ArticlePDF Available

High genetic diversity with Epimeria georgiana (Amphipoda) from the southern Scotia Arc

Authors:

Abstract and Figures

DNA barcoding revealed four well-supported clades among amphipod specimens that keyed out to Epimeria georgiana Schellenberg, 1931, three clades with specimens from the southern Scotia Arc and one clade with specimens from the Weddell Sea. Detailed morphological investigations of sequenced specimens were conducted, through light and scanning electron microscopy. High magnification (500–2,000 fold) revealed features such as comb-scales on the first antenna and trich bearing pits on the fourth coxal plate to be similar for all specimens in the four clades. Consistent microstructure character differences in the Weddell Sea specimens combined with high genetic distances (COI divergence > 20%) allowed the description of Epimeria angelikae, a species new to science. Specimens of E. georgiana in the other three COI clades from the Scotia Arc were morphologically indistinguishable. Representative specimens of clade A are also illustrated in detail. Our results on the high genetic divergences in epimeriid amphipods support the theory of the southern Scotia Arc being a centre of Antarctic diversification.
Content may be subject to copyright.
ORIGINAL PAPER
High genetic diversity within Epimeria georgiana
(Amphipoda) from the southern Scotia Arc
Anne-Nina Lörz &Peter Smith &Katrin Linse &
Dirk Steinke
Received: 9 February 2011 /Revised: 25 May 2011 / Accepted: 6 July 2011
#Senckenberg, Gesellschaft für Naturforschung and Springer 2011
Abstract DNA barcoding revealed four well-supported
clades among amphipod specimens that keyed out to
Epimeria georgiana Schellenberg, 1931, three clades with
specimens from the southern Scotia Arc and one clade with
specimens from the Weddell Sea. Detailed morphological
investigations of sequenced specimens were conducted,
through light and scanning electron microscopy. High
magnification (5002,000 fold) revealed features such as
comb-scales on the first antenna and trich bearing pits on
the fourth coxal plate to be similar for all specimens in the
four clades. Consistent microstructure character differences
in the Weddell Sea specimens combined with high genetic
distances (COI divergence> 20%) allowed the description
of Epimeria angelikae, a species new to science. Specimens
of E. georgiana in the other three COI clades from the
Scotia Arc were morphologically indistinguishable. Repre-
sentative specimens of clade A are also illustrated in detail.
Our results on the high genetic divergences in epimeriid
amphipods support the theory of the southern Scotia Arc
being a centre of Antarctic diversification.
Keywords DNA barcoding .Epimeriidae .New species .
Scanning electron microscopy.Scotia Arc .High biodiversity
Introduction
The intensified use of mitochondrial gene sequences for the
identification of morphologically indistinguishable and poly-
morphic taxonomic groups has lead to the discovery of species
complexes in many groups (e.g. Costa and Carvalho 2007;
Radulovici et al. 2010;Wilsonetal.2009;OLoughlin et al.
2011). Furthermore, species complexes of Antarctic benthic
peracarid crustaceans have been identified by DNA barcoding
(e.g. Leese et al. 2010;Held2003; Raupach and Wagele 2006;
Lörz et al. 2009; Havermans et al. 2010,2011). This method
utilizing a fragment of the mitochondrial cytochrome coxidase
Igene(COI) for species discrimination was successfully
applied among crustaceans in general (e.g. Leese et al. 2008;
Chu et al. 1999) and amphipods in particular thereby already
contributing to the taxonomic knowledge of this group
(Meyran et al. 1997;Wittetal.2006; Radulovici et al. 2009).
DNA barcoding has proven to be most beneficial when
used in an integrative approach together with morphological
or ecological data (Meier 2008). Only in concert with
morphological investigations barcodes allow the establish-
ment of formal species boundaries and species descriptions.
A taxon of special interest is the amphipod family
Epimeriidae Boeck, 1871. The globally distributed family
Epimeriidae Boeck, 1871 belongs to the dominant members
of Antarctic shelf benthos (Coleman 2007;Lörzetal.2009).
Epimeriidae are far more diverse in the Southern Ocean than
anywhere in the world. In temperate and warm oceans, they
A.-N. Lörz (*)
National Institute of Water and Atmospheric Research (NIWA),
Private Bag 14 901, Kilbirnie,
Wellington, New Zealand
e-mail: a.loerz@niwa.co.nz
P. Smith
Museum Victoria,
GPO Box 666, Melbourne Vic 3001, Australia
K. Linse
British Antarctic Survey,
High Cross, Madingley Road,
Cambridge CB3 0ET, UK
D. Steinke
Biodiversity Institute of Ontario, University of Guelph,
50 Stone Road East,
Guelph, ON, N1G2W1, Canada
Mar Biodiv
DOI 10.1007/s12526-011-0098-8
are only found in deep waters, while they occur in shallower
waters of the continental shelf in Antarctica and in
Scandinavia. Twenty-six species of Epimeriidae are known
from Antarctic waters (Lörz 2011). Recent research on
circum-Antarctic species or species nominally found in both
the Weddell and Ross Seas has shown that they belong to
species complexes and represent sister species (Lörz et al.
2007,2009). Investigations at smaller spatial scales have not
yet been undertaken.
Synopsis of Epimeria georgiana species complex
1903 Walker describes Epimeria inermis new spec from
Cape Adare, Ross Sea, 50 m depth, with the illustration of
one habitus drawing.
1907 Walker illustrates E. inermis: pereopods 5 and 6
with strong hooks.Systematics
1931 Schellenberg describes E. georgiana from
Cumberland Bay, South Georgia (75-310 m) as very
similar to E. inermis, except for shape of basis of
pereopods 5, 6 and 7. No illustrations of the new species
are provided by Schellenberg. No further details were
provided by Schellenberg 1931, except one sentence
tooth on basis of pereopod 7 blunt 90 degrees corner,
placed further distally than basis P5 and P6(translation
from the German original by first author)
1932 Barnard describes Epimeria exisipes new spec,
with a photograph, and one figure of the coxa 47 with the
bases of pereopods 57 from South Shetlands, South
Georgia and the Palmer Archipelago.
1989 Watling and Thurston synonymise Epimeria excisipes
K.H. Barnard, 1932 with Epimeria georgiana Schellenberg,
1931 and draw the habitus, antenna 1, lower lip, maxilliped,
parts of gnathopod 1 and the telson. Watling and Thurston
(1989) do not draw or describe the pereopods.
2007 Coleman presents a synopsis for all Antarctic
Epimeriidae and mentions in his diagnosis for E. georgiana
Bases 57 ridged, with deep notches on posterior margin,
creating prominent teeth.Coleman(2007) noted that E.
inermis can be differentiated from E. georgiana by the
unsculptured coxa, which has a straight or convex ventral
margin and a linear posterodistal margin. The posterior margin
of the basis of pereopods 56 is not developed to a ventrally
directing tooth, as it is the case in E. georgiana, but these
articles have posterobasal rounded lobes showing posteriorly.
2009 Lörz et al. discovered high genetic difference
between four specimens of the Epimeria georgiana group
from the Antarctic Peninsula and the Weddell Sea.
Here we use the concept of integrative taxonomy and
combine DNA barcoding and morphological analyses of
specimens of the Epimeria georgiana complex, from the
Antarctic Peninsula and the eastern Weddell Sea to describe
diversity in this Southern Ocean biota.
Material and methods
Taxon sampling
Epimeriid amphipods were collected during a RV Tangaroa
voyage to the Western Ross Sea (IPY, TAN0802), during RV
Polarstern voyages to the Weddell Sea (BENDEX and
ANDEEP III) and a RRS James Clark Ross voyage to the
Antarctic Peninsula (BIOPEARL I) (Fig. 1). Specimens
were sorted on deck, often photographed alive to record the
colour morphs, fixed in 98% ethanol and later transferred to
70% ethanol.
The amphipod specimens were registered and curated at
the National Institute for Water and Atmospheric Research
(NIWA) in Wellington, New Zealand; the Natural History
Collection London, UK; the British Antarctic Survey (BAS),
Cambridge, UK; and the Zoological Museum Hamburg,
Germany (Table 1). Specimens and especially DNA samples
from marine Antarctic invertebrates are highly valuable.
Morphological description
More than 100 specimens that keyed out to Epimeria
georgiana from the NIWA Invertebrate Collection (New
Zealand), the Zoological Museum Hamburg (Germany) and
the British Antarctic Survey (UK) were morphologically
examined. Additional material examined: Epimeria georgiana
Schellenberg, 1931, one specimen, type material SMNH673,
Stockholm, Swedish Museum of Natural History.
Epimeria georgiana registered as Epimeria exisipes Bar-
nard, 1932, 13 specimens, 15361550, Natural History
Museum London. Epimeria inermis Wa l k e r 1907, one speci-
men, BMNH 1903.10.5.19, Natural History Museum London.
Twelve specimens were dissected under a Leica MZ12
stereomicroscope and drawn using a camera lucida. Small
appendages and bodyparts (mouthparts, uropods, telson) were
temporarily mounted in glycerin, examined and drawn using a
Nikon compound microscope fitted with a camera lucida. The
body lengths of specimens examined were measured by
tracing individual mid-trunk lengths (tip of the rostrum to end
of telson) using a camera lucida. All illustrations have been
digitally inkedfollowing Coleman (2003;2009).
Parts of selected specimens (mouthparts, antennae, coxal
plates) were air dried, coated with goldpaladium and
investigated via a Scanning electron microscope LEO1525.
DNA extraction and analyses
DNAwas extracted from sub-samples of muscle tissue from 18
specimens of E. georgiana, three specimens of E. rimicarinata
and one specimen of E. inermis using an automated Glass
Fiber protocol (Ivanova et al. 2006). The 650-bp barcode
region of COI was amplified by polymerase chain reaction
Mar Biodiv
(PCR) under the following thermal conditions: 1 min at 94°C;
five cycles of 94°C for 40s, 45°C for 40s and 72°C for 1 min,
followed by 35 cycles at 94°C for 40s, 40s at 51°C, and 1 min
at 72°C; and a final step of 72°C for 1 min. The 12.5 μlPCR
reaction mixes included 6.25 μl of 10% trehalose, 2.00 μlof
ultrapure water, 1.25 μl of 10 × PCR buffer [200 mM Tris-HCl
(pH 8.4), 500 mM KCl], 0.625 μlMgCl
2
(50 mM), 0.125 μl
of each primer [0.01 mM, using LCO1490/HCO2198
(Folmer et al. 1994) with M13 tails], 0.062 μlofeachdNTP
(10 mM), 0.060 μl of Platinum Taq Polymerase (Invitrogen),
and 2.0 μl of DNA template. PCR amplicons were visualized
on a 1.2% agarose gel E-Gel (Invitrogen) and bidirectionally
sequenced using sequencing primers M13F or M13R and the
BigDye Terminator v. 3.1 Cycle Sequencing Kit (Applied
Biosystems) on an ABI 3730 capillary sequencer following
manufacturers instructions. Sequence data are available both
on BOLD (Ratnasingham and Hebert 2007) in the public
project Epimeria georgiana species complexEPIMEand
GenBank (accession numbers are given in Table 1).
Sequences were edited in CHROMAS 2.3 (Technely-
sium, Queensland, Australia), and aligned using CLUSTAL
in MEGA v. 4.1 (Tamura et al. 2007). K2P distances among
taxa were estimated in MEGA v. 4.1 (Tamura et al. 2007).
Initial neighbor-joining (NJ) clustering used the BOLD
Management and Analysis System. Maximum likelihood
(ML) trees were built using PAUP* (Swofford 2003), with
heuristic searches, employing tree bisection-reconnection
branch swapping; support for each internode was evaluated
by 1000 bootstrap replications (Felsenstein 1985). Bayesian
phylogenetic analyses were estimated with MrBayes ver-
sion 3.0 (Ronquist and Huelsenbeck 2003). Four simulta-
neous Monte Carlo chains were run for 1 × 10
7
generations,
saving the current tree every 1,000 generations. Consensus
trees with posterior probabilities were created with a burn-
in value equal to 1000 (the first 1,000 trees were discarded).
Nucleotide substitution models were selected in jModeltest
version 0.1.1 (Posada 2008) using both the Akaike
Information Criterion (AIC) and the Bayesian information
criterion (BIC); the transition model TVM + Γmodel was
selected by both criteria. The epimeriid Epimeria rimicar-
inata was used to root the trees because it is closely related
to E. inermis and E. georgiana.
Fig. 1 Map of collections sites
for studied Epimeria specimens.
Key: E. angelikae new spec,
E. georgiana type locality,
E. georgiana clade A, E.
georgiana clade B, E. georgi-
ana clade C, E. inermis
Mar Biodiv
Table 1 Station locations, vial numbers, individual specimen codes and GenBank accession numbers. BMNH British Museum of Natural History, EI Elephant Island, LI Livingston Island, n
number of specimens, RS Ross Sea, SG South Georgia, SMNH Swedish Museum of Natural History, WS Weddell Sea, ZMH Zoological Museum Hamburg
GenBank Latitute Longitute Depth
Taxon Spec/vial id n COI Station (S) (m) Date Expedition Location
Epimeria angelikae
Holotype ZMH K-42632 1 - PS65/233-1 71° 19.19013° 57.45W 844-848 21.12.2003 BENDEX WS
Paratype NIWA 42844 1 FM955305 PS65/232-1 71° 18.37013° 56.70W 899-910 21.12.2003 BENDEX WS
Paratype ZMH K-42633 1 FM955299 PS65/233-1 71° 19.19013° 57.45W 844-848 21.12.2003 BENDEX WS
BAS KL03-441 3 1 - PS65/232-1 71° 18.37013° 56.70W 899-910 21.12.2003 BENDEX WS
BAS KL03-441 2 1 - PS65/232-1 71° 18.37013° 56.70W 899-910 21.12.2003 BENDEX WS
BAS KL03-441 4 - PS65/232-1 71° 18.37013° 56.70W 899-910 21.12.2003 BENDEX WS
Paratype NIWA 34944 (BAS 03-441-4) 1 - PS65/232-1 71° 18.37013° 56.70W 899-910 21.12.2003 BENDEX WS
NIWA 34941 (BAS 03494 1) 1 - PS65/232-1 71° 18.37013° 56.70W 899-910 21.12.2003 BENDEX WS
NIWA 34943 (BAS 03 441 1) 1 - PS65/232-1 71° 18.37013° 56.70W 899-910 21.12.2003 BENDEX WS
Epimeria georgiana
Syntype SMNH673 1 - 34 54°11.0036º18.00W 252-310 05.06.1902 Swenska Sypolar exp SG
BNHM 1536-1550 13 - ???
Clade A
NIWA 34945 1 JF271115 EI-AGT-2 61°34.52055º15.38W 990-976 12.03.2006 BIOPEARL I EI
BAS KL06-378 1 JF271114 EI-AGT-2 61°34.52055º15.38W 990-976 12.03.2006 BIOPEARL I EI
BAS KL06-3766 1 JF271111 EI-AGT-2 61°34.52055º15.38W 990-976 12.03.2006 BIOPEARL I EI
NIWA 34935 1 JF271112 EI-AGT-2 61°34.52055º15.38W 990-976 12.03.2006 BIOPEARL I EI
NIWA 34936 1 JF271113 EI-AGT-3 61°23.16055º11.60W 463-483 12.03.2006 BIOPEARL I EI
NIWA 69496 1 JF271110 EI-AGT-2 61°34.52055º15.38W 990-976 12.03.2006 BIOPEARL I EI
Berlin 1 AY061802 PS/44-1 61°43.50055º12.75W 590 27.11.1996 ANT XIV/2 LI
BAS KL06-376 5 - EI-AGT-2 61°34.52055º15.38W 990-976 12.03.2006 BIOPEARL I EI
Clade B
BAS KL06-5742 1 JF271106 PB-AGT-2 61°02.13046º51.92W 964-1,014 17.03.2006 BIOPEARL I PB
NIWA 69497 1 JF271105 PB-AGT-2 61°02.13046º51.92W 964-1,014 17.03.2006 BIOPEARL I PB
BAS KL06-5743 1 JF271108 PB-AGT-2 61°02.13046º51.92W 964-1,014 17.03.2006 BIOPEARL I PB
NIWA 69498 1 JF271109 PB-AGT-2 61°02.13046º51.92W 964-1,014 17.03.2006 BIOPEARL I PB
BAS KL06-5741 1 JF271107 PB-AGT-2 61°02.13046º51.92W 964-1,014 17.03.2006 BIOPEARL I PB
Clade C
NIWA 69499 1 JF271104 EI-AGT-4 61°20.04055º11.70W 199-201 12.03.2006 BIOPEARL I EI
ZMH K-39888 1 AF451341 ANTXVII-3/177-1 61°49.50060º49.32W 202 01.05.2000 EASIZ III LI
ZMH K-400520 1 - ANTXVII-3/183-1 62°06.70060º21.70W 204 03.05.2000 EASIZ III LI
BAS KL06-4411 1 JF271103 EI-AGT-4 61°20.04055º11.70W 199-201 12.03.2006 BIOPEARL I EI
NIWA 34942 1 JF271102 EI-AGT-4 61°20.04055º11.70W 199-201 12.03.2006 BIOPEARL I EI
Mar Biodiv
Results
DNA results
DNA barcodes revealed four well supported clades among
18 specimens that had keyed out to Epimeria georgiana
Schellenberg, 1931 (Fig. 2). The clades are referred to as A,
B, C and new species (= clade D). Clade A consists of
specimens collected on the continental shelf off Elephant
and Livingston Island in 463990 m depth, clade B of
specimens from the Powell Basin (9691,014 m), clade C
of specimens collected on the shallow shelf off Elephant
and Livingston Island (199204 m), while the specimens of
the new species (clade D) were collected in the eastern
Weddell Sea in 844910 m depth (Table 1). Sequence
divergence (K2P) was low within each of five clades,
including the outgroup E. rimicarinata, ranging from 0 to
0.22% (Table 2). Pairwise inter-clade distances ranged from
2.59 to 22.46%; comparisons including clade D or the
outgroup E. rimicarinata showed the greatest distances
(12.9-22.5%, Table 2).
Clades A, B, and C showed lower inter-clade divergences,
but were well supported by ML and Bayesian analyses, and
the divergences were more than 10-times the intra-clade
divergences (Table 2). It has been suggested that the barcode
gapbetween species should be based on the smallest rather
than mean inter-specific distances (Meier et al. 2008); these
values are shown in parentheses in Table 2. For the Epimeria
COI data set there is little difference between the mean and
smallest values due to the low intra-specific divergences in
all clades with three or more specimens.
Morphology
Based on the genetic results, detailed morphological
examinations on specimens of the four clades were carried
out, including SEM imaging of coxa and antennae micro-
structures (Table 3). No permission was given to take tissue
samples of the type material of E. inermis and as no DNA-
suitable tissue samples from the type locality of E.
georgiana were available, we included type specimens in
the detailed morphological examinations.
Morphological differences between specimens of the
clades A, B, C and specimens of clade D (new species)
were consistent and therefore a new species of Epimeria
from the Weddell Sea is described in detail herein.
The morphological investigation failed to obtain distinct
and significant differences between specimens of the clades
A, B, and C. However, specimens from clade A exhibited
small morphological differences to specimens of clades B
and C (see Table 3) but the selected morphological
characters did not justify new morpho-species descriptions.
Specimens from clade C were morphologically most similar
Table 1 (continued)
GenBank Latitute Longitute Depth
Epimeria inermis
Holotype BMNH 1903.10.5.19 1 - Cape Adare 50 13.05.1903 RS
NIWA 36151 1 JF271116 TAN0802/56 75°37.95169º51.00E 525 14.02.2008 TAN0802 RS
NIWA 20164 1 FM955280 TAN0402/ 94 71°31.80170°06.66E 220 17.02.2004 TAN0402 RS
NIWA 20169 1 FM955281 TAN0402/ 184c 71°30.03171°36.42E 480 27.02.2004 TAN0402 RS
NIWA 20171 1 FM955282 TAN0402/233 67°25.07163°54.93E 230 04.03.2004 TAN0402 RS
NIWA 20168 1 FM955292 TAN0402/134 71°38.50170°09.15E 65 23.02.2004 TAN0402 RS
NIWA 20162 1 FM955285 TAN0402/33 71°45.28171°25.02E 282 10.02.2004 TAN0402 RS
Epimeria rimicarinata
NIWA 35470 1 JF271118 TAN0802/17 73°07.48174º19.25E 321 09.02.2008 TAN0802 RS
NIWA 37662 1 GU804288 TAN0802/161 72°04.53172º54.26E 535 24.02.2008 TAN0802 RS
NIWA 35469 1 JF271117 TAN0802/17 73°07.48174º19.25E 321 09.02.2008 TAN0802 RS
Mar Biodiv
to the E. georgiana type material. However, since the
specimens of clade A showed a significant genetic
divergence of about 6% to clade C, and the type material
was never fully illustrated, we present detailed illustrations
of one specimen from clade A (Figs. 3,4,5).
Systematics
Order AMPHIPODA Latreille, 1816
Suborder GAMMARIDEA Latreille, 1802
Family EPIMERIIDAE Boeck, 1871
Genus Epimeria Costa,1851
Epimeria angelikae sp. nov.(Figs. 6,7,8,9,10,11,
12.1,12.2)
Lörz and Linse, 2011
Material examined
Holotype: ZMH K-42632, male, 20.2 mm, collected ANT-
XXI/2 via Agassiztrawl station 233, 71°19.19 S, 13º57.45 W,
850 m, 21 Dec 2003.
Paratype: NIWA 42844, male, 25.5 mm, collected ANT-
XXI/2 via an Epibenthic sled, station 232, 71°18.8 S,
13º56.84 W, 870 m, 21 Dec 2003. NIWA 34944, 18.8 mm,
collected same station, GenBank accession number COI
FM955305.
Paratype: ZMH K-42633, 21.2 mm, collected ANT-XXI/
2 via an Epibenthic sled, station 233, as holotype, GenBank
accession number COI FM955299.
Additional material: five further specimens from ANT-
XXI/2 st 232 (NIWA 34941, NIWA 34943, BAS
KL034413, BAS KL034412, BAS KL03441).
Etymology
The species is dedicated to Prof. Dr. Angelika Brandt
in acknowledgement of her devotion to Antarctic
Peracarida.
Diagnosis
Anterior cephalic margin sinuous, lateral cephalic lobe
slightly produced; rostrum as long as the head, reaching
antenna 1 peduncle article 1; eye present, oval, 0.5 × head
height. Pereonite 1 shorter in length than head, pereonite 2
about 0.75×length of 1; pereonites 14 lacking mid-dorsal
Within species Between species/clades
Clade A Clade B Clade C Ea Er
Clade A 0.09
Clade B 0.13 2.59 (2.34)
Clade C 0.16 6.23 (5.18) 5.99 (5.86)
Ea 0.00 20.61 20.21 21.42
Er 0.22 12.90 13.42 15.62 22.46
Ei na 18.55 20.44 22.21 23.14 18.92
Ta b l e 2 Nucleotide distances
(K2P) within and between spe-
cies/clades of Epimeria (values
in parentheseslowest inter-clade
nucleotide distances). Epimeria
aff georgiana clades A, B and C,
Epimeria angelikae new spec
(Ea, Clade D), Epimeria
rimicarinata (Er) and Epimeria
inermis (Ei)
Fig. 2 Relationships of COI
sequences from Epimeria speci-
mens. GenBank accession
numbers are given for each
specimen. Numbers at nodes are
Bayesian inference posterior
probability values and ML
bootstrap percentages (>85%)
after 1000 replications; scale
bar represents an interval of the
TVM+ G model. Location
abbreviations, as in Table 1. The
tree has been rooted with
Epimeria rimicarinata
Mar Biodiv
or dorsolateral processes; pereonite 57 dorsolateral carina
developed; coxa 5 laterally broadly produced; pleonites 13
with well-developed longitudinal dorsal carina. Epimeron 1
antero- and posteroventral angle rounded; epimeron 2 and 3
posteroventral angle produced. Urosomite 1 with a middor-
sal bump. Urosomite 2 shortest middorsally flat. Urosomite
3 dorsally flat.
Description based on light microscopy of the holotype
Antenna 1 accessory flagellum scale-like; primary flagel-
lum broken off after article 24. Antenna 2 peduncle article 1
with three long processes; article 2 with two slight
processes, slightly shorter than article 1; article 3 longest,
articles 35 lacking distal processes; flagellum complete
with 42 articles.
Mandible incisor strongly dentate; molar produced and
triturative; palp article 3 densely setose medially, with long
stout setae distally.
Maxilla 1 medial plate subtriangular, obliquely convex
inner margin with eight plumose setae; lateral plate distal
margin oblique, with 11 medially lobate setae; palp strongly
exceeding outer plate; palp article 1 short, article 2 slightly
curved medially with eight stout setae distomedially.
Table 3 Morphological characterisation of type material of Epimeria angelikae new spec, Epimeria georgiana type material, Epimeria aff
georgiana clade A (NIWA 69496), clade B (BAS KL 5742), clade C (NIWA 69499) and Epimeria inermis type material
E. angelikae E. georgiana Clade A Clade B Clade C E. inermis
1 Body robust x x x x x x
2 Rostrum longer than first peduncular article of antenna 1 no x x x x x
3 Eyes large x x x x x x
4 Shape of ocular lobe reniform round round round round oval
5 Lateral cephalic lobe produced and pointed rounded rounded rounded rounded rounded
6 Pereonites 2 with short, dorsal posteromarginal protrusions,
not carinate
xxxxxx
7 Pereonites 3 with short, dorsal posteromarginal protrusions,
not carinate
begin of carina x x x x x
8 Pereonites 47 with broad, blunt carinae P 37 weak carina x x x x x
9 Less posteriorly protruding humps on pleonites 1-2 x x small x x no definite humps
10 Pleonite 3 with 2 shallow dorsal depressions weak x x x x 3 shallow depressions
11 Urosomite 1 with dorsal depression x x x x x x
12 Urosomite 3 dorsolateral ridges, shallow keel drawn out x x x x x x
13 Epimeral plate 1 lateromarginally rounded, posteroventral
angle produced
xxxxxx
14 Epimeral plates 2 and 3 posteroventrally produced x x x x x x
15 Coxae 13 with ridged surface x x x x x x
16 Coxa 1 apically rounded more truncate x x x x pointed
17 Coxa 2 with posteroapical angle x x x x x pointed
18 Gnathopods subchelate x x x x x x
19 Gnathopod palm inconspicuously serrate x x x x x x
20 Gnathopod dactylus with short spines on inner curvature x x x x x x
21 Coxa 3 posteroapically truncate truncate (x) (x) (x) pointed
22 Coxa 4 largest x x x x x x
23 Coxa 4 sculptered no x x x x no
24 Coxa 4 apically truncate or weakly excavate no x convex x x x no
25 Coxa 4 posterior and apical margin turned back, creating a
rounded ridge
no x x x x no
26 Coxa 5 laterally produced, dorsal viewing weak x no (x) x weak
27 Coxa 6 rounded posteriorly with produced hump on lateral
surface
xxxxxx
28 Basis pereopod 7 ridged, deep notch on posterior margin,
creating prominent teeth
bit (x) no no no no
29 Basis pereopod 6 ridged, deep notch on posterior margin,
creating prominent teeth
xxxxxno
30 Basis pereopod 5 ridged, deep notch on posterior margin,
creating prominent teeth
x x no x x no
Mar Biodiv
Maxilla 2 with long, distally crenulate setae distally on
lateral and medial plates.
Maxilliped outer plate, reaching mid length of merus;
row of robust setae; medial plate reaching half the length of
outer plate; palp medial margin strongly setose; merus,
carpus, propodus margins parallel; dactyl with serrate
medial margin.
Gnathopod 1 coxa long and slender, ventral margin
truncate; basis linear, slender, anterior margin with numer-
ous fine setae; merus longer than ischium, anterior margin
very short, distal margin oblique, posterodistal angle acute,
setose; carpus posterior curved margin with long slender
setae; propodus expanded distally, anterior margin naked
except for distal fringe of short setae, palm finely crenulate,
slightly oblique, with cluster of setae defining rounded
distal margin, posterior margin with numerous long setae;
dactylus slender, curved, as long as palm, posterior margin
strongly serrate.
Fig. 3 Epimeria aff georgiana
clade A. NIWA 34935, 37 mm.
aHabitus lateral, blabrum, c
head with epistome, dmaxilla 1,
emandible, ftelson. Scale bars
a: 0.5 mm, b-f:1mm
Mar Biodiv
Gnathopod 2 coxa slightly wider than coxa 1, coxa and
basis very similar to Gnathopod1, broken off after basis.
Pereopod 3 coxa longer than coxa 2, ventral margin
truncate, basis linear, anterior and posterior margin finely
Fig. 4 Epimeria aff georgiana clade A NIWA 34935, 37 mm. aAntenna 1, bantenna 2, cmaxilliped, dmaxilla 2, epleopod 2. Scale bars a-e:1mm
Mar Biodiv
setulose; merus slightly expanded distally, carpus slightly
shorter than merus, anterior margin naked, posterior margin
with six pairs of setae; propodus naked anteriorly, posterior
margin with seven pairs of setae; dactylus stout, curved.
Fig. 5 Epimeria aff georgiana clade A NIWA 34935, 37 mm. aUropod 1, buropod 2, curopod 3, dgnathopod 1, epereopod 3; fgnathopod 2; g
pereopod 4. Scale bars a-e:1mm
Mar Biodiv
Pereopod 4 coxa longer than 3, very wide, anterior
margin convex, posterior margin with a long posterior lobe
just above mid-length, ventral margin straight, posterodistal
corner rounded; basis to dactylus as for pereopod 3.
Pereopod 5 coxa subrectangular, laterally expanded; basis
expanded midposteriorly with hook, slightly serrated; merus
constricted proximally; carpus slightly widened distally;
propodus linear, posterior margin with five pairs of setae;
dactylus curved, stout, about 0.3×propodus length.
Pereopod 6 coxa anterior half hidden by coxa 5, anterior
margin weakly concave, posterior margin slightly produced;
basis expanded and posteriorly notched, serrated, hook
pointing ventrally; ischium to dactylus as in pereopod 5.
Pereopod 7 coxa small, basis expanded midposteriorly,
slightly serrated, not forming hook; broken off after merus.
Uropod 1 peduncle subequal in length to inner ramus;
medial margin with one robust seta distally, distal margin
with close row of short setae; inner and outer ramus same
length, lateral marins with spaced row of short setae.
Uropod 2 peduncle naked, two distal setae; inner ramus
length 1.5 × outer ramus, lateral margins of rami with
sparse setae.
Fig. 6 Epimeria angelikae new
spec ZMH K-42632, holotype
20.2 mm. aHabitus lateral, b
habitus dorsal, chead with
epistome, dmaxilla 1, ftelson.
Epimeria angelikae new spec
ZMH K-42633, paratype
21.2 mm; eright mandible.
Scale bars 1mm
Mar Biodiv
Uropod 3 peduncle short, about 0.3×length of inner ramus,
two processes produced; rami with sparse row of short setae.
Telson 1.2 ×longer than wide; V-shaped emargination
0.3×length, lobes triangular, rounded apically.
Additional description based on magnification via scanning
electron microscope, based on Paratype ZMH K-42633
Figs. 9a-d,10,11
Antenna 2 peduncle article 2 shows cuticular scales at the
anterior part (Fig. 9a, b). Each scale has its posterior end
lifted up to form a comb like structure, which show several
poresup to three pores at the basis of each tooth of the
comb(Fig. 9c, d).
Coxa 4 is entirely covered with pits, each pit has one
small setae (Fig. 10a-e).
According to Oshel and Steele (1988)a microtrich is
shorter than 25 μm, a macrotric longer than 25 μm.
The setae in the pits on the surface of the fourth coxa
plate are between 20 and 30 μm in length and
therefore can not be clearly classified as micro- or
macrotrich.
The inner plate of the maxilliped is covered with fine
setae (Fig. 11a). The grinding surface of the molar is
Fig. 7 Epimeria angelikae new
spec ZMH K-42632, holotype,
20.2 mm. aAntenna 1, b
antenna 2, cmaxilliped, d
hypopharynx, E) labrum. Scale
bars 1mm
Mar Biodiv
slightly convex and consists of 26 lamella (Fig. 11b, c). The
accessory spine row consists of 11 serrated setae, which
each have one slim simple seta at the base. They seem to be
laterally connected at midheight, but this might be an
artefact (Fig. 11d). The palm of gnathopod 1 bears a row of
stout setae which are slightly curved (Fig. 11e, f), the
dactylus is extending the palm with its lateral margin drawn
out into long, curved serration.
Distribution
Off Kapp Norvegia, eastern Weddell Sea, 844910 m.
Remarks With increasing size of the specimens, the dorsal
carinae on pereonites 47 and on the pleonites 13 seems to
get more pronounced forming a double carina per segment
(never as pronounced as in E. rimicarinata). The eyes are
Fig. 8 Epimeria angelikae new
spec ZMH K-42632 Holotype
20.2 mm. aUropod 1, buropod
2, curopod 3, dgnathopod 2, e
gnathopod 1, fpereopod 3, g
pereopod 4. Scale bars 1mm
Mar Biodiv
oval- to kidney-shaped. The colour of the specimen is
crème-white with light-orange eyes (Fig. 121, 2).
Light microscopy
Comparisons of the type material of Epimeria georgiana
from Stockholm museum and the type material of
Epimeria inermis from the London Natural History
Museum with specimens from each of our four clades
revealed a couple of differences which are summarised in
Ta b l e 3. A special focus was given to the pereopods 57,
which are illustrated in Fig. 13. Clade A specimens do not
have a ventrally directed tooth on the basis of pereopod 5,
but a rounded lobe showing posteriorly as described for E.
inermis. Clade A specimens have a tooth at the basis of
pereopod 6 pointing ventrally, but in a less distal position
than in clades B or C. The tooth on the basis of pereopod 6
is largest in clade C and the type material of Epimeria
georgiana.
Studies of the type material of E. inermis showed no hooks
on the basis of pereopods 57. We assume Walker (1907)
made the drawings of the hook bearing bases of Epimeria
inermis on specimens that actually were Epimeria georgiana.
Electron microscopy
Via scanning electron microscopy, we compared details of
Epimeria angelikae new spec to Epimeria georgiana clade
A, B and C with focus on the second antenna and the fourth
coxa. Antennae 2 showed the same scales at the peduncle in
all clades (see Fig. 9e, f clade A). The antennae of
peracarids are known to have chemosensory organs (e.g.
Kaïm-Malka et al. 1999). The structures observed in
Epimeria angelikae new spec and the E. georgiana clades
are remotely similar to pseudochaetal formationsdescribed
from the antennal peduncle of Isopoda (Kaïm-Malka et al.
1999). The major difference is that the observed setae-
like structures do not end free, but are connected at
both terminal ends.
Fig. 9 a-dScanning electron
microscope images of Epimeria
angelikae new spec. Paratype
ZMH K-42633 and e-fEpimeria
aff georgiana clade A NIWA
34945. a,e) antenna 2, b,f)
scales on peduncle of antenna 2,
cdetails of scales, dfrontal view
of one scale, showing pores.
Scale bars a: 100 μm, b:20μm,
c:10μm, d:1μm, e: 200 μm
Mar Biodiv
The overall shape of coxa 4 is very similar from
Epimeria angelikae new spec and E. georgiana clade A,
B and C (Figs. 10a,14a, c, e, f). E. angelikae new spec
from the Weddell Sea has a slightly wider coxa 4 than the
Peninsula specimens. Epimeria georgiana clade C shows
the most structured (thick) fourth coxa. While the anterior
margin of coxa 4 of clade C seems straight in lateral view
(Fig 14e), it seems to be concave when the coxa is tilted
slightly (Fig. 14f). We show both views of the same plate
(Fig 14e, f) to stress the influence of the angle how the
features are illustrated and therefore proportional compar-
isons of features amongst the clades are to be treated
carefully. All E. georgiana clades show the same pits
covering the surface of coxa 4 (Figs. 14,15) as described
for E. angelikae new spec (Fig 10a-e). Each pit has a half of
its border thickened, forming a semicircle (e.g. Fig 15a-d).
In the middle of the cuticular semi-circle, a seta of 20
30 μm is positioned, always at the side of the pit, under the
border. All semicircles of the fourth coxa are positioned the
same direction, in the middle area of the coxa the opening
are to the ventral side. On the distal extension of the fourths
coxa and towards the ventral margin, the semi circles have
their opening towards the posterior end.
Discussion
DNA Barcoding
DNA barcoding began in 2003 with the proposal that
species could be identified by using a short mitochondrial
gene fragment (COI) of a standardized position in the
mitochondrial genome (Hebert et al. 2003a). Since then,
hundreds of barcode projects, covering a very wide range of
taxa, have been undertaken. Most of these projects share
the goal of contributing to an open-access library derived
from referenced (vouchered) specimens that will improve
understanding of biodiversity, highlight cryptic species, and
provide rapid molecular tools for non-taxonomists to
identify species (Ratnasingham and Hebert 2007). The
Fig. 10 Scanning electron
microscope images of Epimeria
angelikae new spec. Paratype
ZMH K-42633. aFourth coxal
plate, blateral posterior corner
of fourth coxal plate, cpits on
surface of fouth coxal plate, d
cuticular pit with macrotrich
seen laterally; eas dseen from
top, flabrum. Scale bars a
200 μm, b,c:20μm, d,e:
10 μm, f: 100 μm
Mar Biodiv
Census of Antarctic Marine Life Barcoding project started
in 2007 (Grant and Linse 2009) and a major output of the
CAML Barcoding Campaign has been a substantial
increase of Antarctic marine speciesbarcodes, linked with
the discovery of many new fish and invertebrate species, as
well as cryptic species complexes (e.g. Allcock et al. 2011;
Smith et al. 2010; Grant et al. 2011).
While DNA barcoding has its limitations, in particular the
discrimination of recently diverged species that underwent
introgressive hybridisation, the COI barcode region has been
shown to be appropriate for discriminating between closely
related species across diverse animal phyla (Hebert et al.
2003a,b;Wardetal.2005,2009; Bucklin et al. 2011).
Although there is no fixed divergence value that can be
employed as a species criterion, relatively deep divergence
among COI haplotypes within nominal species highlight
potential overlooked species (Shearer and Coffroth 2008;
Ward et al. 2009). Species recognition is based on the
barcode gapbetween intra- and inter-specific variations. In
general, the barcode gaphas provided a valuable tool for
species identification and for highlighting cryptic species
(Waugh, 2007); although substantial overlap in intra- and
inter-specific variation has been reported in some marine
gastropods (Meyer and Paulay 2005) and in corals (Shearer
and Coffroth 2008).
A sequence divergence value set at 10-times the average
of within species variation has been identified as likely to
be effective for detecting cryptic species in birds (Hebert et
al. 2004) and a similar criterion has been applied in the
identification of cryptic species of marine fishes (Steinke et
al. 2009; Ward et al. 2009; Zemlak et al. 2009). For the E.
georgiana COI data from Elephant Island and the Powell
Basin the inter-clade distances are more than 10-times the
intra-clade distances. There are several reports of cryptic
Antarctic species identified by DNA studies, e.g. in crinoids
(Wilson et al. 2009), ophiuroids (Hunter and Halanych,
2008), pygnogonids (Krabbe et al. 2010; Arango et al.
2011), and fishes (Smith et al. 2010; Smith et al. 2008).
Another potential problem for DNA barcoding is the
occurrence of nuclear copies of COI recently shown for
Fig. 11 Scanning electon
microscop images Epimeria
angelikae new spec, paratype
ZMH K-42633. aMaxilliped, b
mandible, cmolar of mandible,
dlacina mobilis; egnathopod 1,
fdetailed serration of propodus
and dactylus of gnathopod 1.
Scale bars a,b,d: 100 μm, c:
20 μm, e:10μm
Mar Biodiv
crustaceans (Song et al. 2008;Buhay2009), which could
result in erroneous tree topologies mimicking diversity.
However, the discovery of this problem also provided
researchers with a variety of tools that help to identify
pseudogene sequences and to avoid their inclusion
analyses. We found no evidence for psuedogene sequences
in the Epimeria data set.
In the present study, the morphological investigation
of E. georgiana specimens of four barcode clades revealed
one new species with distinct phenotypic differences to
described species of Epimeria. The three remaining clades
require further investigation, e.g. through the use of fast-
evolving nuclear gene regions to confirm their taxonomic
status as they potentially represent cryptic species, based
on the COI data.
Distribution
Recently Pearse et al. (2009) proposed that speciation could
be enhanced in taxa with non-pelagic development.
Glaciation on the Antarctic Continental Shelf subdivided
populations into small isolated units that underwent
speciation. The repeated formation of such refugia during
the glacial-interglacial cycles of the Pliocene-Pleistocene
created a species diversity pump. The theory of such an
Antarctic diversity pump predicts the presence of many
closely related often cryptic species around the Antarctic
continent (see Clarke and Crame 1992,2010).
This study further supports this hypothesis, as the
combined DNA and morphological analyses of the Epi-
meria georgiana complex revealed one new species and the
COI results indicated a further three cryptic species
separated by bathymetry, geography, and relatively high
sequence divergences. Epimeria spp are stocky amphipods
unable to swim a long distance. Hence they have a low
capability for dispersion, which results in narrow distribu-
tional ranges of several species.
The Scotia Arc region appears to be unusually diverse
(Barnes et al. 2009; Linse et al. 2007). The high species
richness and high genetic diversity in epimeriid amphi-
pods reported at the Scotia Arc supports the assumption
that the islands of the Scotia Sea might have acted as a
centre of speciation in the Southern Ocean (Linse et al.
2007;Griffithsetal.2011).Ourfindingsofthreecladesof
Epimeria georgiana with less than 7% divergence at
Elephant Island also support the idea of a recent speciation
Fig. 12 Colour photographs
taken from specimens immedi-
ately after sampling. 1,2 Epi-
meria angelikae new spec, 3
Epimeria aff georgiana clade C,
4,5,6 Epimeria aff georgiana
clade A. 1NIWA 34944, 2
BAS_KL034413; 3BAS64411,
4NIWA 34935, 5NIWA 69496,
6NIWA 34936.
Mar Biodiv
among these sympatric populations. We assume that Epimeria
inermis, bearing the smooth basis on pereopods 57,
resembles the ancestral morphology of the georgiana-species
complex. Since all three clades of Epimeria georgiana are
found in relative close proximity of Elephant Island and
Powell Basin, all shallower than 1,000 m depth, we assume
that these clades are descendents of a former E. georgiana
population that diverged since the Last Glacial Maximum,
after the Antarctic continental shelf lost its ice shelf cover
(Thatje et al. 2005). We have taken a conservative approach
Fig. 13 Pereopods 5, 6 and 7 (P5, P6, P7) of the different clades of Epimeria aff georgiana,Epimeria angelikae new species, type material of E.
georgiana and E. inermis
Mar Biodiv
and only described the clade from the Weddell Sea as new
species, and not the morphological differences of the clades
from the southern Scotia Arc to the type material collected at
South Georgia and the northern Scotia Arc.
Discussions about species concepts and the level of
interspecific divergence in amphipods are ongoing (e.g. Held
and Leese 2007;Vogler and Monaghan 2007), but high inter-
clade and low intra-clade sequence divergences are indica-
tive of cryptic species, especially when coupled with
significant, consistent, morphological differences (often
microstructure/scale). Sequencing of additional faster evolv-
ing regions of DNA and morphological investigation of inner
structures could assist in resolving the status of these clades:
specimens from clades A (Elephant Island987 m), clade B
(Powell Basin in 964 m), and clade C (Elephant Island, but
shallower200 m). However, specimens of clade Awere also
collected as shallow as 590 and 463 m on the South Shetland
Islands. A bathymetric tolerance of 500 m is not unusual for
Antarctic epimeriid amphipods. Some species, e.g. E. macro-
donta (Walker 1907)orE. puncticulata Barnard 1932 are
known to have a wide depth distribution over 1,000 m on the
Antarctic shelf (Coleman 2007).
Scanning electron microscopy
Many authors have suggested the use of cuticular structures,
especially setae, to be an important tool for taxonomy of
Peracarida (e.g. Bradbury et al. 1998; Khalaji-Pirbalouty and
Wägele 2010). Zimmer et al. (2009)classified30typesof
setae, four types of microtrichs, different types of pores and
structures formed by setules and denticles of hyalid
amphipods; Halcrow and Bousfield (1987) described surface
microstructures of different amphipod taxa; Kaufmann
(1994) described structure and function of chemoreceptors
in scavenging amphipods. Neither the comb-scale structure
at the peduncle of the second antenna nor the setae bearing
pit with half border thickened of the fourth coxa seem to be
described before.
Fig. 14 Scanning electron mi-
croscopy fourth coxal plate of
the three clades of Epimeria aff
georgiana.a,bclade A NIWA
34945; c,dclade B NIWA
69497; e,fclade C NIWA
34942. Note that eand fare the
same coxal plate pictured from
different angles. Scale bars a,c,
e,f: 1 mm; b,d: 100 μm
Mar Biodiv
The only published scanning electron microscopy
images of epimeriid amphipods are of Paramphithoe
hystrix (Oshel and Steele 1988). Their investigation focused
on the gut content and the modifications of the mouthparts
to allow micropredation on sponges. However, the labrum
and the mandible of Epimeria angelikae new spec
(Figs. 10f,11b-d) bear similar structures of setae as shown
for P. hystrix (Oshel and Steele 1988).
As described above, all semicircles of the fourth coxa are
positioned in the same direction, in the middle area of the
coxa the openings are to the ventral side, on the distal
extension of the fourths coxa and towards the ventral
margin, the semi-circles have their opening towards the
posterior end. One explanation is the current flow. Cuadras
(1982) investigated the morphology and distribution of
microtrichs on the outer surface of different amphipod
species. Gammarus sp., Liljeborgia sp. and Orchomene sp.
are shown to have peg like microtrichs emerging from
cuticular pits of less than one micron(Cuadras 1982). The
pits of the Epimeria species are much larger, more than 30
microns in diameter (see Figs. 10b-e and 14b, d), more
complex in structure, they have a semicircle border, and the
setae or trich is positioned at the side, not middle of the pit.
However, the orientation of microtrichs that Cuadras (1982)
showed for Liljeborgia sp. is similar to the orientation of
the trichs in the pits observed for Epimeria. It is assumed
that water flow can lift the peg like units and, therefore,
they have a sensory function, e.g. for slow currents, or the
small cuticular ring surrounding the base of the trich could
register pressure when the trich is pressed against it.
Colour variations
Epimeriid amphipods are known to be very colourful when
alive and to have intraspecific colour morphs (e.g. Schnabel
and Hebert 2003; Coleman 2007;Lörzetal.2009). While
Schnabel and Hebert (2003) noted a colour-specific pattern
for clades of Paramphithoe hystrix separated by COI,28S
rRNA and allozymes differences, Lörz et al. (2007)noted
two different colour patterns, striped and dotted, in Epimeria
Fig. 15 Details of the fourth
coxal plate Epimeria aff
georgiana clade A and clade C.
aClade A NIWA 34945, b-e
clade C NIWA 34942. Scale
bars a,d,e,f:10μm; b,c:
100 μm
Mar Biodiv
schiaparelli specimens belonging to the same COI clade. Lörz
et al. (2009) also found different colour patterns in Epimeria
robusta specimens from the Ross Sea: white specimens with
red dots, specimens light red and specimens light red with
orange patches, all with an intraspecific variation <1%.
Photographs representing in situ colouration have to be
taken immediately after sampling, before the colour fades.
Colour is lost following fixation in ethanol or formaldehyde,
leading to uniformly whitish specimens. We only have colour
records for specimens in clade A and C (Fig. 12). Specimens of
Epimeria georgiana were coloured in different shades of red
that were not clade-specific. On-deck photographs (not
included here) showed specimens of the E.cf.georgiana
clade B to be dark red. Orange patterned Epimeria georgiana
specimens from the Antarctic Peninsula can be separated from
the whitish Epimeria angelikae new spec. based on colour in
live specimens The colour of E. georgiana from the type
locality was not recorded.
Conclusion
DNA barcoding performs well in species and taxa discrimi-
nation of epimeriid amphipods and has highlighted potentially
cryptic species. However, formal descriptions will only be
possible in combination with morphological investigations, as
demonstrated with a new species described here.
Acknowledgements We are grateful to the team at the Canadian
Centre for DNA Barcoding (supported by Genome Canada through the
Ontario Genomics Institute) for providing they sequences for the CAML
project. Angelika Brandt (Hamburg) kindly let the senior author use her
microscope. Renate Walter (Hamburg) helped with the scanning electron
microscopy. Erika Mackay (NIWA) kindly inked the drawings. Niamh
Kilgallen (NIWA) and three anonymous reviewers are thanked for
constructive criticism on an earlier version of the manuscript.
The Natural History Museums of Stockholm and London are thanked
for the loan of type material. The curational help of the NIWA Invertebrate
Collection (NIC) team is highly appreciated. A.N.L and P.S were
supported by research funded by the New Zealand Government under
the NZ International Polar Year-Census of Antarctic Marine Life Project,
and gratefully acknowledge the Ministry of Fisheries Science Team and
Ocean Survey 20/20 CAML Advisory Group (Land Information New
Zealand, Ministry of Fisheries, Antarctica New Zealand, Ministry of
Foreign Affairs and Trade, and National Institute of Water and
Atmospheric Research Ltd.). K.L. was funded by The Natural Environ-
ment Research Council. D.S. was supported by funding of the Alfred P.
Sloan Foundation to MarBOL. This study is part of the British Antarctic
Survey Polar Science for Planet Earth Programme and the NZ
International Polar Year-Census.
References
Allcock AL, Barratt I, Eleaume M, Linse K, Norman MD, Smith PJ,
Steinke D, Stevens DW, Strugnell J (2011) Cryptic speciation and
the circumpolarity debate: a case study on endemic Southern
Ocean octopuses using the COI barcode of life. Deep-Sea Res Pt
II 58:230241. doi:10.1016/j.dsr2.2010.05.016
Arango CP, Soler-Membrives A, Miller KJ (2011) Genetic differenti-
ation in the circum-Antarctic sea spider Nymphon australe
(Pycnogonida; Nymphonidae). Deep Sea Res Pt II58:212219.
doi: 10.1016/j.dsr2.2010.05.019
Barnard KH (1932) Amphipoda. Discov Rep 5:1326
Barnes DKA, Kaiser S, Griffiths HJG, Linse K (2009) The marine,
intertidal, fresh-water and terrestrial fauna of the South Orkney
Islands, Antarctica. J Biogeogr 36:756759
Boeck A (1871) Crustacea Amphipoda borealia et arctica Forhandliner I
Videnskabs-Selskabet I Christiana 1870:83280
Bradbury MR, Bradbury JH, Williams WD (1998) Scanning electron
microscope studies of rugosities, cuticular microstructures of
taxonomic significance of the Australian amphipod family
Neoniphargidae (Amphipoda). Crustaceana 71:603614
Bucklin A, Steinke D, Blanco-Bercial L (2011) DNA Barcoding of
Marine Metazoa. Ann Rev Mar Sci 3:18.11-18.38.
Buhay JE (2009) COI-likesequences are becoming problematic in
molecular systematic and DNA barcoding studies. J Crustac Biol
29(1):96110
Chu KH, Tong JG, Chan TY (1999) Mitochondrial cytochrome
oxidase I sequence divergence in some Chinese species of
Charybdis (Crustacea: Decapoda: Portunidae). Biochem Syst
Ecol 27:461468
Clarke A, Crame JA (1992) The Southern Ocean benthic fauna and
climate change: a historical perspective. Philos Trans R Soc Lond
B Biol Sci 338:99109
Clarke A, Crame JA (2010) Evolutionary dynamics at high latitudes:
speciation and extinction in polar marine faunas. Philos Trans R
Soc Biol Sci 365:36553666. doi:10.1098/rstb.2010.0270
Coleman CO (2003) Digital inking: how to make perfect line
drawings on computers. Org Divers Evo 3(Electr Suppl 14):114
Coleman CO (2007) Synopsis of the Amphipoda of the Southern
Ocean. Volume 2: Acanthonotozomellidae, Amathillopsidae,
Dikwidae, Epimeriidae, Iphimediidae, Ochlesidae and Vicmusiidae.
Bull Inst R Sci Nat Belg Biol 77:1134
Coleman CO (2009) Drawing setae the digital way. Zoosyst Evol 85
(2):305310
Costa FO, Carvalho GR (2007) The Barcode of Life Initiative:
synopsis and prospective societal impacts of DNA barcoding of
fish. Genom Soc Policy 3:2940
Cuadras J (1982) Microtrichs of amphipod Crustacea. Morphology
and distribution. Mar Behav Physiol 8:333343
Felsenstein J (1985) Confidence limits on phylogenies: an approach
using the bootstrap. Evol 39:783791
Folmer O, Black M, Hoeh W, Lutz R, Vrijenhoek R (1994) DNA
primers for amplification of mitochondrial cytochrome c oxidase
subunit 1 from diverse metazoan invertebrates. Mol Mar Biol
Biotech 3:294299
Grant RA, Linse K (2009) Barcoding Antarctic biodiversity: current
status and the CAML initiative, a case study of marine
invertebrates. Polar Biol 32(11):16291637. doi:10.1007/
s00300-009-0662-x
Grant RA, Griffiths HJ, Steinke D, Wadley V, Linse K (2011) Antarctic
DNA barcoding; a drop in the ocean? Polar Biol 34:775780.
doi:10.1007/s00300-010-0932-7
Griffiths HJ, Arango CP, Munilla T, McInnes SJ (2011) Biodiversity
and biogeography of Southern Ocean pycnogonids. Ecography
34:616627. doi:10.1111/j.1600-0587.2010.06612.x
Halcrow K, Bousfield EL (1987) Scanning electron microscopy of
surface microstructures of some Gammaridean amphipod crusta-
ceans. J Crustac Biol 7:274287
Havermans C, Nagy ZT, Sonet G, De Broyer C, Martin P(2011) DNA
barcoding reveals new insights into the diversity of Antarctic
species of Orchomene sensu lato (Crustacea: Amphipoda:
Mar Biodiv
Lysianassoidea). Deep-Sea Res Pt II 58:230241. doi: 10.1016/j.
dsr2.2010.09.028
Havermans C, Nagy ZT, Sonet G, De Broyer C, Martin P (2010)
Incongruence between molecular phylogeny and morphological
classification in amphipod crustaceans: a case study of Antarctic
lysianassoids. Mol Phylol Evo 55:202209
Hebert PDN, Cywinska A, Ball SL, DeWaard JR (2003a) Biological
identifications through DNA barcodes. Proc R Soc Lond Ser B
Biol Sci 270:313321. doi:10.1098/rspb.2002.2218
Hebert PDN, Ratnasingham S, deWaard JR (2003b) Barcoding animal
life: cytochrome c oxidase subunit 1 divergences among closely
related species. Proc R Soc Lond Ser B - Biol Sci 270:S96S99.
doi:10.1098/rsbl.2003.0025
Hebert PDN, Stoeckle MY, Zemlak TS, Francis CM (2004) Identifi-
cation of birds through DNA barcodes. PloS Biol 2:16571663.
doi:10.1371/journal.pbio.0020312
Held C (2003) Molecular evidence for cryptic speciation within the
widespread Antarctic crustacean Ceratoserolis trilobitoides
(Crustacea, Isopoda). In: Huiskes AH, Gieskes WW, Rozema J,
Schorno RM, van der Vies SM, Wolff WJ (eds) Antarctic biology
in a global context. Backhuys, Leiden, pp 135139
Held C, Leese F (2007) The utility of fast evolving molecular markers for
studying speciation in the Antarctic benthos. Polar Biol 30:513521
Hunter RL, Halanych KM (2008) Evaluating connectivity in the
brooding brittle star Astrotoma agassizii across the drake passage
in the Southern Ocean. J Hered 99:137148
Ivanova NV, deWaard JR, Hebert PDN (2006) An inexpensive,
automation-friendly protocol for recovering high-quality DNA.
Mol Ecol Notes 6:9981002
Kaïm-Malka RA, Maebe S, Macquart-Moulin C, Bezac C (1999)
Antennal sense organs of Natatolana borealis (Lilljeborg 1851)
(Crustacea: Isopoda). J Nat Hist 33(1):6588
Kaufmann RS (1994) Structure and function of chemoreceptors in
scavenging Lysianassoid amphipods. J Crustac Biol 14:5471
Khalaji-Pirbalouty V, Wägele J-W (2010) Two new species of Ligia
Fabricius, 1798 (Crustacea: Isopoda: Ligiidae) from the coasts of
the Persian and Aden gulfs. Org Divers Evol 10:135145.
doi:10.1007/s13127-010-0003-5
Krabbe K, Leese F, Mayer C, Tollrian R, Held C (2010) Cryptic
mitochondrial lineages in the widespread pycnogonid Colossendeis
megalonyx Hoek, 1881 from Antarctic and Subantarctic waters.
PolBiol33:281292. doi:10.1007/s00300-009-0703-5
Leese F, Kop A, Wägele J-W, Held C (2008) Cryptic speciation in a
benthic isopod from Patagonian and Falkland Island waters and the
impact of glaciations on its population structure. Front Zool 5:115
Leese F, Agrawal S, Held C (2010) Long-distance island hopping
without dispersal stages: transportation across major zoogeo-
graphic barriers in a Southern Ocean ispod. Naturwissenschaften
97:583594. doi:10.1007/s00114-010-0674-y
Linse K, Cope T, Lörz A-N, Sands C (2007) Is the Scotia Sea a centre
of Antractic marine diversification? Some evidence of cryptic
speciation in the circum-Antarctic bivalve Lissarca notorcadenis
(Arcoidea: Philobryidae). Pol Biol 30:10591068
Lörz A-N (2011) Pacific Epimeriidae (Amphipoda: Crustacea):
Epimeria. J Mar Biol Assoc UK 91:471-477
Lörz A-N, Maas EW, Linse K, Fenwick GD (2007) Epimeria schiaparelli
sp. nov., an amphipod crustacean (family Epimeriidae) from the
Ross Sea, Antarctica, with molecular characterisation of the species
complex. Zootaxa 1402:2337
Lörz A-N, Maas EW, Linse K, Coleman CO (2009) Do circum-
Antarctic species exist in peracarid Amphipoda? A case study in
the genus Epimeria Costa, 1851 (Crustacea, Peracarida, Epimer-
iidae). ZooKeys 18:91128
Meier R (2008) DNA sequences in taxonomy: opportunities and
challenges. In: Wheeler QD (ed) The new taxonomy. CRC Press/
Taylor and Francis, Boca Raton, pp 95128
Meier R, Zhang GY, Ali F (2008) The use of mean instead of smallest
interspecific distances exaggerates the size of the barcoding
gapand leads to misidentification. Syst Biol 57(5):809813.
doi:10.1080/10635150802406343
Meyer CP, Paulay G (2005) DNA barcoding: error rates based on
comprehensive sampling. PloS Biol 3(12):22292238.
doi:10.1371/journal.pbio.0030422
Meyran JC, Monnerot M, Taberlet P (1997) Taxonomic status and
phylogenetic relationships of some species of the genus Gammarus
(Crustacea, Amphipoda) deduced from mitochondrial DNA
sequences. Mol Phylogenet Evol 8:110
OLoughlin PM, Paulay G, Davey N, Michonneau F (2011) The
Antarctic region as a marine biodiversity hotspot for echino-
derms: diversity and diversification of sea cucumbers. Deep-Sea
Res Pt II 58:264275. doi:10.1016/j.dsr2.2010.10.011
Oshel PE, Steele DH (1988) Comparative morphology of amphipod
setae, and a proposed classification of setal types. Crustaceana
(Suppl 13):9099
Pearse JS, Mooi R, Lockhard S, Brandt A (2009) Brooding and
species diversity in the Southern Ocean: selection for brooders or
speciation within brooding clades? In: Krupnik I, Lang MA,
Miller SE (eds) Smithsonian at the poles: contributions to
International Polar Year science. Smithsonian Institution Scholarly
Press, Washington, pp 181196
Posada D (2008) jModelTest: phylogenetic model averaging. Mol Biol
Evol 25(7):12531256. doi:10.1093/molbev/msn083
Radulovici AE, Sainte-Marie B, Dufresne F (2009) DNA barcoding of
marine crustaceans from the Estuary and Gulf of St Lawrence: a
regional-scale approach. Mol Ecol Resour 9:181187
Radulovici AE, Archambault P, Dufresne F (2010) DNA barcodes for
marine biodiversity: moving fast forward? Diversity 2:450472.
doi:10.3390/d2040450
Ratnasingham S, Hebert PDN (2007) The Barcode of Life Data
System. Mol Ecol Notes 7:355364
Raupach MJ, Wagele JW (2006) Distinguishing cryptic species in
Antarctic Asellota (Crustacea: Isopoda)a preliminary study of
mitochondrial DNA in Acanthaspidia drygalskii. Antarct Sci
18:191198. doi:10.1017/s0954102006000228
Ronquist F, Huelsenbeck JP (2003) MrBayes 3: Bayesian phyloge-
netic inference under mixed models. Bioinforma 19:15721574.
doi:10.1093/bioinformatics/btg180
Schellenberg A (1931) Gammariden und Caprelliden des Magellangebietes,
Südgeorgiens und der Westantarktis. In: Odhner T (ed) Further
zoological results of the Swedish Antarctic Expedition 19011903,
Vol. 2, P.A. Norstedt, Stockholm, pp 1290, pl 291
Schnabel KE, Hebert PDN (2003) Resource-associated divergence in
the Arctic marine amphipod Paramphithoe hystrix. Mar Biol
143:851857. doi:10.1007/s00227-003-1126-4
Shearer TL, Coffroth MA (2008) Barcoding corals: limited by
interspecific divergence, not intraspecific variation. Mol Ecol
Resour 8:247255. doi:10.1111/j.1471-8286.2007.01996.x
Smith PJ, Steinke D, McVeagh SM, Stewart AL, Struthers CD,
Roberts CD (2008) Molecular analysis of Southern Ocean skates
(Bathyraja) reveals a new species of Antarctic skate. J Fish Biol
73:11701182
Smith PJ, Steinke D, McMillan P, Stewart AL, McVeagh SM, Astarloa
JD, Welsford D, Ward R (2010) DNA barcoding highlights a
cryptic species of grenadier (genus Macrourus) in the Southern
Ocean. J Fish Biol. doi:10.1111/j.1095-8649.2010.02846.x
Song H, Buhay JE, Whiting MF, Crandall KA (2008) Many species in
one: DNA barcoding overestimates the number of species when
nuclear mitochondrial pseudogenes are coamplified. Proceedings
of the National Academy of Sciences USA 105:1348613491
Steinke D, Zemlak TS, Hebert PDN (2009) Barcoding Nemo: DNA-
Based Identifications for the Ornamental Fish Trade. Plos One 4.
doi:10.1371/journal.pone.0006300
Mar Biodiv
Swofford DL (2003) PAUP*: phylogenetic analysis using parsimony
(*and other methods). Version 4. Sinauer Associates, Sunderland,
MA, United States
Tamura K, Dudley J, Nei M, Kumar S (2007) MEGA4: Molecular
evolutionary genetics analysis (MEGA) software version 4.0.
Mol Biol Evol 24(8):15961599. doi:10.1093/molbev/msm092
Thatje S, Hillenbrand CD, Larter R (2005) On the origin of Antarctic
marine benthic community structure. Trend Ecol Evol 20:534540
Vogler AP, Monaghan MT (2007) Recent advances in DNA taxonomy.
J Zool Syst Evol Res 45:110
Walker AO (1903) Amphipoda of the Southern CrossAntarctic
Expedition. J Linn Soc Lond Zool 29:386
Walker AO (1907) Crustacea III. Amphipoda. In: National Antarctic
Expedition 19011904, Natural History Vol 3, British Museum,
London pp 138, pls 113.
Ward RD, Zemlak TS, Innes BH, Last PR, Hebert PDN (2005) DNA
barcoding Australias fish species. Philos Trans R Soc Lond B
Biol Sci 360:18471857
Ward RD, Hanner R, Hebert PDN (2009) The campaign to DNA
barcode all fishes, FISH-BOL. J Fish Biol 74:329356.
doi:10.1111/j.1095-8649.2008.02080.x
Watling L, Thurston M (1989) Antarctica as an evolutionary
incubator: evidence from the cladistic biogeography of the
amphipod Family Iphimediidae. In: Crame J (ed) Origins and
evolution of the Antarctic biota. Geological Society, London.
Geol Soc Spec Publ 47:297313
Waugh J (2007) DNA barcoding in animal species: progress, potential
and pitfalls. Bioessays 29:188197. doi:10.1002/bies.20529
Wilson NG, Schroedl M, Halanych KM (2009) Ocean barriers and
glaciation: evidence for explosive radiation of mitochondrial
lineages in the Antarctic sea slug Doris kerguelenensis (Mollusca,
Nudibranchia). Mol Ecol 18:965984
Witt JDS, Threloff DL, Hebert PDN (2006) DNA barcoding reveals
extraordinary cryptic diversity in an amphipod genus: implica-
tions for desert spring conservation. Mol Ecol 15:30733082.
doi:10.1111/j.1365-294X.2006.02999.x
Zemlak TS, Ward RD, Connell AD, Holmes BH, Hebert PDN (2009)
DNA barcoding reveals overlooked marine fishes. Mol Ecol
Resour 9:237242. doi:10.1111/j.1755-0998.2009.02649.x
Zimmer A, Araujo PB, Bond-Buckup P (2009) Diversity and arrangement
of the cuticular structures of Hyalella (Crustacea: Amphipoda:
Dogielinotidae) and their use in taxonomy. Zoologia 26:127142
Mar Biodiv
... % K2P distances: three in the Scotia Arc area and one in the eastern Weddell Sea. This latter clade shows conspicuous morphological differences with the original description of E. georgiana and was therefore recently described as Epimeria angelikae Lörz & Linse, 2011. Aforementioned studies were carried out on a limited geographical scale and focused on one or a few Epimeria taxa. ...
... Only one of these new species (WA1) has a wider distribution, occurring also in the eastern Weddell Sea ( Fig. 4; map 3). One well-delineated species of the georgiana complex from the Adélie Coast (GE5) corresponds to the description of E. angelikae (type locality: eastern Weddell Sea) (Lörz et al. 2011). An additional well-delineated new species from the georgiana complex from the Adélie Coast (GE4) corresponds to the description of E. larsi Lörz, 2009. ...
... An additional well-delineated new species from the georgiana complex from the Adélie Coast (GE4) corresponds to the description of E. larsi Lörz, 2009. Similar to the study of Lörz et al. (2011), we found three georgiana clades in the Scotia arc area, which were here identified as putative new species: two in the Drake Passage (GE1, GE3), while GE1 is also found in the Bransfield Strait and northeastern Peninsula, and one on the plateau of the South Orkney Islands (GE2) ( Fig. 4; map 5). Two species were delimited within the E. inermis clade by the GMYC analysis (COI) and BPP, whereas the bPTP analyses of both gene trees identified a single species. ...
Article
Full-text available
The amphipod genus Epimeria is very speciose in Antarctic waters. Although their brooding biology, massive and heavily calcified body predict low dispersal capabilities, many Epimeria species are documented to have circum-Antarctic distributions. However, these distribution records are inevitably dependent on the morphological species definition. Yet, recent DNA evidence suggests that some of these Epimeria species may be complexes of species with restricted distributions. Mitochondrial COI and nuclear 28S rDNA sequence data were used to infer evolutionary relationships among 16 nominal Epimeria species from the Antarctic Peninsula, the eastern Weddell Sea and the Adélie Coast. Based on this phylogenetic framework, we used morphology and the DNA-based methods GMYC, bPTP and BPP to investigate species boundaries, in order to revise the diversity and distribution patterns within the genus. Most of the studied species appeared to be complexes of pseudocryptic species, presenting small and previously overlooked morphological differences. Altogether, 25 lineages were identified as putative new species, increasing twofold the actual number of Antarctic Epimeria species. Whereas most of the species may be geographically restricted to one of the three studied regions, some still have very wide distribution ranges, hence suggesting a potential for large-scale dispersal.
... Despite of extensive studies and description of numerous species over the last decade (e.g., Coleman 2007;Lörz et al. 2012), the genus Epimeria has proved to be much more specious than previously thought. Southern Oceans has been the focus of recent studies with the discovery of a large series of new species, a situation that suggested that "this region and its widely diversified Epimeriidae fauna could be of special interest for studying speciation and evolutionary patterns in Antarctic seas and world oceans" (d'Udekem d'Acoz & Verheye 2017). ...
Article
A single ovigerous female specimen of a new species of Epimeria Costa in Hope, 1851 was collected from deep sea, off southwestern Mexico, in the eastern Pacific. Epimeria karamani sp. nov., is most similar to females of E. cora J.L. Barnard, 1971, E. pacifica Gurjanova, 1995 and Epimeria morronei Winfield, Ortiz & Hendrickx, 2013. However, it differs from these species by: eyes long and slightly kidney-shaped; pleonite 3 strongly carinate, with dorsal tooth produced and acute; urosomite 1 with a wide mid-dorsal notch and a strong, upright blunt tooth; coxa 3 anterior margin slightly truncate and with two processes marginally; coxa 4 ventral margin linear, with facial granules and simple setae; gnathopods palm with distal bifid setae; telson straight medially, distal margin crenulate and with minute setae. The new species described herein increases the number of Epimeria species from the Pacific Ocean to 14, and from the eastern Pacific to three.
... Only recently this perspective started to change with a deeper appreciation of the heterogeneity and spatial complexity of the marine environment (Selkoe et al., 2016). Reports of deep genetic structure and cryptic diversity in the marine environment have been accumulating, with various examples comprising a taxonomically diverse set of marine amphipods from several regions of the globe (Radulovici et al., 2009;Havermans et al., 2011;Knox et al., 2011;Lörz et al., 2012;Cabezas et al., 2013;Yang et al., 2013;Raupach et al., 2015;Lobo et al., 2017). ...
Article
Amphipods of the genus Gammarus are a vital component of macrozoobenthic communities in European inland and coastal, marine and brackish waters of the Mediterranean and the Black Sea. Exceptional levels of cryptic diversity have been revealed for several widespread freshwater Gammarus species in Europe. No comprehensive assessment has yet been made for brackishwater counterparts, such as Gammarus aequicauda and G. insensibilis, which are among the most widely dispersed members of the so-called “G. locusta group” in the Mediterranean and in the Black Sea. Here we probe the diversity of these morphospecies examining the partitioning of mtDNA and nDNA across multiple populations along their distribution range and discuss it within the regional paleogeographic framework. We gathered molecular data from a collection of 166 individuals of G. aequicauda and G. insensibilis from 47 locations along their distribution range in the Mediterranean including the Black Sea. They were amplified for both mitochondrial COI and 16S rRNA as well as the nuclear 28S rRNA. All five MOTU delimitation methods (ABGD, BIN, bPTP, GMYC single and multiple threshold models) applied revealed deep divergence between Black Sea and Mediterranean populations in both G. aequicauda and G. insensibilis. There were eight distinct MOTUs delimited for G. aequicauda (6-18% K2P) and 4 MOTUs for G. insensibilis (4-14% K2P). No sympatric MOTUs were detected throughout their distribution range. Multimarker time-calibrated phylogeny indicated that divergence of both G. aequicauda and G. insensibilis species complexes started already in the late Oligocene/early Miocene with the split between clades inhabiting eastern and western part of the Mediterranean occurring in both species at the similar time. Our results indicate a high cryptic diversity within Mediterranean brackishwater Gammarus, similar to that observed for freshwater counterparts. Moreover, the phylogenetic history combined with the current geographic distribution indicate that the evolution of both studied Gammarus morphogroups has been strongly connected with the geological events in the Mediterranean Basin and it reflect the turbulent history of the area.
... The existence of species complexes and cryptic species has been observed in different isopod families, such as the Janiridae (Carvalho and Piertney 1997), Munnopsidae (Wilson 1982;Raupach and Wägele 2006), Parammunidae (Just and Wilson 2004), Haploniscidae (Brökeland and Raupach 2008;Brix et al. 2011), Serolidae (Held 2003;Leese et al. 2008), and Chaetiliidae (Held and Wägele 2005), potentially Desmosomatidae (Brix et al. 2014b), as well as in other peracarid crustaceans, for instance amphipods (Baird et al. 2011;Lörz et al. 2012;Havermans et al. 2013). Thus, overlooked morphologically similar species and the presence of cryptic speciation can lead to an underestimation of biodiversity (Vrijenhoek 2009). ...
Article
Eurycope producta Sars, 1868 and Eurycope inermis Hansen, 1916 are two widely distributed and highly abundant isopod species complexes within Icelandic waters, a region known for its highly variable environment. The two species complexes have bathymetric depth ranges from 103 to 2029 m (E. producta) and from 302 to 2113 m (E. inermis). Molecular evidence was used for species delimitation within these species complexes by analyzing nuclear (18S rDNA, H3) and mitochondrial (16S rDNA, COI) sequence data. Tree-based methods (BI and ML) and four species delimitation methods (ABGD, GMYC, NDT, PTP) were applied, in order to disentangle the two species complexes. A total of eight and four species clades could be identified within samples of the E. producta and E. inermis complexes and respectively included the closely related species E. dahli Svavarsson, 1987; E. hanseni Ohlin, 1901; and E. cornuta Sars, 1864. The morphological findings coincide with the observed molecular species clades. The elucidated species clades were geographically and bathymetrically much more restricted than previously assumed. Eight species clades featured depth spans of less than 400 m and only four species clades featured depth spans of 1000 to 1500 m. Only two species clades (E. producta sensu stricto and E. inermis sensu stricto) were found on both sides of the Greenland-Scotland Ridge. Further, species distribution maps were generated using random forest, to predict potential distributional patterns for the resolved species clades of the two species complexes. We present the first attempt of combining morphological, molecular, and species distribution models in marine isopods thus far.
... However, the assumption of monophyly was based on a previous COI phylogeny of Epimeria, comprising 17 Antarctic species, but only two non-Antarctic (New Zealand) species ). Yet, the genus is cosmopolitan, but particularly well represented in the Southern Ocean, with 26 described species out of a total of 54 worldwide (Coleman, 2007;Lörz, 2009;Lörz et al., 2007Lörz et al., , 2009Lörz et al., , 2011. Moreover, a recent study of COI and 28S sequence data identified 24 lineages as putative new Antarctic species, showing that the species richness of this genus on the shelf is still greatly underestimated (Verheye et al., 2016a). ...
Article
The Antarctic shelf's marine biodiversity has been greatly influenced by the climatic and glacial history of the region. Extreme temperature changes led to the extinction of some lineages, while others adapted and flourished. The amphipod genus Epimeria is an example of the latter, being particularly diverse in the Antarctic region. By reconstructing a time-calibrated phylogeny based on mitochondrial (COI) and nuclear (28S and H3) markers and including Epimeria species from all oceans, this study provides a temporal and geographical framework for the evolution of Antarctic Epimeria. The monophyly of this genus is not supported by Bayesian Inference, as Antarctic and non-Antarctic Epimeria form two distinct well-supported clades, with Antarctic Epimeria being a sister clade to two stilipedid species. The monophyly of Antarctic Epimeria suggests that this clade evolved in isolation since its origin. While the precise timing of this origin remains unclear, it is inferred that the Antarctic lineage arose from a late Gondwanan ancestor and hence did not colonize the Antarctic region after the continent broke apart from the other fragments of Gondwanaland. The initial diversification of the clade occurred 38.04 Ma (95% HPD [48.46 Ma; 28.36 Ma]) in a cooling environment. Adaptation to cold waters, along with the extinction of cold-intolerant taxa and resulting ecological opportunities, likely led to the successful diversification of Epimeria on the Antarctic shelf. However, there was neither evidence of a rapid lineage diversification early in the clade's history, nor of any shifts in diversification rates induced by glacial cycles. This suggests that a high turnover rate on the repeatedly scoured Antarctic shelf could have masked potential signals of diversification bursts.
... In some groups, morphological investigations support the distinction of previously unrecognized species that were identified with molecular data (e.g. [25][26][27][28][29]). ...
Article
Full-text available
Assessing the enormous diversity of Southern Ocean benthic species and their evolutionary histories is a central task in the era of global climate change. Based on mitochondrial markers, it was recently suggested that the circumpolar giant sea spider Colossendeis megalonyx comprises a complex of at least six cryptic species with mostly small and non-overlapping distribution ranges. Here, we expand the sampling to include over 500 mitochondrial COI sequences of specimens from around the Antarctic. Using multiple species delimitation approaches, the number of distinct mitochondrial OTUs increased from six to 15–20 with our larger dataset. In contrast to earlier studies, many of these clades show almost circumpolar distributions. Additionally, analysis of the nuclear internal transcribed spacer region for a subset of these specimens showed incongruence between nuclear and mitochondrial results. These mito-nuclear discordances suggest that several of the divergent mitochondrial lineages can hybridize and should not be interpreted as cryptic species. Our results suggest survival of C. megalonyx during Pleistocene glaciations in multiple refugia, some of them probably located on the Antarctic shelf, and emphasize the importance of multi-gene datasets to detect the presence of cryptic species, rather than their inference based on mitochondrial data alone.
... Both regions share 129 species, i.e., 23% of the Antarctic fauna or 31% of the sub-Antarctic fauna (De Broyer et al. 2007, updated). Moreover, in addition to ongoing identification of new records and taxonomic revisions of several genera, recent molecular studies revealed a number of cryptic species increasing the known species richness (e.g., Lörz et al. 2007Lörz et al. , 2011Lörz et al. , 2012Baird et al. 2011Baird et al. , 2012Havermans 2012, Havermans et al. 2010, 2011, 2013 and this trend should obviously continue. ...
... Both regions share 129 species, i.e., 23% of the Antarctic fauna or 31% of the sub-Antarctic fauna (De Broyer et al. 2007, updated). Moreover, in addition to ongoing identification of new records and taxonomic revisions of several genera, recent molecular studies revealed a number of cryptic species increasing the known species richness (e.g., Lörz et al. 2007Lörz et al. , 2011Lörz et al. , 2012Baird et al. 2011Baird et al. , 2012Havermans 2012, Havermans et al. 2010, 2011, 2013 and this trend should obviously continue. ...
... Both regions share 129 species, i.e., 23% of the Antarctic fauna or 31% of the sub-Antarctic fauna (De Broyer et al. 2007, updated). Moreover, in addition to ongoing identification of new records and taxonomic revisions of several genera, recent molecular studies revealed a number of cryptic species increasing the known species richness (e.g., Lörz et al. 2007Lörz et al. , 2011Lörz et al. , 2012Baird et al. 2011Baird et al. , 2012Havermans 2012, Havermans et al. 2010, 2011, 2013 and this trend should obviously continue. ...
Article
Full-text available
Members of the family Epimeriidae are reported in Australian waters for the first time and Epimeria rafaeli sp. nov. is described from deep water just south of the Abrolhos Island, Western Australia.
Article
Full-text available
A fast and accurate way for making perfect scientific illustrations is described. A pencil drawing or a photo is scanned. The resulting file is imported into Adobe Illustrator and the line drawing is made using a WACOM Intuous digitiser board. After the habitus and detailed drawings have been made, the plates can be arranged using the same software. Lettering and arrows can be placed very quickly on the plates. The plates can be exported as graphic files for printing or further manipulation.
Article
Full-text available
We summarize and evaluate explanations that have been proposed to account for the unusually high number of benthic marine invertebrate species in the Southern Ocean with nonpelagic development. These explanations are divided between those involving adaptation to current conditions in this cold-water environment, selecting for nonpelagic larval development, and those involving vicariant events that either exterminated a high proportion of species with pelagic development (the extinction hypothesis) or enhanced speciation in taxa that already had nonpelagic development. In the latter case, glacial maxima over the Antarctic Continental Shelf in the Pliocene/Pleistocene gla-cial cycles could have created refuges where speciation occurred (the ACS hypothesis), or the powerful Antarctic Circumpolar Current passing through Drake Passage for over 30 million years could have transported species with nonpelagic development to new habitats to create new species (the ACC hypothesis). We examine the distribution and phylogenetic history of echinoderms and crustaceans in the Southern Ocean to evaluate these different explanations. We could fi nd little or no evidence that nonpelagic development is a direct adaptation to conditions in the Southern Ocean. Some evidence supports the three vicariant hypotheses, with the ACC hypothesis perhaps the best predictor of observed patterns, both the unusual number of species with nonpelagic development and the notably high biodiversity found in the Southern Ocean.
Article
Full-text available
Although much biological research depends upon species diagnoses, taxonomic expertise is collapsing. We are convinced that the sole prospect for a sustainable identification capability lies in the construction of systems that employ DNA sequences as taxon 'barcodes'. We establish that the mitochondrial gene cytochrome c oxidase I (COI) can serve as the core of a global bioidentification system for animals. First, we demonstrate that COI profiles, derived from the low-density sampling of higher taxonomic categories, ordinarily assign newly analysed taxa to the appropriate phylum or order. Second, we demonstrate that species-level assignments can be obtained by creating comprehensive COI profiles. A model COI profile, based upon the analysis of a single individual from each of 200 closely allied species of lepidopterans, was 100% successful in correctly identifying subsequent specimens. When fully developed, a COI identification system will provide a reliable, cost-effective and accessible solution to the current problem of species identification. Its assembly will also generate important new insights into the diversification of life and the rules of molecular evolution.
Article
Epimeria schiaparelli sp. nov. from the Ross Sea, Antarctica, is described in detail. The new species occurs on the shelf in 130–350 m depth. Epimeria schiaparelli can be distinguished from the most similar species, E. similis Chevreux, 1912 and E. macrodonta Walker, 1906 by a relatively short rostrum and a short second pereonite amongst other characters. Two distinct colour patterns are reported. Partial gene sequences of the mitochondrial cytochrome oxidase subunit I (COI) from 11 specimens of E. schiaparelli confirm that this species is new to science and closely related to E. similis, E. macrodonta and E. reoproi. The recent and historical separation of this Antarctic species is discussed. The syntypes of E. macrodonta consist of two species, so a lectotype is here designated.