Accepted by M. deMaintenon: 1 Nov. 2017; published: 13 Dec. 2017
ISSN 1175-5326 (print edition)
Copyright © 2017 Magnolia Press
Zootaxa 4363 (4): 592
First columbellid species (Gastropoda: Buccinoidea) from deep-sea
hydrothermal vents, discovered in Okinawa Trough, Japan
, HIROMI KAYAMA WATANABE
& JUAN FRANCISCO ARAYA
Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and
Technology (JAMSTEC), 2–15 Natsushima, Yokosuka 237–0061, Japan
Department of Marine Biodiversity Research (BIO-DIVE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2–
15 Natsushima, Yokosuka 237–0061, Japan
Universidad de Atacama, Copayapu 485, Copiapó, Región de Atacama, Chile
Corresponding author. Tel: +81-(0)46-867-9717; E-mail: firstname.lastname@example.org
The molluscan diversity of deep-sea chemosynthetic ecosystems in Japan has been in general well documented with
about 80 described species, of which over half are gastropods (Sasaki et al. 2005; Fujikura et al. 2012; Sasaki et al.
2016). Recently, however, a number of novel hydrothermal vent sites were discovered in the area using multibeam echo-
sounding (Nakamura et al. 2015), providing opportunities for new discoveries. As a part of ongoing studies documenting
the biodiversity of such sites, we present the first record of Columbellidae from hydrothermal vents, with a new species
recovered from Natsu and Aki sites, in the Iheya North hydrothermal field (for map and background on the vent field see
Nakamura et al. 2015).
Columbellidae is a diverse family of caenogastropods in the superfamily Buccinoidea which include 70 genera and
several hundred species (deMaintenon 2014; Araya et al. 2016), most of which inhabit shallow waters and carry distinct
colour patterns. Generally, columbellids are small in size (mostly less than 20 mm although some large specimens exceed
40 mm) and are either active carnivores or scavengers (Squires 2015). More than 65 species are known from Japan alone
(Okutani 2017), although the deep-water diversity of the family remains poorly understood with a number of unnamed
species (Hasegawa 2009). The present new species is the first columbellid recorded not only from hydrothermal vent
ecosystems in Okinawa Trough, but from global vent communities as a whole. Prior to the present study, the only
columbellids reported from chemosynthetic ecosystems have been from whale-falls (Smith et al. 1989; Levin et al.
Material and methods
During the R/V K
research cruise KY14-01, two newly detected hydrothermal vent sites named Natsu and Aki near
the Iheya North field (Nakamura et al. 2015) were explored for the first time using the ROV H
with a slurp gun for collection of biological samples. In the Natsu site, a bush of tubeworms (Lamellibrachia sp. and
Alaysia sp.) was collected, and nine specimens of a columbellid gastropod were recovered from their washings. In Aki
site, five specimens of the same columbellid were found in washings of Bathymodiolus mussels.
The columbellid specimens were measured for shell diameter (SD), shell height (SH), and height of last whorl (LW)
using Vernier callipers to ±0.1 mm accuracy. The radula was dissected out under a microscope and the remaining tissue
dissolved using 20% strength commercial bleach. Cleaned radula and protoconch were observed using a Hitachi
TM3000 SEM. Phylogenetic reconstruction was carried out using a 618 bp alignment of the cytochrome c oxidase
subunit I (COI) gene. In addition to the present columbellid species, other columbellid species with COI sequences
available on GenBank and three additional caenogastropods were included. The vetigastropod Turbo sazae Fukuda, 2017
served as an outgroup. Sequencing and phylogenetic methods follow that of Chen et al. (2017). Type materials are
deposited in the collections of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), the National
Science Museum, Tsukuba (NSMT) and the University Museum, the University of Tokyo (UMUT).
Zootaxa 4363 (4) © 2017 Magnolia Press ·
NEW COLUMBELLID FROM OKINAWA VENTS
Clade CAENOGASTROPODA Cox, 1960
Superfamily BUCCINOIDEA Rafinesque, 1815
Family COLUMBELLIDAE Swainson, 1840
Genus Astyris H. Adams & A. Adams, 1853
Astyris thermophilus n. sp.
Type specimens. Holotype (Fig. 1A–D) [SH 8.5 mm, SD 4.3 mm, LW 4.1 mm], UMUT RM32644. Paratypes. #1 (Fig.
1E) [SH 8.3 mm, SD 4.5 mm, LW 4.6 mm], NSMT Mo 78990. #2 (Fig. 1F) [SH 7.4 mm, SD 4.2 mm, LW 4.1 mm],
periostracum removed with diluted bleach to reveal fine sculpture, operculum and radula removed for SEM, UMUT
RM32645. #3 [SH 7.1 mm, SD 4.0 mm, LW 4.0 mm], NSMT Mo 78991. #4 [SH 7.7 mm, SD 4.1 mm, LW 4.3 mm],
NSMT Mo 78992. #5 [SH 6.5 mm, SD 3.7 mm, LW 3.9 mm], JAMSTEC 1140053525. #6 [SH 3.0 mm, SD 1.7 mm, LW
1.6 mm], juvenile with intact protoconch, UMUT RM32646. All type specimens fixed and stored in 99% ethanol.
Type locality. Natsu hydrothermal vent site, Iheya North field, Okinawa Trough, Japan; 27°46.843’N,
126°54.024’E, 1074 m deep; 2014/Jan/24, collected by slurp gun, ROV H
Dive #1614, R/V K
KY14-01, principal scientist: Ken Takai.
Additional material examined. Two specimens from type locality, fixed and stored in 99 % ethanol, used for
genetic barcoding (tissue dissolved). Five specimens, live collected, fixed and stored in 99% ethanol. Aki hydrothermal
vent site, Iheya North field, Okinawa Trough, Japan; 27°46.130’N, 126°54.159’E, 1087 m deep; 2014/Jan/25, collected
by slurp gun, ROV H
Dive #1614, R/V K
cruise KY14-01, principal scientist: Ken Takai.
Etymology. From ‘Thermós’ (Greek), warm or hot, and ‘philíā’ (Greek), love or affection; combined to mean heat-
loving, referring to its habitat in hydrothermal vent fields.
Japanese Name. ‘Yomotsu-mugi-gai’, meaning ‘mitrid from the underworld’.
Diagnosis. A moderate-sized (up to SH 8.5 mm) Astyris with rather tall-spired, uniformly white, thin, semi-
transparent shell; smooth including base, except 25 to 30 very fine spiral striae. Columella lacking columellar fold.
Periostracum thin, greyish brown. Protoconch paucispiral. Radula stenoglossate with acuspate centre plate, three sharp
cusps on each lateral.
Description. Shell (Fig. 1A–F) moderate-sized for genus (up to SH 8.5 mm), rather tall-spired. Apex always
decollate in adults, leaving at most three whorls remaining. Teleoconch thin, semi-transparent, uniformly white in
colouration. Periostracum thin, greyish brown, earlier whorls slightly darker coloured. Often covered by further sulfide
deposits. Teleoconch largely smooth except approximately 25 to 30 very fine, shallow, evenly spaced spiral striae present
across entire whorl (see Fig. 1F), increasing in strength anteriorly towards siphonal canal. Striations on posterior half of
shell usually too fine to detect when covered by periostracum. Whorls elevated, slowly expanding, slightly convex but
not angulated. Suture distinct, shallowly constricted. Aperture entirely lacking dentition, semi-circular in shape,
siphonate, approximately twice as tall as wide, posteriorly acuminate. Outer lip simple, not thickened, completely
smooth on inside. Columella straight, simple, with slightly thickened callus. Siphonal canal short with weakly
constricted but distinct siphonal notch. Protoconch (Fig. 1G) paucispiral, about 1.5 whorls, smooth, lacking velar sinus,
sculpture or distinct growth lines. Transition edge between protoconch and teleoconch clearly marked by a varix. Suture
of protoconch shallow, slightly higher than teleoconch.
Operculum (Fig. 1H) corneous, small, length about half of aperture height. Lamellate with lateral nucleus on right
often eroded away.
Radula (Fig. 1I) stenoglossate, typical of columbellids with one lateral on each side separated by an acuspate centre
plate instead of rachidian. Laterals sigmoid, well-supported, with three strong cusps. Two distal cusps sharper, longer,
closer spaced compared to basal cusp. Centre plate rectangular, slightly wider posteriorly, without sculpture.
Distribution and ecology. Only known from Natsu and Aki sites of the Iheya North hydrothermal field (Nakamura
et al. 2015), mid-Okinawa Trough, Japan. Found in tubeworm bushes attached on the tubes, presumably a predator of
other animals inhabiting the same habitat or alternatively it may be ovophagous and feed on eggs of other animals.
Remarks. The present new species is assigned to genus Astyris as it matches well with the diagnosis for the genus
given by McLean & Gosliner (1996), most notably by having a small, high-spired shell with smooth surface and a
paucispiral protoconch (Garcia 2009). Of those species currently in Astyris, the new species most closely resembles A.
permodesta (Dall, 1890) from methane seeps at Monterey Canyon and whale falls in California (Smith et al. 1989;
Bennett et al. 1994) and A. atacamensis Araya, Catalán & Aliaga, 2016 from northern Chile. Although A. permodesta
has been reported also from off Callao, Perú (Levin et al. 2002), this is likely in fact another record of A. atacamensis
(Sellanes 2017). Both of these species are easily separable from A. thermophilus n. sp. as they have a thicker, broader
CHEN ET AL.
· Zootaxa 4363 (4) © 2017 Magnolia Press
shell with wider aperture and less constricted siphonal canal, as well as having spiral grooves on the base. The
pronounced columellar fold seen in A. atacamensis and the lirae inside the outer lip are also lacking in A. thermophilus n.
sp. Until the discovery of A. thermophilus n. sp., Astyris permodesta was the only other columbellid species known from
deep-sea chemosynthetic ecosystems.
Astyris thermophilus n. sp. is conchologically similar to Zemitrella cera Okutani, 1964 from 1000–3000 m deep off
Izu Islands, Japan (Okutani, 1964; 2017), but differs by having spiral striation across the entire teleoconch whorl
(sculpture is only present on the base in Z. cera) and a slightly longer siphonal canal. As the protoconch of Z. cera is
unknown, it is not transferred to Astyris at this point. Furthermore, the new species is also very similar to a yet
undescribed species reported from deep-water trawls and dredges carried out in northern Pacific coast of Honshu, Japan
(Mitrella sp. 1 sensu Hasegawa, 2009: figs. 162–166), but differs from that species in the spiral striae on the teleoconch
being less distinct and that the columella is always straight. At this point we cannot entirely dismiss the possibility that
Mitrella sp. 1 (sensu Hasegawa, 2009) may be conspecific with Astyris thermophilus n. sp. and the morphological
differences may be due to environmental factors.
The phylogenetic reconstruction (Fig. 2) confirmed the placement of the present new species within Columbellidae.
Its generic placement cannot be tested at present because sequences from other Astyris species were not available.
FIGURE 1. Astyris thermophilus n. sp. A–D. Holotype (UMUT RM32644). E. Paratype #1 (NSMT Mo 78990). F. Paratype #2
(UMUT RM32645), periostracum removed to show spiral striae. G. Protoconch of paratype #6, a juvenile specimen (UMUT RM
32646). H. Operculum of paratype #2 (UMUT RM32645). I. Radula of paratype #2, UMUT RM32645). Scale bars = 2 mm (A–F),
500 μm (G, H ), 20 μm (I).
Zootaxa 4363 (4) © 2017 Magnolia Press ·
NEW COLUMBELLID FROM OKINAWA VENTS
FIGURE 2. Phylogenetic reconstruction using the COI gene (618 bp) showing Astyris thermophilus n. sp. nested within
Columbellidae. Node values indicate Bayesian posterior probability, those lower than 0.7 are omitted. The DDBJ/EMBL/GenBank
accession numbers for each sequence used are shown inside brackets (LC329027 and LC329028 for the two sequenced specimens of
A. thermophilus n. sp.).
The authors would like to express their sincere gratitude towards the operation team of ROV H
as well as
the Captain and crews of R/V K
for their tireless support of the scientific activity during the research cruise KY14-
01. Kevin Monsecour and the handling editor Marta deMaintenon helped improve an earlier version of the manuscript.
The principal scientist on-board of cruise KY14-01, Ken Takai (JAMSTEC), is gratefully acknowledged for his diligent
execution of the research cruise. Ken Nagata (JAMSTEC) is thanked for his help in obtaining molecular sequences used
in this study. The genetic work was funded by a Japan Society for the Promotion of Science KAKENHI (grant no.
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