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First records, rediscovery and compilation of deep-sea
echinoderms in the middle and lower continental slope
of the Mediterranean Sea
Ariadna Mecho 1, David S.M. Billett 2, Eva Ramírez-Llodra 3, Jacopo Aguzzi 1, Paul A. Tyler 4,
Joan B. Company 1
1 Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta, 37-49, 08003 Barcelona, Spain.
E-mail: mecho@icm.csic.es
2 National Oceanography Centre, University of Southampton Waterfront Campus, European Way,
Southampton SO14 3ZH, UK.
3 Research Centre for Coast and Ocean, Norwegian Institute for Water Research (NIVA), Gaustadalléen 21,
N-0349 Oslo, Norway.
4 Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton SO14 3ZH, UK.
Summary: This study provides a compilation of all available information on deep-sea echinoderms from the middle and
lower slopes of the Mediterranean Sea, with the aim of providing a unified source of information on the taxonomy of this
group. Previous records of species are updated with new data obtained from 223 trawl hauls conducted in 11 cruises within
the northwestern Mediterranean Sea between 800 m and 2845 m depth. Valid names, bathymetric ranges and geographic dis-
tributions are given for all species. The new data report, for the first time, the presence of the Atlantic echinoid Gracilechinus
elegans (Düben and Koren, 1844) in the Mediterranean Sea. We also report the presence of the endemic holothurians Hed-
ingia mediterranea (Bartolini Baldelli, 1914), dredged only once previously in 1914 in the Tyrrhenian Sea, and Penilpidia
ludwigi (von Marenzeller, 1893), known previously only from three samples, two in the Aegean Sea and one in the Balearic
Sea. Additionally, the deeper limits of the bathymetric distribution of four species have been expanded: the asteroid Cera-
master grenadensis (Perrier, 1881) to 2845 m; the echinoid Brissopsis lyrifera (Forbes, 1841) to 2250 m; and the holothurians
Hedingia mediterranea and Holothuria (Panningothuria) forskali Delle Chiaje, 1823, to 1500 m and 850 m, respectively.
Keywords: deep-sea echinoderms; Mediterranean Sea; Gracilechinus elegans; submarine canyons; taxonomy; bathymetric
range.
Primera cita, redescubrimiento y recopilación de los equinodermos de profundidad en el talud continental medio e
inferior del Mediterráneo
Resumen: Este estudio presenta una recopilación de toda la información disponible sobre los equinodermos de profundidad
en el talud continental medio e inferior del mar Mediterráneo, con el fin de proporcionar una fuente de información unificada
sobre la taxonomía de este grupo. Se han actualizado los registros anteriores mediante nuevos datos provenientes de 223
pescas de arrastre de 11 campañas oceanográficas realizadas en el noroeste Mediterráneo entre 800 y 2845 m de profundi-
dad. Se ha actualizado el nombre de las especies, sus rangos batimétricos y sus distribuciones geográficas. Los nuevos datos
presentan, por primera vez, la presencia del equinoideo Atlántico Gracilechinus elegans (Düben and Koren, 1844) en el mar
Mediterráneo. También se cita la presencia en el noroeste Mediterráneo de dos especies de holoturias endémicas del Medite-
rráneo, Hedingia mediterranea (Bartolini Baldelli, 1914), muestreada una única vez en 1914 en el mar Tirreno, y Penilpidia
ludwigi (von Marenzeller, 1893), muestreada tres veces, dos en el mar Egeo y una en el mar Balear. Además se expanden
los límites de distribución batimétrica para cuatro especies: el asteroideo Ceramaster grenadensis (Perrier, 1881) hasta 2845
m; el equinoideo Brissopsis lyrifera (Forbes, 1841) hasta los 2250 m; y las holoturias Hedingia mediterranea y Holothuria
(Panningothuria) forskali Delle Chiaje, 1823, hasta los 1500 m y 850 m respectivamente.
Palabras clave: equinodermos de profundidad; mar Mediterráneo; Gracilechinus elegans; cañones submarinos; taxonomía;
rango batimétrico.
Citation/Como citar este artículo: Mecho A., Billett D.S.M., Ramírez-Llodra E., Aguzzi J., Tyler P.A., Company J.B.
2014. First records, rediscovery and compilation of deep-sea echinoderms in the middle and lower continental slope of the
Mediterranean Sea. Sci. Mar. 78(2): 281-302. doi: http://dx.doi.org/10.3989/scimar.03983.30C
Editor: X. Turon.
Received: November 8, 2013. Accepted: February 21, 2014. Published: May 29, 2014.
Copyright: © 2014 CSIC. This is an open-access article distributed under the Creative Commons Attribution-Non Com-
mercial Lisence (by-nc) Spain 3.0.
Scientia Marina 78(2)
June 2014, 281-302, Barcelona (Spain)
ISSN-L: 0214-8358
doi: http://dx.doi.org/10.3989/scimar.03983.30C
282 • A. Mecho et al.
SCI. MAR., 78(2), June 2014, 281-302. ISSN-L 0214-8358 doi: http://dx.doi.org/10.3989/scimar.03983.30C
INTRODUCTION
The deep Mediterranean Sea has a wide variety of
geological and ecological settings. Their faunal com-
position and local biodiversity are largely unknown
(Danovaro et al. 2010). The western Mediterranean
deep basin is no exception. It has a complex assem-
blage of markedly different habitats (Sardà et al. 2004),
including sedimentary slopes, submarine canyons and
seamounts (Company et al. 2012). The specific geo-
morphological characteristics of these habitats (e.g. the
elevation of seamounts, the walls and axes of the sub-
marine canyons and the inclination of the continental
slopes) and associated abiotic processes (e.g. variation
in oceanographic currents, hard vs. soft substratum
and food availability) result in large-scale heterogene-
ity of the continental margin seafloor (Carpine 1970,
Emig 1997, D’Onghia et al. 2003). This high habitat
heterogeneity plays a major role in the establishment
and maintenance of diverse faunal communities (Levin
et al. 2010), which, to date, are still largely unexplored
in the deep Mediterranean Sea (Bienhold et al. 2013,
Mecho et al. 2014).
The shallow Mediterranean marine fauna inhabit-
ing the shelf and upper slope areas have been studied
since ancient times. Consequently, they are relatively
well known at many levels (taxonomic, ecological, and
biological) (Riedl 1986, Bolam et al. 2002, Danovaro
and Pusceddu 2007, Coll et al. 2010). Nevertheless,
because of the difficulties in sampling the deep sea,
the bathyal and abyssal fauna of the Mediterranean Sea
remains poorly studied (Pérès and Picard 1956a, Fredj
1974, Galil and Goren 1995, Danovaro et al. 2010,
Tecchio et al. 2011a,b).
The description of the benthic fauna occurring
deeper than 800 m in the Mediterranean started in the
19th century. Cruises carried out by the RN Washing-
ton (1881-1882) and SMS Pola (1890-1898) provided
the first extensive descriptions of bathyal and abyssal
Mediterranean fauna (Marenzeller 1893, Bartolini
Baldelli 1914), including many new species of non-
crustacean invertebrates. From the late 1920s to the
1960s the number of deep-sea Mediterranean research
cruises decreased, resulting in limited new informa-
tion (Pérès and Picard 1956a,b, Pérès 1958). Since the
late 1970s, improvements in sampling methods and
equipment have allowed a second period of deep-sea
scientific exploration and investigation below 1000 m
depth, conducted by ships such as the Bambu, Mango,
and Ruth Ann in Italian waters, the RV Jean Charcot
in the Alboran Sea, and the RV Garcia del Cid in the
Balearic Sea.
Specimens collected by these expeditions have
stimulated a number of publications and new records
of species (Carpine 1970, Parenzan 1970, Reyss
1971, Fredj 1974). However, most of this deep-sea
literature focuses on the dominant groups such as
fishes and crustaceans, the commercial use of Medi-
terranean marine resources, and the management of
these resources (Sardà et al. 1994, 2004, Moranta et
al. 1998, Company et al. 2004, Aguzzi et al. 2009,
Bahamon et al. 2009). Thus, both fish and crustaceans
are well known taxonomically in comparison with
other megafaunal groups, such as ascidians, sponges,
echinoderms, sipunculans and echiurans (Monniot
and Monniot 1975, Alvà 1987a, Uriz and Rosell 1990,
Villanueva 1992, Pancucci-Papadopoulou et al. 1999,
Quetglas et al. 2000).
In this context, Mediterranean Echinodermata
from middle and lower slopes have been poorly
studied, particularly in comparison with the Atlantic
Ocean, where echinoderms are important in terms
of abundance, biomass and ecosystem function (Bil-
lett 1991). The large number of investigations con-
ducted in the Atlantic Ocean have resulted in a good
taxonomic knowledge of the echinoderms (Mortensen
1903, 1927, 1943, Koehler 1921, 1927, Hérouard
1923, Hyman 1955, Sibuet 1979, Borrero Perez et
al. 2003, among others). In contrast, there have only
been a few studies on the taxonomy of Mediterranean
deep-sea echinoderms (Marenzeller 1893, Bartolini
Baldelli 1914, Tortonese 1954, 1965, Sibuet 1974,
Alvà 1987b). Most reports provide only species lists;
morphological descriptions are of secondary impor-
tance (Cherbonnier and Guille 1967, Alvà 1987a,
1991, Koukouras et al. 2007) or totally absent (Tor-
tonese 1958, 1972, 1979, Pérez-Ruzafa and López-
Ibor 1988, Rinelli 1998, Coll et al. 2010).
It is in this context of dispersed and relatively
scarce information that we have undertaken a study of
all bathyal echinoderms, including samples collected
in the last five years in the northwestern Mediterra-
nean in the framework of four different projects. New
records of species and their bathymetric distributions
have been added to provide a thorough review of ex-
isting data and an updated account of the taxonomy,
geographical and bathymetrical distribution of bathyal
echinoderms in the Mediterranean Sea.
MATERIALS AND METHODS
New echinoderm samples
Ten oceanographic cruises were conducted between
October 2008 and April 2013 to sample the deep sea-
floor of the western Mediterranean Sea. The sampling
areas included the Blanes Canyon and its adjacent open
slope, the Palamós Canyon (also named La Fonera)
and the Cap de Creus Canyon (Fig. 1). These cruises
took place in the framework of three Spanish research
projects (PROMETEO, DOSMARES, and PRO-
MARES) sampling at depths between 850 and 2845 m.
Additionally, a trans-Mediterranean cruise took place
in the context of the European project BIOFUN (Eu-
roDEEP Eurocores, European Science Foundation) in
July 2009. This cruise sampled the western, central and
eastern Mediterranean basins at 1200, 2000 and 3000
m depth. In addition, a 4000-m depth station was sam-
pled in the central basin. However, because of the low
number of echinoderms collected in the central and
eastern basins (n=2), only the western Mediterranean
samples were used in the present study (Fig. 1).
A total of 223 deployments were completed (Table
1), resulting in a total swept area of 10.3 km². Of these
Deep-sea Mediterranean echinoderms • 283
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hauls, 119 samples were obtained by a single-warp
otter-trawl Maireta system (OTMS, Sardà et al. 1998)
with a net length of 25 m and a cod-end mesh size of
40 mm. A SCANMAR system was used to estimate the
width of the net mouth. An average horizontal open-
ing of 12.7±1.4 m was calculated. As the SCANMAR
system can only operate down to 1200 m depth, the
same value for the net mouth width was used also for
deployments deeper than 1200 m. The height of the
trawl mouth was estimated to be 1.4 m (Sardà et al.
1998). In addition, 49 hauls were conducted with an
Agassiz dredge made of a square steel frame with a
mouth width of 2.5 m and a mouth height of 1.2 m, and
fitted with a 12-mm mesh net. Further, 55 samples were
obtained with an epibenthic sledge, which consisted of
a rectangular steel frame with three nets attached at dif-
ferent heights (10-50 cm, 55-95 cm and 100-140 cm
above the bottom) with a mesh size of 300 µm (only
one epibenthic sledge sample contained echinoderms).
Faunal samples were also obtained from 15 bottles
in five different sediment traps deployed in the Blanes
Canyon axis from November 2008 to February 2009,
four of them at 1200 m and one at 1500 m depth. All
were deployed at 22 m above the bottom.
Fig. 1. – Study area. Areas sampled on the cruises PROMETEO, DOSMARES and PROMARES to the Blanes Canyon, Palamós Canyon, Cap
de Creus Canyon and the adjacent open slope.
Table 1. – Number of benthic trawls and dredges used in the present study by depth and geomorphological area. Canyon area (including La
Fonera, Cap de Creus and Blanes canyons). A.C, Agassizz trawl sampled on Canyon area; OTMS.C, otter-trawl Maireta system sampled on
Canyon area; ES.C, epibenthic sledge sampled on Canyon area; A.O.S, Agassizz trawl sampled on open slope; OTMS.O.S, otter-trawl Maireta
system sampled on open slope; ES.O.S, epibenthic sledge sampled on open slope.
Depth Canyon Open slope Total
A.C OTMS.C ES.C A.O.S OTMS.O.S ES.O.S
850 1100002
900 4 1 2 7 18 7 39
1050 0 0 0 5 10 5 20
1200 2 0 1 9 21 10 43
1350 0 0 0 3 11 5 19
1500 6 8 3 5 18 11 51
1750 0 0 1 2 8 3 14
2000 0 0 1 2 12 3 18
2250 1 2 1 1 4 2 11
28500001506
Total 14 12 9 35 107 46 223
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Finally, video-observations were made during the
PROMARES cruise using the remotely operated ve-
hicle (ROV) Liropus 2000. Thirty six video transects
were conducted along the axes of the Blanes, Palamós
and Cap de Creus canyons between depths of 300 and
1800 m.
A total of 1503 individuals belonging to 11 species
were sampled (Table 2). Of these, 196 were asteroids,
494 echinoids and 813 holothurians. The classes Cri-
noidea and Ophiuroidea were absent from all samples.
Specimen identification
The echinoderms were sorted, weighed, counted
and fixed with 40% formalin diluted with seawater and
neutralized with borax on board ship. After 30 days,
the samples were transferred to 70% alcohol in the lab-
oratory for further examination. Some specimens were
fixed in absolute ethanol on board to allow for molecu-
lar analyses (not included in this study). All specimens
are stored in the Biological Reference Collection of the
Institute of Marine Science, Barcelona (Spain).
In the laboratory, all specimens were classified to
species level. For microscopic examination of holo-
thurian spicules, small pieces of soft tissue (i.e. skin,
tentacles and gonads) were dissolved in bleach solu-
tion and mounted on glass slides for identification. The
taxonomic results were compared with previous taxo-
nomic studies. The nomenclature was checked against
the World Register of Marine Species (WoRMS). The
identification of the echinoid Gracilechinus elegans
(Düben and Koren, 1844) was based on taxonomic de-
scriptions from the Atlantic Ocean (Mortensen 1903,
1927, 1943, Koehler 1927, Minin 2012). This species
has not been cited previously in the Mediterranean Sea.
Its geographic distribution was compared with data in
the Atlantic Ocean and other echinoid records from the
Mediterranean Sea.
Synthesis of taxonomic information on deep-sea
Mediterranean echinoderms
A comprehensive table was created of all the echi-
noderms present in the Mediterranean Sea and cited
in the literature as having a maximum depth of oc-
currence below 800 m (see Table 3). This table was
constructed based on Tortonese (1965) and Koukouras
(2007). New data acquired during the PROMETEO,
DOSMARES and PROMARES cruises was added (see
above).
RESULTS
Class ASTERIODEA de Blainville, 1830
Two species of Asteroidea were collected in our
study: Ceramaster grenadensis (Perrier, 1881) (n=149)
Table 2. – Echinoderms sampled in the present study from the deep Mediterranean Sea. * 19 specimens of P. ludwigi were collected in sedi-
ment trap samples in the Blanes Canyon.
Species N. sampled N total Depth of occurrence (m)
Open slope Canyon
ASTEROIDEA
Ceramaster grenadensis (Perrier, 1881) 146 3 149 850-2845
Hymenodiscus coronata (G.O. Sars, 1872) 31 16 47 1500-2250
ECHINOIDEA
Gracilechinus elegans (Danielssen and Koren, 1883) 0 7 7 1500
Brissopsis lyrifera (Forbes, 1841) 5 482 487 900-2250
HOLOTHUROIDEA
Mesothuria (Allantis) intestinalis (Ascanius, 1805) Östergren, 1896 52 4 56 900-1750
Pseudostichopus occultatus von Marenzeller 1893 474 0 474 2000-2250
Holothuria (Panningothuria) forskali Delle Chiaje, 1823 0 1 1 850
Molpadia musculus Risso, 1826 25 0 25 900-1050
Hedingia mediterranea (Bartolini Baldelli, 1914) Tortonese, 1965 1 10 11 900-1500
Penilpidia ludwigi (von Marenzeller, 1893) 200 19* 219 900 -1500
Ypsilothuria bitentaculata (Ludwig, 1893) 27 0 27 900-1350
Total number of echinoderms collected 961 542 1503 850-2845
Fig. 2. – Bathymetric distribution and densities of echinoderms
sampled in present study. The top and bottom of each box-plot
represent 75% (upper quartile) and 25% (lower quartile) of all val-
ues, respectively. The horizontal line is the median. The ends of
the whiskers represent the 10th and 90th percentiles. Cross marks
represent means and blue spots maximum and minimum depth of
occurrence. Species codes: Hol_for, Holothuria (Panningothuria)
forskali; Mol_mus, Molpadia musculus; Pen_lud, Penilpidia lud-
wigi; Yps_bit, Ypsilothuria bitentaculata; Hed_med, Hedingia
mediterranea; Mes_int, Mesothuria (Allantis) intestinalis; Gra_ele,
Gracilechinus elegans; Bri_lyr, Brissopsis lyrifera; Cer_gre,
Ceramaster grenadensis; Hym_cor, Hymenodiscus coronata; and
Pse_occ, Pseudostichopus occultatus.
Deep-sea Mediterranean echinoderms • 285
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and Hymenodiscus coronata (G.O. Sars, 1872) (n=47).
Both are bathyal species. Ceramaster grenadensis
sampled in the present study has a wide bathymetric
range (850 to 2845 m, Fig. 2). The second species,
Hymenodiscus coronata shows a narrower bathymetric
range (1500 to 2250 m; Fig. 2).
Order VALVATIDA Perrier, 1884
Family GONIASTERIDAE Forbes, 1841
Genus Ceramaster Verrill, 1899
Ceramaster grenadensis (Perrier, 1881)
(Fig. 3)
Pentagonaster deplasi Perrier, 1885: 34.
Pentagonaster gosselini Perrier, 1885: 35.
Pentagonaster haesitans Perrier, 1885: 36.
Ceramaster grenadensis Halpern, 1970: 213-218, Figs. 8-9.
Material: 149 specimens collected during the PROMETEO 01-02-
03-04-05, BIOFUN, PROMARES and DOSMARES 01-02-03-04
cruises. Depth of occurrence: from 850 to 2845 m. Zones: western
Mediterranean Sea open slope, Blanes Canyon, Cap de Creus Can-
yon (Table 2).
Description: Shape pentagonal to stellate, very
variable (Fig. 3A, B). Body flattened dorso-ventrally.
Oral and aboral surface composed by more or less tab-
ulate hexagonal plates covered by little granules. Mar-
ginal plates thick and massive, from 18 to 22; sampling
methods could remove them. R=6 to 45 mm. r=3 to
25 mm. R/r=1.54 to 2.53. Colour variable, from cream,
pale-yellow to pale pink. Polygonal madreporite, well
defined, larger than surrounding plates. Adambulacral
plate with 4 to 6 furrow spines, outside these a series of
usually four club-shaped spines and outer spines simi-
lar to internal ones. Pedicellariae valvate, scarce on
aboral side, larger and more numerous on oral side near
ambulacral furrow. One of the specimens collected in
the present study had six arms (Fig. 3C)
Distribution: Atlantic Ocean and Mediterranean
Sea (Clark and Downey 1992).
New depth range: 200-2845 m (present study). The
previous reported maximum depth of distribution for
this species was 2500 m in the Atlantic Ocean (Clark
and Downey 1992). The previous Mediterranean Sea
bathymetric range was 600-2400 m (Tortonese 1972).
Remarks: Similarities were observed between the
genus Litonotaster described by Halpern (1969, 1970).
However, owing to 1) the absence of the characteristic
flat and thin abactinial plates of the genus Litonotaster,
and 2) the presence of tabulate abactinial plates cov-
ered by granules, the marginal plate disposition, and
in agreement with available literature, we consider
our specimens to be Ceramaster grenadensis. Litono-
taster has not been reported in the Mediterranean Sea.
Great intraspecific morphological variations have been
signalled for Ceramaster grenadensis in the Mediter-
ranean (Halpern 1970, Tortonese 1972, Sibuet 1974,
Alvà 1987a). It is likely that a revision of the genus
Ceramaster is needed.
Order BRISINGIDA Fisher, 1928
Family BRISINGIDAE G.O. Sars, 1875
Genus Hymenodiscus Perrier, 1884
Hymenodiscus coronata (G.O. Sars, 1872)
(Fig. 4)
Brisinga coronata Sars, 1873: 102
Brissingella coronata Tortonese, 1965: 194-196, Fig. 93.
Material: 47 specimens collected during cruises PROMETEO
05, BIOFUN and DOSMARES 01-02. Depth of occurrence: from
1500 to 2250 m. Zones: western Mediterranean Sea open slope and
Blanes Canyon (Table 2).
Fig. 3. – Ceramaster grenadensis. A, dorsal view; B, ventral view (Photo: A. Bozzano, ICM-CSIC); C, specimen with six arms.
Fig. 4. – Hymenodiscus coronata.
286 • A. Mecho et al.
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Description: Diameter of disc 11 mm; from 9 to 13
long and slender arms. Colour orange to reddish. Very
difficult to collect intact, usually the disc and the arms
are broken and separate (Fig. 4). Madreporite large,
channelled. Gonadal region slightly to highly inflated.
Abactinal arm plates rod-like. Two to four tiny, ac-
icular furrow spines and one to two moderately long
subambulacral ones.
Distribution: North Atlantic and Mediterranean Sea
(Alvà 1987a).
Depth range: 100-2904 m (Bartolini Baldelli 1914).
Remarks: Description taken from (Clark and
Downey 1992).
Class ECHINOIDEA Leske, 1778
Only two sea urchin species were sampled: the
regular echinoid Gracilechinus elegans (Düben and
Koren, 1844) (n=7) and the irregular echinoid Bris-
sopsis lyrifera (Forbes, 1841) (n=487). Gracilechinus
elegans, known in the Atlantic, has been reported for
the first time in the Mediterranean Sea in the present
study. It was sampled in the Blanes Canyon at 1500
m depth (Fig. 2). Other specimens were observed and
collected with the ROV during the PROMARES cruise
(Mecho, pers. obs.) in the lower Palamós Canyon and
Blanes Canyon areas (1500 m). Brissopsis lyrifera was
found over a wide bathymetric range in the present
study (from 900 to 2250 m; Fig. 2). It was abundant in
some canyons between 900 and 1500 m (Table 2). In
contrast, only five small specimens of B. lyrifera were
collected on the open slope at depths between 1750 and
2250 m (Table 2).
Order CAMARODONTA Jackson, 1912
Family ECHINIDAE Gray, 1825
Genus Gracilechinus Fell and Pawson,
in Moore, 1966
Gracilechinus elegans (Düben and Koren, 1844)
(Fig. 5)
Echinus elegans Düben and Koren, 1844: 272. Koehler, 1927: 51-
53, pl. XII, Fig. 12 a-g; pl. XVII, Fig. 5
Material: 7 specimens from cruises PROMETEO 04, PROMARES
and DOSMARES 04. Depth of occurrence: 1500 m. Zones: Blanes
Canyon and Palamós Canyon (Table 2).
Description: Diameter test 38.5 to 48.3 mm; h=25.6
to 34.7mm. Test low, from conical and flattened above
to slightly flattened on both sides, usually the height of
the test is more than half the diameter (Fig. 5A). Col-
our whitish pink to pink, sometimes a few green (Fig.
5B, C). Long primary spines usually flat at the end.
One primary tubercle present on each plate, forming
a very regular series from oral to aboral side; usually
secondary ones form a short longitudinal series from
the middle to the oral side. A small tubercle is present
between the pores and the primary tubercle, but not be-
tween the pores and the end of the plate. Some miliary
tubercles are present, giving a rough appearance to the
test. Three pairs of pores very clear and disposed in a
sharp angle. The boundary between the areas was more
straight than sinuous. Periproct (Fig. 5D) covered by
large irregular plates, one of them with a spine. The
plates surrounding the anus are irregularly club-shaped
and smaller than the other plates. Ocular plates not in
contact with the periproct. No spines on the buccal
plates, where pedicellariae were present and abundant.
Tridentate pedicellariae have the valves flat, narrow
and mesh-worked, with the edge sinuate (500 to 650
µm long). In some cases small individuals had flatter
valves than larger individuals (Fig. 5E). These valves
have a narrow area near the base (Fig. 5F). Globiferous
pedicellariae (500 to 550 µm) usually have 1 or 2 lat-
eral teeth on either side of the blade and a more or less
round to rectangular shape (Fig. 5G-I). Ophicephalus
pedicellariae, broad, sinuate and with small teeth in the
edge, and an intricate mesh-work.
Distribution: North Atlantic (OBIS). First record in
the Mediterranean Sea.
Depth range: 50-1710 m. (Mortensen 1943, Minin
2012). Only reported at 1500 m depth in the Mediter-
ranean Sea (present study).
Remarks: Mortensen (1903) reported this spe-
cies from the Mediterranean, but he later discarded
this identification (Mortensen 1943). Alvà (1987b)
described another species, Gracilechinus alexandri,
in the Mediterranean Sea. Both G. elegans and G.
alexandri have many similar characteristics, making
their true identification difficult (Mortensen 1903,
Ramírez-Llodra and Tyler 2006, Minin 2012). Fur-
thermore, juvenile G. alexandri have characteristics
that might be confused with G. elegans. It is possible
that the specimen of G. alexandri reported by Alvà
(1987b) was a juvenile and was a misidentification
of G. elegans. The specimen is no longer available
for comparison. In our specimens, the presence of
one or two teeth on the globiferous pedicellariae,
their narrow base and their mesh-work are similar
to those described in the literature (Mortensen 1903,
Minin 2012). The tubercular pattern, the periproct,
the shape of the ocular and genital plates and their
disposition allowed us to classify these specimens as
G. elegans. Mortensen (in 1903, p. 144, pl. XX, Fig.
9) found a small form for G. elegans with tridentate
pedicellariae that had more flattened and truncate
blades without mesh-work. This characteristic and
the overlapping range in the number of teeth in the
globiferous pedicellariae (1 to 4 in G. elegans and 2
to 5 in G. alexandri) could lead to a misidentification
if only one individual was available, as appears to be
the case in Alvà (1987b).
Order SPATANGOIDA Agassiz, 1840a
Family BRISSIDAE Gray, 1855
Genus Brissopsis Agassiz, 1847
Brissopsis lyrifera (Forbes, 1841)
(Fig. 6)
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Brissus lyrifeer Forbes, 1841: 187
Brissopsis lyrifera Tortonese 1965: 372-374
Material: 487 specimens from cruises PROMETEO 02-04-05,
PROMARES and DOSMARES 01-03. Depth of occurrence: 900
to 2250 m. Zones: western Mediterranean Sea open slope, Blanes
Canyon, Cap de Creus Canyon and Palamós Canyon (Table 2).
Description: Body oval, arched, sloping anteriorly.
Colour from yellow to red-brown with a narrow band
of ciliated dark spines which rings all five ambulacra
petals on the upper surface (Fig. 6A, B). Anterior am-
bulacral zone slightly depressed. Periproct terminal,
near aboral zone. Posterior petals shorter than the an-
terior ones, diverging and well separated. Globiferous
pedicellariae short, ending in two long teeth. Triden-
tate pedicellariae of various forms, with three more or
less leaf-shaped blades. Rostrate pedicellariae blade
slender.
Distribution: Atlantic and Mediterranean Sea
(OBIS).
New depth range: 200-2845 m (present study). The
previous reported maximum depth of distribution for
this species was 1650 m in the Atlantic Ocean (OBIS).
Previous Mediterranean maximum depth was 1500 m
(Tortonese 1965).
Remarks: Differences from Brissopsis atlantica med-
iterranea (Mortensen 1913) are evident in the posterior
Fig. 5. – Gracilechinus elegans. A, test; B, oral view; C, aboral view; D, periproct structure; E, F, tridentate pedicellariae; G, H, globiferous
pedicellariae; I, globiferous pedicellariae, detail of teeth.
Fig. 6. – Brissopsis lyrifera A, oral view; B, ventral view (Photo
from A. Bozzano).
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petals: diverging and well separated in B. lyrifera and
confluent on the base, as opposed to nearly parallel in B.
atlantica mediterranea (Lacour and Néraudeau 2000).
Class HOLOTHUROIDEA de Blainville, 1834
The Holothuroidea was the most abundant echino-
derm class sampled in this study, with a total of 813
specimens and 7 species (Table 2). Three species be-
longing to the order Aspidochirotida were collected:
Mesothuria (Allantis) intestinalis, (Ascanius, 1805)
Östergren, 1896 (n=56), Pseudostichopus occultatus,
Marenzeller 1893 (n=474) and Holothuria (Panningo-
thuria) forskali, Delle Chiaje, 1823 (n=1).
In the present study, Mesothuria intestinalis had a
bathymetric range between 900 and 1750 m depth (Fig.
2). In contrast Pseudostichopus occultatus had a very
narrow depth range (2000 to 2250 m; Fig. 2). This spe-
cies was sampled only in open slope areas. Although
one individual was collected at 2250 m depth in the
Blanes Canyon, we consider this as a residual sample,
based on the high number of specimens collected in the
previous catch, the bad condition of the specimen and
the absence of this species in other trawls conducted at
this depth in the canyon. This species was sampled in
great numbers at 2250 m (maximum of 145 individu-
als) (Table 2). Only one individual of H. forskali was
sampled (850 m in the Blanes Canyon).
The order Molpadiida was represented by two spe-
cies: Molpadia musculus, Risso, 1826 (n=25) and Hed-
ingia mediterranea (Bartolini Baldelli, 1914) Tortonese,
1965 (n=11). Molpadia musculus had a bathymetric
range between 900 and 1050 m depth (Fig. 2) and was
sampled only on the open slope. Hedingia mediterranea
had a bathymetric range between 900 and 1500 m (Fig.
2) and was sampled mainly in canyon areas.
The order Elasipodida was represented by one
species Penilpidia ludwigi (von Marenzeller, 1893)
(n=219). The bathymetric distribution of this species
ranged from 900 to 1500 m. Most of the individu-
als (n=200; Table 2) were sampled by the epibenthic
sledge at a single open slope site in the western
Mediterranean Sea at 900 m depth. A few individuals
(n=19) were reported from sediment trap samples lo-
cated in the Blanes Canyon at 1200 and 1500 m depth
(Fig. 2).
The order Dactylochirotida was represented by a
single species: Ypsilothuria bitentaculata (Ludwig,
1893) (n=27). This species was distributed in the pre-
sent study between 900 and 1350 m depth (Fig. 2) and
was sampled only in an open slope area (Table 2).
Order ASPIDOCHIROTIDA
Family Synallactidae Ludwig, 1894
Genus Mesothuria Ludwig, 1894
Subgenus Allantis Heding, 1942
Mesothuria (Allantis) intestinalis (Ascanius, 1805)
Östergren, 1896
(Fig. 7)
Holothuria intestinalis Ascanius 1805: 5, pl. 45
Mesothuria intestinalis Gebruk 2012: 291-391, Fig.1-9C, D
Material: 56 specimens were collected during cruises PROMETEO
02-03-04-05, BIOFUN and PROMARES. Depth of occurrence: 900
to 1750 m. Zones: western Mediterranean Sea open slope, Blanes
Canyon and Cap de Creus Canyon (Table 2).
Description: Large species, up to 30 cm long (Koe-
hler 1927). Body nearly cylindrical with both ends
flattened (Fig. 7A). Mouth subventral surrounded by
20 peltate tentacles. Scattered small tube feet all over
the body, more abundant near the anterior and posterior
ends. Dermis usually covered by shells, skin very frag-
ile and thin in fresh specimens. On preservation, the
dermis becomes thicker and more wrinkled. Character-
istic ossicles are round tables (±100 µm), more or less
regular with small peripheral holes around a central
hole, and with central spire built by four rods, ending
in a crown of several thorns (Perrier 1898) (Fig. 7B, C).
Hermaphroditic species (Hyman 1955), gonads consti-
tuted by one branched tuft attached to left side of the
dorsal mesentery, with some tubules male and some
female, not found ripe at the same time (Mortensen
1927). Two respiratory trees, gelatinous and transpar-
ent. The species produces a substance which gels in
formaldehyde and alcohol when preserved. Specimens
usually eviscerate during capture.
Distribution: Mediterranean Sea, North Atlantic
and West Indian seas (Gebruk et al. 2012).
Depth range: 18-2000 m (Gebruk et al. 2012). Medi-
terranean depth range 20 to 1927 m (Cartes et al. 2009).
Remarks: The presence of a second Mesothuria
species of the genus in the Mediterranean Sea, Meso-
thuria verrilli (Théel, 1886), was discarded by Gebruk
et al. (2012).
Genus Pseudostichopus Ludwig, 1894
Pseudostichopus occultatus Marenzeller 1893
(Fig. 8)
Pseudostichopus occultatus Marenzeller, 1893a: 15-17, pl. 4, Fig. 9.
O’Loughlin, 2005: 173-174.
Fig. 7. – Mesothuria (Allantis) intestinalis characteristic. A, general
view; B, ossicle crown with several thorns; C, ossicle plates with
four rods and central spire.
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Material: 474 specimens collected from cruises DOSMARES 01-
02-04. Depth of occurrence: 2000 and 2250 m. Zone: western Medi-
terranean Sea open slope (Table 2).
Description: Specimens smaller than 40 mm long;
usually with pteropods and sand encrusted in the skin
giving an external vitreous structure, colour dusty
brown (Fig. 8A). Body dorsally convex, flat ventrally.
The specimens sampled in this study do not have the
pygal furrow which is generally characteristic of the
group; some authors also note the absence of a pygal
furrow in some specimens. Mouth subventral surround-
ed by 16-20 orange peltate tentacles, anus terminal.
When the encrusted material is discarded the dermis is
thin. The dorsolateral tube feet are sometimes difficult
to see (Fig. 8B). Muscular bands cylindrical and sub-
divided, visible by transparency. Calcareous ring solid,
radial plates with two central and lateral projections
providing a ribbon-like shape to each plate (Fig. 8C).
Two respiratory trees long and slim clustering along a
central strap. Usually dredged in great numbers. Os-
sicles present in tentacles, tube feet, respiratory trees
and near anus; absent in skin and gonads. Spiny rods
(150 to 350 µm) (Fig. 8D) and scarce irregular, mesh-
like perforate plates. Gonads in one tuft, with long
unbranched tubules arising separately along gonoduct;
one dissected specimen had little tufts full of eggs free
in the coelom.
Distribution: Mediterranean Sea, North Atlantic
(O’Loughlin and Ahearn 2005)
Depth range: 360-4400 m (Koehler 1927). Mediter-
ranean depth range 415 to 3624 m (Bartolini Baldelli
1914).
Remarks: O’Loughlin (2002) reconsidered the ge-
nus Pseudostichopus and classified P. occultatus as
Meseres occultatus. Later, (O’Loughlin and Ahearn
2005) returned this species to the genus Pseudosticho-
pus. The colour of tentacles and internal structures
shows great variability between individuals and is not
suitable as a diagnostic character.
Fig. 8. – Pseudostichopus occultatus characteristics. A, general view, with and without pteropod cover (Photo from A. Bozzano); B, tube
feet detail and encrusted pteropods; C, detached pieces of the calcareous ring; D, irregular spiny ossicles from respiratory trees and tentacles.
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Family HOLOTHURIIDAE Ludwig, 1894
Genus Holothuria Linnaeus, 1767
Subgenus Panningothuria Rowe, 1969
Holothuria (Panningothuria) forskali
Delle Chiaje, 1823
(Fig. 9)
Holothuria forskahli Delle Chiaje, 1824: 77-116, pl. 6-8. Tortonese,
1965: 64, Fig. 23
Material: 1 specimen from cruise PROMETEO 05. Depth of occur-
rence: 850 m. Zone: Blanes Canyon (Table 2).
Description: 60 mm long. Cylindrical body flat-
tened ventrally (Fig. 9A). Numerous tube feet in three
or four rows. Conical papillae on its dorsal surface.
Subventral mouth with about 20 stumpy, branched
tentacles. Calcareous deposits scarce, as small discs in
skin (Fig. 9B) and branched and curved rods in tube
feet and tentacles. Colour, usually black with white
spots, sometimes brown with a yellow ventral side.
Cuverian tubules are present.
Distribution: Mediterranean Sea and northeast At-
lantic Ocean (Pérez Ruzafa et al. 1987).
New depth range: 20-850 m depth (present study).
The previous maximum depth reported for this spe-
cies in the Atlantic Ocean was 348 m (Pérez Ruzafa et
al. 1987). The previous Mediterranean Sea maximum
depth was 193 m (Pérez Ruzafa et al. 1987).
Remarks: The one small specimen collected had a
pale grey-pinkish colour. Some authors (Koehler 1921,
1927, Tortonese 1965) described deeper specimens of
H. forskali as pale in colour and smaller in body length
compared with shallower individuals. O’Loughlin and
Paulay (2007) describe a related species to H. forskali,
living at greater depths (800 m) in Australian waters.
Order MOLPADIIDA
Family MOLPADIIDAE Müller, 1850
Genus Molpadia (Cuvier, 1817) Risso, 1826
Molpadia musculus Risso, 1826
(Fig. 10)
Molpadia musculus Risso, 1826: 293. Pawson, 2001: 317-318, Fig.
2A-B.
Material: 25 specimens collected during cruises PROMETEO 01-
02-03-04-05, PROMARES and DOSMARES 04. Depth of occur-
rence: 900 and 1050 m. Zones: only present on western Mediter-
ranean Sea open slope (Table 2).
Description: Up to 50 mm long. Sausage-shaped,
with a small tail (Fig. 10A). Terminal, mouth surround-
ed by 15 pink digitate tentacles with two small pro-
longations (Fig. 10B). Skin rough and thick, coloured
from grey to dark purple due to phosphatic deposits
(Fig. 10A, B). Ossicle tables have few perforations
and a small solid spine (500 to 700 µm). Rosette and
racquet-shape plates and anchors present (Fig. 10C).
Fusiform rods (±1000 µm) always present in tail, usu-
ally also on body wall (Fig. 10D). Calcareous ring
with posterior bifurcate projections on radial plates.
Two long and slender respiratory trees. Ossicles and
body shape could vary, but fusiform rods of the tail are
diagnostic. Colour varies with the age and growth of
the animal. In the early stages they are grey-white and,
when grown to the adult size, the colour turns darker
from the accumulation of phosphatic deposits.
Distribution: Cosmopolitan (Pawson et al. 2001).
Depth range: 35-5205 m (Pawson et al. 2001).
Mediterranean Sea depth range 50 to 2500 m (Paren-
zan 1970).
Remarks: In the Mediterranean Sea, the maximum
depth of distribution for this species was 1050 m (Tor-
tonese 1965, Sibuet 1974, Cartes et al. 2009, Ramírez-
Llodra et al. 2010, present study). However, Parezan
(1970, pp. 10 and 33) sampled ten M. musculus between
2300 and 2500 m, with the RV Ruth Ann in 1969 while
dredging the Ionian Sea (central Mediterranean Sea).
Family CAUDINIDAE Heding, 1931
Genus Hedingia Deichmann, 1938
Hedingia mediterranea (Bartolini Baldelli, 1914)
Tortonese, 1965
(Fig. 11)
Fig. 9. – Holothuria (Panningothuria) forskali characteristics. A, general view; B, ossicles.
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Trochostoma mediterraneum Bartolini Baldelli, 1914: 105-107, pl.
6 Figs. 9-10.
Hedingia mediterranea Tortonese 1965: 100-101, Fig. 43.
Material: 11 specimens collected from cruises PROMETEO 02-05
and PROMARES. Depth of occurrence: 900 to 1500 m. Zones: west-
ern Mediterranean Sea open slope and Blanes Canyon (Table 2).
Description: Fresh specimens pale violet or white,
acquiring a yellowish white colouring when conserved
(Fig. 11A, B). Body divided into two regions, an elon-
gated body and a long caudal appendage (more than
half the length of the body). Body oval, without podia.
Rough skin due to calcareous plates. Anterior region
wrinkled and cylindrical, with a terminal mouth. Skin
without phosphatic deposits. Fifteen tentacles without
digitations. Anus situated at the end of the caudal ap-
pendage. Five subdivided muscular bands visible by
transparency. Ossicles very similar to H. albicans;
tables (from 150 to nearly 250 µm) present all over the
skin with very irregular holes and a central spine with
three spiny columns (Fig. 11C -E). Smooth plates on
anal papillae (Fig. 11F, G). Two respiratory trees (right
and left), low-ramified and attached along the mesen-
tery. Gonads long and unbranched tubules extending
to the posterior end of the body, disposed in two tuffs
attached to the mesentery on the upper part and free for
the rest of their length in the coelom (Fig. 11H). Cal-
careous ring with five radial pieces, each with two pos-
terior bifurcated projections and five interradial pieces
(Fig. 11I, J). Tentacular ampullae long and digitate.
Distribution: Endemic from Mediterranean Sea,
reported once on Tyrrhenian Sea. First citation in the
western Mediterranean Sea.
Depth range: 800-1500 m (present study). The pre-
vious Mediterranean Sea depth range was 800 to 1000
m (Bartolini Baldelli 1914).
Remarks: Only one specimen has been reported
previously in the Mediterranean Sea, dredged by RN
Washington (1881-1882) in the Tyrrhenian Sea at 800-
1000 m depth and described as Trochostoma mediter-
raneum by Bartolini Baldelli (1914). Later, Koehler
(1927) classified the specimen as Trochostoma ar-
ticum. Tortonese (1965) classified it definitively as
Hedingia mediterranea. Pawson (2001) considered
the specimen to be Hedingia albicans (Théel, 1886)
Deichmann, 1938, and cited it in the Mediterranean.
Molecular data are required for Hedingia species in
order to resolve their taxonomic status.
Fig. 10. – Molpadia musculus characteristics. A, general view; B, detail of the tentacles; C, rosettes and racquet-shaped ossicles with phos-
phatic deposits; D, fusiform rod ossicles from tail.
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Order ELASIPODIDA Théel, 1882
Family ELPIDIIDAE Théel, 1879
Genus Penilpidia Gebruk, 1988
Penilpidia ludwigi (von Marenzeller, 1893)
(Fig. 12A-G)
Kolga ludwigi Marenzeller, 1893: 20-23, pl. III Fig. 7, pl. IV Fig. 8.
Penilpidia ludwigi Gebruk, 2013: 1030-1032, Fig. 1.
Fig. 11. – Hedingia mediterranea characteristics. A, B, external colour diversity; C, D, skin ossicles; E, detail of ossicles central spine; F, anal
calcareous plates; G, anal papillae; H, gonadal tuffs and Polian vesicle; I, J, calcareous ring and detached pieces of calcareous ring.
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Material: 219 specimens from cruise PROMETEO 01 and sediment
traps of PROMETEO project. Depth of occurrence: from 900 to
1500 m. Zone: western Mediterranean Sea open slope and Blanes
Canyon (Table 2).
Description: Small species of 5-20 mm in length.
Fragile animals with skin usually broken. Digestive
tract visible by transparency (Fig. 12A). Body elon-
gated ovoid, with ventral side flattened. Six pairs of
Fig. 12. – Penilpidia ludwigi characteristic. A, general view; B, oral region detail; C, tentacle ossicles; D, interlinked pieces of the calcareous
ring; E, F, pieces of the calcareous ring G, wheel from skin.
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tube feet on the posterior half of the flattened ventral
sole. Three pairs of papillae are present on the dorsal
side, two pairs on the anterior part of the body and one
pair on the posterior part. Ten tentacles surrounding
the mouth (Fig. 12B), each divided into six to eight
marginal lobes. Tentacles spicules curved rods with
spines (130-300 µm) at their ends and in the middle
on the external side of the curve (Fig. 12C). Calcare-
ous ring with five interlinked pieces, usually visible by
transparency. Each piece has four pair of arms radiat-
ing from the centre (Fig. 12D). Arched rods with one
or two spines and four spiny leg ossicles (Fig. 12E, F).
Papillae spicules smooth rods (Fig. 12G). Marenzeller
(1893) reports males and females, describing gonads as
one tuft slender and ramified for males and short and
less ramified for females.
Distribution: Endemic to the Mediterranean Sea
(Pagés et al. 2007, Gebruk et al. 2013).
Depth range: 755-4766 m (Fiege and Liao 1996).
Remarks: Penilpidia ludwigi has been reported
twice in the eastern Mediterranean Sea basin (Maren-
zeller 1893, Fiege and Liao 1996) at depths of 755 to
4766 m. Its presence was reported in the northwestern
Mediterranean Sea from sediment traps at 22 m above
the bottom at depths between 1200 and 1700 m in the
Palamós Canyon (Pagés et al. 2007). Although a speci-
men has been reported from a depth of only 48 m on
the southwestern coast of Portugal (Cunha de Jesus and
Cancela da Fonseca 1999), there is some doubt about
this identification owing to depth (very shallow) and
substrate (i.e. rocky area), as well as the poor condition
of the specimen. Gebruk et al. (2008, 2013) described
a related species in the North Atlantic and included a
re-description of the genus and its species.
Order DACTYLOCHIROTIDA
Pawson and Fell (1965)
Family YPSILOTHURIIDAE Heding, 1942
Genus Ypsilothuria E. Perrier, 1886
Ypsilothuria bitentaculata (Ludwig, 1893)
(Fig. 13)
Sphaerothuria bitentaculata Ludwig, 1893:184. 1894: 141 pl.
12-14.
Ypsilothuria bitentaculata attenuata Alvà, 1991: 459-460.
Material: 27 specimens collected during cruises PROMETEO 01 to
05, PROMARES and DOSMARES 01. Depth of occurrence: 900 m
to 1350 m. Zone: western Mediterranean Sea open slope (Table 2).
Description: Typically U-shaped (Fig. 13A). Two
opposite siphons, oral and anal. Body wall thorny due
to the presence of intricate scales, also visible with
naked eye. Eight digitiform tentacles, of very unequal
size, one on each side, being larger than the others.
Calcareous plates visible with naked eye (Fig. 13B).
Fig. 13. – Ypsilothuria bitentaculata characteristics. A, general view; B, plates from skin; C, calcareous plate detail with central spine; D, E,
calcareous ring detail of bifurcated projections.
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Plates subcircular. Strong short spire placed near the
edge of the plate (Fig. 13C). The plates are perforated
by many small holes giving an irregular shape. Calcar-
eous deposits in tentacles. Calcareous ring with eight
plates. Lateral interradial plates with anterior bifurcat-
ed projections (Fig. 13D, E). The projections are often
asymmetric.
Distribution: Cosmopolitan (Cherbonnier and Féral
1978).
Depth range: 225-4440 m (Cherbonnier and Féral
1978). Mediterranean Sea depth range 900 to 1560 m
(Alvà 1991).
Remarks: Differs from Y. talismani in the bifur-
cated projections of the calcareous ring and the size of
the plates (Gage et al. 1985, Alvà 1991).
Taxonomic information on deep-sea
Mediterranean echinoderms
Fifty species of echinoderms present in the Medi-
terranean Sea and cited in the literature as presenting
maximum depth of occurrence below 800 m were
grouped in a table (Table 3). After carefully analys-
ing all published data, we observed that from the initial
50 species shown in Table 3 only 29 were signalled at
depths below 800 m depth in the Mediterranean Sea.
Geographically, five of the studied species in Table 3
were endemic to the Mediterranean. Three were cos-
mopolitan and one had a broad Indo-Pacific and Medi-
terranean distribution (while all the other species had
an Atlanto-Mediterranean distribution). Of the 50 spe-
cies, 11 were sampled in our study. One of them was a
first record for the Mediterranean. Four of the sampled
species increased their maximum depth of distribution,
and one increased the maximum depth of distribution
in the Mediterranean Sea.
DISCUSSION
General remarks
This study provides a thorough review of all cita-
tions and distribution information of deep-sea echi-
noderms in the Mediterranean Sea. The literature re-
view showed that for some species only very limited
biological/ecological data were available, and in many
cases only species lists were provided (Tortonese
1979, Pérez-Ruzafa and López-Ibor 1988). This paper
provides new information of specimens collected in the
last few years, including new records and extensions
of geographic and bathymetric distributions. Our new
data include information from areas with complex to-
pography such as canyons, which previously have been
sampled inadequately. We have collected together in-
formation of echinoderms living deeper than 800 m.
Our results report, for the first time, the presence of
the echinoid Gracilechinus elegans (Düben and Koren,
1844) in the Mediterranean Sea. In addition, there are
new records of two species considered previously as
“rare” in the Mediterranean Sea. At present, there is no
consensus regarding what determines a “rare species”
(Cunningham and Lindenmayer 2005). In our study,
taking into account all published information, we con-
sidered “rare” those species that have been reported
less than five times in the whole basin. Based on this,
two “rare” holothurians endemic to the Mediterranean
Sea, Hedingia mediterranea (Bartolini Baldelli, 1914)
Tortonese, 1965 and Penilpidia ludwigi (von Maren-
zeller, 1893), were identified. Additionally, we note
greater bathymetric ranges for four species. The depth
range of the asteroid Ceramaster grenadensis (Per-
rier, 1881), previously dredged in the Mediterranean
Sea down to 2400 m (Carpine 1970, Tortonese 1979,
Alvà 1987a), was extended to 2845 m. The echinoid
Brissopsis lyrifera (Forbes, 1841), previously dredged
around 1500 m (Sibuet 1974, Tortonese 1979, Cartes
et al. 2009), was extended to 2250 m. Parezan (1970)
reported the presence of B. lyrifera at 2500 m depth
in the Ionian Sea. However, the specimen reported by
Parezan (1970) was the test of a dead animal. Conse-
quently later studies have not reported the presence of
B. lyrifera at depths greater than 1500 m. The holothu-
rian Hedingia mediterranea had been dredged previ-
ously only around 1000 m (Bartolini Baldelli 1914).
Our data extend its bathymetric distribution range to
1500 m. Finally, the depth range of Holothuria (Pan-
ningothuria) forskali Delle Chiaje, 1823, which had
been dredged previously down to 348 m in the Atlantic
Ocean and around 193 m in the Mediterranean Sea
(Pérez Ruzafa et al. 1987), is extended to 850 m in the
Mediterranean Sea.
Below, we discuss the results by class. At the be-
ginning of each section, if appropriate, we discuss first
any new records and those of rare species. We then
compare our results with the published literature, as
detailed in Table 3.
Class Asteroidea
Our results for the class Asteroidea were based on
two typical bathyal species, Hymenodiscus coronata
(G.O. Sars, 1872) and Ceramaster grenadensis (Per-
rier, 1881). The depth range of C. grenadensis has
been expanded to 2845 m. Where their depth ranges
overlapped (1500 to 2250 m) the two species co-oc-
curred, perhaps facilitated by their contrasting diets: H.
coronata is a suspension feeder and C. grenadensis a
secondary consumer (Carlier et al. 2009).
Other deep-sea asteroids reported previously from
the Mediterranean at depths greater than 800 m (Table
3), such as Astropecten irregularis irregularis (Pen-
nant, 1777), Luidia sarsi sarsi Düben and Koren, in
Düben, 1845, Odontaster mediterraneus (Marenzel-
ler, 1893), Henricia cylindrella (Sladen, 1883) and
Plutonaster bifrons (W. Thompson, 1873), were not
sampled in the recent work. Plutonaster bifrons was
reported by Tortonese (1979) at 2715 m. However, this
depth distribution was not supported by the specific
data or citations in Tortonese’s publication. Thus, we
consider the Plutonaster bifrons sample of the “Pola”
(Marenzeller 1893) to be the deepest known record of
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Table 3. – Echinoderms cited as present in the deep Mediterranean Sea. Atl. Depth, Maximum depth of distribution in the Atlantic Ocean; Med. Depth, Maximum depth of distribution in the Mediterranean
Sea; Pre. Stu, Maximum depth sampled in the present study; Distribution, Atl-Med, Atlanto-Mediterranean distribution.
Atl. Depth Literature Med. Depth Literature Pre. Stu. Distribution
Crinoidea
Leptometra celtica (Barrett and McAndrew, 1858) 1279 m Mortensen 1927 538 m Sibuet 1974 xAtl-Med
Leptometra phalangium (J. Müller, 1841) x x 1300 m Tortonese 1979 xMediterranean
Neocomatella europaea AH Clark, 1913 1700 m Sibuet 1974 337 m Sibuet 1974 xAtl-Med
Asteroidea
Astropecten irregularis pentacanthus (Delle Chiaje, 1827) x x 932 m Tortonese 1958 xMediterranean
Astropecten irregularis irregularis (Pennant, 1777) 1000 m Clark and Downey 1992 900 m Koukouras et al. 2007 xNorth Atl-Med
Ceramaster grenadensis grenadensis (Perrier, 1881) 2500 m Clark and Downey 1992 2845 m Present study 2845 m Atl-Med
Chaetaster longipes (Retzius, 1805) 1140 m Clark and Downey 1992 100 m Tortonese 1958 xAtl-Med
Henricia cylindrella (Sladen, 1883) 1383 m Clark and Downey 1992 960 m Sibuet 1974 xAtl-Med
Hymenodiscus coronata (Sars G.O., 1872) 2600 m Clark and Downey 1992 2904 m Bartolini Baldelli 1914 2250 m North Atl-Med
Luidia sarsi sarsi Düben and Koren, in Düben, 1845 1300 m Clark and Downey 1992 1292 m Marenzeller 1893 xAtl-Med
Marginaster capreensis (Gasco, 1876) x x 600 m Tortonese 1965 xMediterranean
Nymphaster arenatus (Perrier, 1881) 3000 m Clark and Downey 1992 ???? Pérez Ruzafa and López-Ibor 1988 xAtl-Med
Odontaster mediterraneus (Marenzeller, 1893) 1804 m Koehler 1909 1196 m Tortonese 1965 xAtl-Med
Plutonaster bifrons (W. Thompson, 1873) 2442 m Cherbonnier and Sibuet 1972 2525 m Marenzeller 1893 xAtl-Med
Tethyaster subinermis (Philippi, 1837) 1425 m Koehler 1895 320 m Koukouras et al. 2007 xAtl-Med
Ophiuroidea
Amphilepis norvegica (Ljungman, 1865) 2900 m Mortensen 1927 533 m Tortonese 1965 xNorth Atl-Med
Amphiura chiajei Forbes, 1843 1200 m Mortensen 1927 766 m Tortonese 1965 xAtl-Med
Amphiura filiformis (O. F. Müller, 1776) 1200 m Mortensen 1927 760 m Marenzeller 1893 xAtl-Med
Ophiacantha setosa (Retzius, 1805) 1480 m Koehler 1921 300 m Tortonese 1965 xAtl-Med
Ophiactis balli (W. Thompson, 1840) 1765 Mortensen 1927 557 m Sibuet 1974 xAtl-Med
Ophiothrix fragilis (Abildgaard, in O. F. Müller, 1789) 1244 m Mortensen 1933 450 m Sibuet 1974 xAtl-Med
Ophiotreta valenciennesi (Lyman, 1879) 1440 m Paterson 1985 819 m Misfud et al. 2009 x Cosmopolitan
Ophiura albida Forbes, 1839 850 m Mortensen 1927 500 m Misfud et al. 2009 x Atl-Med
Ophiura (Dictenophiura) carnea Lütken, 1858 ex M. Sars 1260 m Mortensen 1927 1196 m Tortonese 1979 xAtl-Med
Echinoidea
Asterechinus elegans Mortensen, 1942 1500 Samadi et al. 2010 1700 m Bienhold et al. 2013 x Indo-Pacific/Med
Brissopsis atlantica var. mediterranea Mortensen, 1913 3200 m Tortonese 1965 679 m Mastrotaro et al. 2010 xAtl-Med
Brissopsis lyrifera (Forbes, 1841) 1650 m OBIS 2250 m Present study 2250 m Atl-Med
Cidaris cidaris (Linnaeus, 1758) 1800 m Tyler and Gage 1984 1777 m Alvà 1987a x Atl-Med
Echinocyamus pusillus (O. F. Müller, 1776) 1250 m Mortensen 1927 436 m Misfud et al. 2009 x Atl-Med
Echinus melo Olivi, 1792 1100 m Minin et al. 2012 679 m Mastrotaro et al. 2010 x Atl-Med
Gracilechinus acutus Lamarck, 1816 1280 m Minin et al. 2012 1880m Cartes et al. 2009 x Atl-Med
Gracilechinus elegans (Düben and Koren, 1844) 1750 m Mortensen 1943/ Minin 2012 1500 m Present study 1500 m Atl-Med
Hemiaster expergitus Lovén, 1874 3120 m Tortonese 1972 1249 m Koukouras et al. 2007 xAtl-Med
Neolampas rostellata A. Agassiz, 1869 1260 m Tortonese 1958 400 m Bartolini Baldelli 1914 xAtl-Med
Spatangus purpureus O.F. Müller, 1776 969 m Koehler 1927 932 m Tortonese 1958 xAtl-Med
Stylocidaris affinis (Philippi, 1845) 779 m Mortensen 1903 1000 m Fredj 1974 xAtl-Med
Holothuroidea
Hedingia mediterranea (Bartolini Baldelli, 1914) Tortonese, 1965 x x 1500 m Present study 1500 m Mediterranean
Holothuria (Panningothuria) forskali Delle Chiaje, 1823 348 m Pérez- Ruzafa et al. 1987 850 m Present study 850 m Atl-Med
Leptosynapta inhaerens (O.F. Müller, 1776) Uncertain WorMs 1200 m Ramírez Llodra et al. 2008 xAtl-Med
Mesothuria intestinalis (Ascanius, 1805) Östergren, 1896 2000 m Gebruk et al. 2012 1927 m Cartes et al. 2009 1750 m Atl-Med
Mesothuria verrilli (Théel, 1886) 2600 m Gebruket al. 2012 x x xAtlantic
Molpadia musculus Risso, 1826 5205 m Pawson et al. 2001 2500 m Parezan 1970 1050 m Atl-Med
Oestergrenia digitata (Montagu, 1815) var. profundicola (Kemp, 1905)
268 m Mortensen 1927 914 m Tortonese 1958 xAtl-Med
Panningia hyndmanni (W. Thompson, 1840) 1150 m Mortensen 1927/ Harvey 1988 150 m Fredj 1974 xAtl-Med
Parastichopus regalis (Cuvier, 1817) 747 OBIS 834 m Marenzeller 1893 xAtl-Med
Penilpidia ludwigi (Marenzeller, 1893) x x 4766 m Fiege and Liao 1996 1500 m Mediterranean
Pseudostichopus occultatus Marenzeller, 1893 4400 m Herouard 1902 3624 m Bartolini Baldelli 1914 2250 m Cosmopolitan
Pseudothyone raphanus (Düben and Koren, 1846) 1150 m Harvey et al. 1988 110 m Cherbonnier and Guille 1967 xAtl-Med
Thyone gadeana R. Perrier, 1902 970 m WoRMS 300 m Fredj 1974 xAtl.-Med
Ypsilothuria bitentaculata (Ludwig, 1893) 4440 m Cherbonnier and Féral 1978 1580 m Cartes et al. 2009 1350 m Cosmopolitan
Deep-sea Mediterranean echinoderms • 297
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P. bifrons (2525 m), in agreement with other authors
(Alvà 1987a, Koukouras et al. 2007). Two other aster-
oid species, Marginaster capreensis (Gasco, 1876) and
Astropecten irregularis pentacanthus (Delle Chiaje,
1827), have been considered to be Atlanto-Mediterra-
nean species. Both species were reviewed by Clark and
Downey (1992), who considered them to be endemic
to the Mediterranean Sea. Astropecten irregularis pen-
tacanthus (Delle Chiaje, 1827) was cited by Tortonese
(1958, 1965) at 932 m depth from the “Pola” cruise.
Two other species with a maximum depth of distribu-
tion at 1000-1500 m in the Atlantic Ocean, Chaetaster
longipes (Retzius, 1805) and Tethyaster subinermis
(Philippi, 1837), occurred considerably shallower (100
and 320 m, respectively) in the Mediterranean Sea.
Finally, Nymphaster arenatus (Perrier, 1881), with
a maximum depth at 3000 m in the Atlantic Ocean,
has been cited from the Mediterranean Sea by Pérez-
Ruzafa and López-Ibor (1988) and Koukouras (2007),
but no depth data were given.
Class Echinoidea
This study reports for the first time the presence of
Gracilechinus elegans (Düben and Koren, 1844) in the
Mediterranean Sea. While Mortensen (1903) reported
this species from the Mediterranean, he discarded the
record in a later publication (Mortensen 1943). The
lack of observations of G. elegans in the Mediterranean
Sea could be caused by misidentification of congeneric
species. For instance, adults of G. elegans are similar
to juveniles of G. alexandri (see G. elegans description
above). The only specimen of G. alexandri reported
from the Mediterranean Sea (Alva 1987b) was not
available for comparison. Another species that could
lead to misidentification in the Mediterranean Sea is
Gracilechinus acutus var. norvegicus (Düben and
Koren, 1844). The possibility of hybridization between
species should be taken into account. Hybridization has
been described for other species of the same genus in
the Atlantic (Shearer et al. 1911). Hybrids themselves
may be responsible for some failures in identification.
Molecular studies of Mediterranean Sea and Atlantic
Ocean specimens may be able to determine the species
more clearly in the future, including hybridization and
phylogenetic differences.
Brissopsis lyrifera was present in canyon muddy
sediments below 900 m, as suggested originally by
Carpine (1970). Large and dense aggregations of dead
and live Brissopsis were observed by ROV in canyons.
The gregarious behaviour of this species has been re-
ported in previous studies (Laubier and Emig 1993,
Ramírez-Llodra et al. 2008). Many echinoid tracks
were visible on the sediment, suggesting a “herd”
in movement, similar to what has been observed for
other bathyal echinoids (Salazar 1970, Gage and Tyler
1991). Although the number of collected specimens
was too low to conduct population structure analyses,
we observed that smaller specimens appeared to oc-
cur at greater depths. This contrasts with the results of
Ferrand et al. (1988), who proposed the recruitment of
smaller individuals at shallower depths. Our results are
in agreement with Harvey et al. (1988), who suggested
a possible ‘dwarfism’ for this species at greater depths.
Brissopsis lyrifera is usually reported from the upper
slope (250-400 m depth) on the Mediterranean conti-
nental margin (Tortonese 1965, Carpine 1970, Ferrand
et al. 1988, Koukouras et al. 2007, Ramírez-Llodra et
al. 2008, Cartes et al. 2009). The abundance of this spe-
cies has decreased greatly in recent years on the upper
and middle continental slopes at depths down to 1000
m (Mecho, pers. obs.), which may be related to inten-
sive commercial trawling activity down to depths of
900 m (Ramírez-Llodra et al. 2010, Puig et al. 2012).
Local fishermen have noted a large decrease in B. lyr-
ifera in their by-catch in the last decade.
No specimens of the closely related species Bris-
sopsis atlantica var. mediterranea Mortensen, 1913
were found.
Eight other species of echinoids have been reported
from the Mediterranean Sea at depths below 800 m
(Table 3). Two of these species, Stylocidaris affinis
(Philippi, 1845) and Cidaris cidaris (Linnaeus, 1758),
are common in the deep sea and have been sampled
frequently below 800 m in the Mediterranean Sea
(Alvà 1987a, Cartes et al. 2009). However, these two
species were absent from our samples. Other species
that occur mainly at shallower depths, such as Spatan-
gus purpureus O.F. Müller, 1776 and Gracilechinus
acutus Lamarck, 1816, were also not sampled in the
recent cruises, even though they have been reported
previously at depths greater than 800 m.
Two deep “rare echinoid species” are reported in
the literature from the Mediterranean Sea: Hemiaster
expergitus Lovén, 1874, sampled only three times
(Cherbonnier 1958, Tortonese 1972, Koukouras et
al. 2007) and Asterechinus elegans Mortensen, 1942,
an Indo-Pacific species recently found in the eastern
Mediterranean in association with sunken wood (Bien-
hold et al. 2013). These two species were not sampled
in the present study. Three other species, Echinocya-
mus pusillus (O. F. Müller, 1776), Echinus melo Olivi,
1792, and Neolampas rostellata A. Agassiz, 1869,
have maximum depths of distribution at 1100 m in the
Atlantic Ocean. Their maximum depths of distribu-
tions are shallower (not exceeding 700 m depth) in the
Mediterranean Sea.
Class Holothuroidea
The holothurian Hedingia mediterranea was first
described by Bartolini Baldelli (1914) in the Tyrrhe-
nian Sea. Its presence has not been reported since in the
Mediterranean. It is possible that specimens reported as
H. mediterranea have been misclassified as sipunculids
because of the similar body shape of the two groups.
Some studies have cited H. mediterranea as endemic to
the Mediterranean Sea (Koehler 1921, 1927, Tortonese
1963, 1965, Parenzan 1970, Fredj 1974, Koukouras
et al. 2007, Matarrese 2010), but only by referring to
the original record of the type specimen. Accordingly,
we consider the individuals sampled in this study as
a truly ‘rediscovered’ species and extending both its
geographic range to the northwestern Mediterranean
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Sea and its bathymetrical distribution. One sample col-
lected in the Blanes Canyon at 1200 m included four
individuals and another at 1500 m in the same area
included five individuals, suggesting a greater pres-
ence of this species in canyons. Pawson et al. (2001)
considered the Bartolini Baldelli specimen as Hedingia
albicans (Théel, 1886) Deichmann, 1938. This species
is known from several locations in the North Atlantic.
However, no explanation was provided for the syn-
onymy of H. albicans and H. mediterranea. The infor-
mation available does not allow us to clarify whether
the Mediterranean specimens (classified as Hedingia
mediterranea) are the same species as or distinct from
the Atlantic species (classified as Hedingia albicans).
In the present study we continue to classify the species
as H. mediterranea following Tortonese (1963, 65). A
molecular comparison between species of Hedingia
would help to resolve the taxonomic discrepancies.
The only species of Elpidiidae present in the Mediter-
ranean Sea is Penilpidia ludwigi. This is also considered
to be a “rare” species, because it has been reported only
three times previously, twice from the eastern Mediter-
ranean Sea (Marenzeller 1893, Fiege and Liao 1996) and
once from the deep western Mediterranean Sea (Pagés et
al. 2007). However, when it does occur it may be found
in abundance. Pagés et al. (2007) collected 150 individu-
als. More than 200 individuals were collected in one epi-
benthic sledge sample, suggesting that the species may
occur in dense aggregations (Fiege and Liao 1996, Pagés
et al. 2007) similar to those reported for other Elpidiidae
in the Atlantic Ocean (Billett and Hansen 1982, Billett
et al. 2001, 2010, Gebruk et al. 2003, Ruhl and Smith
2004). The presence of P. ludwigi in the Blanes Canyon
sediment traps adds new faunistic records for this area.
Pagés et al. (2007) collected P. ludwigi in the Palamós
Canyon also with sediment traps moored at 22 m above
the bottom. Our sediment traps sampled greater numbers
in autumn and winter, coinciding with a stormy period
in the northwestern Mediterranean (Sanchez-Vidal et al.
2012). This may have resulted in greater resuspension of
bottom sediments and associated small fauna, such as P.
ludwigi. Another factor that can cause resuspension of
sediments, and thus the collection of small holothurians
in sediment traps, are deep currents (Gebruk et al. 2013).
In addition, swimming behaviour has been described in
other Elpidiidae (Ohta 1985, Pawson and Foell 1986,
Miller and Pawson 1990) and has also been proposed
for P. ludwigi (Pagés et al. 2007). Swimming cannot
be discarded as an explanation of the presence of this
species in sediment traps. Pagés (2007) suggested that
aggregations of P. ludwigi might occur during periods
coincident with phytoplankton spring blooms and the
flux of new organic matter to the seafloor. Although our
sediment traps sampled greater numbers of specimens
in autumn (similarly to the epibenthic sledge sample)
and winter, these seasonal peaks of abundance may also
indicate periodic recruitment of opportunistic species,
as reported for other small species of Elpidiidae (Billett
and Hansen 1982, Ohta 1985, Billett 1991, Billett et al.
2001, 2010).
The class Holothuroidea was the most speciose and
most abundant of all the groups collected in our sam-
ples, as in the North Atlantic deep sea (Billett 1991,
Gage and Tyler 1991). The order Aspidochirotida had
the greatest number of species. Unlike in other studies,
we did not observe dense aggregations of Mesothuria
(Allantis) intestinalis (Ascanius, 1805) Östergren,
1896, as reported by Cartes et al. (2009) from 1600 m
in the same region. Another species of the same genus,
Mesothuria verrilli (Théel, 1886), has been reported
from the Mediterranean Sea (Koukouras et al. 2007),
but the presence of this species in the Mediterranean
Sea was reviewed and discarded by Gebruk et al.
(2012). Pseudostichopus occultatus Marenzeller 1893,
a cosmopolitan aspidochirotid species, showed a re-
stricted geographic and bathymetric distribution in our
samples, occurring only between 2000 and 2200 m on
the open slope, but in very high abundances.
The presence of large aggregations of individuals
near the canyon axis could be related to food inputs
(Morgan and Neal 2012). Submarine canyons act as
conduits of organic matter from the shelf to bathyal/
abyssal depths (Company et al. 2012). The aggregations
of P. occultatus may be due to the periodic changes in
food availability originating from canyon refluxes, as
proposed for Mesothuria. To the best of our knowl-
edge, the presence of Holothuria (Panningothuria)
forskali Delle Chiaje 1823 at mid-bathyal depths has
not been reported previously. The deepest records were
at 345 m off the Canary Islands (Pérez Ruzafa et al.
1987, Hernández et al. 2013). The specimen sampled
in the present study came from the Blanes Canyon at
850 m depth.
Two species of the order Molpadiida were collect-
ed. Molpadia musculus Risso, 1826 was present only
in open slope areas. Hedingia mediterranea occurred
mainly in canyon areas. Both species are deposit feed-
ers and live infaunally. Molpadia musculus was report-
ed as a typical canyon species in the Atlantic Ocean
(Amaro et al. 2009) and in other Mediterranean Sea
areas (Ramírez-Llodra et al. 2008, Cartes et al. 2009).
However, no specimens of M. musculus were found in
our canyon samples. The high presence of H. mediter-
ranea inside canyons suggests habitat specialization,
but further sampling inside canyons is necessary to
confirm this hypothesis.
The order Dactylochirotida was represented by a
single species, Ypsilothuria bitentaculata (Ludwig,
1893). The presence of this species only at middle
slope depths is commonly reported (Pawson 1965,
Gage et al. 1985). This species was reported from
the Mediterranean Sea only in the early 1990s (Alvà
1991). Subsequently, Ypsilothuria bitentaculata has
been cited by other authors (Massin 1996, Cartes et al.
2009) and also as Y. talismani by Ramírez-Llodra et al.
(2008). Little information is available for Ypsilothuria
in the Mediterranean Sea. A detailed discussion on its
taxonomy must await further sampling.
Of the holothurians species reported previously
from the deep (occurrence below 800 m) Mediterra-
nean Sea, only two species did not occur in our study
(Table 3). First, Leptosynapta inhaerens (O.F. Müller,
1776) occurs at shallower depths of around 500 m. A
record of this species by Ramírez-Llodra et al. (2008)
Deep-sea Mediterranean echinoderms • 299
SCI. MAR., 78(2), June 2014, 281-302. ISSN-L 0214-8358 doi: http://dx.doi.org/10.3989/scimar.03983.30C
from 1200 m on the Catalan margin off Barcelona is
uncertain and may have been misidentified (Company,
pers. com). Second, Oestergrenia digitata (Montagu,
1815) var. profundicola (Kemp, 1905) has been report-
ed at 900 m (Marenzeller 1893, Tortonese 1958). One
species typical of shallower Mediterranean waters,
Parastichopus regalis (Cuvier, 1817), has been cited
at 834 m depth by Marenzeller (1893), but no other
reports are known for these depths. Finally, there are
three other species, Panningia hyndmanni (W. Thomp-
son, 1840), Pseudothyone raphanus (Düben and Kor-
en, 1846) and Thyone gadeana Perrier R., 1898, which
have maximum depth ranges extending to around 1000
m in the Atlantic Ocean but occur no deeper than 300
m in the Mediterranean Sea.
Class Crinoidea
Crinoids were totally absent from our samples.
Three species of crinoids have been cited from the
bathyal Mediterranean seafloor (Table 3). Only one of
them, the endemic crinoid Leptometra phalangium (J.
Müller, 1841), has a maximum depth of distribution
greater than 800 m. Stalked crinoids were not reported
in the Mediterranean Sea (David et al. 2006).
There are some records of high abundances of Lep-
tometra phalangium in upper slope areas (100 to 400
m depth) (Pérès and Picard 1956a, Mifsud et al. 2009),
as observed for the same genus in other areas (Fonseca
et al. 2013). The deepest record for this species is 1292
m (Marenzeller 1893). However, despite these deeper
records, not a single crinoid was collected in any of
our hauls or observed during the ROV dives. Their
occurrence at predominantly shallower depths (Hellal
2012) may explain the absence of these crinoids in our
samples.
Class Ophiuroidea
Ophiuroids were also totally absent from our
samples. Nine species of ophiuroids have been cited
previously from the Mediterranean Sea at depths be-
tween 300 and 1219 m (Table 3), with only two spe-
cies, Ophiura (Dictenophiura) carnea Lütken, 1858
ex M. Sars, and Ophiotreta valenciennesi (Lyman,
1879), cited below 800 m (Tortonese 1979, Mifsud
et al. 2009). All nine species have been reported from
depths greater than 800 m in the Atlantic Ocean, but
their maximum depth of distribution in the Mediter-
ranean Sea is shallower. This may explain the lack of
ophiuroids in our study.
Endemicity in echinoderms from the
Mediterranean
There has been considerable debate as to whether
the deep-sea fauna of the Mediterranean is truly endem-
ic or is a sub-population of Atlantic species (Bouchet
and Taviani 1992, Tyler 2003). The shallow Gibraltar
Sill may be a significant barrier for the influx of larvae
of echinoderms from the Atlantic and may act as an
isolating mechanism once populations are established
in the Mediterranean. The higher temperatures of deep
water in the Mediterranean may mitigate the immigra-
tion of species from the deep Atlantic. However, an
increased sampling effort and molecular analyses are
required before this aspect is fully resolved. Our sam-
ples increase the availability of genetic data necessary
for future comparative studies between populations.
ACKNOWLEDGEMENTS
The authors would like to thank the Officers and
Crews of the R/V García del Cid and R/V Sarmiento
de Gamboa and the scientific parties of the BIOFUN,
PROMETEO and DOSMARES cruises for their con-
tributions at sea. We would like to thank Dr. Daniel
Martin and Mrs. Marta Segura (CEAB-CSIC) for the
sediment trap samples and Dr. Craig Young for his
help in the classification of G. elegans. The authors
acknowledge the Biodiversity Heritage Library (http://
www.biodiversitylibrary.org/) for making ancient
biodiversity literature openly available. This study
was funded by the PROMETEO project (CTM2007-
66316-C02/MAR, CICYT), the BIOFUN project
(CTM2007-28739-E, European Science Foundation
and national funding agencies) and the DOSMARES
project (CTM2010-21810-C03-03). ERLL was funded
by a JAE-DOC postdoctoral grant (CSIC, Spain) with
co-funding from the European Social Fund. JA is a fel-
low of the Ramón y Cajal Programme (MICINN).
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