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New species of the genus Ariosoma, A. dolichopterum (Bathymyrinae), from the waters of Central Vietnam

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A new species, Ariosoma dolichopterum is described from 30 specimens collected in the coastal waters of Central Vietnam. This species differs from a related species A. anago in lower total number of vertebrae (127–131), lower number of precaudal vertebrae (58–61) and preanal pores (46–50), and larger length of the pectoral fins (39–48% of head length). The distribution of adult and larval forms of this species of congrid eels (Bathymyrinae) in the South China Sea and adjacent waters of western Pacific is given.
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ISSN 00329452, Journal of Ichthyology, 2015, Vol. 55, No. 6, pp. 906–910. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © E.S. Karmovskaya, 2015, published in Voprosy Ikhtiologii, 2015, Vol. 55, No. 6, pp. 719–723.
906
According to the data of several authors, the fol
lowing species of the genus
Ariosoma
are distributed in
the South China Sea:
A. anago
(Temminck and Schle
gel, 1846),
A. major
(Asano, 1958),
A. anagoides
(Bleeker, 1853),
A. megalops
Fowler, 1938 (Smith,
1989, 1999, 2000; Shen, 1998), and, most likely,
A. sazonovi
Karmovskaya, 2004. The latter species is
known from the eastern South China Sea off Philip
pines at the border with the Sibuyan Sea, southwestern
coast of Luzon Island (Karmovskaya, 2004). In the
coastal waters of Central Vietnam, in addition to
A. anago
and
A. megalops
, I found
A. meeki
known off
Japan, as well as
A. dolichopterum
sp. nov, a new spe
cies described earlier (based on adult specimens) as
A. anagoides
(Shen, 1998) from the waters of Tai
wan.According to the number of vertebrae/myomeres,
the latter species of congrid eels (Bathymyrinae) can
be associated with leptocephali described previously as
Ariosoma
sp. 6 (Tabeta and Mochioka, 1988) and
Type II (Mochioka et al., 1991) from the waters off
Taiwan and Okinawa.
This study is devoted to the description of a new
species based on the materials collected from 2005 to
2010 in the coastal waters of Central and South Viet
nam. The fishes were caught with bottom shrimp
trawls on board of local wooden trawlers at the depths
ranging from 10 to 130 m. Measurements and counts
of pores of the seismosensory system were made using
traditional methods applied for congrid eels (Smith,
1989). Numbers of fin rays and vertebrae were counted
on the xrays photographs.
Ariosoma dolichopterum
sp. nova
(Fig. 1)
Ariosoma anagoides
: Shen, 1998, p. 9 (four speci
mens, description, off southwestern Taiwan).
Ariosoma
sp. 6: Tabeta and Mochioka, 1988, p. 49
(brief description, drawing).
Ariosoma
Type II: Mochioka et al., 1991, p. 611.
Figs. 5 and 6 (leptocephali, partim, description and
distribution, waters of Taiwan and Okinawa).
Material. ZMMU 23861, holotype, male
311 mm
TL
, between June 30 and July 1, 2006,
12
°
37
N,
109
°
28
E, depth 29–44 m, collector
A.M. Prokofiev. Paratypes, eight specimens 104–
320 mm
TL
; ZMMU 23862, two specimens 168 and
193 mm
TL
, June 21, 2005, polygon 4,
12
°
14
–12
°
16
N,
109
°
17
–109
°
19
E, depth 22–24 m; ZMMU 23863,
one specimen 320 mm
TL
, collected together with the
holotype; ZMMU 23864, one specimen 291 mm
TL
,
November 24, 2005,
12
°
15
N,
109
°
18
E, depth 22–
24 m; ZMMU 23865, one specimen 233 mm
TL
, Sep
tember 21, 1984, scientific and commercial vessel
Odis
sei
,
11
°
09
N,
110
°
01
E, depth 480 m; IO RAS 02824,
one specimen, 132 mm
TL
, June 10, 2006,
12
°
03
N,
109
°
13
E, depth 11–18 m; IO RAS 02825, one spec
imen 104 mm
TL
, June 17, 2006,
12
°
14
N,
109
°
19
E,
depth 7–10 m; IO RAS 02826, one specimen 307 mm
TL
, June 26, 2006,
12
°
13
N,
109
°
20
E, depth 23–
33 m. Nontype specimens: IO RAS 02827, 13 speci
mens 261–365 mm
TL
, 2010,
10
°
47
–10
°
38
N,
108
°
00
–108
°
58
E, depth 100–130 m, Phu Quy
Island.
New Species of the Genus
Ariosoma
,
A. dolichopterum
(Bathymyrinae), from the Waters of Central Vietnam
E. S. Karmovskaya
Shirshov Institute of Oceanology, Russian Academy of Sciences,
pr. Nakhimovskii 36, Moscow, 117218 Russia
email: ekarmovs@ocean.ru
Received June 26, 2015
Abstract
—A new species,
Ariosoma dolichopterum
is described from 30 specimens collected in the coastal
waters of Central Vietnam. This species differs from a related species
A. anago
in lower total number of ver
tebrae (127–131), lower number of precaudal vertebrae (58–61) and preanal pores (46–50), and larger length
of the pectoral fins (39–48% of head length). The distribution of adult and larval forms of this species of con
grid eels (Bathymyrinae) in the South China Sea and adjacent waters of western Pacific is given.
DOI:
10.1134/S0032945215060077
Keywords
: congrid eels, Bathymyrinae,
Ariosoma dolichopterum
, new species, Vietnam, South China Sea
BRIEF
COMMUNICATIONS
JOURNAL OF ICHTHYOLOGY
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NEW SPECIES OF THE GENUS
Ariosoma, A. dolichopterum
907
Material for comparison.
Ariosoma
sp.,
North West Shelf of Australia: AMS I 26 943001, one
specimen 183 mm
TL
,
20
°
04
S,
116
°
10
E, depth
64 m; CSIRO, CA 2712, female 266 mm
TL
, the same
data; B 2028, one specimen 149 mm
TL
,
20
°
01
S,
115
°
58
E, depth 80 m; CA 2714, one specimen
132 mm
TL
, the same data; CA 2721, one specimen
174 mm
TL
, the same data; CA 2339, male 200 mm
TL
,
19
°
52
S,
116
°
27
E, depth 70 m.
L e p t o c e p h a l i. 37 specimens 35–182 mm
TL
.
Danaexp
, 1929: station 3687 V, one specimen
104 mm
TL
,
08
°
34
N,
119
°
36
E, Sulu Sea, station
3690 IV, 24 specimens 45–105 mm
TL
,
8
°
02
N,
109
°
36
E, South China Sea to the southeast of Viet
nam; station 3712 IV, one specimen 150 mm
TL
,
12
°
44
N,
110
°
45
E, South China Sea, Vietnam; station
3715 I, two specimens 98 and 102 mm
TL
,
18
°
18
N,
119
°
36
E, South China Sea, Philippines, northwest
ern part of Luzon Island; station 3723 V, three speci
mens 35–78 mm
TL
,
25
°
30
N,
125
°
28
E, East China
Sea, Okinawa Trough; station 3730 I, one specimen
182 mm
TL
,
16
°
55
N,
120
°
02
E, South China Sea,
Philippines, Luzon Island; station 3731 II, one speci
men 95 mm
TL
,
14
°
37
N,
119
°
52
E, South China
Sea, Philippines, Luzon Island; station 3750 IV, three
specimens 70–90 mm
TL
,
4
°
11
N,
136
°
36
E, Philip
pine Sea, to the south of Palau.
Gal.exp
, station 408,
one specimen 138 mm
TL
,
13
°
44
N,
118
°
50
E, east
ern South China Sea, Philippines.
(c)
(b)
(a)
Fig. 1.
Ariosoma dolichopterum
sp. nova, holotype ZMMU 23861, 311 mm
TL
: (a) general view; (b, c) head from a side and from
below.
908
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KARMOVSKAYA
D i a g n o s i s. Species of the genus
Ariosoma
with
six supraorbital, eight infraorbital, ten preoperculo
mandibular, and three temporal large pores; with a
welldefined dark medial stripe on the lower surface of
the snout; pectoral fin length 39–48% of head length.
Preanal pores 46–50; total vertebral number 127–131,
precaudal vertebrae 58–61.
D e s c r i p t i o n. Dorsalfin origin slightly before
pectoral fin base, over sixth to eighth pore of lateral
line. Pores in canals of head and lateral line large.
Vert.
129 (127–131), preanal vertebrae 49 (48–50), precau
dal vertebrae 58 (58–61).
D
180–185,
A
120–140,
P
13
(1214). Rays of dorsal fin to vertical through
anal fin origin 69–79. Pores of lateral line to anal fin
origin 47 (46–50).
SO
6,
IO
8,
POM
10,
ST
3
. Myo
rhabdoi absent.
Teeth not large, about the same size; sharpened on
premaxilloethmoid and in marginal rows of both jaws;
teeth bluntconical on vomer. Anterior end of lower
jaw completely covers premaxilloethmoid at closed
mouth. Premaxilloethmoid comparatively wide, its
length only slightly larger than its width; teeth in five
to seven transverse rows. Posterior end of upper jaw
reaches vertical through middle of orbit. Teeth on jaws
in narrowing bands: in four to seven irregular rows
anteriorly and in one or two rows posteriorly. Vomer
elongated, narrower posteriorly, reaching about one
half of upper jaw length; teeth small, bluntconical, in
five or six irregular rows anteriorly and in two or three
rows posteriorly.
Swimming bladder far behind anal opening. Stom
ach reaches 1/2–2/3 of the distance from gill openings
to the vent.
Leptocephali (nonexterilium type): length 35–
182 mm, total myomere number 127–135, preanal
myomeres 119–124. Last blood vessel at 59 – 66th
myomere.
Some measurements of holotype and
(in the parentheses) six paratypes 104–320 mm
TL
. As
%
TL
: antedorsal distance 15.3 (14.9–17.8), anteanal
distance 45.0 (43.846.4), head length 16.7 (16.1
18.9), body depth at anus 6.6 (5.3–7.6). As %
c
: snout
length 22.6 (20.5–25.2), horizontal eye diameter 18.2
(17.3–23.9), mouth cleft length 29.8 (28.0–33.2),
interorbital width 11.7 (9.3–14.1), pectoral fin length
48.0 (39.4–46.7), branchial opening depth 15.3
(14.2–20.2), interbranchial width 22.1 (14.2–23.6).
Largest specimen 320 mm
TL
, mature female.
C o l o r a t i o n of preserved specimens similar to
that in
A. anago
, but color pattern on dorsal and lateral
surfaces of head more bright and distinct. Head and
back darker than belly; in postorbital area, dark stripes
alternated with more narrow and light stripes. Distal ends
of the rays of dorsal and anal fins black (Figs. 1a and 1b).
At lower surface of snout along axial line, congestion
of melanophores forming a conspicuous dark stripe
(Fig. 1c).
E t y m o l o g y. Latin name “dolichopterum”
means long pectoral fins are typical of this species.
Comparative comments.
A. doli
chopterum
is similar to
A. anago
in the coloration of the
head and body, size, shape, and arrangement of teeth
on the jaws and in the majority of morphometric mea
surements. It differs from
A. anago
in the following
characters: presence of dark stripe on the lower surface
of the snout, smaller number of preanal pores (46–50
vs. 51–55), smaller total number of vertebrae (127–
131 vs. 139–144), smaller number of precaudal verte
brae (58–61 vs. 69–73), longer pectoral fins (39.4–
48.0 vs. 31.0 – 37.2%
с
), and longer swimming bladder
(reached almost the posterior edge of the kidney vs. its
posterior end only slightly behind the anal opening or
before this opening). The new species is similar to the
specimens described by Shen (1998) from the waters
of Taiwan and called
Ariosoma anagoides
in the total
number of vertebrae (127–131 vs. 130–131) and num
ber of rays in the unpaired fins (
D
180–185,
A
120–
140 vs.
D
178–188,
A
132–135) but it differs in slightly
larger number of preanal pores (46–50 vs. 45–46). In
our specimens a ratio between the pectoral fin length
and head length (2.08–2.54) is also similar to that
(2.21–2.60) in the specimens from Taiwan. However,
the pectoral fins are substantially shorter (2.68 – 3.22)
in
A. anago
. In a specimen of
A. anagoides
(BMNH
1867.11.28.299, 312 mm
TL
, Indonesia) that I exam
ined at one time, a ratio between the pectoral fin
length and head length is 3.06, and this ratio in the
specimens called
A. anagoides
and collected off Japan
is 2.83–3.46 (Asano, 1962, p. 77). In 1994, I found six
specimens of unknown species of the genus
Ariosoma
collected in the North West Shelf of Australia (Austra
lian museums, AMS and CSIRO). These specimens
are similar to those described in this study, but, most
likely, they belong to another species. The specimens
from Vietnam are similar to the Australian specimens
in the number of preanal pores (46–50 vs. 49–52),
pectoral fin length and head length ratio (39–48 vs.
36–45%
c
), and in a presence of a dark longitudinal
medial stripe on the lower surface of the snout
(Fig. 1c). However,
A. dolichopterum
differs from the
Australian specimens in a slightly smaller number of
vertebrae (127–131 vs. 133–136) and in significantly
less number of precaudal vertebrae (58–61 vs. 66–68).
The leptocephali with the myomere number (127–
135) similar to vertebral number in adult specimens
A. dolichopterum
were found in the South China, East
China, Sulu and Philippine seas (Fig. 2). Their total
myomere numbers and preanal myomere numbers are
very similar to those in the leptocephali named
Ario
soma
sp. 6 and Type II (127–135 vs. 127–134 and
119–124 vs. 118–128, respectively), which have been
described previously (Tabeta and Mochioka, 1988;
Mochioka et al., 1991) from the waters off Taiwan and
Okinawa. However, they slightly differ in the position
of the last blood vessel (at 59–66th myomere vs. at 64–
72nd myomere). I suggest that a more caudal position
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NEW SPECIES OF THE GENUS
Ariosoma, A. dolichopterum
909
of the posterior blood vessel in the leptocephali of
Ari
osoma
sp. 6 and Type II, most likely, is connected with
a mixed material including some specimens belonged
to another species (
Ariosoma
sp. 7 and Type III) char
acterized by 71–80 myomeres before the vertical
through the last blood vessel. The leptocephali of
Ari
osoma
sp. 6 and
Ariosoma
sp. 7 differ in the total num
ber of myomeres (127–135 vs. 136–151) and in the
number of myomeres to the vertical through the last
blood vessel. However, they show a substantial e xternal
similarity: in both species, the upper part of the last
blood vessel near the notochord is divided into two
short branches (Mochioka et al., 1991. Figs. 5 and 7).
D i s t r i b u t i o n. The new species is distributed in
the West Pacific; and, most likely, it is an endemic spe
cies for the Northern Hemisphere. (In the Southern
Hemisphere in the North West Shelf of Australia, this
species is replaced by another similar not described
species
Ariosoma
sp.). Adult specimens, including sex
ually mature individuals, were collected in the South
China Sea, Nha Trang Bay, at a depth 10–44 m and off
40°
30°
20°
10°
20°
30°
40°
S
160°140°120°100° 130°110° 150° E
10°
N
Fig. 2.
Sites of capture of the studied (
) adult specimens and (
) leptocephali of
Ariosoma dolichopterum
sp. nova in the western
Pacific and (
) adult specimens of
Ariosoma
sp. in the North West Shelf of Australia.
910
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KARMOVSKAYA
Phu Quy Island at a depth 100–130 m, and on the
continental slope at a depth 480 m (one specimen).
Besides, the species was recorded off Taiwan (Shen,
1998) as
A. anagoides
. Leptocephali with myomere
numbers (127–135) similar to those in adult individu
als of the species were collected in the South China
and East China seas between 8° and 25° N (Fig. 2).
The smallest larvae 35–78 and 33–41 mm
TL
, respec
tively, were collected in the East China Sea (our data)
and to the south of Okinawa Island (Mochioka et al.,
1991).
ACKNOWLEDGMENTS
This work was supported by the Russian Founda
tion for Basic Research, project no. 130400328.
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Mar. Biol. Inst. Kyoto Univ.
, 1962, no. 1, pp. 1–143.
Karmovskaya, E.S., Benthopelagic bathyal [Conger] eels
of families Congridae and Nettastomatidae from the West
ern tropical Pacific, with descriptions of ten new species,
J. Ichthyol.
, 2004, vol. 44, no. 1, pp. S1–S32.
Mochioka, N., Tabeta, O., Kakuda, Sh., and Tsukahara, H.,
Congrid leptocephali in the Western North and Middle
Pacific II. NonExterilium
Ariosoma
type larvae,
Bull. Mar.
Sci.
, 1991, vol. 48, no. 3, pp. 606–622.
Shen, S.C., A review of congrid eels of the genus
Ariosoma
from Taiwan, with description of a new species,
Zool. Stud.
,
1998, vol. 37, no. 1, pp. 7–12.
Smith, D.G., Family Congridae, in
Fishes of the Western
North Atlantic
, Böhlke, E.B., Ed., New Haven, CT: Mem.
Sears. Found. Mar. Res., 1989, part 9, no. 1, pp. 460–567.
Smith, D.G., Congridae, in
FAO Species Identification
Guide for Fishery Purposes. The Living Marine Resources of
the Western Central Pacific
, Carpenter, K.E. and
Niem, V.H.P., Eds., Rome: Food Agric. Org., 1999, vol. 3,
pp. 1680–1687.
Smith, D.G., Congridae, in
A Checklist of the Fishes of the
South China Sea
, Raffles Bull. Zool., Randall, J.E. and
Lim, K.K.P., Eds., 2000, no. 8, pp. 569–667.
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An Atlas of the
Early Stage Fishes in Japan
, Okiyama, M., Ed., Tokyo:
Tokai Univ. Press, 1988, pp. 44–49.
Translated by D.A. Pavlov
... 6-8); preanal pores 47-49 (vs. 45-50); eye orbit diameter 16. .2% in HL) (Karmovskaya 2015). Ariosoma dolichopterum from the Taiwan waters possesses smaller eye with mean diameter of 16.8% (see Smith et al. 2018), but in the present study, the recorded eye diameter is 18.0% in HL, which falls in the same range as in the holotype (see Karmovskaya 2015). ...
... 45-50); eye orbit diameter 16. .2% in HL) (Karmovskaya 2015). Ariosoma dolichopterum from the Taiwan waters possesses smaller eye with mean diameter of 16.8% (see Smith et al. 2018), but in the present study, the recorded eye diameter is 18.0% in HL, which falls in the same range as in the holotype (see Karmovskaya 2015). Ariosoma dolichopterum resembles A. anago in body colouration, pointed snout, black margin on dorsal and anal fins and also in few morphometric characters, but can be readily distinguished in having a small gap between the intermaxillary and vomerine teeth patch (vs. ...
... According to Smith et al. (2018), A. dolichopterum has a longer pectoral fin mean length of 45.8% HL; type specimens have 39.4-48.0% HL, mean 43.5% (Karmovskaya 2015), whereas other congeners have a range of 28.7-36.4% HL. ...
Article
A new species of congrid eel, Ariosoma melanospilos sp. nov., is described from two specimens collected as bycatch landings of deep-sea trawlers at Colachel fish landing centre, off Kanyakumari, the southwest coast of India. The new species is distinguishable from all the known congeners in having two spots on both sides of the mid-dorsal temporal region (vs. absent in all congeners) and a wide interbranchial width of 25.0–30.3% head length. The new species resembles Ariosoma meeki (Jordan & Snyder, 1900) in possessing the unique character of two dark patches at the posterior margin of the eye but can be readily distinguished by the presence of a fifth supraorbital pore and three pores as ascending branch of the infraorbital canal behind the eye, three supratemporal pores (vs. absent in A. meeki) and four black spots on the temporal region. Genetic analysis reveals that the new species is closely related to Ariosoma anale (Poey, 1860) and A. meeki forming a clade with a genetic distance of 20.5% and 19.6%, respectively. We also report Ariosoma dolichopterum Karmovskaya, 2015, for the first time from Indian waters with meristic and morphological characters.
... The new species possesses significantly less preanal vertebrae counts than A. anago (46-49 vs. 54-56) (Smith et al. 2018). The new species differs from A. dolichopterum by substantially higher total vertebrae count (146-149 vs.127-134) (Karmovskaya, 2015). In the new species the snout length is longer than eye diameter, but in A. gnanadossi, the snout length is almost equal to the eye diameter (11.7-13.7% vs. 18.8-23.6 ...
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Ariosoma bengalense sp. nov. is described on the basis of two specimens having total length (TL) 216–304 mm, collected from the northern part of the Bay of Bengal, India. The new species is characterized by the dorsal-fin origin positioned above the gill-opening margin and above the 9th lateral-line pores, supratemporal pore absent, 9–10 predorsal vertebrae; 46–49 preanal vertebrae and 146–149 total vertebrae. The new species most closely resembles the Indian species Ariosoma gnanadossi, the new species differs from A. gnanadossi having the snout length (SL) longer than eye diameter (snout length 1.4–2.0 in eye diameter) vs. snout length almost equal to the eye diameter in A. gnanadossi. Further, the new species has translucent pectoral fins vs. black pectoral fins in Ariosoma gnanadossi. The new species differs from four of the seven species reported from India: Ariosoma majus, A. melanospilos, A. maurostigma and A. indicum with absence of supratemporal pores vs. three in all the species mentioned.
... At present, 34 species of the genus Ariosoma have been described (Fricke et al., 2021 and this study), at least 74% (26 species) of all species in this genus were described or identified from the Indo-West Pacific, while seven species were distributed along the Atlantic Ocean and two from the Eastern Pacific Ocean (Fricke et al., 2021;Karmovskaya, 1991Karmovskaya, , 2004Karmovskaya, , 2015Karmovskaya, , 2018Kodeeswaran et al., 2021;Roy et al., 2021;Shen, 1998;Smith et al., 2018;Smith & Kanazawa, 1977) and doubtlessly there are many undescribed species that remain to be discovered. ...
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A new congrid eel species, Ariosoma maurostigma sp. nov., is described on the basis of 24 specimens collected from the deep‐sea trawl by‐catch, Kalamukku Fishing Harbour, off Kerala, Arabian Sea. The new species differs from all other congeners in having the following combination of characters: dark mark or spot on the posterodorsal margin of the eyes; dorsal surface of head with two faint darkish bands across the anterior and posterior margin of the eye; origin of the dorsal fin before the pectoral‐fin base; short vomerine teeth patch, ST pores 3, 1 median pore and 1 lateral pore on each side just behind the median pore; preanal vertebrae 47–51; precaudal vertebrae 54–57; total vertebrae 136–142; total pores 129–134. The phylogenetic analysis reveals that the new species is closely related to Ariosoma melanospilos and Ariosoma anale, with divergences of 13.8% and 14.9%, respectively.
... Twenty-two species are found in the Indo-West Pacific Ocean, whereas seven species are found in the Atlantic Ocean and two in the Eastern Pacific Ocean. In the northwestern Pacific Ocean, the following ten species were found: Ariosoma anago (Temminck & Schlegel, 1846), A. dolichopterum Karmovskaya, 2015, A. fasciatum (Günther, 1872), A. majus (Asano, 1958), A. meeki (Jordan & Snyder, 1900), A. megalops Fowler, 1938, A. sazonovi Karmovskaya, 2004 (Strömman, 1896), A. shiroanago (Asano, 1958), and a new species described here. Dorsal-fin origin behind or just above insertion of pectoral Diagnosis. ...
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A review of the congrid eel genus Ariosoma in Taiwan is provided. Eight species are recognized, including A. anago (Temminck & Schlegel, 1846), A. dolichopterum Karmovskaya, 2015, A. fasciatum (Günther, 1872), A. majus (Asano, 1958), A. megalops Fowler, 1938, A. meeki (Jordan & Snyder, 1900), A. shiroanago (Asano, 1958) and a new species which is described based on types and non-types collected from off southwestern Taiwan. These species can be distinguished from each other by the coloration, numbers of head pores, lateral-line pores and vertebrae. A key to all Taiwanese Ariosoma species is provided.
Article
Ariosoma albimaculata sp. nov. is described herein based on ten specimens [240–487 mm total length (TL)] collected from the deep-sea trawl landings at Colachel fishing harbour, off Kanyakumari, Arabian Sea, west coast of India. The new species is easily distinguished from all other congeners reported earlier, except its sympatric species, Ariosoma maurostigma Kodeeswaran, Mohapatra, Dhinakaran, Kumar and Lal 2022, having dark mark or streak present in the posterior-dorsal margin of eye orbit, but it readily differs from A. maurostigma with the presence of more total vertebrae (161–164 vs. 136–142 in A. maurostigma); more preanal vertebrae (66–68 vs. 47–51); occurrence of white spot or dot on just before the dorsal-fin origin (vs. absent in A. maurostigma); larger preanal length (49.7–55.7% TL vs. 44.0–48.8% TL); larger trunk length (30.4–33.3% TL vs. 23.5–30.2% TL); shorter tail length (44.6–48.2% TL vs. 47.8–54.6% TL). Further, A. albimaculata differs from its sister taxon A. maurostigma with a divergence of 8.1% and other congeners with the genetic distance of 15.0–28.8% in partial mitochondrial COI gene.
Article
Ariosoma indicum sp. nov. is described herein based on 12 specimens [(335–433 mm total length (TL)] collected off the Arabian Sea of southwest coast of India and 7 specimens from Digha Mohana, off the Bay of Bengal of northeast coast of India. The new species is distinguished from congeners in having the following combination of the characters: anus positioned anterior to middle of total length, pre‐anal length 40.0%–43.1% of TL; short wedge‐shaped pointed vomerine teeth patch, three or four rows in anterior portion, tapering posteriorly with four uniserial teeth; supraorbital canal with four or five pores; pre‐dorsal vertebrae 9–10; pre‐anal vertebrae 49–53; total vertebrae 141–146; body greenish‐brown in colour; extremities of the lower jaw with minute dark pigmentation patches before the rictus, bicoloured pectoral fin. A. indicum shares few characters with the Indian water species, Ariosoma gnanadossi, but readily differs from the latter in having more pre‐anal vertebrae (49–53 vs. 47 in A. gnanadossi); fewer lateral‐line pores (130–137 vs. 145); shorter tail (54.9%–57.9% TL vs. 60.1% TL); smaller eye (15.1%–17.7% HL vs. 19.2% HL); smaller interorbital width (11.8%–15.7% HL vs. 18.2% HL); longer upper jaw (26.9%–30.2% HL vs. 19.2% HL). In addition, molecular analysis using partial mitochondrial COI gene suggests that A. indicum is genetically closer to Ariosoma maurostigma and Ariosoma melanospilos with a divergence of 15.0% and 15.8%, respectively, and forms a well‐supported monophyletic clade.
Article
A new conger eel species is described based on four specimens collected from Petuaghat fishing harbor, West Bengal, India. The combination of morphological characters and molecular data are discordant with the seven congeners currently recognized. Rhynchoconger smithi sp. nov. can be distinguished by having head smaller than trunk; preanal length more than three times in total length; a small eye, diameter 2.0–2.2 in snout length; rictus ending at a vertical through posterior margin of pupil; ethmovomerine teeth patch small, with 58–74 blunt teeth arranged in 7–8 irregular rows; vomerine teeth patch small, with 18–28 granular teeth arranged in 4–6 irregular rows, distinctly separated by narrow spaces from the ethmovomerine and maxillary teeth; 3 supraorbital pores and 1 supra‐temporal pore; and 159+–164 total vertebrae. Moreover, Rhynchoconger smithi differs significantly from four congeners, R. nitens, R. flavus, R. ectenurus and R. gracilior, with K2P distances 14.6–20.3%. This article is protected by copyright. All rights reserved.
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The eel fauna (orders Anguilliformes and Saccopharyngiformes) of Taiwan is increased to 14 families, 79 genera and 232 species. Previous studies (Ho et al., 2015b, c) showed Taiwan had the highest diversity of eels in the world: this is further supported in the present updated work. Elsewhere in this volume, 16 species are newly described and 13 species are newly added to the Taiwanese ichthyofauna, mainly in the families Congridae and Synaphobranchidae. In addition, one new genus and four new species are described from adjacent waters in the Pacific Ocean. A total of 58 new species of the two eel orders are described from Taiwan; 52 of them are valid, and 37 are only found in Taiwan. Four names previously recorded in Taiwan are described as new in present special issue and are removed from the fauna of Taiwan accordingly. This work provides a foundation for the study of eel diversity in Taiwan.
Article
Diagnosis, description, and figures are presented for the 4 Formosan species of Ariosoma which include A. anago (Temminck and Schlegel, 1842), A. anagoides (Bleeker, 1864), A. shiroanago major (Asano, 1958) and a new species A. nancyae. Ariosoma nancyae is distinctive in its combination of a stout body; 157 total vertebrae; 53 preanal lateral-line pores, and 95 pores behind anus to tail; upper end of gill opening at level of 1/4 upper end of pectoral-fin base; black spots on head, and black bands on body, tail, and fins.
Article
Ariosoma type larvae with no outer-intestine of the eel family Congridae from the western North and Middle Pacific are described and figured. Five types are recorded based on total number of myomeres, position of the last vertical blood vessel in the serial number of myomere and geographical distribution. The types and their relationship with the adult are discussed. None have been certainly identified with the adult. A key is provided to the non-exterilium Ariosoma type larvae from the western North and Middle Pacific. Distribution maps showing capture locations are given for each type.
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