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FAUNA OF ARABIA 20 193-209 Date of publication:
05.09.2004
Anostraca
(Crustacea:
Branchiopoda) from Socotra
Island:
A new Branchipodopsis
and
its relationship
with its African and Aian congeners
Kay Van Damme, Henri J. Dumont and Peter H.H. 'Weekers
Abstract:'fhe freshwater
Anostraca
oÍ:Socotra Island
(Yemen)
have been investigated. In addition to the occurrence of
Streptocephalus
sp., Branchipodopsis
relictus n. sp. is described and illustrated. Morphologically, it is reiated to the Asian
Branchipodopsis
ffinis Sars,
1901 and the African Branchipodopsis
wolf Daday, 1910, but analysis of the SSU rDNA (185, 5.8S,
ITS 1, ITS 2) reveals
substantial
differences in the internal transcribed
spacer
regions
of these species.
(Branchiopoda
J*-,Xl crtÁ;l.l.i : Crustacea
c/tJ-J:.iJI)
é+1 Ólo1Jt
*-4t '," ,. i
\) \, l_/
.,o-L(;Jt
q-Ul
- .Lt, tr
6'cl- P)l t +Jt I
Y-U_-
18s,5.8S)
Authors' address:
Kay Van Damme, ProÍr.
Dr HenriJ. Dumont and l)r Peter
H.H. 'Weekers,
Ghent
Biology, Laboratory of Animal Ecology, K.L. Ledegancksrraar
35, 9000 Ghent,
Henri.
Dumont@UGent.be and Peter.Weekers@UGent.be
Universiry Faculry of Sciences,
Department of
Belgium; e-mai[:
Kav.VanI)amme@UGent.be,
q-x3*ïlS *-j)l 4it{1.:,r.
*iXo-f Branchipodopsis
Jr-J* Ly:e };- ólf Q
:-&.: -Ê,) ÉjJ{) éPS ir: i-rl'!
s;tí
)f ) Jl ajtr)! 'a;pi". i ;--r * ri'Jr ofll J *4' ;l )\ a\yi a-*tr,
6 :A.ê\.*
-t bS Js1 cBrunchipotlopsis
relic:tus
-tr--b (_y y,ó1 --w) ( tstreptocepholus
Branchipoclopsís
ctffinís
Sars, 1901 ,qs;*"-it a/l ) -L-rfl i_/1 .-4J
il4 -iU,o ii
SSU rDNA é)y.)\ qSl\ "z^Lt ji, ii U cBrcutchipoclopsis
wolfi Daday, l9l0
.z \y!r oiÁ altJt -Jl \Àbb ,: *.5 é; )f ) ,-r:.
(ITS I,ITS 2
INTRODUCTION
During an expedition
to the Socotra Archipelago
in February
and March 1999
within the frame-
work of the project "Conservation
and Sustainable
Use of Biodiversity
of Socotra Archipelàgo",
brackish and freshwater
habitats
were extensively
sampled
for the first time throughout the
archipelago in order to investigate
the microfauna.
Results on the Polychaeta and Copepoda
have
194 K. V.rr D,rrr,rrc., H.J. Durroxr & P.H.H.
\i/rrxrns
already been published (Frec;r
& V,qx DevvE 2002, MtnasouLLAyEV et al. 2002). In addition to
freshwater
samples,
dry mud was collected from ephemeral
pools to culture anomopod branchio-
pods with drought-resistant
eggs.
From a sample collected at Rewgid (Plate
1), " new species of
Branchipodopsis hatched. Thanks to the availability of specimen
s of Branchipodopsis
ffinis Sars,
1901, hatched from dry mud from Mongolia collected by H.J. Dumont,, and of Branchipodopsis
wolfr Daday, 1910, collected
in Botswana
by L. Brendonck, the ribosomal
DNA of these
three
species could be compared.
In a freshwater
sample
from a swamp
found (Fig.
3 b). No specimens could be
Streptocep halus Baird, 1852.
As well as adding to the biodiversity of the Socotra
Archipelago, where the group was
previously unknown, Anostraca have
an economic
value through their use as
fishfood in aqua-
culture in other parts
of the world (Duivoxr & MuNUS\íAMv
1997). More specifically,
the ability
of Branchipodopszi
species to mature more rapidly than other Anostraca
enables
them to be
cultured easily and used as
model organisms, as
has
been extensively the case
with B. wzlrt
(BnrxnoNCK
er al. 1998, 2000; Vrx Doonrx & BruxooNCK
1998).
MATERIALS AND METHODS
Experimental procedures
Freshwater
samples were taken
using a plankton net (150
pm-mesh)
and preserved
in 4o/o
formaldehyde.
Dry crusts
of mud were collected by hand, transported
in non-hermetically
sealed
plastic bags and wetted one month later in the laboratory
in plastic
one-litre aquaria.
This was
done by pouring distilled
water on to 30-50
g of dry material, after which the culture was
kept
under constant light at room temperature. No external oxygen was added. On the second
day of
hatching,
nauplii were isolated
from the original culture and reared in a separate aquarium, to
which algae
(Scenedesmus
sp.) were added; water was renewed
daily. Animals were preserved
in
B0
% ethanol.
A \íild M5 Stereoscope
was
used
for the investigation
and aLertz Vetzlar Orthoplan equipped
with a camera lucida for drawings. SEM pictures
were
prepared
using a JEOl-scanning electron
microscope.
Molecular analysis
For Branchipodopsis
re/ictu.r n. sp. and B. ffinis, total DNA was prepared
from complete newly
hatched nauplii using the protocol of the Puregener-N4 DNA isolation kit, type D-5000 A (BIOzym,
Landgraal The Netherlands). For B. wnlf and Branchipus species,
dorsal
muscular
tissue of adult
specimens
was isolated, followed by the same protocol. Frozen
genomic
DNA of each of these taxa
is stored
at the Universiry of Ghent, Belgium, Department
of Animal Ecology.
The complete region
of the ribosomal
spacers
(lTS 1 and ITS 2) and the nuclear ribosomal
1BS,
5.85 and a part of the 28S
DNA genes
were amplified using PCR (Polymerase
Chain
Reaction)
with Qiagen
DNA polymerase
('Westburg,
Leusden, The Netherlands). Eukaryote-
specific
external
primers
complementary
to the 5'-terminus
of the small subunit ribosomal
gene
(1BS
rDNA) (5'-TACCTGGTTGATCCTGCCAG-3') and the 5'-terminus
of the large subunit
at Diksam, the resting eggs of a second anostracan
were
hatched,,
but the q/sts
presumably
belong to the genus
Nerv Bzzzcltipodopsis
(Crtrstacea:
Branchiopoda)
Plate 1: Karst linrestonc
at Rervgid,
Socotr:r
lsland,
tl'pe localiw of
Bra u ch ip o dops
ís re /i cttts
n. sp. Photo: K. Van
f)amnre.
ribosomal
gene
(2BS
rDNA) (5'-TGAICCTTCCGAGGTTCACCT-3') were used to amplify the
18S-ITS 1-5.8S-ITS
2-2BS
(partim).
PCR amplifications
were
done
using a total volume of i00 pl, containing
1.5 mM MgClr,,
0.5;rM each
primer and
0.2 mM dNTP mixture; a 10 t Taq polymerase
reaction
buffer and
2.5 unns of Taq DNA polymerase
(Qiagen)
were added to each reaction. The samples were
covered
with two drops of mineral oil, and PCR reactions
were performed in a Progene Thermal
Cycler
(NBS-Techne).
Cycling
conditions were
95 "C for I minute, 55 "C for 2 minutes,
and
72 "C for 3 minutes
during 30 cycies.
External
(see
above) and internal
primers
in conserved
regions
of the 18S rDNA; 570C, 570, 1262C and 1262 (\X/rgrcns
et al. 1994),
3'-RV (5'-
TGATCCATCTGCAGGTTYCACCT- 3'
), ITS
-F\7 (
5'
-TAGAG GAAGTAAAAGTCG_3' ), ANd
in conserved regions
of the 5.8S
rDNA; 5.8S
F\f (i'-TGGATCACTCGGCTCGT-3'), 5.8S
RV
(5'-CTGCCATGTGCGTTCGAAG-3') were used
for sequencing. PCR products were used
for
direct
sequencing
according
to the BigDyer\{ technology, the protocol of the ABI Prism BigDye
Terminator Cycle Sequencing
Ready
Reaction Kit, and subsequently analysed
on an ABI Pris m 377
DNA sequencer
(PE
Applied Biosystems).
Sequences
were
aligned
automatically
using CLUSTAL \f (Tnovnsor et al. 1994) and the
alignments
were visually
optimised
using the Eyeball
Sequence
Editor program
(Caectr'
& Btc.KF,N-
IIACH
1989). Two different
datasets were used
for phylogenetic analysis: one containing
oniy the
1BS, ITS 1,
5.85,
ITS 2 and partial 2BS
sequence
data, the second
containing only the
ITS 1,
5.BS
and ITS 2 sequence
data. Phylogenetic
reconstructions
were
performed using the neighbour-
joining
method
and
Jrx & Nr.r's
(1990)
correcrion method
of TREECON 1.3
b (Vax pr.
PnEn
&
Dr. \7ncH'l't-.R 1994); bootstrap
values
were calculated
with the same program (Frr-scxs.r'r-rx
1989)
to assess
the stability
of each
branching
point.
For B. re /ictus n. sp.
, B. wo/fi from Botswana
(collected
by Luc Brendonck)
, B. ffinis from
Mongolia (collected
by H.J.D.), and Branchipus
schaffiri Fischer, 1834, from Algeria
and Italy
and
B. uisnyai
Kertesz, 1.956,
their sister-group
within Branchipodidae
(\(/nnr<nns
et al. 2002),
complete
unambiguous
sequences
of the ribosomal
1BS,
5.BS
rDNA, internal
transcribed spacers and partial
195
t96 K. VaN Dar,tr,tr.
H.T. Dur,roNr
& P.H.H.'W'EErcEns
sequences of the 2BS
rDNA genes
were obtained.
as outgroup to the Branchipodidae.
Frozen DNA
of Ghent, Belgium.
Abbreviations:
bp Base
pair(s)
EMBL European
Molecular Biology Laboratory
GU Collection at Ghent Universiry Laborato
ry of Animal Ecology,
Belgium
ITS Internal transcribed spacer
KBIN Koninklijk Belgisch
Instituut voor Natuurwetenschappen,
Brussels,
Belgium
NHCY Natural History Collection Yemen
SPECIES
ACCOUNT
Family Branchipodidae Baird, lB52
Genus
Branchipodopsis Sars,
1898
So far as
is known, the genus
Branchipodopsis
includes 22 species.
The highest number is found in
Africa, with 15 species
restricted
to the south (Havln & Appl-EroN
I 996).
The three other African
species are
B. abiadi (Brauer, 1877) from Sudan, the B. wolfi-species group reported from south-
ern, eastern and central
Africa, and B. candea
Lóffler, 1968, reported from central
Africa (Bnnxnm
1929.,
Her,rEn & ApplrroN 1
996, Bnlrc & Bnrnr 1995).
Asian species
are represented by one un-
named species
from Oman (Trurnv 1996), B. ffinis from central
Asia, B. acanthzpenes
(Malhotra
& Duda, 1970) from India and B. terpossogiazi
Smirnov, 1936 from Armenia. The last rwo are
thought to be synonyms of B. ffinis (Boxo 1934, BnrEr et al. l9B4).
Compared with other anostracans,
species of this genus
are known to hatch and mature very
rapidly,
which enables them to colonise short-lived pools in desert
regions
or at high altitudes.
These
aspects of the animals'
ecology
have
been
extensively
studied
(Bru,xooNCK
et al. 1998,
2000;
Vex Dooru,x & BnsxooNCK
1998).
Branchipodopsis relictus n. sp. Figs
1-5, Plate I
Holotype: I d, Yemen,
Socotra
Island, hatched
from dried
mud collected
in limestone rockholes at Rewgid,
12"34.926'N
53"58.04I'E,685
m,03.III.1999, K. Van Damme, KBIN
IG30.018.
- Paratypes: Yemen, Socotra Islan d: 7 ó ó,
5 99, samedataasholotype, KBINIG30.018
(including2
ó6 and3cystsonSEM
stub);
5 aa,5 ?
?, l0nauplii, samedata
as holotype, NHCY.
- Non-type specimens: Yemen, Socotra Island:5 nauplii, CU.
Diagnosis: The combination
of the following features
is unique to male B. relictu.t
n. sp.:
bilobed basal
process
(Figs
1 c-d, 2 c) on clypeus
consisting
of an outer lobe devoid of a tubercle,
an inner lobe with a subapical
projection not reaching its apex, and a sharp median tubercle
leaning
towards inner lobe; slender
'foot-shaped'
apex of terminal joint (Fig. I a); relatively
short,
blunt projections
on ultimate abdominal segment
(Fig.
2 d); apical part of penis
with B-9
hook-
like lateral
spines
(Figs
t f,2 g).
Tiznymastigites perrieri (Daday, 1910) was used
of each
of these
taxa
is stored
at the University
Fig. l: SEM micrographs of male Branchipodopsis relictus
n. sp.; a: clypeus of subadult, dorsal
view; c: right basal process of subadult, dorsal view; d: right basal
process
of adult, dorsal view;
of adult, ventral view; g: detail of apex of right penis;
h: denticulated inner projections on basal
view; b: clypeus of adult, dorsal
e: medioventral process;
fi penes
part of penes,
ventral view.
New Branchipodopsis
(Crustacea:
Branchiopoda) r97
:1r l
r98 K.
V,rs
D,+nrr,
H.J. Durrorr E<
P.H.H. \írrrrns
Description of male:Total
body
length on average
9.1
mm (n
= 10).Clypeus
(Figs
1 a-b,
2 a-b) as
for genus,
but with strongly
developed
basal
joint. Basal
process
(Figs
I c-d, 2 c) bilobed,
in size
not longer
than width of basal
joint; consisting
of a median tubercle,, an outer lobe and a
projection-bearing
inner lobe,
each of different
shape.
Median tubercle acutely
conical, about the
same size as the inner lobe,
directed
more dorsally than anteriorly,
Ieaning towards
and lying in the
same
plane
as the inner lobe.
Outer lobe without lateral tubercle,
longer
than
wide, with wide apex
and directed
lateroventrally.
Inner lobe about as
long as broad at its maximum width, oriented in
the opposite direction from outer lobe (the latter directed
more ventrally),
with a small
medio-
dorsal projection implanted about halfway, not reaching beyond apex.
Terminal joint (Figs
I a-b,
2 a-b) curved medioventrally
and back anteriorly towards
the apex, depending
on the age of the
animal.
Apex slender,,
'foot-shaped'.
Median ventral process
(Fig. I e) more round than oval,
bearing short spinules on its surface.
Lamelliform process
(Fig.
I a-b) rounded, about as
long as
wide, bearing hair-like setules on surface.
Cercopods
(Fig.
2 d-0 with 28-30 plumose
setae along outer margin, followed by four naked
spines. Apex with rwo, sometimes three spines.
Inner margins of cercopods bearing
11-12
plumose
setae each, on less
than half but more than a third of the entire length, followed by 12 spines and
spine-like setae
(Fig.2 e). Short spinose
outgrowths
present
on last
abdominal segment,
in length
a quarter
or less
of basal width of cercopods.
Number of spines
and spine-like setae
on the
cercopods
increasing
with age,
fewer in subadult (Fig.2 f) than in fully-grown males.
Penes
(Figs
I Êh, 2 g) in basal part with anteriorly spinulated
rounded
protuberance
situated
on less
than a third of inner margin (Fig.
t h). Another, relatively smaller distinct process
found
apically on outer
margin of basal part. Distal part as
long as basal
part, bearing
B-9 conical
hook-
like lateral spines.
Description of female: Total body
length
on
averageS.T
mm (n
= 10). Egg
sac brightly
coloured,
iridescent
blue-orange
in live animals,
not reaching
midpoint of third abdominal
segment. Elongated button-like outgrowth present on ventral surface
near
gonopore
(Fig.
2 h).
Resting eggs
(Fig.
3 ^) as
for the genus
(Hr"vEn & AppLEroN 1996, BRExoctxcK
& Rtooocu
1999),
with irregular
polygonal ornamentation,
ridges relatively unpronounced.
Affiniti es: Branchipodopsis relictu.r
n. sp. can be distinguished
from the following three
morphologically
close relatives
(see
also
Thble
3):
In B. ffinis,, the projection on the inner lobe mostly reaches beyond the apex,
the median
tubercle
leans
towards the outer lobe (instead
of towards
the inner lobe as
rn B. relictus
n. sp.) and
the apical part of the penis
bears more lateral spines.
For the variabiliry of clypei in B. ffinis, see
BnlErc
et al. (1984). Other reference
drawings
can be found in Sans
(1901), Boxo (1934) and
BnnxnoxcK (1
995).
Members
of the B. woffi-group share finger-shaped terminal joints with widened apex,
a basal
process with blunt median tubercle and extra tubercle on the outer lobe. Originally thought to be
highly variable in morphology (B,tnx,tno
1929), B. tuolfi
is probably a group of closely
related
species
(Hrvln 1999, Hevln & Applp'r'oN 1996).
Branchipodopsis
hutchinsoni
Hamer & Appleton, 1996 has a bilobed basal process
similar to
that of B. relictu.r
n. sp., with a median tubercle
leaning towards
a projection-bearing
inner lobe,
but the latter can easily be distinguished by the strongly curved cercopods, the scalloped
lamelliform
process
and the rod-shaped broad apex of the terminal antennal
joint (Ha"vnn
& Appr-r,roN 1
996).
In females, the button-like outgrowth on the ventral
surface of the brood pouch (Fig.
2 h) is a
striking character,
which is also
found rn B. kalaharensis
Daday, 1910.
It should be emphasised that male anostracans are more diagnostic
than females,
and females
of different species cannot always
be compared because
they are
not mentioned in most descriptions.
New Branchipodopsís
(Crustacea:
Branchiopoda) 199
Projection
VInner
lobe
<- Outer lobe
I Median
tubercle
Y
I\10-!Í" '100
pm
----
l- I ---.-- -,,, -""''-1
t\
Fig. 2: Branchipodopsis
re/ictus
n. sp.; a: head of adult male, lateral vier,vl
b: clvpeus of adult male, dorsal vierv; c: rigl-rt
basal
process
of adult male, dorsal view; d: ce
rcopods
of adult male, f-ine
setulation
omittedl e: detail of inncr rrargin of cercopocl,
showing fine setulation; fi ce
rcopods of subadult male, detail; g: penes of adult nr:rle,
dorsal
vierv; h: ferr-rale
egg sac, lareral vie
rv.
K. V,.,x
D.q"\{\lr,
H.J. Dur'roxr & P.H.H.
'JílEt<lRs
Fig. 3: SEM micrographs of resting eggs;
a: Branchipodopsis
relious n. sp.; b: Streptocephalus
sp.
Further commenrs
on the morphological
affinities
and phylogenetic
position of the new
species can
be found under
Discussion.
Biology: Under the rearing conditions
described,
nauplii of B. relictu.t
n. sp. appeared
l0-I2 hours after inoculation;
in comparison,
B. ffinis cysts
reared
in the laboratory under the
same conditions hatched after periods from 24 hours onwards.
Females of B. relictus
n. sp. were
able
to produce cysts
from the seventh day onwards.
The maximum age
reached by a female was
14 days,
and by males
15
days.
From the original culture,
nauplii still hatched after
wetting the
mud for a fourth time and cysts
were still viable three years
after collection. In some reared
specimens,
asymmetry
was observed
(Fig.
2 b).
Habitat: Branchipodopsis
relictus
n.sp. was
found on Socotra
Island,
where
it inhabits
shallow temporary
rock pools
of the karst limestone
region
in Rewgid (600-700
m altitude),
at
the north-wesrern base
of the granite
Hagghier
Mountains. The grey,
eroded
karst limestone
rocks
at Rewgid can be dated
back to the Palaeo-Eocene, using the description
of limestone
facies in
Blyooux & Brcn,rx (1970).
As the rock pools
were dry at the time of sampling,
no additional
data on the habitar can be provided. However, a subterraneous
rock pool from the same
localiry
had a pH of 7.2 and a conductiviry of 200 ;rS
cm-r.
These
parameters
are similar to those of the
habitat described
for B. wnlf in granite rock pools in Botswana
(BnENDONCK
& RrooocH 1997),
but with a higher conductiviry (maximum of 89.5 pS cm-r for *zffi).
Molecular data: EMBL accession
numbers:
Branchipodopsis
ffinis: AJ42IB26;
B. relictus
n.
sp.:
AJ307675; B. wolfi:
AJ238067,
AJ307676;
Branchipus
schaffiri
from ltaly:
AJ42IB27;
B.
schaffiri
from Algeria: AJ238068,
AJ307677;
B. uisnyai:
AJ307678
and
T perrieri:
,\J238066,
AJ3o7
679
.
The sizes
of the 1BS,
5.8S
and
2BS
(partim)
genes
and GC-contents
are
listed inThbles
I and2.
Apart from four base-pair differences
in the 5.8S
gene
(1,75
bp long, with a GC-content of 56.0
o/o),
no differences
were
found berween the rDNA gene
sequences
of the three
Branchipodopsis species.
Table 1: Comparison of
with Branc h ipus schaeferi
New Branchipodopsis
(Crustacea: Branchiopoda)
the structural differences
and length variation of Branchipodopsis
and Branchipus
uisnyai.
The asterisk indicates
the partial 2BS gene
201
wolf, B. relictus n. sp. and B. ffinis
(5'-end).
lBS
gene ITS 1 5.BS
gene ITS 2 28S
gene*
B ra
n ch ip odop
s is wo lfi (Botswana)
Branchipodopsis
re/ictus
n. sp. (Socotra)
B
ran chip
odops is ffinis (Mongolia)
Differences between Branch
ip odopszj
taxa
Size
differences
Structural differences
B ran
c h ip
us s c h affi ri (Algeria)
B
ran c h ip
us s c h aefferi (ltaiy)
B ranch
ípus u isnyai (ltaly)
Differences between Branchipus taxa
Size differences
Structural differences
1806
bp
1806
bp
I 806
bp
0
0
1806
bp
1806
bp
I
806 bp
405
bp
265
bp
261
bp
144
198
437
6p
437 6p
z+1,/ hn
l,/-'! frn
175 6p
l/) hn
0
4
1746p
| /4 hn
t74
6p
l9R hn
"'" "Y
4226p
405
bp
/,+
80
463 6p
LÁ7 l-n
,vJ vY
463
6p
67
bp
65
bp
65 bp
0
4
26
bp
26 6p
266p
Table 2: Difference in
(lTS) of B. wolf from size
[bpJ,
base-pair
composition
Botswana, B. relictus n. sp. from and CC-content of the ribosomal genes
and internal transcribed spacers
Socotra Island and B. offi"it from Mongolia.
C
[base
pairs] lVol
G
fbase
pairs] lo/o)
Branchipodopsis
lBS
ITS 1
5.
BS
ITS
2
2BS
Branchipodopsis relictus n. sp.
450 24.9
56 22.r
46 23.6
90 22.3
16 23.8
w0n
450
B1
46
92
lo
449
57
24.9
20.0
/11
23.8
)4q
2r.8
26.3
24.2
./.o.L
417
108
48
t2r
1B
417
77
1Á)
l1L
18
417
6B
46
122
16
./1 |
/.o.
/
27.4
30.4
26.9
z). I
29.1
25.6
33.6
26.9
26.1
26.3
30.1
24.6
496
r.).)
50
r14
17
496
B2
5r
r29
17
496
79
50
r14
17
)7\
32.8
28.6
28.6
)7<
30.9
29.1
30.6
75 5
)a<
30.3
28.5
28.1
26.2
443
B3
1l
7r
r6
443
t0
JI
61
I6
444
57
33
71
r)
24.5
20.5
17.7
17.9
23.8
)4\
18.9
17.7
Á.5
23.8
24.5
21.8
18.9
17.6
23.0
50.6
59.5
56.0
59.0
<))
50.6
60.0
56.0
64.2
\))
50.6
56.4
54.8
58.2
50.8
1BS
ITS 1
5.85
ITS
2
2BS
Branchipodopsis
affnis
]BS
ITS
1
5.85
ITS
2
2BS
46
98
17
202
Branchipodopsis wolfi
B ra nch i
pod op si s aff
i n i s
B ra
nch i
pod op si s rel ictu s
Branchipodopsis wolfi
B
ra nc h i
pod op
si s aff
i n i
s
B ra nch i
podop s
i s re I ictu s
Branchipodopsis wolfi
B ra n
c
h i
pod op s
i
s aff
i n i
s
B ra nch i
pod op s
i
s re I i ctu s
Branchipodopsis wolfi
B ra
nch i
podop s
i s aff
i n is
B ra nch i
pod op s
t
s re I t
ctu s
Branchipodopsis wolfi
B ra nch i
pod o
ps
i
s aff i n is
B
ra nch i
pod opsi
s rel
i
ctu s
Branchipodopsis wolfi
B ra nch i
pod o
psi
s aff
i n i s
B ra nch i
pod op si s rel ictu s
Branchipodopsis wolfi
B
ra nc h i
pod op si
s aff
i n i
s
B ra n
ch i
pod op si s rel i
ctu s
Branchipodopsis wolfi
B ra
nch i
pod op si
s aff
i n i
s
B ra nch i
pod op si s rel ictu s
Branchipodopsis wolfi
B ra nch i
pod op si s aff
i n i s
B ra nch i
podop s
i
s re I ictu s
Branchipodopsis wolfi
B ra n
ch
i
pod op si s aff
i n i
s
B ranch i
podop s i s re I ictu
s
Branchipodopsis wolfi
B ra nch i
podop s
i
s aff i n is
B ra nch i
podop s i s re I i
ct u s
Branchipodopsis wolfi
B ra
nch i
pod op s
i
s aff i n
is
B
ran ch i
podop s
i
s re I ictu s
Branchipodopsrs wolfi
B
ra nch i
podop s
i s aff i n
is
B ra nch i
podop s i s re
I
i ctu s
Branchipodopsis wolfi
B ra nch i
pod op s
i
s aff i n is
B ra nch i
podop s
i
s re I ictu s
Branchipodopsis wolfi
B ra nch i
pod op si s aff
i n i
s
B ra nch i
podop s
i s re
I ictu s
Branchipodopsis wolfi
B ra nch i
pod opsi s aff i n is
B
ra nch i
pod op si s rel ictu s
Branchipodopsis wolfi
B ra nch i
pod opsi
s aff
i n i
s
B ra nch i
pod op si s rel i
ctu s
Branchipodopsis wolfi
B ra nch ipod ops i s aff i n
is
B ra nch ipod op st s r
el
i
ctu s
=====18S]
GATCATTA]
GATCATTÀ]
GATCATTA]
********]
K. Vrr D.*ntr.
H.J. Dtrro\I & P.H.H.'iít,t,xr.ns
LJ.I5--L=======---
tAccAcTTGcTcTccc - cTÀeTTGCGGGGTATAAAGCÀAT CGAAAGTÀCCCGGAC
I
ACGÀcTTGCTCTCGC - CTÀcTT ccGGGGTAAAÀÀGCÀÀTCGAÀÀGTACCCGGÀC
t
AccAGT TccT cTcccÀcTAGTT GCGGGGT
GAAAGGCAÀTCGACÀGTACCCGGAC
r*************** ************* ** ******** ***********
GCCGGÀCGAGGGCCTCTG - - GCCAT CGACCGT GTCGT CGGGGGÀÀÀCAAAAÀGT GGCAGG
CGCGGÀCGAGGGCCTCCGCGGCTAT CGACCGT GTC GTCGGGGGÀAÀCAÀAÀÀ-
C G T G G T C G A G G G G C C T T G C G G C C A T C G À C C G C G T C G T C G G G G G A À À A C A A À À - - -
** ****** * * ** ******** ************** ****
CGCCGACTCTGGACGCGAGACCGAGCTT GGGÀTGCGÀCC GAAGGGCGCGCT TGT CÀCATG
GT GGCÀTGCGCCGACT
TTGGACGCGAGACCTAGCT
TGGGATGCGACCGAAGGGCGCGCCT
GCCCACAAGTGGCAAGCGCCGACTT TGGÀT GCGÀGACCTATCTT GGGAC GCG- TCCGAAG
- - -ÀGTGGCAÀGCGCCGACITTGG GÀG-CÀ- - GCGÀTGCG-ÀCCAAAC
- - - À G T G A C A A G C G C C G A C À C C G G - - - T C À G - C A - - G C G A T G C G G A C C G À A C
**** *********** **
GGCGCGCTT
GCCCACCGCGGGCGCAAGCCCAT
CTGTT
GT
TGT ÍGTTTTGÀAAACAAACGT
GACGCGCTTGT
CCÀCCGCGGGCGCAÀGCCCATCTGTT
GT
TGTTGTTTTGGAAÀCÀAACGT
GCCGCGCTT
GCCCACCGCGGGCGCAÀGCCCÀT
CTGTT
GTTGTTGTT TTGGAAACAAACGT
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
======== =======================================f TS
- 1] t
5 . 8 S
G T G C T T T T - G C A C T A À A C C G T T G C T À G T G G A A T T À T C T T T G A G G G C C T T T T G G C T C ] I G A C G
G T G C T T T T - G C À C C A A A C C G T T G C T A G T G G A C T T A T C T T T G A G G G C C T T T T G G C T C ] [ G A C G
G T G C T C T À C G C A C C À À A C C G T C G C T À G T G G À A T T À T C Í C T T A G G G C G C T T G C G C T C ] [ G A C G
***** * **** ******* ********* ****** * ***** ** ****] [****
ÀGACÀÀCGAAAGÀAÀC GACC CT GGGGGAT GGAT CÀCT C GGCT CGTAT TAC GÀAGÀC GAAC
ÀGACAÀTTAAAGÀÀACGACCCTGGGGGATGGATCACT CGGCTCGTATTACGAAGÀCGAÀC
AGÀCAACGAAAGAAACGACCCTGGGGGATGGÀTCACTCGGCT CGTATTACGÀÀGACGAAC
* * * * * * * * * * * * * * * * * * * * * * * * * * ** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
GCAGCTAGACGCGTGATT
CCATGCGAÀCTGCAGGACACATGGÀÀCGTCTACCCT TCTAAC
GCAGCTAGACGCGTGATTCCÀTGCGAACTGCAGGÀCACATGGAACGTCTAT CCT
TCGAAC
GCÀGCTAGACGCGTGATTCCATGCGAACTGCAGGACACATGGÀACGTCTATCCT TCGAÀC
* * * * *
* * * * * * * *
* * * * * *
* * * * * *
* * * **
* * * *
* * * * *
* * * * *
* * * * * * * * * * * * * *
======== ===================================$.8S] tITS-f====
G C A C A T G G C A G T C C A G C C T C T G G C T T G G A C T A C A C C T G G C T G A G G G T C G G T ] [ T A À À C C A À T
G C À C A T G G C À G T C C A G C C T C T G G C T T G G A C T A C A C C T G G C T G À G G G T C G G T ] [ T A A À C C A A T
G C A C À T G G C A G T C C À G C C T C T G G C T T G G À C T A C À C C T G G C T G À G G G T C G G T ] [ T À À A C C A A T
* * * * * * * * * * * * * * * * * * ** * * * * * * * * ** * * * * * * * * * * * * * * * * * * * * * ] [ * * * * * * * * *
CCATACCGAC
- - - - - GTCGTGTGA- -
ACGGCGCCT
- - - C GGTCACT
GGGAGGAT
CTCGAA
CCÀTACCGÀC
- - - - - GTCGT
GCGA- -ÀCGGCGTCT - - - CGGT
TAAT GGGAGGÀT
CT
CGÀA
C CATGCCGAAAGGGTGTCGCGTGACÀÀCGGCACCCTCÀCGGCCÀCTGGGAGGATCT CGGA
**** **** *** * ************* *
CGCGÀT
CGGÀAÀCGA- TTGT CGCTT
CGACGACCTCTTTAAAT GCÀCGGCAGCGACGÀT
CA
CGCÀAT
CGGÀAACGACTTGT
CGATT
CGACGACCTCCTCAAÀT GCÀCGGCAGCGÀCGAT
CA
CGCGGTCGGAAACGÀ- CCGT
CGCTCCGACGACCTCCTCAAAT GCACGGCAGCGACGATCA
*** ********** **** * ********** * **********************
- GACTCCGCGCCT
GCGGAAACG-
TCAGGTT CG
-
ÀGÀAGT
TGGATCGCTCGGGAGTCCCGA
- GACTCCGTACCT
GÀGGAAACG- ÍT GGGTTCÀCAGÀÀGT
CGGATCGCTCGGGAGTCCCGA
CGACTCCGCGCCTGCGGAAACGCTCAGGCTCÀ-AGAAGT CGGAT
CGCTCGGGAGTCCCGA
******* **** ******* * ** ** ****** ********************
ÀCAGCGCAAGAGT
GCCCTCCGCGAGACCTCGGCAT
- - - - - T
- - - GCCGÀAT
GAT GT
CT CC
ÀCÀGCGCAAGAGT
GCCCTCCGCGAGACCTCGGCAT
- - - - - TTATGCCGÀATGGTGT CT CT
ACAGCGCÀAGAGTGCCCT
CCGCGAGACCT
CGGCCCCCCCGTGGGGCCGAATGGTGT
CTCT
ACGAAGGCC GCGAAGCTCTGCCCTCTGT GGAAÀGCGACGCAAGCGCAAGTÀTCGGT CCCA
ACGÀÀGGCGGCGÀAGCTCTGCCCTCCGT GGGAAGCGACGCAAGCGCAAGTTTCGGT CCCÀ
ACGÀAGGCGGCGAÀGCTCTGCCCTCCGT GGAAÀGCGACGCAAGCGCACGTCTCGGT CCCA
******** **************** **** **************** ** *********
AGCGGT
T
- T
CGACGÀCGAGAÀCT
TGAGCÀGTACCTAGGCACCAGTCGAGTCCA- AT
TGTT
AGCGÀT
TCT
CGACGACGAGGACATCÀGCAGTÀCCAÀGGCACCAGTCGAGTCCA- ÀT TGTT
ÀGCGAGTCÀCGÀCGACGAGGTCCTGÀGCAGTACCTAGGCACCAGTCGAGTCGÀGAT ÍGTT
**** * ********** * * ********* **************** * ******
======== =======================================ITS-2
C G A G C C C - G G T T C C C G T T C G A C G C T C - _ T C G C G A G C G T G G T G A A C A A C C G A À A C C C
CGÀGCCCCGGT
TGCCGTTCGACGCT
C
- - TCGCGÀGCGCGGTGAÀCÀÀCC
-AAÀÀCC
CGAGCCT
- GGT
TCCCGTTCGACGCT
CGT
TGCCGAGCGCGGTGAACGACC
GAAACCC
****** **** ************* * ****** ******* *** *** **
T TCÀCTGÀCCT CÀGCTCAGGTGAGGCGACCCGCTTGACTTAAGCÀTATTAGTCAGCGGAG
ÀTCACT GACCT CAGCT
CÀGGTGÀGGCGACCCGCTTGACT
TÀAGCATATTAGTCAGCGGÀG
rTCÀCT GACCT
CÀGCT CAGGTGAGGCGÀCCCGCTT
GÀCT
TAAGCATATTÀGTCAGCGGÀG
***********************************************************
[28S==-
fr.mr.rÍrrF'Ï|
tvrv-4r
ICTTAAT
r.rF.rF.FÍn
[** *
New Branchipodopsis
(Crustacea:
Branchiopoda)
0.1 substitutions
oer site
B ranchi
podopsis
aff i n is (
Mon
go
I ia)
B ranch i
podopsi
s wolf i (
Botswana) Branchipodopsis
Branchipodopsis relictus
(Socotra
lsland)
B ranch i
pus schaeffe
ri (Algeria)
B ranch i
pus schaeffe ri (ltaly)
Branchi
pus visnyai
(
ltaly)
Branchipus
Tanymastigites
perrei
ri (Morocco) Outgroup
Fig. 5: Distance tree using the neighbour-joining method to shorv the phylogenetic difference betr.veen Branchipodopsis wolf ,
lJ. re/icttts n. sp. and B. ffinis. Bmnchipus schdelJèrí:rnd B. uisn-yairvere used as ingroup relatives and 'l-an-ymttstigites
perrieri .ts
outgroup. Numbers at the nodes indicirte
the number of times a cluster appeared in rhe consensus tree after a sequential
bootstrap anal1'sis
of 100 runs in a distar-rce matrix using
the neighbour-joining
rnerhod.
The 18S rDNA genes
of B. relictus
n. sp., B. ffinzi and B. wolf are
identical: 1806
bp long,
with a GC-content of 50.6o/o.There
is, however,
a substantial difference
in length,
base-pair
composition
and GC-content in the internal transcribed
spacer
regions
berween the three taxa: the
sequence variation is 27.3 o/o
for the ITS 1-5.8S-ITS
2 region,
caused by 168
indels
and
276 variable
nucleotides
in BB regions
(Fig.
4).
Phylogenetic
analysis
resulted
in a tree inferred from evolutionary distances
in a distance
matrix method. The phylogenetic trees
for the rwo different datasets,
18S-ITS 1-5.8S-ITS 2-28S
region
(not shown)
and ITS 1-5.8S-ITS
2 region
(Fig.5) resulted in identical
tree topologies.
Etymology: The epithet'relictus'refers
to the hypothesis
that this
is
a relict
species,
which
is further argued
under Discussion.
Family Streptocephalidae
Daday, 1910
Genus Streptocephalus Baird, IB52
Streptocephalus
sp. Fig. 3
Specimens exarnine
d: Yemen, Socotra lsland: 3
cysts,
zooplankton
sample
from
L)iksam Plateau,
12'.12.436'N
53"57.240'F.,
i010 m, 23.11.1999,
K. Van
l)amme, KBIN IG30.018; 2 cysts, sirme dara,
NHCY.
Remarks: The presence
of isolated lips
on the outer surface
of these spherical cysts
(Fig.3
b)
is known from the 'second'
egg rype of Streptncephalus uitreus
(Brauer,
lB77), a species occurring
in Chad, Sudan,
Zimbabwe and other parts of East Africa, and in that of Streptocephalus toruicornis
(\Waga,
1842), found in North Africa, Arabia and Europe (BnnxDoNCK
& Coorrnus 1994).
The
cyst morphology in Yemen
populations of S. toruicornis has
been
discussed
by Dr \Tnlscul et al.
203
100
Fig. 4: Position of variable sites in the ITS 1 and ITS 2 and the 5.BS
gene of Branchipodopsis
wolf
(Socotra
Island)
and B. ffinis (Mongolia).
lbp line shows the 1BS
(partial),
ITS 1, 5.8S,
ITS 2 and
symbol separates individual regions in the nucleotide
sequence.
(Botsu'ana),
B. re/ictí$ n. sp.
2BS
(partial)
regions. The lI
204 K. V,rx D,+nrF.,
H.J. Durrroxr & P.H.H.
\íEr,rlus
Table 3: Morphological dil1èrences between B. ffinis, B. wolf species
group and B. relictus
n. sp.
B. u'olf species
group
(Africa) R noli.t,r, n <n
(Socotra) B.
afinis
(Asia)
ClvP.ut
Basal
process
Projection
on inner lobe
Lateral
tubercle on outer
lobe
Median tubercle
Shape of lamellifbrm process
(dorsal
view)
Shape of apex of terminal
joint (frontal
vierv)
Cercopods
Lerrgth
of processes
on last abdorninal segment
Pcnis
Numbe r of lateral
spines
(apic:rl
part)
If present,
reaching
a.pex
of inner lobe or
beyond
Prese nt
Blunt, leirning
towards
inner lobe
Ror"rnd to oval
Finger-shaped
More thirn one third of
cercopod r,vidth
10
Present, never reaching
bevond
apex of inner'
lobe
Absent
Pointed,
leaning
towards
inrrer lobe
More round than oval
Foot-shaped
Present, reaching
bcyonJ apcx ofinner
lobe
Absent
Pointed, leaning
towards outer lobe
More oval than round
Foot-shaped
Less than one third of One third or more
of
cercopod w'idth cercopod
rvidth
8 or less I4 or n'rore
(\991) and TutÉnv
(1996).
These
cysts seem similar to those
of .t toruicornzi, but have relatively
larger
isolated lips, placed closer together.
As only cysts were found, it is not possible to identify this anostracan conclusively,
nor to
establish whether it is currently living on the island, as the cysts could not be tested
for their
viability. It could well be that there
is a new
Streptocephalu.r
present on the island which remains to
be discovered.
The cysts were found in a small, shallow permanent
wetland in Diksam:,
an important
drinking place
for the local inhabitants
and their cattle.
DISCUSSION
Morphology
Of all the Branchipodopszi
species, the closest in morphology to B. relictus
n. sp. seems to be
B. ffinis. The main characters to distinguish
male B. relictu.r
n. sp.
from B. ffinis and members
of
the B. uzlf complex are given in Thble
3 and have
already been
mentioned under Diagnosis and
Affinities. Although the variation of each
of these characters
was not studied, it is clear that the
relative
orientation,
size and form of the elements on the basal process can be used to distinguish
closely
related
species.
In B. relictus n. sp., no noticeable variation was
found in the basal
processes,
except
for their age-dependency.
Regarding basal
process
morphology, it has
been suggested
(Dnoev 1910, HavER & Applprox
1996)
that a simple
bilobed basal process
represents
an ancestral condition, as
is the situation in
New Branchipodopsis
(Crustacea:
Branchiopoda) 205
the South African species B. kalaharensis. This species
and females
of B. relictu.r n. sp. also share a
morphologically
similar
brood pouch (Fig.
2h), illustrated
in BnTNDoNCK
(1995).
Simple basal
processes,
derived
from the B. kalaharensis-type
but with a projection on the
inner lobe
, are found in B. karroensis Barnard, 1929, B. dayae Hamer & Appleton, 1996 and
B, natalensis Barnard, 1
929, the latter also with a small
mediodorsal
tubercle.
The inner projection
and a larger mediodorsal
tubercle are found in B. hutchinsoni, B. ffinis and B. relictus n. sp.
Although the basal
process
of B. wzlf seems more complex, having a tubercle on the outer lobe,, it
belongs
to the B. ffinis-type. \Thether these
rypes
of basal
process
morphology can be regarded
as
primitive can only be decided after more extensive
phylogenetic
analysis.
The importance of the
basal
process
in anostracan
phylogeny
is currently unclear.
Males
of Branchipodopszi
species from Oman, illustrated
in TutÉny (1996),,
have a specific
clypeus with an elongated
basal
process, revealing no obvious
morphological
relationship
with the
specimens
from Socotra Island
or other species.
Ribosomal DNA
Phylogenetic
utiliry for identifying closely related
species
DNA sequence
data pl"y an essential role in the reconstruction
of evolutionary relationships
among organisms,
and have
led to new genetic
classifications
that may confirm or conflict with
traditional
taxonomy.
Ribosomal
DNA (rDNA) is popular for examining phylogeneric relation-
ships
and for studying
genetic
variability
and divergence
within and berween species, because it
possesses attractive
properties
such as secondary/
structure features,
differential
rates
of evolution
berween
different
regions
and tandemly repeated
genes
(AnxHl.nl 1983,
Grenr 1985).
As in other
eukaryotes,
the rDNA of anostracans
contains
tandemly repeated
transcriptional
unirs, which are
separated
by intergenic
spacers.
\Tithin each transcriptional
unit, the internal transcribed spacer I
(ITS 1) separates
the lBS small subunit (1BS
rDNA) from the 5.8S,
while the internal
transcribed
spacer
2 (ITS 2) separates
the 5.8S
from the 2BS large
subunit (28S
rDNA). The coding regions
show little sequence
divergence
among closely related
species,
whereas the spacer regions may
exhibit variability.
Mutations occur at a relatively
rapid rate in internal transcribed
spacers. These
regions
may therefore resolve
closely related
species that otherwise
show little genetic divergence
(Ponru,n
& Colr-rNS 1991, FRI'lz
et al. 1994,
Tnrc et al. 1996). For assessing molecular
phylo-
genetic
relationships
at various
infrafamilial levels
among anostracans,
the rapidly evolving
nuclear
ribosomal
ITS have
an exciting
potential.
Comparison
of B. relictu.r
n. sp. with B. ffinis Sars, 1901 and
B. wnlrt Daday, 1910
The 18S
rDNAgenes of Branchipodopsis
relictus n. sp., B. ffinis and
B. wllrt are
identical,
theyare
1806
bp long and have
a GC-content
of 50.6
%, which is
within the normal
range for crustaceans,
as available
from the Genbank/EMBL database
and literature
(Srrens
et al. 1994.,
Spr,ans
& AeEr-E
1997, Cru,,qsl
& Tnn-oR 1998,
\íEnrERs et al. 2002).
The 5.8S
rDNA genes of the three
species
show only four base-pair
differences, they are
175
bp long and their GC-content is 56.0 %0. Compared with Branchipzs
Schaeffer, 1776 and
TanymastigitesDaday,
1910, there are only minor size
differences, 174 and 173bp respecrively.
Within the Branchipodidae,
the GC-content
of the 5.BS
gene does
not show much variation; it is
54.8-56.0
o/o
for Branchipodopsis
and 56.9 o/o
for Branchipus.
In Tanymastigites,
the GC-contenr is
K. Vrx D,rurtr, H.J. DL:rroxt & P.H.H.
\rVttr.t'ns
lower (50.+
%). However,
the internal transcribed spacers
of the three species
showed
remarkable
length variation
, 265 6p, 261 bp and 405 bp respectively
for ITS 1', and 422 6p, 404 bp and
398 bp respectively for ITS 2. The GC-content did not vary
dramatically,
with 56.4-60.0
o/o
for
ITS 1 and 58.2-64.2
o/o
for ITS 2, and was
in the normal range
for the Branchipodidae.
The two different datasets
investigated showed
identical tree topologies with high bootstrap
support. The tree reconstruction method used
for identifying the phylogenetic
relationship of
B. relictu.r
n. sp. with other anostracans
positioned
the new species
as a sister taxon to the B. wolfi -
B. ffinis cluster. It clearly shows that the genetic difference
berween the three Branchipodopsis taxa
is much larger
than that berween the three
Branchipus
taxa.
Relative
position of B. relictus
n. sp.
The length
variation and the presence
of structural differences
in the internal transcribed spacers
generates genetic
distance between the Branchipodopsis taxa,
resulting
in a tree
(Fig.
5) which shows
that B, wzlf and B. ffinis are clustering together and suggests
that they are closely
related.
The rDNA of B. relictu.r
n. sp. is most similar to that of B. ffinis. However,
the new species is
genetically
closer to a common ancestor of B. won and ^8.
offi"it than to either
B. tuolf or B. ffinis
themselves.
As mutation rates
are taxon- and sequence-specific
and would require
specific study of
the ITS regions
of Branchipodopsis, no time-estimation can
be made as to how long B. relictu.r
n. sp.
could have
been
isolated.
Biogeography
Palaeogeography
It is assumed that the platform of the Socotra
Archipelago was separated
from Arabia during the
Gulf of Aden rifting which started in the Oligocene
(Br,voouN
& BtcHex 1970), its pre-rift
position beingsouth of Dhofar
in south-western Oman (Snvutl et al. 1997, BInsn et al. tg97).As
the Afro-Arabian mainland was
submerged under a shallow epicontinental sea
from the end of the
Palaeocene
onwards
(Monntsox et al. 1997, Snvunt- et al. 1997),
the Dhofar-Socotra highs may
have
been
isolated
even earlier.
Because
of their geographical position
being
relatively
close
to India and Pakistan,
as shown
in
BosEt-t-txr
(1989),
until the separation
of this subcontinent
in the Late Cretaceous, and" a significant
period of tectonic
isolation
of the Socotra platform from Arabia since the Oligocene
(Bevnoux &
BtcHnx 1970),
the islands
of the Socotra
Archipelago
are
known for the high degree
of endemism
in their terrestrial fauna and flora as well as
for their Indo-Asian affinities. These affinities are also
noted for the southern part of the Arabian Peninsula, mainly the Hadramaut
and Dhofar regions
(THrÉ.nv
1996, MrEs
Ec
BEyur-
1998).
Palaeogeographic
maps including the Socotra platform during Cretaceous times and its
position
relative
to the Gondwana
landmasses
are found in MonnrsoN
et al. (1997)
and Bosr.r.r.rNl
(1989).
Post-Cretaceous
events in the Dhofar-Socotra region
are discussed
by S,wutl et al. (1997).
Distribution of the genus
The combination
of colonisation by short-range wind dispersal
(Bnnxooxct<
& Rtooocn \999)
and their short maturation times enables species of Branchipodopsis to inhabit short-lived
pools in
Nerv Bzrzchipodopsis
(Crustacea:
[3ranchiopocla) 207
extreme,
unpredictable
environments
such as
the karst limestone
at Rewgid on Socotra
Island,
where overall
precipitation is low (Mrns
& BEvHL 1998)
and which is struck annually by a strong
rain-bearing
summer monsoon (FTxoLATER
1969).
Most Branchipodopsis
species seem to have
a
restricted
distribution, with the largest number in southern Africa which, for this reason, is
assumed
to be the ancestral
stock
(Baxnnnscu
1990,
Hmrnn &Apnlllox 1996);
other species are
known from central Africa (8. candea), Matritania (8. abiadi), Oman (Branchipodopsis
sp.),
Armenia (8. terpossogiani)
and India (8.ltcdnthzpenes).
More widespread species(-groups) are
the
African B. trideni Daday, 1910, B. wolfi and the central
Asian B. ffinis. Together
with THm,Ry's
(1996) unnamed animal from Oman, B. relictu.r n. sp. forms a geographical
link berween the Asian
and Afric an Branchipodopsis
species.
Mtr.s
6r Bpvut.
(1998)
discussed
a similar
distribution
pattern
in the xeric vegetation
of
Socotra Island,
stating
that instead
of originating in southern Africa, where the highest
diversiry
is
currently found, the vegetation
belt from the southern Tethys
coasts
"moved
south" [sic]
during
the Late Cretaceous
to Early Tertiary,
leaving
behind trail-relicts which survived in suitable
arid
environments
and gave
rise
to the endemic
drought-adapted
plants of the island (e.g.
Kleinia,
Dracaena).
The authors
based this on the hypothesis
that seeds
of the flora in question
were
unlikely to be dispersed
over
large
distances by wind. Something
similar could
well be the case in
Branchipodopsis.
The so-called
'trail-relicts'
would then include the species
found in India, Socotra,
Oman, Mauritania
and
East
Africa,
with more
to be expected in the mountainous
areas of Somalia
and the karst regions
of Madagascar,
while area expansions
by species such
as
B. w0lrt and
B. nffinis
could be interpreted
as more recent
colonisations. Although purely hypothetical, it could mean
that the genus
had a Gondwana
origin, as
previously suggested
by BexeRES(,u
(1990). However,
caution is needed
in the interpretation
of current
distribution
patterns, especially
in Branchiopoda,
since
the mechanisms
by which they disperse
remain unclear, and the fossil record is poor (Fnvr.n
1987).
CONCLUSIONS
Although morphologically
close to the Asian B. ffini.i, and to a lesser
exrent ro rhe African
B. wolfi, molecular
analysis
of the ribosomal
DNA shows that B. relictus
n. sp. occupies an isolated
position in relation
to the cluster formed
by B. ffinis and B. wolf
,suggesring
that it is genetically
cioser to the stock
that gave
rise
to these
two species.
Taking zoogeographical,
morphological
and molecular
considerations into accounr, we suggesr
that B. relictus n. sp. is a relict species
(hence
the epithet),, having closer affinities with its Asian
congeners
than with the African congeners
studied.
ACKNO\TLEDGEMENTS
This study was
conducted
with in the framework
of the GEF-funded
project
"Conservation
and
Sustainable
Use of Biodiversity
of Socotra Archipelago",,
overseen
by the United Nations Office
for Project
Services
(UNOPS YEM
196lG32) in conjunction
with the Environmenral
Protection
Council (EPC) of Yemen,
ro whom we are
grateful.
The first author wishes
to express his gratitude to the other members
of the expedition
ream,
especially
Dr A. Miller, Dr M. Morris, Dr E. Neubert,
Dr H. Pohl, Dr U. Joger
and Dr \M Vranik.
Special
thanks are also
due to our Yemeni
colleagues A. Raheeb,
Dr A. Karim Nasher,
Dr M. Al-
208 K.
V,rx
D,rrrur. H.T. Durroxr & P.H.H. Wrnxrns
Jumaily
and A.S.
Said.
The authors also thank Dr H. Segers
for the help in preparing the scanning
micrographs,
Dr L. Brendonck for providing
B. wolf specimens
from Botswana,
and Dr M. Hamer
for valuable
suggestions.
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Manuscript
submitted: 15 April 2002
M:rnuscript
accepted: 27 August 2003
