Supplement to DeepSea Research, 24.
MEAD, G . W., 1958. Ichthyology-Three new species of-archibenthic iniomous fishes from the western North
Atlantic. Journal ofthe Washington Academy ofSciences, 48: 362-372.
MEAD, G. W., 1966. Family Ipnopidae. In G. W . Mead (Ed.). Fishes ojthe Western North Atlantic. Memoir. Sears
Foundation forMartneResearch, 5 (1): 147-161.
NIELSEN, J . G., 1966. Synopsis of the Ipnopidar (Pisces. Iniomi) with description of two new abvssal species.
Gaiathea Report, 8:49-75.
NORMAN, J . R., 1939. Fishes. Scientijc Report.!, TheJohn Murray Expedition, 1933-34, 7 : 1-1 16.
OKIYAMA, M., 1972. Morphology and identification of the young ipnopid, “Macrisliella” from the tropical
western Pacific. Japanese Journal oflchthyolagy, 19: 145-153.
PAKR, A. E., 1956. O n the original variates of taxonomy and their regression upon size in fishes. Bulletin ofthe
American Museum of Nalural History, 110: 373-397.
SLILAK, K. J., 1974. Morphological and ecological observations on Atlantic ipnopid fishes of the genus
Bathylyphlops. Copeia. 1974: 570-573.
SULAK, K. J . , 197 7 . The systematics and biology of Ealhypterois (Pisces, Chlorophthalmidae) with a revised
c-lassilication of benthic inyctophiform fishes. Galathea Report, 1 4 : 49-108.