skeneimorph species (gastropoda) from the rockall and
TRANSCRIPT
47
Miscellanea Malacologica 4(4): 47-61, 31.X.2010
Skeneimorph species (Gastropoda) from the Rockall and Hatton Banks,
northeastern Atlantic Ocean
L. HOFFMAN1, B. Van HEUGTEN
2 & M. S. S. LAVALEYE
3
1Zoetermeer, the Netherlands ([email protected]), 2Oosterhout, the Netherlands ([email protected]), 3NIOZ, Texel, the Netherlands ([email protected])
ABSTRACT
A record is given on the occurrence and abundance of skeneimorph species in the families Trochaclididae, Pendromidae and
Turbinidae (including those species formerly placed in Skeneidae) that have been collected during the NIOZ expeditions to
the Rockall and Hatton Banks (2004-2008). A description is provided for two new species: Mikro hattonensis, and
Xyloskenea xenos (Skeneinae, Turbinidae, Gastropoda). Their holotypes have been deposited in the Zoological Museum
Amsterdam (University of Amsterdam). Two poorly known species have been figured and re-described: Granigyra tenera
(Jeffreys, 1883), and Ganesa nitidiuscula Jeffreys, 1883.
Key words: Northeastern Atlantic Ocean, Rockall Bank, Hatton Bank, Turbinidae, Skeneidae, Skenea, Ganesa, Mikro,
Xyloskenea, Granigyra, taxonomy, new species, HERMES, Moundforce.
INTRODUCTION
The Rockall and Hatton Banks are sea bottom
highs that have developed over Jurassic fault
blocks. These fault blocks were formed during
early failed continental rifts in the Early
Cretaceous. The failed rift systems are
preceding the successful rift that has developed
since the Cretaceous between the Western
European continent and the East Greenland
coastline in the North East Atlantic. The deep
Rockall Trough separates the Rockall Bank
from Ireland and Scotland. The Hatton Bank is
the NW extent of the larger Rockall and Hatton
Bank area. The Rockall Bank has a miniscule
island as a tip of a fault block in the North of
the structure.
The Hatton Bank is fully submerged. It
may be assumed that the sea bottom
environment in the Rockall-Hatton area has
been in a stable state for at least 65 million
years, i.e. the end of the Cretaceous. These
stable and isolated environments are known to
develop endemic species. The highs of the
present day banks form a conglomerate of
cold-water coral reefs. A rich fauna
community populates these highs of which the
most prominent groups are Mollusca, corals
and sponges.
Typical water depths where these
communities thrive are 500-700 m on the
Rockall Bank to 600-1100 m on the Hatton
Bank. The Royal Netherlands Institute for Sea
Research (NIOZ) has conducted detailed
studies on the faunal communities of cold-
water corals in the NE Atlantic Ocean.
MATERIAL AND METHODS
During expeditions conducted in 2004 (Mienis
et al., 2004 [Moundforce]), 2005 (van Duyl et
al., 2005 [HERMES]) and 2006 (Duineveld et
al., 2006 [HERMES]), box core samples have
been taken from the coral-rich sea-bottom in
the southeastern slope of the Rockall Bank and
in 2008 (Lavaleye et al., 2008 [HERMES]) on
the Hatton Bank.
Whereas some of these box cores have
been preserved and retained for other
investigations, other box core samples have
been investigated for their malacofauna.
Unfortunately, the great majority of these
samples only contained empty shells and,
hence, no material has been available for
anatomical studies.
Bottom samples from box cores have
been washed thoroughly with fresh water,
dried and sieved in fractions of 10 mm, 3 mm,
1 mm, 0.5 mm. Fractions larger than 10 mm
and 3 mm contained mostly large coral
fragments and few larger Mollusca; these have
been hand picked. Fractions of 1-3 mm have
been fully sorted under a microscope. The
fractions of 0.5-1 mm have been sampled and a
small volume has been fully sorted. The
remaining material has been enriched in a
counter-current washing process and the
enriched fraction has been fully sorted. The
smallest fraction has been fully enriched by
counter-current washing and representative
samples have been sorted. Taxonomy of the
specimen has been largely based on the online
CLEMAM database for European Mollusca.
48
Hoffman, Van Heugten & Lavaleye, 2010: Skeneimorph species
For all box core stations, statistical shell counts
have been carried out such that species
abundance by weight or sea-bottom area could
be estimated.
We have used as abundance unit
shells/kg-dry-sediment-weight and it must be
realised that its large uncertainty is caused by
inaccuracies introduced by sampling (location
and depth of penetration) as well as in the
information gathering (subjective hand sorting,
visual counts, statistical extrapolations,
subjective taxonomic classification). Typical
dry-weight sediment samples in the box cores
contain 0.3-20 kg. For large sample sets with
high-related abundance it is not meaningful to
specify the exact number of shells as this has
often been based on statistical extrapolation of
sub-samples. For rare species, frequently the
fully sorted shell set has been investigated but
then the abundance is meaningless with only
few specimens available and it has been
omitted consequently.
Representatives of most species have
been digitally photographed using a
stereomicroscope camera and a computer.
Images have been taken as spherical slices at
regular focusing distances and the set of
images have been synthetically combined into
one sharp image using Helicon Focus software.
Alternatively, rare specimens have been
selected for SEM photography; they have been
cleaned in a weak bleach solution, rinsed in
fresh water, subjected to ultrasonic cleaning.
Subsequently, they have been mounted for
SEM photography.
The class of Archaeogastropoda and in
particular the subfamily Skeneinae in the
family Turbinidae is predominantly
represented in the malacofauna, both in terms
of number of specimens as well in the number
of species. In 2008, Hoffman et al. discussed
four new skeneid species in the new genus
Lopheliella from the Rockall Bank.
The holotypes of the genera
Lopheliella, Mikro and Xyloskenea are in the
collection of the Zoological Museum
Amsterdam (formally part of University of
Amsterdam). All remaining material is either
in the collection of the National Museum of
Natural History ‘Naturalis’ in Leiden, the
Netherlands or in the collections of the authors.
In this paper, we add two more new
species in Skeneinae. Their holotypes have
been deposited in the Zoological Museum
Amsterdam. A few paratypes have been
retained in the collections of the authors.
ABBREVIATIONS
CLEMAM = Check-List of European Marine
Mollusca
HERMES = Hotspot Ecosystem Research of the
Margins of European Seas
n. sp. = new species
NIOZ = Royal Netherlands Institute for Sea
Research, Texel
ZMA = Zoological Museum Amsterdam
ACKNOWLEDGEMENTS
The authors express their appreciation to NIOZ
for allowing to work the unique material and to
publish the results of these studies. We greatly
acknowledge the assistance of captain, crew,
technicians and scientists on board of RV
‘Pelagia’ during the cruises.
We particularly thank Robert G.
Moolenbeek (ZMA) for stimulating
discussions, his knowledgeable advice on the
taxonomy and the provision of literature. He
has been most cooperative in allowing the first
author to use the SEM facility at the University
of Amsterdam for micro-photographic
pictures. Bram van der Bijl, Marien J. Faber
and an anonymous referee critically read the
manuscript.
SYSTEMATICS
Family: Trochaclididae
Trochaclis islandicus Warén, 1989
Trochaclis islandicus Warén, 1989: 9-11, figs 6-7
Material examined.- ROCKALL BANK: Moundforce 2004/29, depth 1443 m,
1 shell; Hermes 2006/12, depth 1091 m, 3 shells;
HATTON BANK: Hermes 2008/36, depth 700 m, 9
shells; Hermes 2008/117, depth 958 m, 12 shells.
49
Miscellanea Malacologica 4(4): 47-61
Family: Pendromiidae
Rugulina fragilis (G.O. Sars, 1878)
(Figs 1-3)
Adeorbis fragilis G.O. Sars, 1878: 213, tab. 22, figs 19a-c
Rugulina fragilis: Warén, 1991: 71-73, figs 11A-E, 13A-
B
Material examined.- ROCKALL BANK: Moundforce 2004/37, depth 557 m;
Hermes 2005/15, depth 593 m; Hermes 2005/34, depth
767 m; Hermes 2006/10C, depth 587 m; Hermes
2006/12, 1091 m; Hermes 2006/23A, depth 578 m;
Hermes 2006/56, depth 578 m; Hermes 2006/65, depth
1087 m; HATTON BANK: Hermes 2008/35, depth 796
m; Hermes 2008/36, depth 700 m; Hermes 2008/59,
depth 788 m; Hermes 2008/92, depth 822 m. Abundances
are 6.5 shells/kg at 400-600 m, 6.9 shells/kg at 600-800
m, 2.7 shells/kg at 1000-1200 m.
Rugulina species
(Figs 4-6)
Material examined.- HATTON BANK: Hermes 2008, St.117, depth 958 m, 1
fragmentary shell.
Description.-
Fragile well rounded tonnoid-shaped shell,
height 2.3 mm, width 2.3 mm, with radial
regular rib structure. Protoconch is eroded and
hence unknown. Teleoconch whorls are well
rounded but somewhat oval in cross-section.
The base of the outline is a well-rounded base.
The outer lip is sharp. The suture is shallow.
Umbilicus is open and deep. The aperture is
prosocline. Sharp radial ribs dominate the
surface texture: about 21 on the body whorl.
Fine prosocline growth lines are evident. The
umbilical area is rather smooth. The single
shell is somewhat translucent cream white.
Discussion.-
The specimen has been placed in Rugulina in
the family Pendromiidae because of its
superficial resemblance to R. fragilis. Once
more complete specimen and/or soft parts are
available, a more conclusive taxonomic
placement can be made.
Family: Turbinidae
Skenea areolata (G.O. Sars, 1878)
Cyclostrema areolatum G.O. Sars, 1878: 345, tab. 34,
figs 6a-d
Skenea areolata: Warén, 1991: 58, figs 3A-C
Material examined.- ROCKALL BANK: Moundforce 2004/29, depth 1443 m;
Moundforce 2004/41C, depth 784 m; Hermes 2005/15,
depth 593 m; Hermes 2005/34, depth 767 m; Hermes
2006/10C, depth 578 m; Hermes 2006/12, depth 1091 m;
Hermes 2006/23A, depth 578 m; Hermes 2006/56, depth
578 m; Hermes 2006/65, depth 1087 m; HATTON
BANK: Hermes 2008/36, depth 700 m; Hermes 2008/92,
depth 822 m; Hermes 2008/117, depth 958 m.
Abundances are 72.2 shells/kg at 400-600 m, 11.8
shells/kg at 600-800 m, 2.2 shells/kg at 1000-1200 m, 2.4
shells/kg at 1443 m.
Skenea basistriata (Jeffreys, 1877)
Cyclostrema basistriata Jeffreys, 1877: 234
Skenea basistriata: Graham, 1988: 138, fig. 47
Skenea basistriata: Warén, 1993: 176, figs 16A-F, 17A-D
Material examined.- ROCKALL BANK: Hermes 2006/12, depth 1091 m;
Hermes 2006/65, depth 1087 m.
Skenea larseni Warén, 1993
Skenea larseni Warén, 1993: 173, figs 11D-F, 12A, 12C,
12E, 13C, 14A-B, 15C-D
Material examined.- ROCKALL BANK: Moundforce 2004/41C, depth 784
m; Hermes 2005/15, depth 593 m; Hermes 2005/23,
depth 667 m; Hermes 2005/34, depth 767 m; Hermes
2006/10C, depth 578 m; Hermes 2006/12, depth 1091 m;
Hermes 2006/23A, depth 578 m; Hermes 2006/56, depth
578 m; Hermes 2006/65, depth 1087 m; HATTON
BANK: Hermes 2008/35, depth 796 m; Hermes 2008/36,
depth 700 m; Hermes 2008/92, depth 822 m; Hermes
2008/117, depth 958 m. Abundances are 22 shells/kg at
400-600 m and 13 shells/kg at 1000-1200 m.
Skenea ossiansarsi Warén, 1991
Skenea ossiansarsi Warén, 1991: 58-60, figs 4C-D, 6F,
9C-D
Material examined.- ROCKALL BANK: Moundforce 2004/41C, depth 784
m; Hermes 2005/15, depth 593 m; Hermes 2005/23,
depth 667 m; Hermes 2005/34, depth 767 m; Hermes
2006/10C, depth 587 m; Hermes 2006/12, depth 1091 m;
Hermes 2006/23A, depth 578 m; Hermes 2006/56, depth
578 m; Hermes 2006/65, depth 1087 m; HATTON
BANK: Hermes 2008/35, depth 796 m; Hermes 2008/36,
depth 700 m; Hermes 2008/59, depth 788 m; Hermes
2008/92, depth 822 m; Hermes 2008/117, depth 958 m.
Abundances are 453 shells/kg at 400-600 m and 703
shells/kg at 600-800 m, 118 shells/kg at 1000-1200 m.
50
Hoffman, Van Heugten & Lavaleye, 2010: Skeneimorph species
Skenea peterseni (Friele, 1877)
Cyclostrema peterseni Friele, 1877: 3
Skenea peterseni: Warén, 1991: 60-61, figs 3F, 4A-B, 6D
Skenea peterseni: Warén, 1993: 175, figs 11A-C, 12B,
12D, 13B, 15A-B
Material examined.- ROCKALL BANK: Moundforce 2004/29, depth 1443 m;
Hermes 2006/12, depth 1091 m; Hermes 2006/65, depth
1087 m.
Skenea polita Warén, 1993
Skenea polita Warén, 1993: 171-173, figs 10A-E, 13A
Material examined.- ROCKALL BANK: Moundforce 2004/12, depth 1443 m,
1 old shell.
Skenea profunda (Friele, 1879)
Cyclostrema profundum Friele, 1879: 272
Skenea profunda: Warén, 1991: 65, figs 5C, 7B
Material examined.- ROCKALL BANK: Moundforce 2004/29, depth 1443 m;
Hermes 2006/65, depth 1087 m.
Skenea rugulosa (G.O. Sars, 1878)
Cyclostrema rugulosum G.O. Sars, 1878: 129, tab. 21,
figs a-d
Skenea rugulosa: Warén, 1991: 63-64, figs 3E, 4E-F, 6C,
9F
Material examined.- ROCKALL BANK: Moundforce 2004/37, depth 557 m;
Hermes 2005/34, depth 767 m; Hermes 2006/10C, depth
578 m; Hermes 2006/12, depth 1091 m; Hermes 2006/56,
depth 578 m; Hermes 2006/65, depth 1087 m; HATTON
BANK: Hermes 2008/35, depth 796 m; Hermes 2008/36,
depth 700 m; Hermes 2008/59, 788 m; Hermes 2008/92,
depth 822 m; Hermes 2008/117, depth 958 m.
Abundances are 120 shells/kg at 400-600 m and 16
shells/kg at 600-800 m, 118 shells/kg at 1000-1200 m and
37 shells/kg at 1443 m.
Skenea trochoides (Friele, 1876)
Cyclostrema trochoides Jeffreys MS - Friele, 1876: 60
Skenea trochoides: Warén, 1991: 58, figs 2E-F, 3D, 3G,
6E, 8B
Material examined.- ROCKALL BANK: Moundforce 2004/29, depth 1443 m;
Hermes 2005/15, depth 593 m; Hermes 2006/12, depth
1091 m; Hermes 2006/65, depth 1087 m; HATTON
BANK: Hermes 2008/36, depth 700 m; Hermes
2008/117, depth 958 m.
Skenea turgida (Odhner, 1912)
Cyclostrema turgidum Odhner, 1912: 79
Skenea turgida: Warén, 1991: 65, figs 5D, 5G, 7D, 9A
Material examined.- ROCKALL BANK: Moundforce 2004/29, depth 1443 m;
Hermes 2006/12, depth 1091 m; Hermes 2006/65, depth
1087 m.
Lopheliella hermesae Hoffman, van Heugten & Lavaleye, 2008
Lopheliella hermesae Hoffman et al., 2008: 43, figs 16-
19, 23
Material examined.- ROCKALL BANK: Hermes 2005/34, depth 767 m,
holotype, 1 shell; Hermes 2005/15, depth 593 m, 1 shell;
Hermes 2005/23, depth 667 m, 1 shell; Hermes 2006/56,
depth 578 m, 1 shell.
Lopheliella moolenbeeki Hoffman, van Heugten & Lavaleye, 2008
Lopheliella moolenbeeki Hoffman et al., 2008: 41-42,
figs 6-9, 21
Material examined.- ROCKALL BANK: Hermes 2006/56, holotype, depth
578 m, >200 paratypes; Moundforce 2004/37, depth 557
m, >200 shells; Hermes 2005/15, depth 593 m, 16 shells;
Hermes 2005/23, depth 667 m, > 20 shells; Hermes
2005/34, depth 767 m, 4 shells; Hermes 2006/10C, depth
587 m, 36 shells. HATTON BANK: Hermes 2008/117,
depth 958 m, 1 shell.
Lopheliella moundforceae Hoffman, van Heugten & Lavaleye, 2008
Lopheliella moundforceae Hoffman et al., 2008: 42-43,
figs 10-15, 22
Material examined.- ROCKALL BANK: Hermes 2006/28A, depth 588 m,
holotype, 1 shell; Moundforce 2004/37, depth 557 m, 2
worn shells; Moundforce 2004/41C, depth 784 m, 6 worn
shells; Hermes 2005/23, depth 667 m, 4 shells; Hermes
2006/10C, depth 578 m, 6 worn shells.
Lopheliella rockallensis Hoffman, van Heugten & Lavaleye, 2008
51
Miscellanea Malacologica 4(4): 47-61
Lopheliella rockallensis Hoffman et al., 2008: 41, figs 1-
5, 20
Material examined.- ROCKALL BANK: Hermes 2006/St.56, holotype, depth
578 m, >100 paratypes; Moundforce 2004/37, depth 557
m, 30 shells; Hermes 2005/15, depth 593 m, 13 shells;
Hermes 2005/23, depth 667 m, >20 shells; Hermes
2005/34, depth 767 m, 11 shells; Hermes 2006/10C,
depth 587 m, 7 shells; Hermes 2006/23A, depth 587 m, 2
shells.
Cirsonella gaudryi (Dautzenberg and Fischer, 1896)
Tharsis gaudryi Dautzenberg & Fischer H., 1896: 486,
plate 21 figs 13-15
Material examined.- HATTON BANK: Hermes 2008/117, 958 m.
Cirsonella romettensis (Granata-Grillo, 1877)
Oxystele romettensis Granata-Grillo, 1877: 5.
Cirsonella romettensis: Warén, 1992: 160, figs 4C, 9E,
11C-E, 12A
Material examined.- ROCKAL BANK: Hermes 2006/St.65, 1087 m.
Ganesa nitidiuscula Jeffreys, 1883
(Figs 7-14)
Ganesa nitidiuscula Jeffreys, 1883: 94, plate 19 fig. 9
Ganesa nitidiuscula: Warén, 1992: 176, fig. 33A
Description.-
A description has been added because a fresh
shell has been imaged for the first time with a
SEM photograph and additional shell details
can be provided. Warén (1992) figured only a
fragmentary topotype without apex; the
authors have not studied this shell.
The skeneid shell is small, globose,
firm and glossy. Outline is slightly
cyrtoconoid. Height 1.91 mm, width 1.51 mm.
Protoconch of slightly more than 1 whorl has a
dimension of 230 x 173 μm with a rough
surface structure consisting of irregularly
shaped grains of 2-10 μm. Transition to the
teleoconch is marked by a clear varix.
Teleoconch has 3.2 well-rounded smooth
whorls with occasionally a growth line. Suture
is very shallow; the joint to the preceding
whorl is slightly sloping downwards. Above
and below the suture, a remarkable etched
band is visible as a line on the
microphotograph but it is not visible with a
normal stereomicroscope. This bands ends
abruptly at the anal side of the aperture. The
umbilicus is very narrow without umbilical
groove. Outer lip is sharp and prosocline below
the suture; then follows a straight line until the
periphery of the whorl; finally, with a marked
curve leading to the basal part of the lip under
nearly 100º. A basal view clearly shows the
prosocline aperture developing in a straight
line from the centre to the periphery of the
whorl. Callus is developed along the lip but is
nearly absent along the columella. The surface
appearance is smooth and glossy. Colour is
translucent cream white.
Locality.-
Hermes 2005/23, N55.50337-W15.78590,
depth 667 m, upper SE flank of the Rockall
Bank, one empty shell. The sediment sample
contained fine biogenic silty clay. Living fauna
included the corals Madrepora and Stylaster as
well as Actiniaria, Bryozoa, Tunicata and
Bivalvia; dead fauna included Lophelia and
Madrepora corals.
Distribution.-
Jeffreys (1883) reported the species from
between the Hebrides and the Faroes. We add
the Rockall Bank to its distribution.
Mikro hattonensis n. sp.
(Figs 15-22)
Description of the holotype (ZMA Moll.
410023; Figs 15-22).-
Very small and elevated skeneimorph shell
with keeled shoulder. Height 0.795 mm, width
0.767 mm. Inflated protoconch with 1.2 whorls
with a clear transition to the teleoconch but no
varix is present. The surface structure of the
protoconch is eroded but it appears to be
smooth. Diameter of the protoconch is 130 μm.
Teleoconch whorls are well rounded, and show
a keel at the shoulder. A strong radial rib
marks the upper edge of the keel. The start of
the teleoconch shows a remarkably pitted
structure both on the shoulder and on the
immediate area below it. A ventral outline
52
Hoffman, Van Heugten & Lavaleye, 2010: Skeneimorph species
shows a step-wise top, obese shell with a well-
rounded base. Surface texture of the peripheral
area of the body whorl is smooth with many
growth lines. The lip is sharp and slightly
flared at the base. The suture is very shallow;
the shoulder is straight. The umbilicus is open
and deep. The umbilical area forms a wide
spiral funnel with a pronounced elevated radial
ridge at the midst of the columella. The
umbilical area is covered with numerous
elongated pits and with some axial growth
lines. A weak spiral rib marks the umbilical
area. The adjacent area on the body whorl also
shows less frequent pitting. The aperture is
slightly opisthocline at the suture; aperture
plane is slightly curved inwards (concave).
Shell is opaque white.
Variability.-
Variability is poorly mapped. Maximum size is
1.5 mm; recorded from the Rockall Bank
specimen. This specimen was in poor
condition and an alternative shell was selected
for the holotype. The clearly adult specimen
from Rockall has a flared lip / varix.
Type locality.-
Hermes 2008/35, N58.74118 -W18.66255,
depth 796 m, Hatton Bank, holotype is based
on an empty shell. Sediment sample contained
fine carbonate mud. Fauna included corals
(Anthozoa), Ophiuroidea and Polychaeta.
Type material.-
The holotype and one paratype have been
found at the type locality. Moundforce
2004/29, N55.422-W15.611, depth 1443 m,
one worn paratype with height 1.5 mm. All
shells were empty.
Distribution.-
This species is only known from the Hatton
and Rockall Banks.
Etymology.-
The species is named after the type locality.
Discussion.-
Only a single genus in Skeneinae fits our new
species: Mikro Warén, 1996. Mikro
hattonensis is very similar to the type species
Mikro globulus Warén, 1996, which has been
described from Iceland. The keeled outline,
general shape, size and protoconch appear very
similar but the protoconch of our species is
smaller. In M. hattonensis, the radial rib on the
shoulder extends over the full spire and, in
contrast, it fades away on the teleoconch of M.
globulus. Finally, the pitting on top of the
teleoconch and in the umbilical area of M.
hattonensis is absent in M. globulus.
Akritogyra curvilineata Warén, 1992
Akritogyra curvilineata Warén, 1992: 162-163, figs 4F,
13A-D, 15A, 16A-B
Material examined.- HATTON BANK: Hermes 2008/117, depth 958 m, 1
shell.
Akritogyra similis (Jeffreys, 1883)
Cyclostrema simile Jeffreys, 1883: 92, plate 19, fig. 4
Akritogyra similis: Warén, 1992: 161-162, figs 13E-F,
14A-B, 15C
Material examined.- ROCKALL BANK: Moundforce 2004/41C, depth 784
m; Hermes 2005/15, depth 593 m; Hermes 2005/23,
depth 667 m; HATTON BANK: Hermes 2008/59, depth
788 m.
Lissotesta minima (Seguenza, 1876)
Margarites minima Seguenza, 1876: 186.
Lissotesta minima: Warén, 1992: 171-172, figs 25E-F,
29A-C
Material examined.- ROCKALL BANK: Hermes 2006/65, depth 1087 m;
HATTON BANK: Hermes 2008/117, depth 958 m, 1
shell.
Lissotesta turrita (Gaglini, 1987)
Cyclostrema turritum Gaglini, 1987: 5
Lissotesta turrita: Warén, 1992: 172-173, figs 26B, 30A-
F
Material examined.- ROCKALL BANK: Hermes 2006/65, depth 1087 m.
Anekes affinis (Jeffreys, 1883)
Cyclostrema affinis Jeffreys, 1883: 92, plate 19 fig. 5
Anekes affinis: Warén, 1992: 164-165, figs 18A-B, 19A
53
Miscellanea Malacologica 4(4): 47-61
Material examined.- ROCKALL BANK: Hermes 2006/65, depth 1087 m;
HATTON BANK: Hermes 2008/36, depth 700 m.
Anekes paucistriata Warén, 1992
Anekes paucistriata Warén, 1992: 165-166, figs 19D,
20B-D, 21A, 22B
Material examined.- ROCKALL BANK: Hermes 2006/65, depth 1087 m.
Granigyra arenosa Warén, 1993
Granigyra arenosa Warén, 1993: 180-181, figs 18-20
Material examined.- HATTON BANK: Hermes 2008/35, depth 796 m, 2
shells.
Granigyra tenera (Jeffreys, 1883)
(Figs 23-27)
Cyclostrema tenerum Jeffreys, 1883: 91-92, plate 19 fig.
2
Granigyra tenera: Warén, 1992: 176, fig. 33B
Description.-
A description has been provided because a
fresh shell has been imaged for the first time
with a SEM photograph and microstructure
and a protoconch can be displayed.
The elevated skeneimorph shell has a
rugose radial and axial surface structure.
Height 1.1 mm, width 1.2 mm. Protoconch
with 1.1 whorls with a clear transition to the
teleoconch; surface structure is granular with a
few very fine spiral ribs. Size of the
protoconch is 180 x 240 μm.
Teleoconch whorls are very well
rounded, slightly oval towards the base. The
first half whorl of the teleoconch has numerous
axial growth ridges. Then radial ridges are
weaved in at the second teleoconch whorl and
these are ultimately dominating in the body
whorl; spacing between the radial ridges on the
last whorl is about 10-20 μm. The outline is
rather inflated ending in a well-rounded base.
The outer lip is sharp thin and fragile. The
suture is deep initially but rather shallow in the
body whorl; the joint is nearly perpendicular to
the previous whorl. Umbilicus is narrow, deep
but tortuous. Regular spiral ribs and axial
ridges cover the umbilical area. Aperture is
slightly prosocline, nearly orthocline with a
slight bend in the lip. Shell is translucent
white.
Locality.-
Hermes 2006/65, carbonate mud with coral
debris, N55.452-W15.766, depth 1087 m,
Rockall Bank, one empty shell.
Retigyra millipunctata (Friele, 1886)
Cyclostrema millipunctatum Friele, 1886: 33, plate 11
figs 17, 18, 18a
Retigyra millipunctata: Warén, 1989: 6, figs 5A-E
Material examined.- HATTON BANK: Hermes 2008/36, depth 700 m;
Hermes 2008/117, depth 958 m.
Xyloskenea naticiformis (Jeffreys, 1883)
Cithna naticiformis Jeffreys, 1883: 112, plate 20 fig. 11
Xyloskenea naticiformis: Warén, 1996: 202-205, figs 3A-
D, 7C
Material examined.- ROCKALL BANK: Moundforce 2004/29, depth 1443 m,
1 eroded shell.
Xyloskenea xenos n. sp.
(Figs 28-33)
Description of the holotype (ZMA Moll.
410024; Figs 28-30).-
Fragile elevated skeneimorph shell with
flattened apex and keeled umbilicus. The
height is 2.9 mm; the width is 3.3 mm. The
protoconch has a typical skeneid form with 1.3
whorls but the surface has been eroded.
Diameter of the protoconch is about 160 μm
and has a smooth surface. Teleoconch has 2.7
whorls that rapidly grow in diameter.
The whorls are well rounded,
somewhat globose, and they show weak yet
clearly visible radial ribs covering the upper
half of the whorls. Outline is flattened at the
top ending in a well-rounded base. The lip is
sharp. The suture is fairly deep. The umbilicus
is open, wide and deep. The umbilical area
shows a pronounced intra-umbilical keel with a
sharp edge leaning towards the umbilical side.
The aperture is prosocline and oval. Surface
texture is fairly smooth with numerous fine
54
Hoffman, Van Heugten & Lavaleye, 2010: Skeneimorph species
growth lines. Shell is dull and white, even
though the surface of the holotype has been
exposed to erosion.
Variability.-
Variability is poorly known with only few
specimens available. Maximum width is 3.3
mm. The initial whorls of subadult specimens
are more flattened; only the single adult
specimen, i.e. the holotype, shows a body
whorl with a suture well below the periphery
of the penultimate whorl. The inside of the
body whorl of the sub-adults is a bit glossy.
Type locality.-
Hermes 2008/35, N58.74118 -W18.66255,
depth 796 m, Hatton Bank, holotype is based
on an empty shell. Sediment sample contained
fine carbonate mud. Fauna included corals
(Anthozoa), Ophiuroidea and Polychaeta.
Type material.-
The holotype and four paratypes have been
found at the type locality. Hermes 2008/59,
biogenic carbonate mud, N58.78065 –
W18.58983, depth 788 m, one paratype. All
type specimens are empty shells.
Distribution.-
This species is only known from the Hatton
Bank.
Etymology.-
Xyloskenea is known to live on sunken wood
but there has been no mention of recovered
wood from any of the box-core localities. The
current species is considered a stranger (xenos
in Greek) at the type locality.
Discussion.-
The genus Xyloskenea Marshall, 1988 shows
the morphological features of the new species
and they are known to exceed the size of 3 mm
globally. Other genera in Skeneinae seldom
exceed this size in the NE Atlantic, only deep-
water species of the genus Cirsonella Angas,
1877 (like Cirsonella ateles Dautzenberg &
Fischer, 1896) form an exception but these
have a totally different shell. Xyloskenea
naticiformis (Jeffreys, 1883) is the only known
representative of Xyloskenea in the NE
Atlantic; see Warén, 1996. Xyloskenea
naticiformis is known from off Iceland and off
Portugal. The authors have also found this
species on the Rockall Bank. An obvious keel
at the base of the whorl can easily distinguish
X. naticiformis from X. xenos. The former
also lacks the weak radial rib structure.
Palazzia ausonia (Palazzi, 1988)
Omalogyra ausonia Palazzi, 1988: 103
Palazzia ausonia: Warén, 1991: 75-77, figs 17A-G, 18A
Material examined.- ROCKALL BANK: Hermes 2006/65, 1087 m.
Palazzia planorbis (Dall, 1927)
Lippistes planorbis Dall, 1927: Art. 18, 131
Palazzia planorbis: Warén, 1991: 75-77, figs 16A-D,
18B
Material examined.- ROCKALL BANK: Moundforce 2004/37, depth 557 m;
Hermes 2006/10C, depth 587 m; Hermes 2006/12, depth
1091 m; Hermes 2006/65, 1087 m.
Eudaronia aperta (Sykes, 1925)
Omalogyra aperta Sykes, 1925: 192
Eudaronia aperta: Warén, 1991: 80, figs 14C-E, 18D
Material examined.- ROCKALL BANK: Hermes 2006/65, depth 1087 m.
Adeuomphalus ammoniformis Seguenza, 1876
Adeuomphalus ammoniformis Seguenza, 1876: 10
Adeuomphalus ammoniformis: Kano, Chikyu & Warén
2009: 401-403, figs 1F-I
Material examined.- ROCKALL BANK: Hermes 2006/65, depth 1087 m.
Adeuomphalus densicostatus
(Jeffreys, 1884)
Homalogyra densicostata Jeffreys, 1884: 129, plate 10
fig. 1
Adeuomphalus densicostatus: Kano, Chikyu & Warén
2009: 403-404, figs 1A-E
Material examined.- ROCKALL BANK: Hermes 2005/15, depth 593 m;
Hermes 2006/12, depth 1091 m; HATTON BANK:
Hermes 2008/36, depth 700 m.
55
Miscellanea Malacologica 4(4): 47-61
Cantrainea globuloides
(Dautzenberg & Fischer, 1896)
Leptothyra globuloides Dautzenberg & Fischer H. 1896:
175, plate 21 fig. 1
Material examined.- HATTON BANK: Hermes 2008/117, depth 958 m.
REFERENCES
Dall W. H., 1927. Small shells from dredgings
off the southeast coast of the United States by
the United States Fisheries Steamer
"Albatross", in 1885 and 1886. Proceedings of
the United States National Museum 70 (18):
1-134
Dautzenberg P. & H. Fischer, 1896. Dragages
effectués par l'Hirondelle et par la Princesse
Alice 1888-1895. 1. Mollusques Gastropodes.
Mémoires de la Société Zoologique de France
9: 395-498
Duineveld, G. C. A [editor], 2006.
Biodiversity, ecosystem functioning and food
web complexity of cold water coral reefs in
the NE Atlantic (Rockall Bank). Cruise
64PE249, Galway-Oban, 19 June – 7 July
2006. Texel: NIOZ. 25 pp. (excluding
appendices)
Friele H., 1876. Bidrag til Vestlandets
Molluskenfauna. Forhandlinger I Viden-
skapsselkabet I Kristiania 1875: 57-64
Friele H., 1877. Preliminary report on the
Mollusca from the Norwegian North Atlantic
Expedition in 1876. Nyt Magazin for
Naturvidenskaberne 23: 1-10
Friele H., 1879. Catalog auf der norwegischen
Nordmeer-expedition bei Spitzbergen
gefundenen Mollusken. Jahrbücher der
Deutschen Malakolozoologischen Gesell-
schaft 6: 264-286
Friele H., 1886. The Norwegian North
Atlantic Expedition 1876-1878, Third
Volume, Zoology, Mollusca II. Christiania:
Grøndahl & Søn, 44 pp.
Granata-Grillo G., 1877. Descriptions de
quelques espèces nouvelles ou peu connues.
Napoli: Salvatore Marchese. 16 pp.
Hoffman, L., B. van Heugten & M. S. S.
Lavaleye, 2008. A new genus and four new
species in the family Skeneidae (Gastropoda)
from the Rockall Bank, northeastern Atlantic
Ocean. Miscellanea Malacologica 3: 39-48
Jeffreys J. G., 1877. New and peculiar
Mollusca of the Patellidae and other families
of Gastropoda procured in the Valorous
expedition. Annals and Magazine of Natural
History (4)19: 231-243
Jeffreys J. G., 1883. On the Mollusca procured
during the H. M. S. "Lightning" and
"Porcupine" expedition. Proceedings of the
Zoological Society of London: 88-115
Jeffreys J. G., 1884. On the Mollusca procured
during the H. M. S. "Lightning" and
"Porcupine" expedition. Proceedings of the
Zoological Society of London: 111-149
Lavaleye, M. S. S. [editor], 2008. HERMES
2008 Coralfish2008, Belgica Mound
Province, Hatton Bank, Cruise Report
64PE291-292, Texel-Cork-Texel, 10-June –
16 July 2008. Texel: NIOZ. 90 pp.
Mienis, F. & H. de Haas [editors], 2004. The
distribution, morphology, sedimentology and
watermass characteristics of and around
mounds in the Gulf of Cadiz and at the SW
Rockall Trough Margin. Cruise report, R.V.
Pelagia, Moundforce 2004 (64PE229), 15
August - 9 September. Texel: NIOZ. 99 pp.
Odhner, N. H., 1912. Northern and Arctic
Invertebrates in the Collection of the Swedish
State Museum. Prosobranchia, 1. Diotocardia.
Kungliga Svenska Ventenskapsakaemiens
Handlingar 54 (1): 1-274
Palazzi, S., 1988. Note sugli Omalogyridae
mediterranei e maderensi. Bollettino Mala-
cologico 24: 101-111
Rubio, F., L. Dantart & Á. A. Luque, 1998.
Two new species of Dikoleps (Gastropoda,
56
Hoffman, Van Heugten & Lavaleye, 2010: Skeneimorph species
Skeneidae) from the Mediterranean coast of
Spain. Iberus 16: 81-93
Rubio, F., L. Dantart & Á. A. Luque, 2004. El
género Dikoleps (Gastropoda, Skeneidae) en
las costas ibéricas. Iberus 22: 115-132
Sars G. O., 1878. Bidrag til kundskaben om
Norges arktiske fauna: 1. Mollusca regionis
Arcticae Norvegiae. Oversigt over de i Norges
arktiske region forekommende bloddyr. Christiania: A.W. Brøgger, xv + 466 pp.
Seguenza G., 1876. Studii stratigrafici sulla
formazione pliocenica dell’Italia Meridionale.
Bollettino del reale Comitato Geologico
d’Italia 7: 7-15
Van Duil, F. C. & G. C. A Duineveld [editors],
2005. Biodiversity, ecosystem functioning and
food web complexity of deep water coral reefs
in the NE Atlantic (Rockall Bank and
Porcupine Bank). Cruise 64PE238, Galway-
Texel, 21 June – 21 July 2005. Texel: NIOZ.
31 pp. [excl. Appendices]
Warén, A., 1989. New and little known
Mollusca from Iceland. Sarsia 74: 1-28
Warén, A., 1991. New and little known
Mollusca from Iceland and Scandinavia.
Sarsia 76: 53-121
Warén, A., 1992. New and little known
skeneimorph gastropods from the
Mediterranean Sea and the adjacent Atlantic
Ocean. Bollettino Malacologico 27: 149-248
Warén, A., 1993. New and little known
Mollusca from Iceland and Scandinavia, Part
2. Sarsia 78: 159-201
Warén, A. 1996. New and little known
Mollusca from Iceland and Scandinavia, Part
3. Sarsia 81: 297-245
57
Miscellanea Malacologica 4(4): 47-61
Figs 1-6. Genus Rugulina. 1-3. R. fragilis (G.O. Sars, 1878), Moundforce 2004/37, depth 557 m, Rockall Bank, height 2.2
mm; 1. Ventral view; 2. Basal view; 3. Surface structure body whorl; 4-6. R. species, Hermes 2008/117, depth 958 m, Hatton
Bank, height 2.3 mm; 4. Ventral view; 5. Basal view; 6. Apical view.
58
Hoffman, Van Heugten & Lavaleye, 2010: Skeneimorph species
Figs 7-14. Ganesa nitidiuscula Jeffreys, 1883, Hermes 2005/23, N55.50337-W15.78590, depth 667 m, Rockall Bank, height
1.9 mm, width 1.5 mm; 7. Ventral view; 8. Side view; 9. Apical view; 10. Protoconch 230 x 173 m; 11. Ventral view
(SEM); 12. Side view (SEM); 13. Apical view (SEM); 14. Surface structure protoconch.
59
Miscellanea Malacologica 4(4): 47-61
Figs 15-22. Mikro hattonensis n. sp., holotype, Hermes 2008/35, N58.74118 -W18.66255, depth 796 m, Hatton Bank, height
0.80 mm, width 0.77 mm; 15. Side view; 16. Ventral view; 17. Apical view; 18. Microstructure umbilical area; 19.
Protoconch 200 x 140 m; 20. Ventral view (SEM); 21. Apical view (SEM); 22. Basal view (SEM).
60
Hoffman, Van Heugten & Lavaleye, 2010: Skeneimorph species
Figs 23-27. Granigyra tenera Jeffreys, 1883, Hermes 2006/65, carbonate mud with coral debris, N55.452-W15.766, depth
1087 m, Rockall Bank, height 1.1 mm, width 1.2 mm; 23. Ventral view; 24. Apical view; 25. Basal view; 26. Protoconch 240
x 180 μm; 27. Detail of body whorl structure.
61
Hoffman, Van Heugten & Lavaleye, 2010: Skeneimorph species
Figs 28-33. Xyloskenea xenos n. sp. Figs 28-30. Holotype, Moundforce Hermes 2008/35, N58.74118 -W18.66255, depth 796
m, Hatton Bank, height 2.9 mm, width 3.3 mm; 28. Ventral view; 29. Apical view; 30. Protoconch diameter 160 m; 31-33.
subadult paratype, Hermes 2008/59, N58.78065 – W18.58983, depth 788 m, Hatton Bank, width 1.7 mm. 31. Ventral view;
32. Basal view; 33. Apical view.